Importing Kubernetes applications into a workspace

This section describes how to import Kubernetes or OpenShift applications into a Che workspace.

For demonstration purposes, the section uses a sample Kubernetes or OpenShift application having the following two Pods:

A Node.js application specified by this nodejs-app.yaml
A MongoDB Pod specified by this mongo-db.yaml

To run the application on a Kubernetes or OpenShift cluster:

$ node=https://raw.githubusercontent.com/redhat-developer/devfile/master/samples/web-nodejs-with-db-sample/nodejs-app.yaml && \
mongo=https://raw.githubusercontent.com/redhat-developer/devfile/master/samples/web-nodejs-with-db-sample/mongo-db.yaml && \
kubectl  apply -f ${mongo} && \
kubectl  apply -f ${node}

To deploy a new instance of this application in a Che workspace, use one of the following three scenarios:

Starting from scratch: Writing a new devfile
Modifying an existing workspace: Using the Dashboard user interface
From a running application: Generating a devfile with chectl

Including a Kubernetes or OpenShift application in a workspace devfile definition

This procedure describes how to define a Che workspace devfile to include a Kubernetes application.

The devfile format is used to define a Che workspace, and its format is described in the Configuring a workspace using a devfile section.

Prerequisites

You are logged in to the cluster with a running instance of Eclipse Che. To install an instance of Eclipse Che, see Installing Che.
chectl management tool is available. See Using the chectl management tool.

Procedure

Create the simplest devfile:

apiVersion: 1.0.0
metadata:
 name: minimal-workspace (1)

1	Only the name `minimal-workspace` is specified. After the Che server processes this devfile, the devfile is converted to a minimal Che workspace that only has the default editor (Che-Theia) and the default editor plug-ins, including, for example, the terminal.

To add Kubernetes applications to a workspace, modify the devfile and add the Kubernetes component type.

For example, to embed the NodeJS-Mongo application in the minimal-workspace:

apiVersion: 1.0.0
metadata:
 name: minimal-workspace
components:
 - type: kubernetes
   reference: https://raw.githubusercontent.com/.../mongo-db.yaml
 - alias: nodejs-app
   type: kubernetes
   reference: https://raw.githubusercontent.com/.../nodejs-app.yaml
   entrypoints:
     - command: ['sleep']  (1)
       args: ['infinity']

1	The `sleep infinity` command is added as the entrypoint of the Node.js application. The command prevents the application from starting at the workspace start phase. This configuration allows the user to start the application when needed for testing or debugging purposes.

Add the commands in the devfile to make it easier for a developer to test the application:

apiVersion: 1.0.0
metadata:
 name: minimal-workspace
components:
 - type: kubernetes
   reference: https://raw.githubusercontent.com/.../mongo-db.yaml
 - alias: nodejs-app
   type: kubernetes
   reference: https://raw.githubusercontent.com/.../nodejs-app.yaml
   entrypoints:
     - command: ['sleep']
       args: ['infinity']
commands:
 - name: run  (1)
   actions:
     - type: exec
       component: nodejs-app
       command: cd ${CHE_PROJECTS_ROOT}/nodejs-mongo-app/EmployeeDB/ && npm install && sed -i -- ''s/localhost/mongo/g'' app.js && node app.js

1	The `run` command added to the devfile is available as a task in Che-Theia from the command palette. When executed, the command starts the Node.js application.

Use the devfile to create and start a workspace:

$ chectl workspace:start --devfile <devfile-path>

Adding a Kubernetes or OpenShift application to an existing workspace using the dashboard

This procedure demonstrates how to modify an existing workspace and import the Kubernetes or OpenShift application using the newly created devfile.

Prerequisites

A running instance of Che. To install an instance of Che, see Installing Che.
An existing workspace defined on this instance of Che.

Procedure

After the creation of a workspace, use the Workspace menu and then click on the desired workspace.
Modify the workspace devfile, use the Devfile tab.
Add a Kubernetes or OpenShift component.
For the changes to take effect, save the devfile and restart the Che workspace.

Generating a devfile from an existing Kubernetes or OpenShift application

This procedure demonstrates how to generate a devfile from an existing Kubernetes or OpenShift application using the chectl tool.

Prerequisites

A running instance of Che. To install an instance of Che, see Installing Che.
The chectl management tool is available. See Using the chectl management tool.
You are logged in to Che. See How to login into Che using chectl

Procedure

To generate a devfile, use:

$ chectl devfile:generate

It is also possible to generate a devfile from, for example, the NodeJS-MongoDB application that includes the NodeJS component, using the chectl devfile:generate command:

Example:

$ chectl devfile:generate --selector="app=nodejs"
apiVersion: 1.0.0
metadata:
  name: chectl-generated
components:
  - type: kubernetes
    alias: app=nodejs
    referenceContent: |
      kind: List
      apiVersion: v1
      metadata:
        name: app=nodejs
      items:
        - apiVersion: apps/v1
          kind: Deployment
          metadata:
            labels:
              app: nodejs
            name: web
(...)

The Node.js application YAML definition is available in the devfile, inline, using the referenceContent attribute.

To include support for a language, use the --language parameter:

$ chectl devfile:generate --selector="app=nodejs" --language="typescript"
apiVersion: 1.0.0
metadata:
  name: chectl-generated
components:
  - type: kubernetes
    alias: app=nodejs
    referenceContent: |
      kind: List
      apiVersion: v1
(...)
  - type: chePlugin
    alias: typescript-ls
    id: che-incubator/typescript/latest

Use the generated devfile to start a Che workspace with chectl.
```
$ chectl workspace:start --devfile=devfile.yaml
```