© 2020 The original authors.

kubernetes-maven-plugin

1. Introduction

The kubernetes-maven-plugin brings your Java applications on to Kubernetes. It provides a tight integration into Maven and benefits from the build configuration already provided. This plugin focus on two tasks: Building Docker images and creating Kubernetes resource descriptors. It can be configured very flexibly and supports multiple configuration models for creating: A Zero-Config setup allows for a quick ramp-up with some opinionated defaults. For more advanced requirements, an XML configuration provides additional configuration options which can be added to the pom.xml. For the full power, in order to tune all facets of the creation, external resource fragments and Dockerfiles can be used.

1.1. Building Images

The k8s:build goal is for creating Docker images containing the actual application. These then can be deployed later on Kubernetes or OpenShift. It is easy to include build artifacts and their dependencies into these images. This plugin uses the assembly descriptor format similar to the one used in maven-assembly-plugin to specify the content which will be added to the image. That images can then be pushed to public or private Docker registries with k8s:push.

Depending on the operational mode, for building the actual image either a Docker daemon is used directly or an OpenShift Docker Build is performed.

A special k8s:watch goal allows for reacting to code changes to automatically recreate images or copy new artifacts into running containers.

1.2. Kubernetes Resources

Kubernetes resource descriptors can be created or generated from k8s:resource. These files are packaged within the Maven artifacts and can be deployed to a running orchestration platform with k8s:apply.

Typically you only specify a small part of the real resource descriptors which will be enriched by this plugin with various extra information taken from the pom.xml. This drastically reduces boilerplate code for common scenarios.

1.3. Configuration

As mentioned already there are three levels of configuration:

  • Zero-Config mode makes some very opinionated decisions based on what is present in the pom.xml like what base image to use or which ports to expose. This is great for starting up things and for keeping quickstart applications small and tidy.

  • XML plugin configuration mode is similar to what docker-maven-plugin provides. This allows for type-safe configuration with IDE support, but only a subset of possible resource descriptor features is provided.

  • Kubernetes & OpenShift resource fragments are user provided YAML files that can be enriched by the plugin. This allows expert users to use a plain configuration file with all their capabilities, but also to add project specific build information and avoid boilerplate code.

The following table gives an overview of the different models

Table 1. Configuration Models
Model Docker Images Resource Descriptors

Zero-Config

Generators are used to create Docker image configurations. Generators can detect certain aspects of the build (e.g. whether Spring Boot is used) and then choose some opinionated defaults like the base image, which ports to expose and the startup command. They can be configured, but offer only a few options.

Default Enrichers will create a default Service and Deployment (DeploymentConfig for OpenShift) when no other resource objects are provided. Depending on the image they can detect which port to expose in the service. As with Generators, Enrichers support a limited set of configuration options.

XML configuration

kubernetes-maven-plugin inherits the XML based configuration for building images from the docker-maven-plugin and provides the same functionality. It supports an assembly descriptor for specifying the content of the Docker image.

A subset of possible resource objects can be configured with a dedicated XML syntax. With a decent IDE you get autocompletion on most objects and inline documentation for the available configuration elements. The provided configuration can be still enhanced by Enhancers which is useful for adding e.g. labels and annotations containing build or other information.

Resource Fragments and Dockerfiles

Similarly to the docker-maven-plugin, kubernetes-maven-plugin supports external Dockerfiles too, which are referenced from the plugin configuration.

Resource descriptors can be provided as external YAML files which will build a base skeleton for the applicable resource.

The "skeleton" is then post-processed by Enrichers which will complete the skeleton by adding the fields each enricher is responsible of (labels, annotations, port information, etc.). Maven properties within these files are resolved to their values.

With this model you can use every Kubernetes / OpenShift resource objects with all their flexibility, but still get the benefit of adding build information.

1.4. Examples

Let’s have a look at some code. The following examples will demonstrate all three configurations variants:

1.4.1. Zero-Config

This minimal but full working example pom.xml shows how a simple spring boot application can be dockerized and prepared for Kubernetes. The full example can be found in directory quickstarts/maven/zero-config.

Example
<project>
  <modelVersion>4.0.0</modelVersion>

  <groupId>org.eclipse.jkube</groupId>
  <artifactId>jkube-maven-sample-zero-config</artifactId>
  <version>1.0.0</version>
  <packaging>jar</packaging>

  <parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId> (1)
    <version>1.5.5.RELEASE</version>
  </parent>

  <dependencies>
    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-web</artifactId> (2)
    </dependency>
  </dependencies>

  <build>
    <plugins>
      <plugin>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-maven-plugin</artifactId> (3)
      </plugin>
      <plugin>
        <groupId>org.eclipse.jkube</groupId>
        <artifactId>kubernetes-maven-plugin</artifactId> (4)
        <version>1.0.0</version>
      </plugin>
    </plugins>
  </build>
</project>
1 This minimalistic spring boot application uses the spring-boot parent POM for setting up dependencies and plugins
2 The Spring Boot web starter dependency enables a simple embedded Tomcat for serving Spring MVC apps
3 The spring-boot-maven-plugin is responsible for repackaging the application into a fat jar, including all dependencies and the embedded Tomcat
4 The kubernetes-maven-plugin enables the automatic generation of a Docker image and Kubernetes / OpenShift descriptors including this Spring application.

This setup make some opinionated decisions for you:

These choices can be influenced by configuration options as described in Spring Boot Generator.

To start the Docker image build, you simply run

mvn package k8s:build

This will create the Docker image against a running Docker daemon (which must be accessible either via Unix Socket or with the URL set in DOCKER_HOST). Alternatively, when connected to an OpenShift cluster then a S2I build will be performed on OpenShift which at the end creates an ImageStream.

To deploy the resources to the cluster call

mvn k8s:resource k8s:deploy

By default a Service and a Deployment object pointing to the created Docker image is created. When running in OpenShift mode, a Service and DeploymentConfig which refers the ImageStream created with k8s:build will be installed.

Of course you can bind all those jkube-goals to execution phases as well, so that they are called along with standard lifecycle goals like install. For example, to bind the building of the Kubernetes resource files and the Docker images, add the following goals to the execution of the kubernetes-maven-plugin:

Example for lifecycle bindings
<plugin>
  <groupId>org.eclipse.jkube</groupId>
  <artifactId>kubernetes-maven-plugin</artifactId>

  <!-- ... -->

  <executions>
    <execution>
      <goals>
        <goal>resource</goal>
        <goal>build</goal>
      </goals>
    </execution>
  </executions>
</plugin>

If you’d also like to automatically deploy to Kubernetes each time you do a mvn install you can add the apply goal:

Example for lifecycle bindings with automatic deploys for mvn install
<plugin>
  <groupId>org.eclipse.jkube</groupId>
  <artifactId>kubernetes-maven-plugin</artifactId>

  <!-- ... -->

  <executions>
    <execution>
      <goals>
        <goal>resource</goal>
        <goal>build</goal>
        <goal>apply</goal>
      </goals>
    </execution>
  </executions>
</plugin>

1.4.2. XML Configuration

XML based configuration is only partially implemented and is not recommended for use right now.

Although the Zero-config mode and its generators can be tweaked with options up to a certain degree, many cases require more flexibility. For such instances, an XML-based plugin configuration can be used, in a way similar to the XML configuration used by docker-maven-plugin.

The plugin configuration can be roughly divided into the following sections:

  • Global configuration options are responsible for tuning the behaviour of plugin goals

  • <images> defines which Docker images are used and configured. This section is similar to the image configuration of the docker-maven-plugin, except that <run> and <external> sub-elements are ignored)

  • <resource> defines the resource descriptors for deploying on an OpenShift or Kuberneres cluster.

  • <generator> configures generators which are responsible for creating images. Generators are used as an alternative to a dedicated <images> section.

  • <enricher> configures various aspects of enrichers for creating or enhancing resource descriptors.

A working example can be found in the quickstarts/maven/xml-config directory. An extract of the plugin configuration is shown below:

Example for an XML configuration
<configuration>
  <namespace>test-ns</namespace>
  <images>  (1)
    <image>
      <name>xml-config-demo:1.0.0</name>
      <!-- "alias" is used to correlate to the containers in the pod spec -->
      <alias>camel-app</alias>
      <build>
        <from>fabric8/java-centos-openjdk8-jre</from>
        <assembly>
           <inline>
              <baseDirectory>/deployments</baseDirectory>
           </inline>
        </assembly>
        <env>
          <JAVA_LIB_DIR>/deployments</JAVA_LIB_DIR>
          <JAVA_MAIN_CLASS>org.apache.camel.cdi.Main</JAVA_MAIN_CLASS>
        </env>
      </build>
    </image>
  </images>

  <resources> (2)
    <labels> (3)
      <all>
        <group>quickstarts</group>
      </all>
    </labels>

    <replicas>2</replicas> (4)
    <controllerName>${project.artifactId}</controllerName> (5)

    <services> (6)
      <service>
        <name>camel-service</name>
        <headless>true</headless>
      </service>
    </services>

    <serviceAccounts>
      <serviceAccount>
        <name>build-robot</name>
      </serviceAccount>
    </serviceAccounts>
  </resources>
</configuration>
1 Standard XML configuration for building one single Docker image
2 Kubernetes / OpenShift resources to create
3 Labels which should be applied globally to all resource objects
4 Number of replicas desired
5 Name of controller created by plugin
6 One or more Service definitions.

The XML resource configuration is based on plain Kubernetes resource objects. When targeting OpenShift, Kubernetes resource descriptors will be automatically converted to their OpenShift counterparts, e.g. a Kubernetes Deployment will be converted to an OpenShift DeploymentConfig.

1.4.3. Resource Fragments

The third configuration option is to use an external configuration in form of YAML resource descriptors which are located in the src/main/jkube directory. Each resource gets its own file, which contains a skeleton of a resource descriptor. The plugin will pick up the resource, enrich it and then combine all to a single kubernetes.yml and openshift.yml file. Within these descriptor files you are can freely use any Kubernetes feature.

Note: In order to support simultaneously both OpenShift and Kubernetes, there is currently no way to specify OpenShift-only features this way, though this might change in future releases.

Let’s have a look at an example from quickstarts/maven/external-resources. This is a plain Spring Boot application, whose images are auto generated like in the Zero-Config case. The resource fragments are in src/main/jkube.

Example fragment "deployment.yml"
spec:
  replicas: 1
  template:
    spec:
      volumes:
        - name: config
          gitRepo:
            repository: 'https://github.com/jstrachan/sample-springboot-config.git'
            revision: 667ee4db6bc842b127825351e5c9bae5a4fb2147
            directory: .
      containers:
        - volumeMounts:
            - name: config
              mountPath: /app/config
          env:
            - name: KUBERNETES_NAMESPACE
              valueFrom:
                fieldRef:
                  apiVersion: v1
                  fieldPath: metadata.namespace
      serviceAccount: ribbon

As you can see, there is no metadata section as would be expected for Kubernetes resources because it will be automatically added by the kubernetes-maven-plugin. The object’s Kind, if not given, is automatically derived from the filename. In this case, the kubernetes-maven-plugin will create a Deployment because the file is called deployment.yml. Similar mappings between file names and resource type exist for each supported resource kind, the complete list of which (along with associated abbreviations) can be found in the Appendix.

Now that sidecar containers are supported in this plugin(if jkube.sidecar is enabled), be careful whenever you’re supplying container name in the resource fragment. If container specified in resource fragment doesn’t have a name or it’s name is equal to default fmp generated application’s container name; it would not be treated as sidecar and it would be merged into main container. However, You can override plugin’s default name for main container via jkube.generator.alias property.

Additionally, if you name your fragment using a name prefix followed by a dash and the mapped file name, the plugin will automatically use that name for your resource. So, for example, if you name your deployment fragment myapp-deployment.yml, the plugin will name your resource myapp. In the absence of such provided name for your resource, a name will be automatically derived from your project’s metadata (in particular, its artifactId as specified in your POM).

No image is also referenced in this example because the plugin also fills in the image details based on the configured image you are building with (either from a generator or from a dedicated image plugin configuration, as seen before).

For building images there is also an alternative mode using external Dockerfiles, in addition to the XML based configuration. Refer to k8s:build for details.

Enrichment of resource fragments can be fine-tuned by using profile sub-directories. For more details see Profiles.

Now that we have seen some examples of the various ways how this plugin can be used, the following sections will describe the plugin goals and extension points in detail.

2. Compatibility with Kubernetes

2.1. Kubernetes Compatibility

Table 2. Kubernetes Compatibility
KMP Kubernetes 1.18 Kubernetes 1.17 Kubernetes 1.14 Kubernetes 1.12

KMP 1.0.0

KMP 0.2.0

x

KMP 0.1.1

x

x

KMP 0.1.0

x

x

3. Installation

This plugin is available from Maven central and can be connected to pre- and post-integration phase as seen below. The configuration and available goals are described below.

By default, Maven will only search for plugins in the org.apache.maven.plugins and org.codehaus.mojo packages. In order to resolve the provider for the JKube plugin goals, you need to edit ~/.m2/settings.xml and add the org.eclipse.jkube namespace so the <pluginGroups> configuration.

<settings>
      ...

      <pluginGroups>
        <pluginGroup>org.eclipse.jkube</pluginGroup>
      </pluginGroups>

      ...
</settings>
<plugin>
  <groupId>org.eclipse.jkube</groupId>
  <artifactId>kubernetes-maven-plugin</artifactId>
  <version>1.0.0</version>

  <configuration>
     ....
     <images>
        <!-- A single's image configuration -->
        <image>
          ...
          <build>
           ....
          </build>
        </image>
        ....
     </images>
  </configuration>

  <!-- Connect k8s:resource, k8s:build and k8s:helm to lifecycle phases -->
  <executions>
    <execution>
       <id>jkube</id>
       <goals>
         <goal>resource</goal>
         <goal>build</goal>
         <goal>helm</goal>
       </goals>
    </execution>
  </executions>
</plugin>

4. Goals Overview

This plugin supports a rich set for providing a smooth Java developer experience. These goals can be categorized in multiple groups:

  • Build goals are all about creating and managing Kubernetes build artifacts like Docker images or S2I builds.

  • Development goals target help not only in deploying resource descriptors to the development cluster but also to manage the lifecycle of the development cluster as well.

Table 3. Build Goals
Goal Description

k8s:build

Build images

k8s:push

Push images to a registry

k8s:resource

Create Kubernetes or OpenShift resource descriptors

k8s:apply

Apply resources to a running cluster

Table 4. Development Goals
Goal Description

k8s:deploy

Deploy resources descriptors to a cluster after creating them and building the app. Same as k8s:apply except that it runs in the background.

k8s:undeploy

Undeploy and remove resources descriptors from a cluster.

k8s:watch

Watch for file changes and perform rebuilds and redeployments

k8s:log

Show the logs of the running application

k8s:debug

Enable remote debugging

Depending on whether the OpenShift or Kubernetes operational mode is used, the workflow and the performed actions differs :

Table 5. Workflows
Use Case Kubernetes OpenShift

Build

k8s:build k8s:push

  • Creates an image against an exposed Docker daemon (with a docker.tar)

  • Pushes the image to a registry which is then referenced from the configuration

k8s:build

  • Creates or uses a BuildConfig

  • Creates or uses an ImageStream which can be referenced by the deployment descriptors in a DeploymenConfig

  • Starts an OpenShift build with a docker.tar as input

Deploy

k8s:deploy

  • Applies a Kubernetes resource descriptor to cluster

k8s:deploy

  • Applies an OpenShift resource descriptor to a cluster

5. Build Goals

5.1. k8s:resource

This goal generates Kubernetes resources based on your project. It can either be opinionated defaults or based on the configuration provided in XML config or resource fragments in src/main/jkube. Generated resources are in target/classes/META-INF/jkube/kubernetes directory.

5.1.1. Labels and Annotations

Labels and annotations can be easily added to any resource object. This is best explained by an example.

Example for label and annotations
<plugin>
  <!-- ... -->
  <configuration>
    <!-- ... -->
    <resources>
      <labels> (1)
        <all> (1)
          <property> (2)
            <name>organisation</name>
            <value>unesco</value>
          </property>
        </all>
        <service> (3)
          <property>
            <name>database</name>
            <value>mysql</value>
          </property>
          <property>
            <name>persistent</name>
            <value>true</value>
          </property>
        </service>
        <replicaSet> (4)
          <!-- ... -->
        </replicaSet>
        <pod> (5)
          <!-- ... -->
        </pod>
        <deployment> (6)
          <!-- ... -->
        </deployment>
      </labels>

      <annotations> (7)
         <!-- ... -->
      </annotations>
      <remotes> (8)
        <remote>https://gist.githubusercontent.com/lordofthejars/ac2823cec7831697d09444bbaa76cd50/raw/e4b43f1b6494766dfc635b5959af7730c1a58a93/deployment.yaml</remote>
      </remotes>
    </resource>
  </configuration>
</plugin>
1 <labels> section with <resources> contains labels which should be applied to objects of various kinds
2 Within <all> labels which should be applied to every object can be specified
3 <service> labels are used to label services
4 <replicaSet> labels are for replica set and replication controller
5 <pod> holds labels for pod specifications in replication controller, replica sets and deployments
6 <deployment> is for labels on deployments (kubernetes) and deployment configs (openshift)
7 The subelements are also available for specifying annotations.
8 <remotes> you can set location of fragments as URL.

Labels and annotations can be specified in free form as a map. In this map, the element name is the name of the label or annotation respectively, whereas the content is the value to set.

The following subelements are possible for <labels> and <annotations> :

Table 6. Label and annotation configuration
Element Description

all

All entries specified in the <all> sections are applied to all resource objects created.

deployment

Labels and annotations applied to Deployment (for Kubernetes).

pod

Labels and annotations applied pod specification as used in ReplicationController, ReplicaSets, Deployments and DeploymentConfigs objects.

replicaSet

Labels and annotations applied to ReplicaSet and ReplicationController objects.

service

Labels and annotations applied to Service objects.

5.1.2. Secrets

Once you’ve configured some docker registry credentials into ~/.m2/setting.xml, as explained in the Authentication section, you can create Kubernetes secrets from a server declaration.

XML configuration

You can create a secret using xml configuration in the pom.xml file. It should contain the following fields:

key required description

dockerServerId

true

the server id which is configured in ~/.m2/setting.xml

name

true

this will be used as name of the kubernetes secret resource

namespace

false

the secret resource will be applied to the specific namespace, if provided

This is best explained by an example.

Example for XML configuration
<properties>
    <jkube.docker.registry>docker.io</docker.registry>
</properties>
<configuration>
    <resources>
        <secrets>
            <secret>
                <dockerServerId>${docker.registry}</dockerServerId>
                <name>mydockerkey</name>
            </secret>
        </secrets>
    </resources>
</configuration>

Yaml fragment with annotation

You can create a secret using a yaml fragment. You can reference the docker server id with an annotation maven.jkube.io/dockerServerId. The yaml fragment file should be put under the src/main/jkube/ folder.

Example
apiVersion: v1
kind: Secret
metadata:
  name: mydockerkey
  namespace: default
  annotations:
    maven.jkube.io/dockerServerId: ${docker.registry}
type: kubernetes.io/dockercfg

5.1.3. Resource Validation

Resource goal also validates the generated resource descriptors using API specification of Kubernetes.

Table 7. Validation Configuration
Element Description Property

skipResourceValidation

If value is set to true then resource validation is skipped. This may be useful if resource validation is failing for some reason but you still want to continue the deployment.

Default is false.

jkube.skipResourceValidation

failOnValidationError

If value is set to true then any validation error will block the plugin execution. A warning will be printed otherwise.

Default is false.

jkube.failOnValidationError

5.1.4. Supported Properties for Resource goal

Table 8. Options available with resource goal
Element Description Property

profile

Profile to use. A profile contains the enrichers and generators to use as well as their configuration. Profiles are looked up in the classpath and can be provided as yaml files.

Defaults to default.

jkube.profile

sidecar

Whether to enable sidecar behavior or not. By default pod specs are merged into main application container.

Defaults to false.

jkube.sidecar

skipHealthCheck

Whether to skip health checks addition in generated resources or not.

Defaults to false.

jkube.skipHealthCheck

workDir

The JKube working directory. Defaults to ${project.build.directory}/jkube.

jkube.workDir

environment

Environment name where resources are placed. For example, if you set this property to dev and resourceDir is the default one, plugin will look at src/main/jkube/dev.

Defaults to null.

jkube.environment

useProjectClassPath

Should we use the project’s compile time classpath to scan for additional enrichers/generators.

Defaults to false.

jkube.useProjectClassPath

resourceDir

Folder where to find project specific files.

Defaults to ${basedir}/src/main/jkube.

jkube.resourceDir

targetDir

The generated Kubernetes manifests target direcotry.

Defaults to ${project.build.outputDirectory}/META-INF/jkube.

jkube.targetDir

resourceType

The artifact type for attaching the generated resource file to the project. Can be either 'json' or 'yaml'.

Defaults to yaml.

jkube.resourceType

mergeWithDekorate

When resource generation is delegated to Dekorate, should JKube resources be merged with Dekorate generated ones.

Defaults to false.

jkube.mergeWithDekorate

skipResource

Skip resource generation.

Defaults to false.

jkube.skip.resource

createExternalUrls

Should we create external Ingress for any LoadBalancer Services which don’t already have them.

Defaults to false.

jkube.createExternalUrls

domain

Domain added to the Service ID when creating Kubernetes Ingresses or OpenShift routes.

jkube.domain

5.2. k8s:build

This goal is for building Docker images.

5.2.1. Kubernetes Build

A normal Docker build is performed by default. The connection configuration to access the Docker daemon is described in Access Configuration.

In order to make the generated images available to the Kubernetes cluster the generated images need to be pushed to a registry with the goal k8s:push. This is not necessary for single node clusters, though as there is no need to distribute images.

5.2.2. Configuration (XML)

The following sections describe the usual configuration, which is similar to the build configuration used in the docker-maven-plugin.

In addition a more automatic way for creating predefined build configuration can be performed with so called Generators. Generators are very flexible and can be easily created. These are described in an extra section.

Global configuration parameters specify overall behavior common for all images to build. Some of the configuration options are shared with other goals.

Table 9. Global configuration
Element Description Property

buildStrategy

Defines what build strategy to choose while building container image. Possible values are docker and jib out of which docker is default.

jkube.build.strategy

apiVersion

Use this variable if you are using an older version of docker not compatible with the current default use to communicate with the server.

jkube.docker.apiVersion

authConfig

Authentication information when pulling from or pushing to Docker registry. There is a dedicated section Authentication for how to do security.

autoPull

Decide how to pull missing base images or images to start:

  • on : Automatic download any missing images (default)

  • off : Automatic pulling is switched off

  • always : Pull images always even when they already exist locally

  • once : For multi-module builds images are only checked once and pulled for the whole build.

jkube.docker.autoPull

buildRecreate

If the effective mode is openshift then this option decides how the OpenShift resource objects associated with the build should be treated when they already exist:

  • buildConfig or bc : Only the BuildConfig is recreated

  • imageStream or is : Only the ImageStream is recreated

  • all : Both, BuildConfig and ImageStream are recreated

  • none : Neither BuildConfig nor ImageStream is recreated

The default is none. If you provide the property without value then all is assumed, so everything gets recreated.

jkube.build.recreate

imagePullPolicy

Specify whether images should be pull when looking for base images while building or images for starting. This property can take the following values (case insensitive):

  • IfNotPresent: Automatic download any missing images (default)

  • Never : Automatic pulling is switched off always

  • Always : Pull images always even when they already exist locally.

By default a progress meter is printed out on the console, which is omitted when using Maven in batch mode (option -B). A very simplified progress meter is provided when using no color output (i.e. with -Djkube.useColor=false).

jkube.docker.imagePullPolicy

certPath

Path to SSL certificate when SSL is used for communicating with the Docker daemon. These certificates are normally stored in ~/.docker/. With this configuration the path can be set explicitly. If not set, the fallback is first taken from the environment variable DOCKER_CERT_PATH and then as last resort ~/.docker/. The keys in this are expected with it standard names ca.pem, cert.pem and key.pem. Please refer to the Docker documentation for more information about SSL security with Docker.

jkube.docker.certPath

dockerHost

The URL of the Docker Daemon. If this configuration option is not given, then the optional <machine> configuration section is consulted. The scheme of the URL can be either given directly as http or https depending on whether plain HTTP communication is enabled or SSL should be used. Alternatively the scheme could be tcp in which case the protocol is determined via the IANA assigned port: 2375 for http and 2376 for https. Finally, Unix sockets are supported by using the scheme unix together with the filesystem path to the unix socket.

The discovery sequence used by the docker-maven-plugin to determine the URL is:

  1. Value of dockerHost (jkube.docker.host)

  2. The Docker host associated with the docker-machine named in <machine>, i.e. the DOCKER_HOST from docker-machine env. See below for more information about Docker machine support.

  3. The value of the environment variable DOCKER_HOST.

  4. unix:///var/run/docker.sock if it is a readable socket.

jkube.docker.host

filter

In order to temporarily restrict the operation of plugin goals this configuration option can be used. Typically this will be set via the system property jkube.image.filter when Maven is called. The value can be a single image name (either its alias or full name) or it can be a comma separated list with multiple image names. Any name which doesn’t refer an image in the configuration will be ignored.

jkube.image.filter

machine

Docker machine configuration. See Docker Machine for possible values.

maxConnections

Number of parallel connections are allowed to be opened to the Docker Host. For parsing log output, a connection needs to be kept open (as well for the wait features), so don’t put that number to low. Default is 100 which should be suitable for most of the cases.

jkube.docker.maxConnections

access

Group of configuration parameters to connect to Kubernetes/OpenShift cluster.

outputDirectory

Default output directory to be used by this plugin. The default value is target/docker and is only used for the goal k8s:build.

jkube.build.target.dir

profile

Profile to which contains enricher and generators configuration. See Profiles for details.

jkube.profile

registry

Specify globally a registry to use for pulling and pushing images. See Registry handling for details.

jkube.docker.registry

skip

With this parameter the execution of this plugin can be skipped completely.

jkube.skip

skipBuild

If set not images will be build (which implies also skip.tag) with k8s:build.

jkube.skip.build

skipBuildPom

If set the build step will be skipped for modules of type pom. If not set, then by default projects of type pom will be skipped if there are no image configurations contained.

jkube.skip.build.pom

skipTag

If set to true this plugin won’t add any tags to images that have been built with k8s:build.

jkube.skip.tag

skipMachine

Skip using docker machine in any case

jkube.docker.skip.machine

sourceDirectory

Default directory that contains the assembly descriptor(s) used by the plugin. The default value is src/main/docker. This option is only relevant for the k8s:build goal.

jkube.build.source.dir

verbose

Boolean attribute for switching on verbose output like the build steps when doing a Docker build. Default is false.

jkube.docker.verbose

logDate

The date format to use when logging messages from Docker. Default is DEFAULT (HH:mm:ss.SSS)

jkube.docker.logDate

logStdout

Log to stdout regardless if log files are configured or not. Default is false.

jkube.docker.logStdout

5.2.3. Kubernetes Access Configuration

You can configure parameters to define how plugin is going to connect to Kubernetes cluster instead of relying on default parameters.

<configuration>
  <access>
    <username></username>
    <password></password>
    <masterUrl></masterUrl>
    <apiVersion></apiVersion>
  </access>
</configuration>
Element Description Property

username

Username on which to operate.

jkube.username

password

Password on which to operate.

jkube.password

namespace

Namespace on which to operate.

jkube.namespace

masterUrl

Master URL on which to operate.

jkube.masterUrl

apiVersion

Api version on which to operate.

jkube.apiVersion

caCertFile

CaCert File on which to operate.

jkube.caCertFile

caCertData

CaCert Data on which to operate.

jkube.caCertData

clientCertFile

Client Cert File on which to operate.

jkube.clientCertFile

clientCertData

Client Cert Data on which to operate.

jkube.clientCertData

clientKeyFile

Client Key File on which to operate.

jkube.clientKeyFile

clientKeyData

Client Key Data on which to operate.

jkube.clientKeyData

clientKeyAlgo

Client Key Algorithm on which to operate.

jkube.clientKeyAlgo

clientKeyPassphrase

Client Key Passphrase on which to operate.

jkube.clientKeyPassphrase

trustStoreFile

Trust Store File on which to operate.

jkube.trustStoreFile

trustStorePassphrase

Trust Store Passphrase on which to operate.

jkube.trustStorePassphrase

keyStoreFile

Key Store File on which to operate.

jkube.keyStoreFile

keyStorePassphrase

Key Store Passphrase on which to operate.

jkube.keyStorePassphrase

5.2.4. Image Configuration

The configuration how images should be created a defined in a dedicated <images> sections. These are specified for each image within the <images> element of the configuration with one <image> element per image to use.

The <image> element can contain the following sub elements:

Table 10. Image Configuration
Element Description

name

Each <image> configuration has a mandatory, unique docker repository name. This can include registry and tag parts, but also placeholder parameters. See below for a detailed explanation.

alias

Shortcut name for an image which can be used for identifying the image within this configuration. This is used when linking images together or for specifying it with the global image configuration element.

registry

Registry to use for this image. If the name already contains a registry this takes precedence. See Registry handling for more details.

build

Element which contains all the configuration aspects when doing a k8s:build. This element can be omitted if the image is only pulled from a registry e.g. as support for integration tests like database images.

The <build> section is mandatory and is explained in below.

When specifying the image name in the configuration with the <name> field you can use several placeholders which are replaced during runtime by this plugin. In addition you can use regular Maven properties which are resolved by Maven itself.

Table 11. Image Names
Placeholder Description

%g

The last part of the Maven group name, sanitized so that it can be used as username on GitHub. Only the part after the last dot is used. E.g. for a group id org.eclipse.jkube this placeholder would insert jkube

%a

A sanitized version of the artefact id so that it can be used as part of an Docker image name. I.e. it is converted to all lower case (as required by Docker)

%v

The project version. Synonym to ${project.version}

%l

If the project version ends with -SNAPSHOT then this placeholder is latest, otherwise its the full version (same as %v)

%t

If the project version ends with -SNAPSHOT this placeholder resolves to snapshot-<timestamp> where timestamp has the date format yyMMdd-HHmmss-SSSS (eg snapshot-). This feature is especially useful during development in oder to avoid conflicts when images are to be updated which are still in use. You need to take care yourself of cleaning up old images afterwards, though.

Example for <image>
<configuration>
  <!-- .... -->
  <images>
    <image> (1)
      <name>%g/jkube-build-demo:0.1</name> (2)
      <alias>service</alias> (3)
      <build>....</build> (4)
    </image>
    <image>
      ....
    </image>
  </images>
</configuration>
1 One or more <image> definitions
2 The Docker image name used when creating the image. Note that %g would be replaced by project group id.
3 An alias which can be used in other parts of the plugin to reference to this image. This alias must be unique.
4 A <build> section as described in Build Configuration

5.2.5. Build Configuration

There are two different modes how images can be built:

Inline plugin configuration

With an inline plugin configuration all information required to build the image is contained in the plugin configuration. By default its the standard XML based configuration for the plugin but can be switched to a property based configuration syntax as described in the section External configuration. The XML configuration syntax is recommended because of its more structured and typed nature.

When using this mode, the Dockerfile is created on the fly with all instructions extracted from the configuration given.

External Dockerfile or Docker archive

Alternatively an external Dockerfile template or Docker archive can be used. This mode is switched on by using one of these three configuration options within

  • contextDir specifies docker build context if an external dockerfile is located outside of Docker build context. If not specified, Dockerfile’s parent directory is used as build context.

  • dockerFile specifies a specific Dockerfile path. The Docker build context directory is set to contextDir if given. If not the directory by default is the directory in which the Dockerfile is stored.

  • dockerArchive specifies a previously saved image archive to load directly. If a dockerArchive is provided, no dockerFile must be given.

All paths can be either absolute or relative paths. A relative path is looked up in ${project.basedir}/src/main/docker by default. You can make it easily an absolute path by using ${project.basedir} in your configuration.

Adding assemblies in Dockerfile mode

You can also use an assembly if specified in an assembly configuration. However, you need to add the files on your own in the Dockerfile with an ADD or COPY command. The files of the assembly are stored in a build context relative directory maven/ but can be changed by changing the assembly name with the option <name> in the assembly configuration.

E.g. the files can be added with

Example
COPY maven/ /my/target/directory

so that the assembly files will end up in /my/target/directory within the container.

If this directory contains a .maven-dockerignore (or alternatively, a .maven-dockerexclude file), then it is used for excluding files for the build. Each line in this file is treated as a FileSet exclude pattern as used by the maven-assembly-plugin. It is similar to .dockerignore when using Docker but has a slightly different syntax (hence the different name). Example .maven-dockerexclude or .maven-dockerignore is an example which excludes all compiled Java classes.

Example 1. Example .maven-dockerexclude or .maven-dockerignore
target/classes/**  (1)
1 Exclude all compiled classes

If this directory contains a .maven-dockerinclude file, then it is used for including only those files for the build. Each line in this file is also treated as a FileSet exclude pattern as used by the maven-assembly-plugin. Example .maven-dockerinclude shows how to include only jar file that have build to the Docker build context.

Example 2. Example .maven-dockerinclude
target/*.jar  (1)
1 Only add jar file to you Docker build context.

Except for the assembly configuration all other configuration options are ignored for now.

Simple Dockerfile build

When only a single image should be built with a Dockerfile no XML configuration is needed at all. All what need to be done is to place a Dockerfile into the top-level module directory, alongside to pom.xml. You can still configure global aspects in the plugin configuration, but as soon as you add an <image> in the XML configuration, you need to configure also the build explicitly.

The image name is by default set from the Maven coordinates (%g/%a:%l, see Image Name for an explanation of the params which are essentially the Maven GAV) This name can be set with the property jkube.image.name.

Filtering

kubernetes-maven-plugin filters given Dockerfile with Maven properties, much like the maven-resource-plugin does. Filtering is enabled by default and can be switched off with a build config <filter>false</filter>. Properties which we want to replace are specified with the ${..} syntax. Replacement includes Maven project properties such as ${project.artifactId}, properties set in the build, command-line properties, and system properties. Unresolved properties remain untouched.

This partial replacement means that you can easily mix it with Docker build arguments and environment variable reference, but you need to be careful. If you want to be more explicit about the property delimiter to clearly separate Docker properties and Maven properties you can redefine the delimiter. In general, the filter option can be specified the same way as delimiters in the resource plugin. In particular, if this configuration contains a * then the parts left, and right of the asterisks are used as delimiters.

For example, the default <filter>${*}</filter> parse Maven properties in the format that we know. If you specify a single character for <filter> then this delimiter is taken for both, the start and the end. E.g a <filter>@</filter> triggers on parameters in the format @…​@, much like in the maven-invoker-plugin. Use something like this if you want to clearly separate from Docker builds args. This form of property replacement works for Dockerfile only. For replacing other data in other files targeted for the Docker image, please use the maven-resource-plugin or an assembly configuration with filtering to make them available in the docker build context.

Example

The following example replaces all properties in the format @property@ within the Dockerfile.

<plugin>
 <configuration>
   <images>
     <image>
       <name>user/demo</name>
       <build>
         <filter>@</filter>
       </build>
     </image>
   </images>
 </configuration>
 ...
</plugin>
Build Plugins

This plugin supports so call dmp-plugins which are used during the build phase. dmp-plugins are enabled by just declaring a dependency in the plugin declaration:

<plugin>
  <groupId>org.eclipse.jkube</groupId>
  <artifactId>kubernetes-maven-plugin</artifactId>

  <dependencies>
    <dependency>
      <groupId>org.eclipse.jkube</groupId>
      <artifactId>run-java-sh</artifactId>
      <version>1.2.2</version>
    </dependency>
  </dependencies>
</plugin>
org.eclipse.jkube.runsh.RunShLoader

During a build with kubernetes-maven-plugin:build, those classes are loaded and certain fixed method are called.

The following methods are supported:

Method Description

addExtraFiles

A static method called by dmp with a single File argument. This will point to a directory docker-extra which can be referenced easily by a Dockerfile or an assembly. A dmp plugin typically will create an own subdirectory to avoid a clash with other dmp-plugins.

If a configured plugin does not provide method of this name and signature, then it will be simply ignored. Also, no interface needs to be implemented to keep the coupling low.

The following official dmp-plugins are known and supported:

Name G,A Description

run-java.sh

jkube.io, run-java

General purpose startup script fo running Java applications. The dmp plugin creates a target/docker-extra/run-java/run-java.sh which can be included in a Dockerfile (see the example above). See the run-java.sh Documentation for more details.

Check out samples/run-java for a fully working example.

All build relevant configuration is contained in the <build> section of an image configuration. The following configuration options are supported:

Table 12. Build configuration (<image> )
Element Description

assembly

Specifies the assembly configuration as described in Build Assembly

args

Map specifying the value of Docker build args which should be used when building the image with an external Dockerfile which uses build arguments. The key-value syntax is the same as when defining Maven properties (or labels or env). This argument is ignored when no external Dockerfile is used. Build args can also be specified as properties as described in Build Args

buildOptions

Map specifying the build options to provide to the docker daemon when building the image. These options map to the ones listed as query parameters in the Docker Remote API and are restricted to simple options (e.g.: memory, shmsize). If you use the respective configuration options for build options natively supported by the build configuration (i.e. noCache, cleanup=remove for buildoption forcerm=1 and args for build args) then these will override any corresponding options given here. The key-value syntax is the same as when defining environment variables or labels as described in Setting Environment Variables and Labels.

cleanup

Cleanup dangling (untagged) images after each build (including any containers created from them). Default is try which tries to remove the old image, but doesn’t fail the build if this is not possible because e.g. the image is still used by a running container. Use remove if you want to fail the build and none if no cleanup is requested.

contextDir

Path to a directory used for the build’s context. You can specify the Dockerfile to use with dockerFile, which by default is the Dockerfile found in the contextDir. The Dockerfile can be also located outside of the contextDir, if provided with an absolute file path. See External Dockerfile for details.

cmd

A command to execute by default (i.e. if no command is provided when a container for this image is started). See Startup Arguments for details.

compression

The compression mode how the build archive is transmitted to the docker daemon (k8s:build) and how docker build archives are attached to this build as sources (k8s:source). The value can be none (default), gzip or bzip2.

dockerFile

Path to a Dockerfile which also triggers Dockerfile mode. See External Dockerfile for details.

dockerArchive

Path to a saved image archive which is then imported. See Docker archive for details.

entryPoint

An entrypoint allows you to configure a container that will run as an executable. See Startup Arguments for details.

env

The environments as described in Setting Environment Variables and Labels.

filter

Enable and set the delimiters for property replacements. By default properties in the format ${..} are replaced with Maven properties. You can switch off property replacement by setting this property to false. When using a single char like @ then this is used as a delimiter (e.g @…​@). See Filtering for more details.

from

The base image which should be used for this image. If not given this default to busybox:latest and is suitable for a pure data image.

fromExt

Extended definition for a base image. This field holds a map of defined in <key>value</key> format. The known keys are:

  • <name> : Name of the base image

A provided <from> takes precedence over the name given here. This tag is useful for extensions of this plugin.

healthCheck

Definition of a health check as described in Healthcheck

imagePullPolicy

Specific pull policy for the base image. This overwrites any global pull policy. See the global configuration option imagePullPolicy for the possible values and the default.

labels

Labels as described in Setting Environment Variables and Labels.

maintainer

The author (MAINTAINER) field for the generated image

noCache

Don’t use Docker’s build cache. This can be overwritten by setting a system property docker.noCache when running Maven.

cacheFrom

A list of <image> elements specifying image names to use as cache sources.

optimise

if set to true then it will compress all the runCmds into a single RUN directive so that only one image layer is created.

ports

The exposed ports which is a list of <port> elements, one for each port to expose. Whitespace is trimmed from each element and empty elements are ignored. The format can be either pure numerical ("8080") or with the protocol attached ("8080/tcp").

shell

Shell to be used for the runCmds. It contains arg elements which are defining the executable and its params.

runCmds

Commands to be run during the build process. It contains run elements which are passed to the shell. Whitespace is trimmed from each element and empty elements are ignored. The run commands are inserted right after the assembly and after workdir into the Dockerfile.

skip

if set to true disables building of the image. This config option is best used together with a maven property

skipTag

If set to true this plugin won’t add any tags to images.

tags

List of additional tag elements with which an image is to be tagged after the build. Whitespace is trimmed from each element and empty elements are ignored.

user

User to which the Dockerfile should switch to the end (corresponds to the USER Dockerfile directive).

volumes

List of volume elements to create a container volume. Whitespace is trimmed from each element and empty elements are ignored.

workdir

Directory to change to when starting the container.

From this configuration this Plugin creates an in-memory Dockerfile, copies over the assembled files and calls the Docker daemon via its remote API.

Example
<build>
  <from>java:8u40</from>
  <maintainer>john.doe@example.com</maintainer>
  <tags>
    <tag>latest</tag>
    <tag>${project.version}</tag>
  </tags>
  <ports>
    <port>8080</port>
  </ports>
  <volumes>
    <volume>/path/to/expose</volume>
  </volumes>
  <buildOptions>
    <shmsize>2147483648</shmsize>
  </buildOptions>

  <shell>
    <exec>
      <arg>/bin/sh</arg>
      <arg>-c</arg>
    </exec>
  </shell>
  <runCmds>
    <run>groupadd -r appUser</run>
    <run>useradd -r -g appUser appUser</run>
  </runCmds>

  <entryPoint>
    <!-- exec form for ENTRYPOINT -->
    <exec>
      <arg>java</arg>
      <arg>-jar</arg>
      <arg>/opt/demo/server.jar</arg>
    </exec>
  </entryPoint>

  <assembly>
    <mode>dir</mode>
    <targetDir>/opt/demo</targetDir>
    <descriptor>assembly.xml</descriptor>
  </assembly>
</build>

In order to see the individual build steps you can switch on verbose mode either by setting the property jkube.docker.verbose or by using <verbose>true</verbose> in the Build Goal configuration

5.2.6. Assembly

The <assembly> element within <build> element has an XML structure and defines how build artifacts and other files can be added to the Docker image.

Table 13. Assembly Configuration (<image> : <build> )
Element Description

name

Assembly name, which is maven by default. This name is used for the archives and directories created during the build. This directory holds the files specified by the assembly. If an external Dockerfile is used then this name is also the relative directory which contains the assembly files.

targetDir

Directory under which the files and artifacts contained in the assembly will be copied within the container. The default value for this is /<assembly name>, so /maven if name is not set to a different value.

inline

Inlined assembly descriptor as described in Assembly - Inline below.

exportTargetDir

Specification whether the targetDir should be exported as a volume. This value is true by default except in the case the targetDir is set to the container root (/). It is also false by default when a base image is used with from since exporting makes no sense in this case and will waste disk space unnecessarily.

excludeFinalOutputArtifact

By default, the project’s final artifact will be included in the assembly, set this flag to true in case the artifact should be excluded from the assembly.

mode

Mode how the how the assembled files should be collected:

  • dir : Files are simply copied (default),

  • tar : Transfer via tar archive

  • tgz : Transfer via compressed tar archive

  • zip : Transfer via ZIP archive

The archive formats have the advantage that file permission can be preserved better (since the copying is independent from the underlying files systems), but might triggers internal bugs from the Maven assembler (as it has been reported in #171)

permissions

Permission of the files to add:

  • ignore to use the permission as found on files regardless on any assembly configuration

  • keep to respect the assembly provided permissions

  • exec for setting the executable bit on all files (required for Windows when using an assembly mode dir)

  • auto to let the plugin select exec on Windows and keep on others.

keep is the default value.

tarLongFileMode

Sets the TarArchiver behaviour on file paths with more than 100 characters length. Valid values are: "warn"(default), "fail", "truncate", "gnu", "posix", "posix_warn" or "omit"

user

User and/or group under which the files should be added. The user must already exist in the base image.

It has the general format user[:group[:run-user]]. The user and group can be given either as numeric user- and group-id or as names. The group id is optional.

If a third part is given, then the build changes to user root before changing the ownerships, changes the ownerships and then change to user run-user which is then used for the final command to execute. This feature might be needed, if the base image already changed the user (e.g. to 'jboss') so that a chown from root to this user would fail.

For example, the image jboss/wildfly use a "jboss" user under which all commands are executed. Adding files in Docker always happens under the UID root. These files can only be changed to "jboss" is the chown command is executed as root. For the following commands to be run again as "jboss" (like the final standalone.sh), the plugin switches back to user jboss (this is this "run-user") after changing the file ownership. For this example a specification of jboss:jboss:jboss would be required.

In the event you do not need to include any artifacts with the image, you may safely omit this element from the configuration.

Assembly - Inline

Inlined assembly description with a format very similar to Maven Assembly Plugin.

Table 14. Assembly - Inline (<image> : <build> : <assembly> )
Element Description

id

Unique ID for the assembly.

files

List of files for the assembly.

Each file has the following fields:

  • source: Absolute or relative path from the project’s directory of the file to be included in the assembly.

  • outputDirectory: Output directory relative to the root of the root directory of the assembly.

  • destName: Destination filename in the outputDirectory.

  • fileMode: Similar to a UNIX permission, sets the file mode of the file included.

fileSets

List of filesets for the Assembly.

Each fileset has the following fields:

  • directory: Absolute or relative location from the project’s directory.

  • outputDirectory: Output directory relative to the root of the root directory of the assembly fileSet.

  • includes: A set of files and directories to include.

    • If none is present, then everything is included.

    • Files can be referenced by using their complete path name.

    • Wildcards are also supported, patterns will be matched using FileSystem#getPathMatcher glob syntax.

  • excludes: A set of files and directory to exclude.

    • If none is present, then there are no exclusions.

  • fileMode: Similar to a UNIX permission, sets the file mode of the files included.

  • directoryMode: Similar to a UNIX permission, sets the directory mode of the directories included.

baseDirectory

Base directory from which to resolve the Assembly files and filesets.

5.2.7. Environment and Labels

When creating a container one or more environment variables can be set via configuration with the env parameter

Example
<env>
  <JAVA_HOME>/opt/jdk8</JAVA_HOME>
  <CATALINA_OPTS>-Djava.security.egd=file:/dev/./urandom</CATALINA_OPTS>
</env>

If you put this configuration into profiles you can easily create various test variants with a single image (e.g. by switching the JDK or whatever).

It is also possible to set the environment variables from the outside of the plugin’s configuration with the parameter envPropertyFile. If given, this property file is used to set the environment variables where the keys and values specify the environment variable. Environment variables specified in this file override any environment variables specified in the configuration.

Labels can be set inline the same way as environment variables:

Example
<labels>
   <com.example.label-with-value>foo</com.example.label-with-value>
   <version>${project.version}</version>
   <artifactId>${project.artifactId}</artifactId>
</labels>

5.2.8. Startup Arguments

Using entryPoint and cmd it is possible to specify the entry point or cmd for a container.

The difference is, that an entrypoint is the command that always be executed, with the cmd as argument. If no entryPoint is provided, it defaults to /bin/sh -c so any cmd given is executed with a shell. The arguments given to docker run are always given as arguments to the entrypoint, overriding any given cmd option. On the other hand if no extra arguments are given to docker run the default cmd is used as argument to entrypoint.

See this stackoverflow question for a detailed explanation.

An entry point or command can be specified in two alternative formats:

Table 15. Entrypoint and Command Configuration
Mode Description

shell

Shell form in which the whole line is given to shell -c for interpretation.

exec

List of arguments (with inner <args>) arguments which will be given to the exec call directly without any shell interpretation.

Either shell or params should be specified.

Example
<entryPoint>
   <!-- shell form  -->
   <shell>java -jar $HOME/server.jar</shell>
</entryPoint>

or

Example
<entryPoint>
   <!-- exec form  -->
   <exec>
     <arg>java</arg>
     <arg>-jar</arg>
     <arg>/opt/demo/server.jar</arg>
   </exec>
</entryPoint>

This can be formulated also more dense with:

Example
<!-- shell form  -->
<entryPoint>java -jar $HOME/server.jar</entryPoint>

or

Example
<entryPoint>
  <!-- exec form  -->
  <arg>java</arg>
  <arg>-jar</arg>
  <arg>/opt/demo/server.jar</arg>
</entryPoint>
INFO

Startup arguments are not used in S2I builds

5.2.9. Build Args

As described in section Configuration for external Dockerfiles Docker build arg can be used. In addition to the configuration within the plugin configuration you can also use properties to specify them:

  • Set a system property when running Maven, eg.: -Ddocker.buildArg.http_proxy=http://proxy:8001. This is especially useful when using predefined Docker arguments for setting proxies transparently.

  • Set a project property within the pom.xml, eg.:

Example
<docker.buildArg.myBuildArg>myValue</docker.buildArg.myBuildArg>

Please note that the system property setting will always override the project property. Also note that for all properties which are not Docker predefined properties, the external Dockerfile must contain an ARGS instruction.

5.2.10. Healthcheck

Healthchecks has been introduced since Docker 1.12 and are a way to tell Docker how to test a container to check that it’s still working. With a health check you specify a command which is periodically executed and checked for its return value. If the healtcheck return with an exit 0 the container is considered to be healthy, if it returns with 1 then the container is not working correctly.

The healtcheck configuration can have the following options

Table 16. Healthcheck Configuration
Element Description

cmd

Command to execute, which can be given in an shell or exec format as described in Startup Arguments.

interval

Interval for how often to run the healthcheck. The time is specified in seconds, but a time unit can be appended to change this.

mode

Mode of the healthcheck. This can be cmd which is the default and specifies that the health check should be executed. Or none to disable a health check from the base image. Only use this option with none for disabling some healthcheck from the base image.

retries

How many retries should be performed before the container is to be considered unhealthy.

startPeriod

Initialization time for containers that need time to bootstrap. Probe failure during that period will not be counted towards the maximum number of retries. However, if a health check succeeds during the start period, the container is considered started and all consecutive failures will be counted towards the maximum number of retries. Given in seconds, but another time unit can be appended.

timeout

Timeout after which healthckeck should be stopped and considered to have failed. Given in seconds, but another time unit can be appended.

The following example queries an URL every 10s as an healthcheck:

Example
<healthCheck>
  <!-- Check every 5 minutes -->
  <interval>5m</interval>
  <!-- Fail if no response after 3 seconds -->
  <timeout>3s</timeout>
  <!-- Allow 30 minutes for the container to start before being flagged as unhealthy -->
  <startPeriod>30m</startPeriod>
  <!-- Fail 3 times until the container is considerd unhealthy -->
  <retries>3</retries>
  <!-- Command to execute in shell form -->
  <cmd>curl -f http://localhost/ || exit 1</cmd>
</healthCheck>

5.3. k8s:push

Section needs review and rearrangements

This goal uploads images to the registry which have a <build> configuration section. The images to push can be restricted with the global option filter (see Build Goal Configuration for details). The registry to push is by default docker.io but can be specified as part of the images’s name the Docker way. E.g. docker.test.org:5000/data:1.5 will push the image data with tag 1.5 to the registry docker.test.org at port 5000. Registry credentials (i.e. username and password) can be specified in multiple ways as described in section Authentication.

By default a progress meter is printed out on the console, which is omitted when using Maven in batch mode (option -B). A very simplified progress meter is provided when using no color output (i.e. with -Djkube.useColor=false).

Table 17. Push options
Element Description Property

skipPush

If set to true the plugin won’t push any images that have been built.

jkube.skip.push

skipTag

If set to true this plugin won’t push any tags

jkube.skip.tag

pushRegistry

The registry to use when pushing the image. See Registry Handling for more details.

jkube.docker.push.registry

retries

How often should a push be retried before giving up. This useful for flaky registries which tend to return 500 error codes from time to time. The default is 0 which means no retry at all.

jkube.docker.push.retries

5.4. k8s:apply

This goal applies the resources created with k8s:resource to a connected Kubernetes cluster. It’s similar to k8s:deploy but does not the full deployment cycle of creating the resource, creating the application image and sending the resource descriptors to the clusters. This goal can be easily bound to <executions> within the plugin’s configuration and binds by default to the install lifecycle phase.

mvn k8s:apply

5.4.1. Supported Properties For Apply goal

Table 18. Other options available with apply goal
Element Description Property

recreate

Should we update resources by deleting them first and then creating them again.

Defaults to false.

jkube.recreate

kubernetesManifest

The generated kubernetes YAML file.

Defaults to ${basedir}/target/classes/META-INF/jkube/kubernetes.yml.

jkube.kubernetesManifest

create

Should we create new resources.

Defaults to true.

jkube.deploy.create

rolling

Should we use rolling updates to apply changes.

Defaults to false.

jkube.rolling

failOnNoKubernetesJson

Should we fail if there is no Kubernetes JSON.

Defaults to false.

jkube.deploy.failOnNoKubernetesJson

servicesOnly

In services only mode we only process services so that those can be recursively created/updated first before creating/updating any pods and replication controllers.

Defaults to false.

jkube.deploy.servicesOnly

ignoreServices

Do we want to ignore services. This is particularly useful when in recreate mode to let you easily recreate all the ReplicationControllers and Pods but leave any service definitions alone to avoid changing the portalIP addresses and breaking existing pods using the service.

Defaults to false.

jkube.deploy.ignoreServices

processTemplatesLocally

Process templates locally in Java so that we can apply OpenShift templates on any Kubernetes environment.

Defaults to false.

jkube.deploy.processTemplatesLocally

deletePods

Should we delete all the pods if we update a Replication Controller.

Defaults to true.

jkube.deploy.deletePods

ignoreRunningOAuthClients

Do we want to ignore OAuthClients which are already running?. OAuthClients are shared across namespaces so we should not try to update or create/delete global oauth clients.

Defaults to true.

jkube.deploy.ignoreRunningOAuthClients

jsonLogDir

The folder we should store any temporary json files or results.

Defaults to ${basedir}/target/jkube/applyJson.

jkube.deploy.jsonLogDir

waitSeconds

How many seconds to wait for a URL to be generated for a service.

Defaults to 5.

jkube.serviceUrl.waitSeconds

resourceDir

Folder where to find project specific files.

Defaults to ${basedir}/src/main/jkube.

jkube.resourceDir

environment

Environment name where resources are placed. For example, if you set this property to dev and resourceDir is the default one, jkube will look at src/main/jkube/dev.

Defaults to null.

jkube.environment

skipApply

Skip applying the resources.

Defaults to false.

jkube.skip.apply

5.5. k8s:helm

This goal is for creating Helm charts for your Maven project so that you can install, update or delete your app in Kubernetes using Helm.

For creating a Helm chart you simply call k8s:helm goal on the command line:

mvn k8s:resource k8s:helm

The k8s:resource goal is required to create the resource descriptors which are included in the Helm chart. If you have already built the resource then you can omit this goal.

The configuration is defined in a <helm> section within the plugin’s configuration:

Example Helm configuration
<plugin>
  <configuration>
    <helm>
      <chart>Jenkins</chart>
      <keywords>ci,cd,server</keywords>
    </helm>
  </configuration>
</plugin>

This configuration section knows the following sub-elements in order to configure your Helm chart.

Table 19. Helm configuration
Element Description Property

chart

The Chart name, which is ${project.artifactId} if not provided.

jkube.helm.chart

version

The Chart SemVer version, which is ${project.version} if not provided.

jkube.helm.version

description

The Chart single-sentence description, which is ${project.description} if not provided.

jkube.helm.description

home

The Chart URL for this project’s home page, which is ${project.url} if not provided.

jkube.helm.home

sources

The Chart list of URLs to source code for this project, defaults to the list of ${project.scm.url} if not provided.

maintainers

The Chart list of maintainers (name+email), defaults to the list of `${project.developers.name}:${project.developers.name}`if not provided.

icon

The Chart URL to an SVG or PNG image to be used as an icon, default is extracted from the kubernetes manifest (kubernetes.yml) jkube.io/iconUrl annotation if not provided.

jkube.helm.icon

keywords

Comma separated list of keywords to add to the chart.

engine

The template engine to use.

additionalFiles

The list of additional files to be included in the Chart archive. Any file named README or LICENSE will always be included by default.

type / types

Platform for which to generate the chart. By default this is kubernetes, but can be also openshift for using OpenShift specific resources in the chart. You can also add both values as a comma separated list.

Please note that there is no OpenShift support yet for charts, so this is experimental.

jkube.helm.type

sourceDir

Where to find the resource descriptors generated with k8s:resource. By default this is ${basedir}/target/classes/META-INF/jkube., which is also the output directory used by `k8s:resource.

jkube.helm.sourceDir

outputDir

Where to create the Helm chart, which is ${basedir}/target/jkube/helm by default for Kubernetes and ${basedir}/target/jkube/helmshift for OpenShift.

jkube.helm.outputDir

tarballOutputDir

Where to create the the Helm chart archive, which is ${basedir}/target if not provided.

jkube.helm.tarballOutputDir

chartExtension

The Helm chart file extension (tgz, tar.bz, tar.bzip2, tar.bz2), default value is tar.gz if not provided.

jkube.helm.chartExtension

In a next step you can install this via the helm command line tool as follows:

helm install nameForChartInRepository target/jkube/helm/${chartName}/kubernetes

or

helm install target/jkube/helm/${chartName}/kubernetes --generate-name

To add the helm goal to your project so that it is automatically executed just add the helm goal to the executions section of the kubernetes-maven-plugin section of your pom.xml.

Add helm goal
<plugin>
  <groupId>org.eclipse.jkube</groupId>
  <artifactId>kubernetes-maven-plugin</artifactId>

  <!-- ... -->

  <executions>
    <execution>
      <goals>
        <goal>resource</goal>
        <goal>helm</goal>
        <goal>build</goal>
        <goal>deploy</goal>
      </goals>
    </execution>
  </executions>
</plugin>

In addition this goal will also create a tar-archive below ${basedir}/target which contains the chart with its template. This tar is added as an artifact with classifier helm to the build (helmshift for the OpenShift mode).

6. Development Goals

6.1. k8s:deploy

This is the main goal for building your docker image, generating the kubernetes resources and deploying them into the cluster (insofar your pom.xml is set up correct; keep reading :)).

mvn k8s:deploy

This goal is designed to run k8s:build and k8s:resource before the deploy if you have the goals bound in your pom.xml:

<plugin>
  <groupId>org.eclipse.jkube</groupId>
  <artifactId>kubernetes-maven-plugin</artifactId>
  <version>1.0.0</version>

  <!-- Connect k8s:resource, k8s:build and k8s:helm to lifecycle phases -->
  <executions>
    <execution>
       <id>jkube</id>
       <goals>
         <goal>resource</goal>
         <goal>build</goal>
         <goal>helm</goal>
       </goals>
    </execution>
  </executions>
</plugin>

Effectively this builds your project then invokes these goals:

By default the behaviour of resource goal is it generates route.yml for a service if you have not done any configuration changes. Sometimes there may be case when you want to generate route.yml but do not want to create route resource on OpenShift Cluster. This can be achieved by the following configuration.

Example for not generating route resource on your cluster
<plugin>
    <groupId>org.eclipse.jkube</groupId>
    <artifactId>kubernetes-maven-plugin</artifactId>
    <version>1.0.0</version>
    <configuration>
        <enricher>
            <excludes>
                <exclude>jkube-expose</exclude>
            </excludes>
        </enricher>
    </configuration>
</plugin>

6.2. k8s:undeploy

This goal is for deleting the kubernetes resources that you deployed via the k8s:apply or k8s:deploy goals

It iterates through all the resources generated by the k8s:resource goal and deletes them from your current kubernetes cluster.

mvn k8s:undeploy

6.3. k8s:log

This goal tails the log of the app that you deployed via the k8s:deploy goal

mvn k8s:log

You can then terminate the output by hitting Ctrl+C

If you wish to get the log of the app and then terminate immediately then try:

mvn k8s:log -Djkube.log.follow=false

This lets you pipe the output into grep or some other tool

mvn k8s:log -Djkube.log.follow=false | grep Exception

If your app is running in multiple pods you can configure the pod name to log via the jkube.log.pod property, otherwise it defaults to the latest pod:

mvn k8s:log -Djkube.log.pod=foo

If your pod has multiple containers you can configure the container name to log via the jkube.log.container property, otherwise it defaults to the first container:

mvn k8s:log -Djkube.log.container=foo

6.3.1. Supported Properties for Log goal

Table 20. Options available with log goal
Element Description Property

logFollow

Get follow logs for your application inside Kubernetes.

Defaults to true.

jkube.log.follow

logContainer

Get logs of some specific container inside your application Deployment.

Defaults to null.

jkube.log.container

logPod

Get logs of some specific pod inside your application Deployment.

Defaults to null.

jkube.log.pod

6.4. k8s:debug

This goal enables debugging in your Java app and then port forwards from localhost to the latest running pod of your app so that you can easily debug your app from your Java IDE.

mvn k8s:debug

Then follow the on screen instructions.

The default debug port is 5005. If you wish to change the local port to use for debugging then pass in the jkube.debug.port parameter:

mvn k8s:debug -Djkube.debug.port=8000

Then in your IDE you start a Remote debug execution using this remote port using localhost and you should be able to set breakpoints and step through your code.

This lets you debug your apps while they are running inside a Kubernetes cluster - for example if you wish to debug a REST endpoint while another pod is invoking it.

Debug is enabled via the JAVA_ENABLE_DEBUG environment variable being set to true. This environment variable is used for all the standard Java docker images used by Spring Boot, flat classpath and executable JAR projects and Wildfly Swarm. If you use your own custom docker base image you may wish to also respect this environment variable too to enable debugging.

6.4.1. Speeding up debugging

By default the k8s:debug goal has to edit your Deployment to enable debugging then wait for a pod to start. It might be in development you frequently want to debug things and want to speed things up a bit.

If so you can enable debug mode for each build via the jkube.debug.enabled property.

e.g. you can pass this property on the command line:

mvn k8s:deploy -Djkube.debug.enabled=true

Or you can add something like this to your ~/.m2/settings.xml file so that you enable debug mode for all maven builds on your laptop by using a profile :

<?xml version="1.0"?>
<settings>
  <profiles>
    <profile>
      <id>enable-debug</id>
      <activation>
        <activeByDefault>true</activeByDefault>
      </activation>
      <properties>
        <jkube.debug.enabled>true</jkube.debug.enabled>
      </properties>
    </profile>
  </profiles>
</settings>

Then whenever you type the k8s:debug goal there is no need for the maven goal to edit the Deployment and wait for a pod to restart; we can immediately start debugging when you type:

mvn k8s:debug

6.4.2. Debugging with suspension

The k8s:debug goal allows to attach a remote debugger to a running container, but the application is free to execute when the debugger is not attached. In some cases, you may want to have complete control on the execution, e.g. to investigate the application behavior at startup. This can be done using the jkube.debug.suspend flag:

mvn k8s:debug -Djkube.debug.suspend

The suspend flag will set the JAVA_DEBUG_SUSPEND environment variable to true and JAVA_DEBUG_SESSION to a random number in your deployment. When the JAVA_DEBUG_SUSPEND environment variable is set, standard docker images will use suspend=y in the JVM startup options for debugging.

The JAVA_DEBUG_SESSION environment variable is always set to a random number (each time you run the debug goal with the suspend flag) in order to tell Kubernetes to restart the pod. The remote application will start only after a remote debugger is attached. You can use the remote debugging feature of your IDE to connect (on localhost, port 5005 by default).

The jkube.debug.suspend flag will disable readiness probes in the Kubernetes deployment in order to start port-forwarding during the early phases of application startup

6.4.3. Supported Properties For Debug Goal

Table 21. Options available with debug goal
Element Description Property

debugPort

Default port available for debugging your application inside Kubernetes.

Defaults to 5005.

jkube.debug.port

debugSuspend

Disables readiness probes in Kubernetes Deployment in order to start port forwarding during early phases of application startup.

Defaults to false.

jkube.debug.suspend

6.5. k8s:watch

This goal is used to monitor the project workspace for changes and automatically trigger a redeploy of the application running on Kubernetes.

In order to use k8s:watch for spring-boot, you need to make sure that devtools is included in the repacked archive, as shown in the following listing:

<plugin>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-maven-plugin</artifactId>
  <configuration>
    <excludeDevtools>false</excludeDevtools>
  </configuration>
</plugin>

Then you need to set a spring.devtools.remote.secret in application.properties, as shown in the following example:

spring.devtools.remote.secret=mysecret

Before entering the watch mode, this goal must generate the docker image and the Kubernetes resources (optionally including some development libraries/configuration), and deploy the app on Kubernetes. Lifecycle bindings should be configured as follows to allow the generation of such resources.

Lifecycle bindings for k8s:watch
<plugin>
  <groupId>org.eclipse.jkube</groupId>
  <artifactId>kubernetes-maven-plugin</artifactId>

  <!-- ... -->

  <executions>
    <execution>
      <goals>
        <goal>resource</goal>
        <goal>build</goal>
      </goals>
    </execution>
  </executions>
</plugin>

For any application having resource and build goals bound to the lifecycle, the following command can be used to run the watch task.

mvn k8s:watch

This plugin supports different watcher providers, enabled automatically if the project satisfies certain conditions.

Watcher providers can also be configured manually. The Generator example is a good blueprint, simply replace <generator> with <watcher>. The configuration is structurally identical.

6.5.1. Spring Boot

This watcher is enabled by default for all Spring Boot projects. It performs the following actions:

  • deploys your application with Spring Boot DevTools enabled

  • tails the log of the latest running pod for your application

  • watches the local development build of your Spring Boot based application and then triggers a reload of the application when there are changes

Spring devtools automatically ignores projects named spring-boot, spring-boot-devtools, spring-boot-autoconfigure, spring-boot-actuator, and spring-boot-starter

You can try it on any spring boot application via:

mvn k8s:watch

Once the goal starts up the spring boot RemoteSpringApplication it will watch for local development changes.

e.g. if you edit the java code of your app and then build it via something like this:

mvn package

You should see your app reload on the fly in the shell running the k8s:watch goal!

There is also support for LiveReload as well.

6.5.2. Docker Image

This is a generic watcher that can be used in Kubernetes mode only. Once activated, it listens for changes in the project workspace in order to trigger a redeploy of the application.

The watcher can be activated e.g. by running this command in another shell:

mvn package

The watcher will detect that the binary artifact has changed and will first rebuild the docker image, then start a redeploy of the Kubernetes pod.

It uses the watch feature of the docker-maven-plugin under the hood.

6.5.3. Supported Properties for Watch goal

Table 22. Options available with watch goal
Element Description Property

kubernetesManifest

The generated kubernetes YAML file.

Defaults to ${basedir}/target/classes/META-INF/jkube/kubernetes.yml.

jkube.kubernetesManifest

watchMode

How to watch for image changes.

  • copy: Copy watched artifacts into container

  • build: Build only images

  • run: Run images

  • both: Build and run images

Defaults to both.

jkube.watch.mode

watchInterval

Interval in milliseconds (how often to check for changes).

Defaults to 5000.

jkube.watch.interval

keepRunning

If set to true all containers will be kept running after k8s:watch has been stopped.

Defaults to false.

jkube.watch.keepRunning

watchPostGoal

A maven goal which should be called if a rebuild or a restart has been performed.

This goal must have the format <pluginGroupId>:<pluginArtifactId>:<goal> and the plugin must be configured in the pom.xml.

For example a post-goal com.example:group:delete-pods will trigger the delete-pods goal of this hypothetic example.

jkube.watch.postGoal

watchPostExec

A command which is executed within the container after files are copied into this container when watchMode is copy. Note that this container must be running.

jkube.watch.postExec

keepContainer

If this is set to false (and keepRunning is disabled) then all containers will be removed after they have been stopped.

Defaults to false.

jkube.watch.keepContainer

removeVolumes

If set to true remove any volumes associated with the container as well.

This option will be ignored if either keepContainer or keepRunning is true.

Defaults to false.

jkube.watch.removeVolumes

watchShowLogs

If set to true, logs will be shown for watched container.

jkube.watch.showLogs

watchFollow

If watchShowLogs is set to false, and there is a run image configuration, logs are followed if set to true.

Defaults to false.

jkube.watch.follow

7. Generators

The usual way to define Docker images is with the plugin configuration as explained in k8s:build. This can either be done completely within the pom.xml or by referring to an external Dockerfile. Since kubernetes-maven-plugin includes docker-maven-plugin the way by which images are built is identical.

However, this plugin provides an additional route for defining image configurations. This is done by so called Generators. A generator is a Java component providing an auto-detection mechanism for certain build types like a Spring Boot build or a plain Java build. As soon as a Generator detects that it is applicable it will be called with the list of images configured in the pom.xml. Typically a generator only creates dynamically a new image configuration if this list is empty. But a generator is free to also add new images to an existing list or even change the current image list.

You can easily create your own generator as explained in Generator API. This section will focus on existing generators and how you can configure them.

The included Generators are enabled by default, but you can easily disable them or only select a certain set of generators. Each generator has a name, which is unique for a generator.

The generator configuration is embedded in a <generator> configuration section:

Example for a generator configuration
<plugin>
  ....
  <configuration>
    ....
    <generator> (1)
      <includes> (2)
        <include>spring-boot</include>
      </includes>
      <config> (3)
        <spring-boot> (4)
          <alias>ping</alias>
        </spring-boot>
      </config>
    </generator>
  </configuration>
</plugin>
1 Start of generators' configuration.
2 Generators can be included and excluded. Includes have precedence, and the generators are called in the given order.
3 Configuration for individual generators.
4 The config is a map of supported config values. Each section is embedded in a tag named after the generator.

The following sub-elements are supported:

Table 23. Generator configuration
Element Description

<includes>

Contains one ore more <include> elements with generator names which should be included. If given only this list of generators are included in this given order. The order is important because by default only the first matching generator kicks in. The generators from every active profile are included, too. However the generators listed here are moved to the front of the list, so that they are called first. Use the profile raw if you want to explicitly set the complete list of generators.

<excludes>

Holds one or more <exclude> elements with generator names to exclude. If set then all detected generators are used except the ones mentioned in this section.

<config>

Configuration for all generators. Each generator support a specific set of configuration values as described in the documentation. The subelements of this section are generator names to configure. E.g. for generator spring-boot, the sub-element is called <spring-boot>. This element then holds the specific generator configuration like <name> for specifying the final image name. See above for an example. Configuration coming from profiles are merged into this config, but not overriding the configuration specified here.

Beside specifying generator configuration in the plugin’s configuration it can be set directly with properties, too:

Example generator property config
mvn -Djkube.generator.java-exec.webPort=8082

The general scheme is a prefix jkube.generator. followed by the unique generator name and then the generator specific key.

In addition to the provided default Generators described in the next section Default Generators, custom generators can be easily added. There are two ways to include generators:

Plugin dependency

You can declare the generator holding jars as dependency to this plugin as shown in this example

<plugin>
  <artifactId>kubernetes-maven-plugin</artifactId>
  ....
  <dependencies>
    <dependency>
      <groupId>io.acme</groupId>
      <artifactId>mygenerator</artifactId>
      <version>1.0</version>
    </dependency>
  </dependencies>
</plugin>
Compile time dependency

Alternatively and if your application code comes with a custom generator you can set the global configuration option useProjectClasspath (property: jkube.useProjectClasspath) to true. In this case also the project artifact and its dependencies are looked up for Generators. See Generator API for details how to write your own generators.

7.1. Default Generators

All default generators examine the build information for certain aspects and generate a Docker build configuration on the fly. They can be configured to a certain degree, where the configuration is generator specific.

Table 24. Default Generators
Generator Name Description

Java Applications

java-exec

Generic generator for flat classpath and fat-jar Java applications

Spring Boot

spring-boot

Spring Boot specific generator

Wildfly Swarm

wildfly-swarm

Generator for Wildfly Swarm apps

Thorntail v2

thorntail-v2

Generator for Thorntail v2 apps

Vert.x

vertx

Generator for Vert.x applications

Karaf

karaf

Generator for Karaf based apps

Web applications

webapps

Generator for WAR based applications supporting Tomcat, Jetty and Wildfly base images

Quarkus

Quarkus

Generator for Quarkus based applications

Open Liberty

openliberty

Generator for Open Liberty applications

WildFly Bootable JAR

wildfly-jar

Generator for WildFly Bootable JAR applications

There are some configuration options which are shared by all generators:

Table 25. Common generator options
Element Description Property

add

When set to true, then the generator adds to an existing image configuration. By default this is disabled, so that a generator only kicks in when there are no other image configurations in the build, which are either configured directly for a k8s:build or already added by a generator which has been run previously.

jkube.generator.add

alias

An alias name for referencing this image in various other parts of the configuration. This is also used in the log output. The default alias name is the name of the generator.

jkube.generator.alias

from

This is the base image from where to start when creating the images. By default the generators make an opinionated decision for the base image which are described in the respective generator section.

jkube.generator.from

fromMode

Whe using OpenShift S2I builds the base image can be either a plain docker image (mode: jib) or a reference to an ImageStreamTag (mode: istag). In the case of an ImageStreamTag, from has to be specified in the form namespace/image-stream:tag. The mode takes only effect when running in OpenShift mode.

jkube.generator.fromMode

name

The Docker image name used when doing Docker builds. For OpenShift S2I builds its the name of the image stream. This can be a pattern as descibed in Name Placeholders. The default is %g/%a:%l.

jkube.generator.name

registry

A optional Docker registry used when doing Docker builds. It has no effect for OpenShift S2I builds.

jkube.generator.registry

When used as properties they can be directly referenced with the property names above.

7.1.1. Java Applications

One of the most generic Generators is the java-exec generator. It is responsible for starting up arbitrary Java application. It knows how to deal with fat-jar applications where the application and all dependencies are included within a single jar and the MANIFEST.MF within the jar references a main class. But also flat classpath applications, where the dependencies are separate jar files and a main class is given.

If no main class is explicitly configured, the plugin first attempts to locate a fat jar. If the Maven build creates a JAR file with a META-INF/MANIFEST.MF containing a Main-Class entry, then this is considered to be the fat jar to use. If there are more than one of such files then the largest one is used.

If a main class is configured (see below) then the image configuration will contain the application jar plus all dependency jars. If no main class is configured as well as no fat jar being detected, then this Generator tries to detect a single main class by searching for public static void main(String args[]) among the application classes. If exactly one class is found this is considered to be the main class. If no or more than one is found the Generator finally does nothing.

It will use the following base image by default, but as explained above and can be changed with the from configuration.

Table 26. Java Base Images
Docker Build S2I Build ImageStream

Community

quay.io/jkube/jkube-java-binary-s2i

quay.io/jkube/jkube-java-binary-s2i

jkube-java

These images always refer to the latest tag.

When a fromMode of istag is used to specify an ImageStreamTag and when no from is given, then as default the ImageStreamTag jkube-java in the namespace openshift is chosen. By default, fromMode = "docker" which use the a plain Docker image reference for the S2I builder image.

Beside the common configuration parameters described in the table common generator options the following additional configuration options are recognized:

Table 27. Java Application configuration options
Element Description Property

targetDir

Directory within the generated image where to put the detected artefacts into. Change this only if the base image is changed, too.

Defaults to /deployments.

jkube.generator.java-exec.targetDir

jolokiaPort

Port of the Jolokia agent exposed by the base image. Set this to 0 if you don’t want to expose the Jolokia port.

Defaults to 8778.

jkube.generator.java-exec.jolokiaPort

mainClass

Main class to call. If not given first a check is performed to detect a fat-jar (see above). Next a class is looked up by scanning target/classes for a single class with a main method. If no such class is found or if more than one is found, then this generator does nothing.

jkube.generator.java-exec.mainClass

prometheusPort

Port of the Prometheus jmx_exporter exposed by the base image. Set this to 0 if you don’t want to expose the Prometheus port.

Defaults to 9779.

jkube.generator.java-exec.prometheusPort

webPort

Port to expose as service, which is supposed to be the port of a web application. Set this to 0 if you don’t want to expose a port.

Defaults to 8080.

jkube.generator.java-exec.webPort

The exposed ports are typically later on use by Enrichers to create default Kubernetes or OpenShift services.

You can add additional files to the target image within baseDir by placing files into src/main/jkube-includes. These will be added with mode 0644, while everything in src/main/jkube-includes/bin will be added with 0755.

7.1.2. Spring Boot

This generator is called spring-boot and gets activated when it finds a spring-boot-maven-plugin in the pom.xml.

This generator is based on the Java Application Generator and inherits all of its configuration values. The generated container port is read from the server.port property application.properties, defaulting to 8080 if it is not found. It also uses the same default images as the java-exec Generator.

Beside the common generator options and the java-exec options the following additional configuration is recognized:

Table 28. Spring-Boot configuration options
Element Description Property

color

If set, force the use of color in the Spring Boot console output.

jkube.generator.spring-boot.color

The generator adds Kubernetes liveness and readiness probes pointing to either the management or server port as read from the application.properties. If the management.port (for Spring Boot 1) or management.server.port (for Spring Boot 2) and management.ssl.key-store (for Spring Boot 1) or management.server.ssl.key-store (for Spring Boot 2) properties are set in application.properties otherwise or server.ssl.key-store property is set in application.properties then the probes are automatically set to use https.

The generator works differently when called together with k8s:watch. In that case it enables support for Spring Boot Developer Tools which allows for hot reloading of the Spring Boot app. In particular, the following steps are performed:

  • If a secret token is not provided within the Spring Boot application configuration application.properties or application.yml with the key spring.devtools.remote.secret then a custom secret token is created and added to application.properties

  • Add spring-boot-devtools.jar as BOOT-INF/lib/spring-devtools.jar to the spring-boot fat jar.

Since during k8s:watch the application itself within the target/ directory is modified for allowing easy reloading you must ensure that you do a mvn clean before building an artifact which should be put into production. Since the released version are typically generated with a CI system which does a clean build anyway this should be only a theoretical problem.

7.1.3. Wildfly Swarm

The WildFly Swarm generator detects a WildFly Swarm build and disables the Prometheus Java agent because of this issue.

Otherwise this generator is identical to the java-exec generator. It supports the common generator options and the java-exec options.

7.1.4. Thorntail v2

The Thorntail v2 generator detects a Thorntail v2 build and disables the Prometheus Java agent because of this issue.

Otherwise this generator is identical to the java-exec generator. It supports the common generator options and the java-exec options.

7.1.5. Vert.x

The Vert.x generator detects an application using Eclipse Vert.x. It generates the metadata to start the application as a fat jar.

Currently, this generator is enabled if:

Otherwise this generator is identical to the java-exec generator. It supports the common generator options and the java-exec options.

The generator automatically:

  • enable metrics and JMX publishing of the metrics when io.vertx:vertx-dropwizard-metrics is in the project’s classpath / dependencies.

  • enable clustering when a Vert.x cluster manager is available in the project’s classpath / dependencies. this is done by appending -cluster to the command line.

  • Force IPv4 stack when vertx-infinispan is used.

  • Disable the async DNS resolver to fallback to the regular JVM DNS resolver.

You can pass application parameter by setting the JAVA_ARGS env variable. You can pass system properties either using the same variable or using JAVA_OPTIONS. For instance, create src/main/jkube/deployment.yml with the following content to configure JAVA_ARGS:

spec:
 template:
   spec:
     containers:
       - env:
         - name: JAVA_ARGS
           value: "-Dfoo=bar -cluster -instances=2"

7.1.6. Karaf

This generator named karaf kicks in when the build uses a karaf-maven-plugin. By default the following base images are used:

Table 29. Karaf Base Images
Docker Build S2I Build ImageStream

Community

quay.io/jkube/jkube-karaf-binary-s2i

quay.io/jkube/jkube-karaf-binary-s2i

jkube-karaf

When a fromMode of istag is used to specify an ImageStreamTag and when no from is given, then as default the ImageStreamTag jkube-karaf in the namespace openshift is chosen.

In addition to the common generator options this generator can be configured with the following options:

Table 30. Karaf configuration options
Element Description Property

baseDir

Directory within the generated image where to put the detected artifacts into. Change this only if the base image is changed, too.

Defaults to /deployments.

jkube.generator.karaf.baseDir

webPort

Port to expose as service, which is supposed to be the port of a web application. Set this to 0 if you don’t want to expose a port.

Defaults to 8080.

jkube.generator.karaf.webPort

7.1.7. Web Applications

The webapp generator tries to detect WAR builds and selects a base servlet container image based on the configuration found in the pom.xml:

  • A Tomcat base image is selected when a tomcat6-maven-plugin or tomcat7-maven-plugin is present or when a META-INF/context.xml could be found in the classes directory.

  • A Jetty base image is selected when a jetty-maven-plugin is present or one of the files WEB-INF/jetty-web.xml or WEB-INF/jetty-logging.properties is found.

  • A Wildfly base image is chosen for a given jboss-as-maven-plugin or wildfly-maven-plugin or when a Wildfly specific deployment descriptor like jboss-web.xml is found.

The base images chosen are:

Table 31. Webapp Base Images
Docker Build S2I Build

Tomcat

quay.io/jkube/jkube-tomcat9-binary-s2i

quay.io/jkube/jkube-tomcat9-binary-s2i

Jetty

quay.io/jkube/jkube-jetty9-binary-s2i

quay.io/jkube/jkube-jetty9-binary-s2i

Wildfly

jboss/wildfly

quay.io/wildfly/wildfly-centos7

In addition to the common generator options this generator can be configured with the following options:

Table 32. Webapp configuration options
Element Description Property

server

Fix server to use in the base image. Can be either tomcat, jetty or wildfly.

jkube.generator.webapp.server

targetDir

Where to put the war file into the target image. By default its selected by the base image chosen but can be overwritten with this option.

Defaults to /deployments.

jkube.generator.webapp.targetDir

user

User and/or group under which the files should be added. The syntax of this options is descriped in Assembly Configuration.

jkube.generator.webapp.user

path

Context path with which the application can be reached by default.

Defaults to / (root context).

jkube.generator.webapp.path

cmd

Command to use to start the container. By default the base images startup command is used.

jkube.generator.webapp.cmd

ports

Comma separated list of ports to expose in the image and which eventually are translated later to Kubernetes services. The ports depend on the base image and are selected automatically. But they can be overridden here.

jkube.generator.webapp.ports

7.1.8. Quarkus

The Quarkus generator tried to detect quarkus based projects looking at project pom.xml:

The base images chosen are:

Table 33. Webapp Base Images
Docker Build S2I Build

Native

registry.access.redhat.com/ubi8/ubi-minimal:8.1

---

Normal Build

openjdk:11

---

S2I builds are currently not yet supported for the Quarkus generator.

7.1.9. Open Liberty

The Open Liberty generator runs when the Open Liberty plugin is enabled in the maven build.

The generator is similar to the java-exec generator. It supports the common generator options and the java-exec options.

For Open Liberty, the default value of webPort is 9080.

7.1.10. Wildfly JAR Generator

The Wildfly JAR generator detects a WildFly Bootable JAR build and disables the Jolokia and Prometheus Java agent TO BE REVISITED WHEN WE HAVE A SOLUTION.

Otherwise this generator is identical to the java-exec generator. It supports the common generator options and the java-exec options.

7.2. Generator API

The API is still a bit in flux and will be documented later. Please refer to the Generator Interface in the meantime.

8. Enrichers

Enriching is the complementary concept to Generators. Whereas Generators are used to create and customize Docker images, Enrichers are use to create and customize Kubernetes resource objects.

There are a lot of similarities to Generators:

  • Each Enricher has a unique name.

  • Enrichers are looked up automatically from the plugin dependencies and there is a set of default enrichers delivered with this plugin.

  • Enrichers are configured the same ways as generators

The Generator example is a good blueprint, simply replace <generator> with <enricher>. The configuration is structural identical:

Table 34. Enricher configuration
Element Description

<includes>

Contains one ore more <include> elements with enricher names which should be included. If given, only this list of enrichers are included in this order. The enrichers from every active profile are included, too. However the enrichers listed here are moved to the front of the list, so that they are called first. Use the profile raw if you want to explicitly set the complete list of enrichers.

<excludes>

Holds one or more <exclude> elements with enricher names to exclude. This means all the detected enrichers are used except the ones mentioned in this section.

<config>

Configuration for all enrichers. Each enricher supports a specific set of configuration values as described in its documentation. The subelements of this section are enricher names. E.g. for enricher jkube-service, the sub-element is called <jkube-service>. This element then holds the specific enricher configuration like <name> for the service name. Configuration coming from profiles are merged into this config, but not overriding the configuration specified here.

This plugin comes with a set of default enrichers. In addition custom enrichers can be easily added by providing implementation of the Enricher API and adding these as a dependency to the build.

8.1. Default Enrichers

kubernetes-maven-plugin comes with a set of enrichers which are enabled by default. There are two categories of default enrichers:

  • Generic Enrichers are used to add default resource object when they are missing or add common metadata extracted from the given build information.

  • Specific Enrichers are enrichers which are focused on a certain tech stack that they detect.

Table 35. Default Enrichers Overview
Enricher Description

jkube-configmap-file

Add ConfigMap elements defined as XML or as annotation.

jkube-controller

Create default controller (replication controller, replica set or deployment Kubernetes doc) if missing.

jkube-dependency

Examine build dependencies for kubernetes.yml and add the objects found therein.

jkube-git

Check local .git directory and add build information as annotations.

jkube-image

Add the image name into a PodSpec of replication controller, replication sets and deployments, if missing.

jkube-maven-issue-mgmt

Add Maven Issue Management information as annotations to the kubernetes/openshift resources

jkube-maven-scm-enricher

Add Maven SCM information as annotations to the kubernetes/openshift resources

jkube-name

Add a default name to every object which misses a name.

jkube-pod-annotation

Copy over annotations from a Deployment to a Pod

jkube-portname

Add a default portname for commonly known service.

jkube-project-label

Add Maven coordinates as labels to all objects.

jkube-prometheus

Add Prometheus annotations.

jkube-revision-history

Add revision history limit (Kubernetes doc) as a deployment spec property to the Kubernetes/OpenShift resources.

jkube-secret-file

Add Secret elements defined as annotation.

jkube-service

Create a default service if missing and extract ports from the Docker image configuration.

jkube-serviceaccount

Add a ServiceAccount defined as XML or mentioned in resource fragment.

jkube-triggers-annotation

Add ImageStreamTag change triggers on Kubernetes resources such as StatefulSets, ReplicaSets and DaemonSets using the image.openshift.io/triggers annotation.

8.1.1. Generic Enrichers

Default generic enrichers are used for adding missing resources or adding metadata to given resource objects. The following default enhancers are available out of the box.

jkube-configmap-file

This enricher adds ConfigMap defined as resources in plugin configuration and/or resolves file content from an annotation.

As XML you can define:

pom.xml
<configuration>
  <resources>
    <configMap>
      <name>myconfigmap</name>
      <entries>
        <entry>
          <name>A</name>
          <value>B</value>
        </entry>
       </entries>
    </configMap>
  </resources>
</configuration>

This creates a ConfigMap data with key A and value B.

You can also use file tag to refer to the content of a file.

<configuration>
  <resources>
    <configMap>
      <name>configmap-test</name>
      <entries>
        <entry>
          <file>src/test/resources/test-application.properties</file>
        </entry>
       </entries>
    </configMap>
  </resources>
</configuration>

This creates a ConfigMap with key test-application.properties and value the content of the src/test/resources/test-application.properties file. If you set name tag then this is used as key instead of the filename.

If you are defining a custom ConfigMap file, you can use an annotation to define a file name as key and its content as the value:

metadata:
  name: ${project.artifactId}
  annotations:
    maven.jkube.io/cm/application.properties: src/test/resources/test-application.properties

This creates a ConfigMap data with key application.properties (part defined after cm) and value the content of src/test/resources/test-application.properties file.

jkube-controller

This enricher is used to ensure that a controller is present. This can be either directly configured with fragments or with the XML configuration. An explicit configuration always takes precedence over auto detection. See Kubernetes doc for more information on types of controllers.

The following configuration parameters can be used to influence the behaviour of this enricher:

Table 36. Default controller enricher
Element Description Property

name

Name of the Controller. Kubernetes Controller names must start with a letter. If the maven artifactId starts with a digit, s will be prefixed.

Defaults to ${project.artifactId}.

jkube.enricher.jkube-controller.name

pullPolicy

Image pull policy to use for the container. One of: IfNotPresent, Always.

Defaults to IfNotPresent.

jkube.enricher.jkube-controller.pullPolicy

type

Type of Controller to create. One of: ReplicationController, ReplicaSet, Deployment, DeploymentConfig, StatefulSet, DaemonSet, Job.

Defaults to Deployment.

jkube.enricher.jkube-controller.type

replicaCount

Number of replicas for the container.

Defaults to 1.

jkube.enricher.jkube-controller.replicaCount

jkube-service

This enricher is used to ensure that a service is present. This can be either directly configured with fragments or with the XML configuration, but it can be also automatically inferred by looking at the ports exposed by an image configuration. An explicit configuration always takes precedence over auto detection. For enriching an existing service this enricher actually works only on a configured service which matches with the configured (or inferred) service name.

The following configuration parameters can be used to influence the behaviour of this enricher:

Table 37. Default service enricher
Element Description Property

name

Service name to enrich by default. If not given here or configured elsewhere, the artifactId is used.

jkube.enricher.jkube-service.name

headless

Whether a headless service without a port should be configured. A headless service has the ClusterIP set to None and will be only used if no ports are exposed by the image configuration or by the configuration port.

Defaults to false.

jkube.enricher.jkube-service.headless

expose

If set to true, a label expose with value true is added which can be picked up by the jkube. expose-controller to expose the service to the outside by various means. See the documentation of expose-controller for more details.

Defaults to false.

jkube.enricher.jkube-service.expose

type

Kubernetes / OpenShift service type to set like LoadBalancer, NodePort or ClusterIP.

jkube.enricher.jkube-service.type

port

The service port to use. By default the same port as the ports exposed in the image configuration is used, but can be changed with this parameter. See below for a detailed description of the format which can be put into this variable.

jkube.enricher.jkube-service.port

multiPort

Set this to true if you want all ports to be exposed from an image configuration. Otherwise only the first port is used as a service port.

Defaults to false.

jkube.enricher.jkube-service.multiPort

protocol

Default protocol to use for the services. Must be tcp or udp.

Defaults to tcp.

jkube.enricher.jkube-service.protocol

normalizePort

Normalize the port numbering of the service to common and conventional port numbers.

Defaults to false.

jkube.enricher.jkube-service.normalizePort

Following is the Port mapping that comes in effect, when normalizePort option is set true.

Original Port Normalized Port

8080

80

8081

80

8181

80

8180

80

8443

443

443

443

You specify the properties like for any enricher within the enrichers configuration like in

Example
<configuration>
  <!-- ... -->
  <enricher>
    <config>
      <jkube-service>
        <name>my-service</name>
        <type>NodePort</type>
        <multiPort>true</multiPort>
      </jkube-service>
    </config>
  </enricher>
</configuration>
Port specification

With the option port you can influence the mapping how ports are mapped from the pod to the service. By default and if this option is not given the ports exposed are dictated by the ports exposed from the Docker images contained in the pods. Remember, each image configured can be part of the pod. However you can expose also completely different ports as the images meta data declare.

The property port can contain a comma separated list of mappings of the following format:

<servicePort1>:<targetPort1>/<protocol>,<servicePort2>:<targetPort2>/<protocol>,....

where the targetPort and <protocol> specification is optional. These ports are overlayed over the ports exposed by the images, in the given order.

This is best explained by some examples.

For example if you have a pod which exposes a Microservice on port 8080 and you want to expose it as a service on port 80 (so that it can be accessed with http://myservice) you can simply use the following enricher configuration:

Example
<configuration>
  <enricher>
    <config>
      <jkube-service>
        <name>myservice</name>
        <port>80:8080</port> (1)
      </jkube-service>
    </config>
  </enricher>
</configuration>
1 80 is the service port, 8080 the port opened in from the pod’s images

If your pod exposes their ports (which e.g. all generator do), then you can even omit the 8080 here (i.e. <port>80</port>). In this case the first port exposed will be mapped to port 80, all other exposed ports will be omitted.

By default an automatically generated service only exposes the first port, even when more ports are exposed. When you want to map multiple ports you need to set the config option <multiPort>true</multiPort>. In this case you can also provide multiple mappings as a comma separated list in the <port> specification where each element of the list are the mapping for the first, second, …​ port.

A more (and bit artificially constructed) specification could be <port>80,9779:9779/udp,443</port>. Assuming that the image exposes ports 8080 and 8778 (either directly or via generators) and we have switched on multiport mode, then the following service port mappings will be performed for the automatically generated service:

  • Pod port 8080 is mapped to service port 80.

  • Pod port 9779 is mapped to service port 9779 with protocol UDP. Note how this second entry overrides the pod exposed port 8778.

  • Pod port 443 is mapped to service port 443.

This example shows also the mapping rules:

  • Port specification in port always override the port metadata of the contained Docker images (i.e. the ports exposed)

  • You can always provide a complete mapping with port on your own

  • The ports exposed by the images serve as default values which are used if not specified by this configuration option.

  • You can map ports which are not exposed by the images by specifying them as target ports.

Multiple ports are only mapped when multiPort mode is enabled (which is switched off by default). If multiPort mode is disabled, only the first port from the list of mapped ports calculated as above is taken.

When you set legacyPortMapping to true than ports 8080 to 9090 are mapped to port 80 automatically if not explicitly mapped via port. I.e. when an image exposes port 8080 with a legacy mapping this mapped to a service port 80, not 8080. You should not switch this on for any good reason. In fact it might be that this option can vanish anytime.

jkube-image
jkube-name
jkube-portname
jkube-pod-annotation
jkube-project-label

Enricher that adds standard labels and selectors to generated resources (e.g. app, group, provider, version).

The jkube-project-label enricher supports the following configuration options:

Option Description Property

useProjectLabel

Enable this flag to turn on the generation of the old project label in Kubernetes resources. The project label has been replaced by the app label in newer versions of the plugin.

Defaults to false.

jkube.enricher.jkube-project-label.useProjectLabel

app

Makes it possible to define a custom app label used in the generated resource files used for deployment.

Defaults to the Maven project.artifactId property.

jkube.enricher.jkube-project-label.app

The project labels which are already specified in the input fragments are not overridden by the enricher.

jkube-git

Enricher that adds info from .git directory as annotations.

The git branch & latest commit on the branch are annotated as jkube.io/git-branch & jkube.io/git-commit. jkube.io/git-url is annotated as the URL of your configured remote.

Option Description Property

gitRemote

Configures the git remote name, whose URL you want to annotate as 'git-url'.

Defaults to origin.

jkube.enricher.jkube-git.gitRemote

jkube-dependency
jkube-volume-permission

Enricher which fixes the permission of persistent volume mount with the help of an init container.

jkube-openshift-autotls

Enricher which adds appropriate annotations and volumes to enable OpenShift’s automatic Service Serving Certificate Secrets. This enricher adds an init container to convert the service serving certificates from PEM (the format that OpenShift generates them in) to a JKS-format Java keystore ready for consumption in Java services.

This enricher is disabled by default. In order to use it, you must configure the kubernetes-maven-plugin to use this enricher:

<plugin>
  <groupId>org.eclipse.jkube</groupId>
  <artifactId>kubernetes-maven-plugin</artifactId>
  <version>1.0.0</version>
  <executions>
    <execution>
      <goals>
        <goal>resource</goal>
      </goals>
    </execution>
  </executions>
  <configuration>
    <enricher>
      <includes>
        <include>jkube-openshift-autotls</include>
      </includes>
      <config>
        <jkube-openshift-autotls>
          <!-- ... -->
        </jkube-openshift-autotls>
      </config>
    </enricher>
  </configuration>
</plugin>

The auto-TLS enricher supports the following configuration options:

Element Description Property

tlsSecretName

The name of the secret to be used to store the generated service serving certs.

Defaults to <project.artifactId>-tls.

jkube.enricher.jkube-openshift-autotls.tlsSecretName

tlsSecretVolumeMountPoint

Where the service serving secret should be mounted to in the pod.

Defaults to /var/run/secrets/jkube.io/tls-pem.

jkube.enricher.jkube-openshift-autotls.tlsSecretName

tlsSecretVolumeName

The name of the secret volume.

Defaults to tls-pem.

jkube.enricher.jkube-openshift-autotls.tlsSecretVolumeName

jksVolumeMountPoint

Where the generated keystore volume should be mounted to in the pod.

Defaults to /var/run/secrets/jkube.io/tls-jks.

jkube.enricher.jkube-openshift-autotls.the

jksVolumeName

The name of the keystore volume.

Defaults to tls-jks.

jkube.enricher.jkube-openshift-autotls.jksVolumeName

pemToJKSInitContainerImage

The name of the image used as an init container to convert PEM certificate/key to Java keystore.

Defaults to jimmidyson/pemtokeystore:v0.1.0.

jkube.enricher.jkube-openshift-autotls.pemToJKSInitContainerImage

pemToJKSInitContainerName

the name of the init container to convert PEM certificate/key to Java keystore.

Defaults to tls-jks-converter.

jkube.enricher.jkube-openshift-autotls.pemToJKSInitContainerName

keystoreFileName

The name of the generated keystore file.

Defaults to keystore.jks.

jkube.enricher.jkube-openshift-autotls.keystoreFileName

keystorePassword

The password to use for the generated keystore.

Defaults to changeit.

jkube.enricher.jkube-openshift-autotls.keystorePassword

keystoreCertAlias

The alias in the keystore used for the imported service serving certificate.

Defaults to server.

jkube.enricher.jkube-openshift-autotls.keystoreCertAlias

jkube-prometheus

This enricher adds Prometheus annotation like:

apiVersion: v1
kind: List
items:
- apiVersion: v1
  kind: Service
  metadata:
    annotations:
      prometheus.io/scrape: "true"
      prometheus.io/port: 9779
      prometheus.io/path: "/metrics"

By default the enricher inspects the images' BuildConfiguration and add the annotations if the port 9779 is listed. You can force the plugin to add annotations by setting enricher’s config prometheusPort

jkube-maven-scm-enricher

This enricher adds additional SCM related metadata to all objects supporting annotations. These metadata will be added only if SCM information is present in the maven pom.xml of the project.

The following annotations will be added to the objects that supports annotations,

Table 38. Maven SCM Enrichers Annotation Mapping
Maven SCM Info Annotation Description

scm/connection

jkube.io/scm-con-url

The SCM connection that will be used to connect to the project’s SCM

scm/developerConnection

jkube.io/scm-devcon-url

The SCM Developer Connection that will be used to connect to the project’s developer SCM

scm/tag

jkube.io/scm-tag

The SCM tag that will be used to checkout the sources, like HEAD dev-branch etc.,

scm/url

jkube.io/scm-url

The SCM web url that can be used to browse the SCM over web browser

Lets say you have a maven pom.xml with the following scm information,

<scm>
    <connection>scm:git:git://github.com/jkubeio/kubernetes-maven-plugin.git</connection>
    <developerConnection>scm:git:git://github.com/jkubeio/kubernetes-maven-plugin.git</developerConnection>
    <url>git://github.com/jkubeio/kubernetes-maven-plugin.git</url>
</scm>

This information will be enriched as annotations in the generated manifest like,

# ...
  kind: Service
  metadata:
    annotations
      jkube.io/scm-con-url: "scm:git:git://github.com/jkubeio/kubernetes-maven-plugin.git"
      jkube.io/scm-devcon-url: "scm:git:git://github.com/jkubeio/kubernetes-maven-plugin.git"
      jkube.io/scm-tag: "HEAD"
      jkube.io/scm-url: "git://github.com/jkubeio/kubernetes-maven-plugin.git"
# ...
jkube-maven-issue-mgmt

This enricher adds additional Issue Management related metadata to all objects supporting annotations. These metadata will be added only if the Issue Management information is available in the pom.xml of the Maven project.

The following annotations will be added to the objects that support these annotations,

Table 39. Maven Issue Tracker Enrichers Annotation Mapping
Maven Issue Tracker Info Annotation Description

issueManagement/system

jkube.io/issue-system

The Issue Management system like Bugzilla, JIRA, GitHub etc.,

issueManagement/url

jkube.io/issue-tracker-url

The Issue Management url e.g. GitHub Issues Url

Lets say you have a maven pom.xml with the following issue management information,

<issueManagement>
   <system>GitHub</system>
   <url>https://github.com/reactiverse/vertx-maven-plugin/issues/</url>
</issueManagement>

This information will be enriched as annotations in the generated manifest like,

# ...
  kind: Service
  metadata:
    annotations:
      jkube.io/issue-system: "GitHub"
      jkube.io/issue-tracker-url: "https://github.com/reactiverse/vertx-maven-plugin/issues/"
# ...
jkube-revision-history

This enricher adds spec.revisionHistoryLimit property to deployment spec of Kubernetes/OpenShift resources. A deployment’s revision history is stored in the replica sets, that specifies the number of old ReplicaSets to retain in order to allow rollback. For more information read Kubernetes documentation.

The following configuration parameters can be used to influence the behaviour of this enricher:

Table 40. Default revision history enricher
Element Description Property

limit

Number of revision histories to retain.

Defaults to 2.

jkube.enricher.jkube-revision-history.limit

Just as any other enricher you can specify required properties with in the enricher’s configuration as below,

<!-- ... -->
<enricher>
    <config>
        <jkube-revision-history>
            <limit>8</limit>
        </jkube-revision-history>
    </config>
</enricher>
<!-- ... -->

This information will be enriched as spec property in the generated manifest like,

# ...
kind: Deployment
spec:
  revisionHistoryLimit: 8
# ...
jkube-triggers-annotation

This enricher adds ImageStreamTag change triggers on Kubernetes resources that support the image.openshift.io/triggers annotation, such as StatefulSets, ReplicaSets and DaemonSets.

The trigger is added to all containers that apply, but can be restricted to a limited set of containers using the following configuration:

<!-- ... -->
<enricher>
    <config>
        <jkube-triggers-annotation>
            <containers>container-name-1,c2</containers>
        </jkube-triggers-annotation>
    </config>
</enricher>
<!-- ... -->
jkube-secret-file

This enricher adds Secret defined as file content from an annotation.

If you are defining a custom Secret file, you can use an annotation to define a file name as key and its content as the value:

metadata:
  name: ${project.artifactId}
  annotations:
    maven.jkube.io/secret/application.properties: src/test/resources/test-application.properties

This creates a Secret data with the key application.properties (part defined after secret) and value content of src/test/resources/test-application.properties file (base64 encoded).

jkube-serviceaccount

8.1.2. Specific Enrichers

Specific enrichers provide resource manifest enhancement for a certain tech stack that they detect.

jkube-healthcheck-karaf

This enricher adds kubernetes readiness and liveness probes with Apache Karaf. This requires that jkube.karaf-checks has been enabled in the Karaf startup features.

The enricher will use the following settings by default:

  • port = 8181

  • scheme = HTTP

  • failureThreshold = 3

  • successThreshold = 1

and use paths /readiness-check for readiness check and /health-check for liveness check.

These options cannot be configured.

jkube-healthcheck-spring-boot

This enricher adds kubernetes readiness and liveness probes with Spring Boot. This requires the following dependency has been enabled in Spring Boot

<dependency>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-actuator</artifactId>
</dependency>

The enricher will try to discover the settings from the application.properties / application.yaml Spring Boot configuration file.

The port number is read from the management.port option, and will use the default value of 8080 The scheme will use HTTPS if server.ssl.key-store option is in use, and fallback to use HTTP otherwise.

The enricher will use the following settings by default:

  • readinessProbeInitialDelaySeconds : 10

  • readinessProbePeriodSeconds : <kubernetes-default>

  • livenessProbeInitialDelaySeconds : 180

  • livenessProbePeriodSeconds : <kubernetes-default>

  • timeoutSeconds : <kubernetes-default>

  • failureThreshold: 3

  • successThreshold: 1

These values can be configured by the enricher in the kubernetes-maven-plugin configuration as shown below:

<plugin>
  <groupId>org.eclipse.jkube</groupId>
  <artifactId>kubernetes-maven-plugin</artifactId>
  <version>1.0.0</version>
  <executions>
    <execution>
      <id>jkube</id>
      <goals>
        <goal>resource</goal>
        <goal>helm</goal>
        <goal>build</goal>
      </goals>
    </execution>
  </executions>
  <configuration>
    <enricher>
      <config>
        <jkube-healthcheck-spring-boot>
          <timeoutSeconds>5</timeoutSeconds>
          <readinessProbeInitialDelaySeconds>30</readinessProbeInitialDelaySeconds>
          <failureThreshold>3</failureThreshold>
          <successThreshold>1</successThreshold>
        </jkube-healthcheck-spring-boot>
      </config>
    </enricher>
  </configuration>
</plugin>
jkube-healthcheck-thorntail-v2

This enricher adds kubernetes readiness and liveness probes with Thorntail v2. This requires the following fraction has been enabled in Thorntail

<dependency>
  <groupId>io.thorntail</groupId>
  <artifactId>microprofile-health</artifactId>
</dependency>

The enricher will use the following settings by default:

  • port = 8080

  • scheme = HTTP

  • path = /health

  • failureThreshold = 3

  • successThreshold = 1

These values can be configured by the enricher in the kubernetes-maven-plugin configuration as shown below:

<plugin>
  <groupId>org.eclipse.jkube</groupId>
  <artifactId>kubernetes-maven-plugin</artifactId>
  <version>1.0.0</version>
  <executions>
    <execution>
      <id>jkube</id>
      <goals>
        <goal>resource</goal>
        <goal>helm</goal>
        <goal>build</goal>
      </goals>
    </execution>
  </executions>
  <configuration>
    <enricher>
      <config>
        <jkube-healthcheck-thorntail>
          <port>4444</port>
          <scheme>HTTPS</scheme>
          <path>health/myapp</path>
          <failureThreshold>3</failureThreshold>
          <successThreshold>1</successThreshold>
        </jkube-healthcheck-thorntail>
      </config>
    </enricher>
  </configuration>
</plugin>
jkube-healthcheck-vertx

This enricher adds kubernetes readiness and liveness probes with Eclipse Vert.x applications. The readiness probe lets Kubernetes detect when the application is ready, while the liveness probe allows Kubernetes to verify that the application is still alive.

This enricher allows configuring the readiness and liveness probes. The following probe types are supported: http (emit HTTP requests), tcp (open a socket), exec (execute a command).

By default, this enricher uses the same configuration for liveness and readiness probes. But specific configurations can be provided too. The configurations can be overridden using project’s properties.

Using the jkube-healthcheck-vertx enricher

The enricher is automatically executed if your project uses the vertx-maven-plugin or depends on io.vertx:vertx-core. However, by default, no health check will be added to your deployment unless configured explicitly.

Minimal configuration

The minimal configuration to add health checks is the following:

<plugin>
  <groupId>org.eclipse.jkube</groupId>
  <artifactId>kubernetes-maven-plugin</artifactId>
  <version>1.0.0</version>
  <executions>
    <execution>
      <id>jkube</id>
      <goals>
        <goal>resource</goal>
        <goal>helm</goal>
        <goal>build</goal>
      </goals>
    </execution>
  </executions>
  <configuration>
    <enricher>
      <config>
        <jkube-healthcheck-vertx>
            <path>/health</path>
        </jkube-healthcheck-vertx>
      </config>
    </enricher>
  </configuration>
</plugin>

It configures the readiness and liveness health checks using HTTP requests on the port 8080 (default port) and on the path /health. The defaults are:

  • port = 8080 (for HTTP)

  • scheme = HTTP

  • path = none (disabled)

the previous configuration can also be given use project’s properties:

<properties>
    <vertx.health.path>/health</vertx.health.path>
</properties>
Configuring differently the readiness and liveness health checks

You can provide two different configuration for the readiness and liveness checks:

<plugin>
  <groupId>org.eclipse.jkube</groupId>
  <artifactId>kubernetes-maven-plugin</artifactId>
  <version>1.0.0</version>
  <executions>
    <execution>
      <id>jkube</id>
      <goals>
        <goal>resource</goal>
        <goal>helm</goal>
        <goal>build</goal>
      </goals>
    </execution>
  </executions>
  <configuration>
    <enricher>
      <config>
        <jkube-healthcheck-vertx>
            <readiness>
              <path>/ready</path>
            </readiness>
            <liveness>
              <path>/health</path>
            </liveness>
        </jkube-healthcheck-vertx>
      </config>
    </enricher>
  </configuration>
</plugin>

You can also use the readiness and liveness chunks in user properties:

<properties>
    <vertx.health.readiness.path>/ready</vertx.health.readiness.path>
    <vertx.health.liveness.path>/ready</vertx.health.liveness.path>
</properties>

Shared (generic) configuration can be set outside of the specific configuration. For instance, to use the port 8081:

<plugin>
  <groupId>org.eclipse.jkube</groupId>
  <artifactId>kubernetes-maven-plugin</artifactId>
  <version>1.0.0</version>
  <executions>
    <execution>
      <id>jkube</id>
      <goals>
        <goal>resource</goal>
        <goal>helm</goal>
        <goal>build</goal>
      </goals>
    </execution>
  </executions>
  <configuration>
    <enricher>
      <config>
        <jkube-healthcheck-vertx>
            <port>8081</port>
            <readiness>
              <path>/ready</path>
            </readiness>
            <liveness>
              <path>/health</path>
            </liveness>
        </jkube-healthcheck-vertx>
      </config>
    </enricher>
  </configuration>
</plugin>

Or:

<properties>
    <vertx.health.port>8081</vertx.health.port>
    <vertx.health.readiness.path>/ready</vertx.health.readiness.path>
    <vertx.health.liveness.path>/ready</vertx.health.liveness.path>
</properties>
Configuration Structure

The configuration is structured as follows

<config>
    <jkube-healthcheck-vertx>
        <!-- Generic configuration, applied to both liveness and readiness -->
        <path>/both</path>
        <liveness>
            <!-- Specific configuration for the liveness probe -->
            <port-name>ping</port-name>
        </liveness>
        <readiness>
            <!-- Specific configuration for the readiness probe -->
            <port-name>ready</port-name>
        </readiness>
    </jkube-healthcheck-vertx>
</config>

The same structure is used in project’s properties:

<properties>
  <!-- Generic configuration given as vertx.health.$attribute -->
  <vertx.health.path>/both</vertx.health.path>
  <!-- Specific liveness configuration given as vertx.health.liveness.$attribute -->
  <vertx.health.liveness.port-name>ping</vertx.health.liveness.port-name>
  <!-- Specific readiness configuration given as vertx.health.readiness.$attribute -->
  <vertx.health.readiness.port-name>ready</vertx.health.readiness.port-name>
</properties>

Important: Project’s plugin configuration override the project’s properties. The overriding rules are: specific configuration > specific properties > generic configuration > generic properties.

Probe configuration

You can configure the different aspects of the probes. These attributes can be configured for both the readiness and liveness probes or be specific to one.

Table 41. Vert.x HealthCheck Enricher probe configuration
Element Description Property

type

The probe type among http (default), tcp and exec.

Defaults to http.

vertx.health.type

jkube.enricher.jkube-healthcheck-vertx.type

initial-delay

Number of seconds after the container has started before probes are initiated.

vertx.health.initial-delay

jkube.enricher.jkube-healthcheck-vertx.initial-delay

period

How often (in seconds) to perform the probe.

vertx.health.period

jkube.enricher.jkube-healthcheck-vertx.period

timeout

Number of seconds after which the probe times out.

vertx.health.timeout

jkube.enricher.jkube-healthcheck-vertx.timeout

success-threshold

Minimum consecutive successes for the probe to be considered successful after having failed.

vertx.health.success-threshold

jkube.enricher.jkube-healthcheck-vertx.success-threshold

failure-threshold

Minimum consecutive failures for the probe to be considered failed after having succeeded.

vertx.health.failure-threshold

jkube.enricher.jkube-healthcheck-vertx.failure-threshold

HTTP specific probe configuration

When using HTTP GET requests to determine readiness or liveness, several aspects can be configured. HTTP probes are used by default. To be more specific set the type attribute to http.

Table 42. Vert.x HealthCheck Enricher HTTP probe configuration
Element Description Property

scheme

Scheme to use for connecting to the host.

Defaults to HTTP.

vertx.health.scheme

jkube.enricher.jkube-healthcheck-vertx.scheme

path

Path to access on the HTTP server. An empty path disable the check.

vertx.health.path

jkube.enricher.jkube-healthcheck-vertx.path

headers

Custom headers to set in the request. HTTP allows repeated headers. It cannot be configured using project’s properties. An example is available below.

vertx.health.headers

jkube.enricher.jkube-healthcheck-vertx.headers

port

Port number to access the container. A 0 or negative number disables the check.

Defaults to 8080.

vertx.health.port

jkube.enricher.jkube-healthcheck-vertx.port

port-name

Name of the port to access on the container. If neither the port nor the port-name is set, the check is disabled. If both are set the configuration is considered invalid.

vertx.health.port-name

jkube.enricher.jkube-healthcheck-vertx.port-name

Here is an example of HTTP probe configuration:

<config>
    <jkube-healthcheck-vertx>
        <initialDelay>3</initialDelay>
        <period>3</period>
        <liveness>
            <port>8081</port>
            <path>/ping</path>
            <scheme>HTTPS</scheme>
            <headers>
                <X-Custom-Header>Awesome</X-Custom-Header>
            </headers>
        </liveness>
        <readiness>
            <!-- disable the readiness probe -->
            <port>-1</port>
        </readiness>
    </jkube-healthcheck-vertx>
</config>
TCP specific probe configuration

You can also configure the probes to just open a socket on a specific port. The type attribute must be set to tcp.

Table 43. Vert.x HealthCheck Enricher TCP probe configuration
Element Description Property

port

Port number to access the container. A 0 or negative number disables the check.

vertx.health.port

jkube.enricher.jkube-healthcheck-vertx.port

port-name

Name of the port to access on the container. If neither the port nor the port-name is set, the check is disabled. If both are set the configuration is considered invalid.

vertx.health.port-name

jkube.enricher.jkube-healthcheck-vertx.port-name

For example:

<config>
    <jkube-healthcheck-vertx>
        <initialDelay>3</initialDelay>
        <period>3</period>
        <liveness>
            <type>tcp</type>
            <port>8081</port>
        </liveness>
        <readiness>
            <!-- use HTTP Get probe -->
            <path>/ping</path>
            <port>8080</port>
        </readiness>
    </jkube-healthcheck-vertx>
</config>
Exec probe configuration

You can also configure the probes to execute a command. If the command succeeds, it returns 0, and Kubernetes consider the pod to be alive and healthy. If the command returns a non-zero value, Kubernetes kills the pod and restarts it. To use a command, you must set the type attribute to exec:

<config>
    <jkube-healthcheck-vertx>
        <initialDelay>3</initialDelay>
        <period>3</period>
        <liveness>
            <type>exec</type>
            <command>
                <cmd>cat</cmd>
                <cmd>/tmp/healthy</cmd>
            </command>
        </liveness>
        <readiness>
            <-- use HTTP Get probe -->
            <path>/ping</path>
            <port>8080</port>
        </readiness>
    </jkube-healthcheck-vertx>
</config>

As you can see in the snippet above the command is passed using the command attribute. This attribute cannot be configured using project’s properties. An empty command disables the check.

Disabling health checks

You can disable the checks by setting:

  • the port to 0 or to a negative number for http and tcp probes

  • the command to an empty list for exec

In the first case, you can use project’s properties to disable them:

<!-- Disables tcp and http probes -->
<vertx.health.port>-1</vertx.health.port>

For http probes, an empty or not set path also disable the probe.

jkube-healthcheck-webapp

This enricher adds kubernetes readiness and liveness probes with WebApp. This requires that you have maven-war-plugin set.

The enricher will use the following settings by default:

  • port = 8080

  • scheme = HTTP

  • path = ``

  • initialReadinessDelay = 10

  • initialLivenessDelay = 180

If path attribute is not set (default value) then this enricher is disabled.

These values can be configured by the enricher in the kubernetes-maven-plugin configuration as shown below:

<plugin>
  <groupId>org.eclipse.jkube</groupId>
  <artifactId>kubernetes-maven-plugin</artifactId>
  <version>1.0.0</version>
  <executions>
    <execution>
      <id>jkube</id>
      <goals>
        <goal>resource</goal>
        <goal>helm</goal>
        <goal>build</goal>
      </goals>
    </execution>
  </executions>
  <configuration>
    <enricher>
      <config>
        <jkube-healthcheck-webapp>
          <path>/</path>
        </jkube-healthcheck-webapp>
      </config>
    </enricher>
  </configuration>
    <!-- ... -->
</plugin>
jkube-healthcheck-wildfly-swarm

This enricher adds kubernetes readiness and liveness probes with WildFly Swarm. This requires the following fraction has been enabled in WildFly Swarm

<dependency>
  <groupId>org.wildfly.swarm</groupId>
  <artifactId>microprofile-health</artifactId>
</dependency>

The enricher will use the following settings by default:

  • port = 8080

  • scheme = HTTP

  • path = /health

  • failureThreshold = 3

  • successThreshold = 1

These values can be configured by the enricher in the kubernetes-maven-plugin configuration as shown below:

<plugin>
  <groupId>org.eclipse.jkube</groupId>
  <artifactId>kubernetes-maven-plugin</artifactId>
  <version>1.0.0</version>
  <executions>
    <execution>
      <id>jkube</id>
      <goals>
        <goal>resource</goal>
        <goal>helm</goal>
        <goal>build</goal>
      </goals>
    </execution>
  </executions>
  <configuration>
    <enricher>
      <config>
        <jkube-healthcheck-wildfly-swarm>
          <port>4444</port>
          <scheme>HTTPS</scheme>
          <path>health/myapp</path>
          <failureThreshold>3</failureThreshold>
          <successThreshold>1</successThreshold>
        </jkube-healthcheck-wildfly-swarm>
      </config>
    </enricher>
  </configuration>
</plugin>
jkube-healthcheck-wildfly-jar

This enricher adds kubernetes readiness and liveness probes to WildFly JAR applications. Probes depend on the WildFly microprofile-health subsystem /health/ready and /health/live endpoints. When the WildFly Bootable JAR Maven plugin is configured with the <cloud> configuration item, microprofile_health subsystem is enforced in the bootable JAR server configuration.

This enricher looks for the <cloud> configuration item presence in the bootable JAR Maven plugin in order to add health check probes. If <cloud> item has not been defined, you can still enforce the generation of readiness and liveness probes by setting enforceProbes=true.

The enricher will use the following settings by default:

  • port = 9990

  • scheme = HTTP

  • readinessPath = /health/ready

  • livenessPath = /health/live

  • livenessInitialDelay = 60

  • readinessIntialDelay = 10

  • failureThreshold = 3

  • successThreshold = 1

  • enforceProbes = 'false'

Setting the port to 0 or to a negative number disables liveness and readiness probes.

These values can be configured by the enricher in the kubernetes-maven-plugin configuration as shown below:

<plugin>
  <groupId>org.eclipse.jkube</groupId>
  <artifactId>kubernetes-maven-plugin</artifactId>
  <version>1.0.0</version>
  <executions>
    <execution>
      <id>jkube</id>
      <goals>
        <goal>resource</goal>
        <goal>build</goal>
      </goals>
    </execution>
  </executions>
  <configuration>
    <enricher>
      <config>
        <jkube-healthcheck-wildfly-jar>
          <port>4444</port>
          <scheme>HTTPS</scheme>
          <livenessPath>/myapp/live</livenessPath>
          <failureThreshold>3</failureThreshold>
          <successThreshold>1</successThreshold>
        </jkube-healthcheck-wildfly-jar>
      </config>
    </enricher>
  </configuration>
</plugin>

8.2. Enricher API

How to write your own enrichers and install them.

9. Profiles

Profiles can be used to combine a set of enrichers and generators and to give this combination a referable name.

Profiles are defined in YAML. The following example shows a simple profiles which uses only the Spring Boot generator and some enrichers adding for adding default resources:

Profile Definition
- name: my-spring-boot-apps (1)
  generator: (2)
    includes:
      - spring-boot
  enricher: (3)
    includes: (4)
      # Default Deployment object
      - jkube-controller
      # Add a default service
      - jkube-service
    excludes: (5)
      - jkube-icon
    config: (6)
      jkube-service:
        # Expose service as NodePort
        type: NodePort
  order: 10 (7)
- name: another-profile
# ....
1 Profile’s name
2 Generators to use
3 Enrichers to use
4 List of enricher to include in that given order
5 List of enricher to exclude
6 Configuration for services an enrichers
7 An order which influences the way how profiles with the same name are merged

Each profiles.yml has a list of profiles which are defined with these elements:

Table 44. Profile elements
Element Description

name

Profile name. This plugin comes with a set of predefined profiles. Those profiles can be extended by defining a custom profile with the same name of the profile to extend.

generator

List of generator definitions. See below for the format of these definitions.

enricher

List of enrichers definitions. See below for the format of these definitions.

order

The order of the profile which is used when profiles of the same name are merged.

9.1. Generator and Enricher definitions

The definition of generators and enrichers in the profile follows the same format:

Table 45. Generator and Enericher definition
Element Description

includes

List of generators or enrichers to include. The order in the list determines the order in which the processors are applied.

excludes

List of generators or enrichers. These have precedences over includes and will exclude a processor even when referenced in an includes sections

config

Configuration for generators or enrichers. This is a map where the keys are the name of the processor to configure and the value is again a map with configuration keys and values specific to the processor. See the documentation of the respective generator or enricher for the available configuration keys.

9.2. Lookup order

Profiles can be defined externally either directly as a build resource in src/main/jkube/profiles.yml or provided as part of a plugin’s dependency where it is supposed to be included as META-INF/jkube/profiles.yml. Multiple profiles can be include in these profiles.yml descriptors as a list:

If a profile is used then it is looked up from various places in the following order:

  • From the compile and plugin classpath from META-INF/jkube/profiles-default.yml. These files are reserved for profiles defined by this plugin

  • From the compile and plugin classpath from META-INF/jkube/profiles.yml. Use this location for defining your custom profiles which you want to include via dependencies.

  • From the project in src/main/jkube/profiles.yml. The directory can be tuned with the plugin option resourceDir (property: jkube.resourceDir)

When multiple profiles of the same name are found, then these profiles are merged. If profile have an order number, then the higher order takes precedences when merging profiles.

For includes of the same processors, the processor is moved to the earliest position. E.g consider the following two profiles with the name my-profile

Profile A
name: my-profile
enricher:
  includes: [ e1, e2 ]
Profile B
name: my-profile
enricher:
  includes: [ e3, e1 ]
order: 10

then when merged results in the following profile (when no order is given, it defaults to 0):

Profile merged
name: my-profile
enricher:
  includes: [ e1, e2, e3 ]
order: 10

Profile with the same order number are merged according to the lookup order described above, where the latter profile is supposed to have a higher order.

The configuration for enrichers and generators are merged, too, where higher order profiles override configuration values with the same key of lower order profile configuration.

9.3. Using Profiles

Profiles can be selected by defining them in the plugin configuration, by giving a system property or by using special directories in the directory holding the resource fragments.

Profile used in plugin configuration

Here is an example how the profile can be used in a plugin configuration:

<plugin>
  <groupId>org.eclipse.jkube</groupId>
  <artifactId>kubernetes-maven-plugin</artifactId>
  <configuration>
    <profile>my-spring-boot-apps</profile> (1)
    <!-- ... -->
  </configuration>
</plugin>
1 Name which select the profile from the profiles.yml
Profile as system property

Alternatively a profile can be also specified on the command line when calling Maven:

mvn -Djkube.profile=my-spring-boot-apps k8s:build k8s:deploy

If a configuration for enrichers and generators are provided as part of the plugin’s <configuration> then this takes precedence over any profile specified.

Profiles for resource fragments

Profiles are also very useful when used together with resource fragments in src/main/jkube. By default the resource objects defined here are enriched with the configured profile (if any). A different profile can be selected easily by using a sub directory within src/main/jkube. The name of each sub directory is interpreted as a profile name and all resource definition files found in this sub directory are enhanced with the enhancers defined in this profile.

For example, consider the following directory layout:

src/main/k8s:
  app-rc.yml
  app-svc.yml
  raw/ -->
    couchbase-rc.yml
    couchbase-svc.yml

Here, the resource descriptors app-rc.yml and app-svc.yml are enhanced with the enrichers defined in the main configuration. The files two files couchbase-rc.yml and couchbase-svc.yml in the sub directory raw/ instead are enriched with the profile raw. This is a predefined profile which includes no enricher at all, so the couchbase resource objects are not enriched and taken over literally. This is an easy way how you can fine tune enrichment for different object set.

9.4. Predefined Profiles

This plugin comes with a list of the following predefined profiles:

Table 46. Predefined Profiles
Profile Description

default

The default profile which is active if no profile is specified. It consists of a curated set of generator and enrichers. See below for the current definition.

minimal

This profile contains no generators and only enrichers for adding default objects (controller and services). No other enrichment is included.

explicit

Like default but without adding default objects like controllers and services.

aggregate

Includes no generators and only the jkube-dependency enricher for picking up and combining resources from the compile time dependencies.

internal-microservice

Do not expose a port for the service to generate. Otherwise the same as the default profile.

osio

Includes everything in the default profile, plus additional enrichers and generators relevant only to OpenShift.io.

9.5. Extending Profiles

A profile can also extend another profile to avoid repetition e.g of generators if the profile is only about including certain enrichers. For example, for a profile like:

- name: minimal
   extends: default
   enricher:
     includes:
      - jkube-name
      - jkube-controller
      - jkube-service
      - jkube-image
      - jkube-project-label
      - jkube-debug
      - jkube-namespace
      - jkube-metadata
      - jkube-controller-from-configuration
      - jkube-openshift-deploymentconfig
      - jkube-openshift-project
      - jkube-openshift-service-expose
      - jkube-openshift-route

one then would not need to repeat all generators as they are inherited from the default profile.

Default Profile
# Default profile which is always activated
- name: default
  enricher:
    # The order given in "includes" is the order in which enrichers are called
    includes:
    - jkube-metadata
    - jkube-name
    - jkube-controller
    - jkube-controller-from-configuration
    - jkube-service
    - jkube-namespace
    - jkube-image
    - jkube-portname
    - jkube-project-label
    - jkube-dependency
    - jkube-pod-annotations
    - jkube-git
    - jkube-maven-scm
    - jkube-serviceaccount
    - jkube-maven-issue-mgmt
    # TODO: Documents and verify enrichers below
    - jkube-debug
    - jkube-remove-build-annotations
    - jkube-volume-permission
    - jkube-configmap-file
    - jkube-secret-file

    # Route exposure
    - jkube-openshift-service-expose
    - jkube-openshift-route
    - jkube-openshift-deploymentconfig
    - jkube-openshift-project

    # Ingress
    - jkube-ingress

    # -----------------------------------------
    # TODO: Document and verify enrichers below
    # Health checks
    - jkube-healthcheck-quarkus
    - jkube-healthcheck-spring-boot
    - jkube-healthcheck-wildfly-swarm
    - jkube-healthcheck-thorntail-v2
    - jkube-healthcheck-wildfly-jar
    - jkube-healthcheck-karaf
    - jkube-healthcheck-vertx
    - jkube-healthcheck-docker
    - jkube-healthcheck-webapp
    - jkube-prometheus
    # Dependencies shouldn't be enriched anymore, therefore it's last in the list
    - jkube-dependency
    - jkube-revision-history
    - jkube-docker-registry-secret
    - jkube-triggers-annotation
    - jkube-openshift-imageChangeTrigger

  generator:
    # The order given in "includes" is the order in which generators are called
    includes:
    - quarkus
    - spring-boot
    - wildfly-swarm
    - thorntail-v2
    - wildfly-jar
    - openliberty
    - karaf
    - vertx
    - java-exec
    - webapp
  watcher:
    includes:
    - spring-boot
    - docker-image

10. Access configuration

10.1. Docker Access

For Kubernetes builds the kubernetes-maven-plugin uses the Docker remote API so the URL of your Docker Daemon must be specified. The URL can be specified by the dockerHost or machine configuration, or by the DOCKER_HOST environment variable. If not given

The Docker remote API supports communication via SSL and authentication with certificates. The path to the certificates can be specified by the certPath or machine configuration, or by the DOCKER_CERT_PATH environment variable.

10.2. OpenShift and Kubernetes Access

Plugin reads your kubeconfig file to read your Kubernetes/OpenShift configuration. By default, kubeconfig file is assumed to be either in ~/.kube/config or using the environment variable KUBECONFIG.

11. Registry handling

Docker uses registries to store images. The registry is typically specified as part of the name. I.e. if the first part (everything before the first /) contains a dot (.) or colon (:) this part is interpreted as an address (with an optionally port) of a remote registry. This registry (or the default docker.io if no registry is given) is used during push and pull operations. This plugin follows the same semantics, so if an image name is specified with a registry part, this registry is contacted. Authentication is explained in the next section.

There are some situations however where you want to have more flexibility for specifying a remote registry. This might be because you do not want to hard code a registry into pom.xml but provide it from the outside with an environment variable or a system property.

This plugin supports various ways of specifying a registry:

  • If the image name contains a registry part, this registry is used unconditionally and can not be overwritten from the outside.

  • If an image name doesn’t contain a registry, then by default the default Docker registry docker.io is used for push and pull operations. But this can be overwritten through various means:

    • If the <image> configuration contains a <registry> subelement this registry is used.

    • Otherwise, a global configuration element <registry> is evaluated which can be also provided as system property via -Djkube.docker.registry.

    • Finally an environment variable DOCKER_REGISTRY is looked up for detecting a registry.

This registry is used for pulling (i.e. for autopull the base image when doing a k8s:build) and pushing with k8s:push. However, when these two goals are combined on the command line like in mvn -Djkube.docker.registry=myregistry:5000 package k8s:build k8s:push the same registry is used for both operation. For a more fine grained control, separate registries for pull and push can be specified.

  • In the plugin’s configuration with the parameters <pullRegistry> and <pushRegistry>, respectively.

  • With the system properties jkube.docker.pull.registry and jkube.docker.push.registry, respectively.

Example
<configuration>
  <registry>docker.jolokia.org:443</registry>
  <images>
    <image>
      <!-- Without an explicit registry ... -->
      <name>jolokia/jolokia-java</name>
      <!-- ... hence use this registry -->
      <registry>docker.ro14nd.de</registry>
      <!-- ... -->
    </image>
    <image>
      <name>postgresql</name>
      <!-- No registry in the name, hence use the globally
           configured docker.jolokia.org:443 as registry -->
      <!-- ... -->
    </image>
    <image>
      <!-- Explicitly specified always wins -->
      <name>docker.example.com:5000/another/server</name>
    </image>
  </images>
</configuration>

There is some special behaviour when using an externally provided registry like described above:

  • When pulling, the image pulled will be also tagged with a repository name without registry. The reasoning behind this is that this image then can be referenced also by the configuration when the registry is not specified anymore explicitly.

  • When pushing a local image, temporarily a tag including the registry is added and removed after the push. This is required because Docker can only push registry-named images.

12. Authentication

When pulling (via the autoPull mode of k8s:build) or pushing image, it might be necessary to authenticate against a Docker registry.

There are five different locations searched for credentials. In order, these are:

  • Providing system properties jkube.docker.username and jkube.docker.password from the outside.

  • Using a <authConfig> section in the plugin configuration with <username> and <password> elements.

  • Using OpenShift configuration in ~/.config/kube

  • Using a <server> configuration in ~/.m2/settings.xml

  • Login into a registry with docker login (credentials in a credential helper or in ~/.docker/config.json)

Using the username and password directly in the pom.xml is not recommended since this is widely visible. This is the easiest and transparent way, though. Using an <authConfig> is straight forward:

<plugin>
  <configuration>
    <image>consol/tomcat-7.0</image>
    <!-- ... -->
    <authConfig>
      <username>jolokia</username>
      <password>s!cr!t</password>
    </authConfig>
  </configuration>
</plugin>

The system property provided credentials are a good compromise when using CI servers like Jenkins. You simply provide the credentials from the outside:

Example
mvn -Djkube.docker.username=jolokia -Djkube.docker.password=s!cr!t k8s:push

The most mavenish way is to add a server to the Maven settings file ~/.m2/settings.xml:

Example
<servers>
  <server>
    <id>docker.io</id>
    <username>jolokia</username>
    <password>s!cr!t</password>
  </server>
  <!-- ... -->
</servers>

The server id must specify the registry to push to/pull from, which by default is central index docker.io (or index.docker.io / registry.hub.docker.com as fallbacks). Here you should add your docker.io account for your repositories. If you have multiple accounts for the same registry, the second user can be specified as part of the ID. In the example above, if you have a second account 'jkubeio' then use an <id>docker.io/jkubeio</id> for this second entry. I.e. add the username with a slash to the id name. The default without username is only taken if no server entry with a username appended id is chosen.

The most secure way is to rely on docker’s credential store or credential helper and read confidential information from an external credentials store, such as the native keychain of the operating system. Follow the instruction on the docker login documentation.

As a final fallback, this plugin consults $DOCKER_CONFIG/config.json if DOCKER_CONFIG is set, or ~/.docker/config.json if not, and reads credentials stored directly within this file. This unsafe behavior happened when connecting to a registry with the command docker login from the command line with older versions of docker (pre 1.13.0) or when docker is not configured to use a credential store.

12.1. Pull vs. Push Authentication

The credentials lookup described above is valid for both push and pull operations. In order to narrow things down, credentials can be provided for pull or push operations alone:

In an <authConfig> section a sub-section <pull> and/or <push> can be added. In the example below the credentials provider are only used for image push operations:

Example
<plugin>
  <configuration>
    <image>consol/tomcat-7.0</image>
    <!-- ... -->
    <authConfig>
      <push>
         <username>jolokia</username>
         <password>s!cr!t</password>
      </push>
    </authConfig>
  </configuration>
</plugin>

When the credentials are given on the command line as system properties, then the properties jkube.docker.pull.username / jkube.docker.pull.password and jkube.docker.push.username / jkube.docker.push.password are used for pull and push operations, respectively (when given). Either way, the standard lookup algorithm as described in the previous section is used as fallback.

12.2. OpenShift Authentication

When working with the default registry in OpenShift, the credentials to authenticate are the OpenShift username and access token. So, a typical interaction with the OpenShift registry from the outside is:

oc login
...
mvn -Djkube.docker.registry=docker-registry.domain.com:80/default/myimage \
    -Djkube.docker.username=$(oc whoami) \
    -Djkube.docker.password=$(oc whoami -t)

(note, that the image’s username part ("default" here") must correspond to an OpenShift project with the same name to which you currently connected account has access).

This can be simplified by using the system property docker.useOpenShiftAuth in which case the plugin does the lookup. The equivalent to the example above is

oc login
...
mvn -Ddocker.registry=docker-registry.domain.com:80/default/myimage \
    -Ddocker.useOpenShiftAuth

Alternatively the configuration option <useOpenShiftAuth> can be added to the <authConfig> section.

For dedicated pull and push configuration the system properties jkube.docker.pull.useOpenShiftAuth and jkube.docker.push.useOpenShiftAuth are available as well as the configuration option <useOpenShiftAuth> in an <pull> or <push> section within the <authConfig> configuration.

If useOpenShiftAuth is enabled then the OpenShift configuration will be looked up in $KUBECONFIG or, if this environment variable is not set, in ~/.kube/config.

12.3. Password encryption

Regardless of which mode you choose you can encrypt password as described in the Maven documentation. Assuming that you have setup a master password in ~/.m2/security-settings.xml you can create easily encrypt passwords:

Example
$ mvn --encrypt-password
Password:
{QJ6wvuEfacMHklqsmrtrn1/ClOLqLm8hB7yUL23KOKo=}

This password then can be used in authConfig, docker.password and/or the <server> setting configuration. However, putting an encrypted password into authConfig in the pom.xml doesn’t make much sense, since this password is encrypted with an individual master password.

12.4. Extended Authentication

Some docker registries require additional steps to authenticate. Amazon ECR requires using an IAM access key to obtain temporary docker login credentials. The k8s:push and k8s:build goals automatically execute this exchange for any registry of the form <awsAccountId> .dkr.ecr. <awsRegion> .amazonaws.com, unless the skipExtendedAuth configuration (jkube.docker.skip.extendedAuth property) is set true.

Note that for an ECR repository with URI 123456789012.dkr.ecr.eu-west-1.amazonaws.com/example/image the d-m-p’s jkube.docker.registry should be set to 123456789012.dkr.ecr.eu-west-1.amazonaws.com and example/image is the <name> of the image.

You can use any IAM access key with the necessary permissions in any of the locations mentioned above except ~/.docker/config.json. Use the IAM Access key ID as the username and the Secret access key as the password. In case you’re using temporary security credentials provided by the AWS Security Token Service (AWS STS), you have to provide the security token as well. To do so, either specify the docker.authToken system property or provide an <auth> element alongside username & password in the authConfig.

In case you are running on an EC2 instance that has an appropriate IAM role assigned (e.g. a role that grants the AWS built-in policy AmazonEC2ContainerRegistryPowerUser) authentication information doesn’t need to be provided at all. Instead the instance meta-data service is queried for temporary access credentials supplied by the assigned role.

13. Volume Configuration

kubernetes-maven-plugin supports volume configuration in XML format in pom.xml. These are the volume types which are supported:

Table 47. Supported Volume Types
Volume Type Description

hostPath

Mounts a file or directory from the host node’s filesystem into your pod

emptyDir

Containers in the Pod can all read and write the same files in the emptyDir volume, though that volume can be mounted at the same or different paths in each Container. When a Pod is removed from a node for any reason, the data in the emptyDir is deleted forever.

gitRepo

It mounts an empty directory and clones a git repository into it for your Pod to use.

secret

It is used to pass sensitive information, such as passwords, to Pods.

nfsPath

Allows an existing NFS(Network File System) share to be mounted into your Pod.

gcePdName

Mounts a Google Compute Engine(GCE) into your Pod. You must create PD using gcloud or GCE API or UI before you can use it.

glusterFsPath

Allows a Glusterfs (an open source networked filesystem) volume to be mounted into your Pod.

persistentVolumeClaim

Used to mount a PersistentVolume into a Pod.

awsElasticBlockStore

Mounts an Amazon Web Services(AWS) EBS Volume into your Pod.

azureDisk

Mounts a Microsoft Azure Data Disk into a Pod

azureFile

Mounts a Microsoft Azure File Volume(SMB 2.1 and 3.0 into a Pod.

cephfs

Allows an existing CephFS volume to be mounted into your Pod. You must have your own Ceph server running with the share exported before you can use it.

fc

Allows existing fibre channel volume to be mounted in a Pod. You must configure FC SAN Zoning to allocate and mask those LUNs (volumes) to the target WWNs beforehand so that Kubernetes hosts can access them.

flocker

Flocker is an open source clustered Container data volume manager. A flocker volume allows a Flocker dataset to be mounted into a Pod. You must have your own Flocker installation running before you can use it.

iscsi

Allows an existing ISCSI(SCSI over IP) volume to be mounted into your Pod.

portworxVolume

A portworxVolume is an elastic block storage layer that runs hyperconverged with Kubernetes.

quobyte

Allows existing Quobyte volume to be mounted into your Pod. You must have your own Quobyte setup running the volumes created.

rbd

Allows a Rados Block Device volume to be mounted into your Pod.

scaleIO

ScaleIO is a software-based storage platform that can use existing hardware to create clusters of scalable shared block networked storage. The scaleIO volume plugin allows deployed Pods to access existing ScaleIO volumes.

storageOS

A storageos volume allows an existing StorageOS volume to be mounted into your Pod. You must run the StorageOS container on each node that wants to access StorageOS volumes

vsphereVolume

Used to mount a vSphere VMDK volume into your Pod.

downwardAPI

A downwardAPI volume is used to make downward API data available to applications. It mounts a directory and writes the requested data in plain text files.

14. Integrations

14.1. Dekorate

kubernetes-maven-plugin provides a Zero Configuration approach to delegate deployment manifests generation to Dekorate.

Just by adding a dependency to Dekorate library in the pom.xml file, all manifest generation will be delegated to Dekorate.

  <dependencies>
    <!-- ... -->
    <dependency>
        <groupId>io.dekorate</groupId>
        <artifactId>option-annotations</artifactId>
        <version>${dekorate.version}</version>
      </dependency>
      <dependency>
        <groupId>io.dekorate</groupId>
        <artifactId>openshift-annotations</artifactId>
        <version>${dekorate.version}</version>
      </dependency>
      <dependency>
        <groupId>io.dekorate</groupId>
        <artifactId>kubernetes-annotations</artifactId>
        <version>${dekorate.version}</version>
      </dependency>
      <dependency>
        <groupId>io.dekorate</groupId>
        <artifactId>dekorate-spring-boot</artifactId>
        <version>${dekorate.version}</version>
      </dependency>
  </dependencies>

A full example of the integration can be found in the directory quickstarts/maven/spring-boot-dekorate.

An experimental feature is also provided to merge resources generated both by kubernetes-maven-plugin and Dekorate. You can activate this feature by using the following flag -Djkube.mergeWithDekorate in the command-line, or setting it up as a property (<jkube.mergeWithDekorate>true</jkube.mergeWithDekorate>).

14.2. JIB (Java Image Builder)

kubernetes-maven-plugin also provides user an option to build container images without having access to any docker daemon. You just need to set jkube.build.strategy property to jib. It will delegate the build process to JIB. It creates a tarball inside your target directory which can be loaded into any docker daemon afterwards. You may also push the image to your specified registry using push goal with feature flag enabled.

You can find more details at Spring Boot JIB Quickstart.

15. FAQ

15.1. General questions

15.1.1. How do I define an environment variable?

The easiest way is to add a src/main/jkube/deployment.yml file to your project containing something like:

spec:
  template:
    spec:
      containers:
        -env:
          - name: FOO
            value: bar

The above will generate an environment variable $FOO of value bar

For a full list of the environments used in java base images, see this list

15.1.2. How do I define a system property?

The simplest way is to add system properties to the JAVA_OPTIONS environment variable.

For a full list of the environments used in java base images, see this list

e.g. add a src/main/jkube/deployment.yml file to your project containing something like:

spec:
 template:
   spec:
     containers:
       - env:
         - name: JAVA_OPTIONS
           value: "-Dfoo=bar -Dxyz=abc"

The above will define the system properties foo=bar and xyz=abc

15.1.3. How do I mount a config file from a ConfigMap?

First you need to create your ConfigMap resource via a file src/main/jkube/configmap.yml

data:
  application.properties: |
    # spring application properties file
    welcome = Hello from Kubernetes ConfigMap!!!
    dummy = some value

Then mount the entry in the ConfigMap into your Deployment via a file src/main/jkube/deployment.yml

metadata:
  annotations:
    configmap.jkube.io/update-on-change: ${project.artifactId}
spec:
  replicas: 1
  template:
    spec:
      volumes:
        - name: config
          configMap:
            name: ${project.artifactId}
            items:
            - key: application.properties
              path: application.properties
      containers:
        - volumeMounts:
            - name: config
              mountPath: /deployments/config

Note that the annotation configmap.jkube.io/update-on-change is optional; its used if your application is not capable of watching for changes in the /deployments/config/application.properties file. In this case if you are also running the configmapcontroller then this will cause a rolling upgrade of your application to use the new ConfigMap contents as you change it.

15.1.4. How do I use a Persistent Volume?

First you need to create your PersistentVolumeClaim resource via a file src/main/jkube/foo-pvc.yml where foo is the name of the PersistentVolumeClaim. It might be your app requires multiple vpersistent volumes so you will need multiple PersistentVolumeClaim resources.

spec:
  accessModes:
  - ReadWriteOnce
  resources:
    requests:
      storage: 100Mi

Then to mount the PersistentVolumeClaim into your Deployment create a file src/main/jkube/deployment.yml

spec:
  template:
    spec:
      volumes:
      - name: foo
        persistentVolumeClaim:
          claimName: foo
      containers:
      - volumeMounts:
        - mountPath: /whatnot
          name: foo

Where the above defines the PersistentVolumeClaim called foo which is then mounted into the container at /whatnot

15.1.5. How do I generate Ingress for my generated Service?

Ingress generation is supported by Eclipse JKube for Service objects of type LoadBalancer. In order to generate Ingress you need to enable jkube.createExternalUrls property to true and jkube.domain property to desired host suffix, it would be appended to your service name for host value. You can also also provide a host for it in XML config like this:

<plugin>
  <groupId>org.eclipse.jkube</groupId>
  <artifactId>kubernetes-maven-plugin</artifactId>
  <version>1.0.0</version>

  <configuration>
    <resources>
      <routeDomain>org.eclipse.jkube</routeDomain>
    </resources>

    <enricher>
      <config>
        <jkube-service>
          <type>LoadBalancer</type>
        </jkube-service>
      </config>
    </enricher>
  </configuration>
</plugin>

You can find an example in our spring-boot quickstart in kubernetes-with-ingress profile.

16. Appendix

16.1. Kind/Filename Type Mapping

Kind Filename Type

BuildConfig

bc, buildconfig

ClusterRole

cr, crole, clusterrole

ConfigMap

cm, configmap

ClusterRoleBinding

crb, clusterrb, clusterrolebinding

CronJob

cj, cronjob

CustomResourceDefinition

crd, customerresourcedefinition

DaemonSet

ds, daemonset

Deployment

deployment

DeploymentConfig

dc, deploymentconfig

ImageStream

is, imagestream

ImageStreamTag

istag, imagestreamtag

Ingress

ingress

Job

job

LimitRange

lr, limitrange

Namespace

ns, namespace

OAuthClient

oauthclient

PolicyBinding

pb, policybinding

PersistentVolume

pv, persistentvolume

PersistentVolumeClaim

pvc, persistemtvolumeclaim

Project

project

ProjectRequest

pr, projectrequest

ReplicaSet

rs, replicaset

ReplicationController

rc, replicationcontroller

ResourceQuota

rq, resourcequota

Role

role

RoleBinding

rb, rolebinding

RoleBindingRestriction

rbr, rolebindingrestriction

Route

route

Secret

secret

Service

svc, service

ServiceAccount

sa, serviceaccount

StatefulSet

statefulset

Template

template

Pod

pd, pod

16.2. Custom Kind/Filename Mapping

You can add your custom Kind/Filename mappings. To do it you have two approaches:

  • Setting an environment variable or system property called jkube.mapping pointing out to a .properties files with pairs <kind>⇒filename1>, <filename2> By default if no environment variable nor system property is set, scan for a file located at classpath /META-INF/jkube.kind-filename-type-mapping-default.properties.

  • By embedding in MOJO configuration the mapping:

<plugin>
  <groupId>org.eclipse.jkube</groupId>
  <artifactId>kubernetes-maven-plugin</artifactId>
  <configuration>
    <mappings>
      <mapping>
        <kind>Var</kind>
        <filenameTypes>foo, bar</filenameTypes>
      </mapping>
    </mappings>
  </configuration>
</plugin>