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Version: 9.3.7.v20160115
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Chapter 9. Starting Jetty

Table of Contents

Startup Overview
Managing Server Classpath
Managing Startup Modules
Managing Jetty Base and Jetty Home
Using start.jar
Startup a Unix Service using
Startup via Windows Service

Startup Overview

The start.jar bootstrap manages the startup of standalone Jetty. It is responsible for:

Building the classpath

The start.jar bootstrap builds a classpath for all the required Jetty features and their dependencies. It builds the classpath using either the --lib option to start.jar to add an individual classpath entry, or with the --module option that includes all the libs and their dependencies for a module (a named Jetty feature).

Instantiating the Server Components

The server and its components are instantiated using either Jetty IoC XML or spring. The Jetty server is just a collection of java POJOs for the server, connectors, session managers and others. These are instantiated, injected, and wired up together in XML files, commonly one per module/feature, that are passed as arguments to start.jar.

Resolving Server Filesystem Locations

The start.jar mechanism resolves canonical locations for the ${jetty.home} and the ${jetty.base} directories.

The ${jetty.home} directory is the location of the standard distribution of Jetty.

The ${jetty.base} directory is the location of the local server customization and configurations.

If you want to modify the Jetty distribution, base and home can be the same directory. Separating the base and home directories allows the distribution to remain unmodified, with all customizations in the base directory, and thus simplifies subsequent server version upgrades.

Parameterizing the Server Configuration

XML files primarily determine the server configuration. Many of these files are parameterized to allow simple injection of host names, ports, passwords and more. The start.jar mechanism allows you to set parameters on the command line or in properties files.

To achieve these start up mechanisms, the start.jar uses:

Command line arguments

You can configure the entire server with command line arguments that specify libraries, properties and XML files. However in practice the INI and modules mechanisms (below) reduce the verbosity of the command line.

INI files

The start.jar mechanism uses the contents of the ${jetty.base}/start.ini and ${jetty.base}/start.d/*.ini files with each line equivalent to a start.jar command line argument. This means that either a global start.ini file or multiple start.d/feature.ini files control the configuration of the server.


Instead of explicitly listing all the libraries, properties and XML files for a feature, the start.jar mechanism allows you to create modules. You define a module in a modules/*.mod file, including the libraries, dependencies, XML, and template INI files for a Jetty feature. Thus you can use a single --module=name command line option as the equivalent of specifying many --lib=location, feature.xml, name=value arguments for a feature and all its dependencies. Modules also use their dependencies to control the ordering of libraries and XML files.

XML Files

XML files in either Jetty IoC or Spring format instantiate the actual POJO components of the server. This includes all major components such as connectors, keystores, session managers, and data sources. Typically there are one or more XML files per module, and these are defined and activated in the corresponding module.

Startup Example

The simplest way to start Jetty is via the start.jar mechanism using the following Java command line:

[user]$ cd jetty-distribution-9.3.7.v20160115
[jetty-distribution-9.3.7.v20160115]$ java -jar start.jar --module=http jetty.http.port=8080

This command uses the start.jar mechanism to bootstrap the classpath, properties, and XML files with the metadata obtained from the http module. Specifically the http module is defined in the ${jetty.home}/modules/http.mod file, and includes the following:

[jetty-distribution-9.3.7.v20160115]$ cat modules/http.mod



The http module declares that http depends on the server module, uses the jetty-http.xml file, and can be parameterized with jetty.http.port and http.timeout parameters. The INI-template section is not actually used by the command above, so the jetty.http.port must still be defined on the command line.

Following the server dependency, the ${jetty.home}/modules/server.mod file includes:

[jetty-distribution-9.3.7.v20160115]$ cat modules/server.mod



The server module declares the libraries the server needs and t0 use jetty.xml file. The combined metadata of the http and server modules results in start.jar generating the effective Java command line required to start Jetty.

Another way to see this is by asking Jetty what its configuration looks like:

[jetty-distribution-9.3.7.v20160115]$ java -jar start.jar --module=http jetty.http.port=9099 --list-config

Java Environment:
 java.vm.vendor=Oracle Corporation
 java.vm.version=23.25-b01 HotSpot(TM) 64-Bit Server VM mode SE Runtime Environment

Jetty Environment:

JVM Arguments:
 (no jvm args specified)

System Properties:
 jetty.home = /opt/jetty/jetty-distribution-9.3.7.v20160115
 jetty.base = /opt/jetty/jetty-distribution-9.3.7.v20160115

 jetty.http.port = 9099

Jetty Server Classpath:
Version Information on 7 entries in the classpath.
Note: order presented here is how they would appear on the classpath.
      changes to the --module=name command line options will be reflected here.
 0:                    3.1.0 | ${jetty.home}/lib/servlet-api-3.1.jar
 1:                  3.1.RC0 | ${jetty.home}/lib/jetty-schemas-3.1.jar
 2:               9.3.7.v20160115 | ${jetty.home}/lib/jetty-http-9.3.7.v20160115.jar
 3:               9.3.7.v20160115 | ${jetty.home}/lib/jetty-server-9.3.7.v20160115.jar
 4:               9.3.7.v20160115 | ${jetty.home}/lib/jetty-xml-9.3.7.v20160115.jar
 5:               9.3.7.v20160115 | ${jetty.home}/lib/jetty-util-9.3.7.v20160115.jar
 6:               9.3.7.v20160115 | ${jetty.home}/lib/jetty-io-9.3.7.v20160115.jar

Jetty Active XMLs:

This represents the entirety of the configuration that is applied to start Jetty.

If you don't want to use the start.jar bootstrap, you can start Jetty using a traditional Java command line.

The following is the equivalent java command line for what the start.jar bootstrap above performs.

[user]$ cd jetty-distribution-9.3.7.v20160115
[jetty-distribution-9.3.7.v20160115]$ echo jetty.http.port=8080 > /tmp/
[jetty-distribution-9.3.7.v20160115]$ export JETTY_HOME=`pwd`
[jetty-distribution-9.3.7.v20160115]$ export JETTY_BASE=`pwd`
[jetty-distribution-9.3.7.v20160115]$ export JETTY_VERSION="${project.version}"
[jetty-distribution-9.3.7.v20160115]$ java -Djetty.home=$JETTY_HOME \
-Djetty.base=$JETTY_BASE \
-cp \
:$JETTY_HOME/lib/jetty-server-$JETTY_VERSION.jar \
org.eclipse.jetty.xml.XmlConfiguration \
/tmp/ \
$JETTY_HOME/etc/jetty.xml \

The java command line sets up the classpath with the core Jetty jars and the servlet API, executes the XmlConfiguration class, and passes it some XML files that define the server and an HTTP connector running on the port defined in the file.

You can further simplify the startup of this server by using the INI template defined by the modules to create a start.ini file with the command:

[user]$ cd jetty-distribution-9.3.7.v20160115
[jetty-distribution-9.3.7.v20160115]$ mkdir example-base
[example-base]$ cd example-base
[example-base]$ ls -la
total 8
drwxrwxr-x  2 user webgroup 4096 Oct  4 11:49 ./
drwxrwxr-x 12 user webgroup 4096 Oct  4 11:49 ../
[example-base]$ java -jar $JETTY_HOME/start.jar --add-to-start=http
WARNING: http            initialised in ${jetty.base}/start.ini (appended)
WARNING: http            enabled in     ${jetty.base}/start.ini
WARNING: server          initialised in ${jetty.base}/start.ini (appended)
WARNING: server          enabled in     ${jetty.base}/start.ini
[example-base]$ ls -la
total 12
drwxrwxr-x  2 user webgroup 4096 Oct  4 11:55 ./
drwxrwxr-x 12 user webgroup 4096 Oct  4 11:49 ../
-rw-rw-r--  1 user webgroup  250 Oct  4 11:55 start.ini

Once complete, you can edit the start.ini file to modify any parameters and you can run the server with the simple command:

[example-base]$ java -jar $JETTY_HOME/start.jar

See an error or something missing? Contribute to this documentation at Github!(Generated: 2016-03-17)