Jetty/Feature/Jetty Maven Plugin

Introduction

The Jetty Maven plugin is useful for rapid development and testing. It can be added to any webapp project which is structured according to the usual Maven defaults.

The plugin can then periodically scan your project for changes and automatically redeploy the webapp if any are found. This makes the development cycle more productive by eliminating the build and deploy steps: you use your IDE to make changes to the project, and the running web container will automatically pick them up, allowing you to test them straight away.

Feature

Quick Start

Getting up and running

First, add jetty-maven-plugin to your pom.xml definition:

<plugin>
  <groupId>org.mortbay.jetty</groupId>
  <artifactId>jetty-maven-plugin</artifactId>
</plugin>

Then, from the same directory as your root pom.xml, simply type:

 mvn jetty:run

This will start Jetty and serve up your project on http://localhost:8080/.

Jetty will continue to run until you stop it. While it runs, it will periodically scan for changes to your project files, so if you save changes and recompile your class files, Jetty will redeploy your webapp, and you can instantly test the changes you just made.

Stopping the plugin from the same terminal window

You can terminate the plugin with a <ctrl-c> in the terminal window where it is running.

Running and Deploying

The jetty-maven-plugin has six Maven goals. Each goal is an action you can run to accomplish a specific task, or to work with a particular web application setup. You may need to insert goal-specific configuration to run it properly.

To run the jetty-maven-plugin with a particular goal, use this command:

 mvn jetty:goalname

Here are things you can do with the jetty-maven-plugin:

Run an assembled webapp with mvn jetty:run

The run goal runs on assembled webapps which follow the usual Maven defaults, as follows:

• resources in ${basedir}/src/main/webapp
• classes in ${project.build.outputDirectory}
• web.xml in ${basedir}/src/main/webapp/WEB-INF/

The webapp does not need to be assembled into a WAR, saving time during the development cycle. Once invoked, the plugin can be configured to run continuously, scanning for changes in the project and automatically performing a hot redeploy when necessary. Any changes you make will be immediately reflected in the running instance of Jetty, letting you quickly jump from coding to testing, rather going through the cycle of: code, compile, reassemble, redeploy, test.

A quick example, which turns on scanning for changes (every ten seconds), and sets the webapp context path to "/test":

<plugin>
  <groupId>org.mortbay.jetty</groupId>
  <artifactId>jetty-maven-plugin</artifactId>
  <configuration>
    <scanIntervalSeconds>10</scanIntervalSeconds>
  </configuration>
  <webAppConfig>
    <contextPath>/test</contextPath>
  </webAppConfig>
</plugin>

If, for whatever reason, you cannot run on an unassembled webapp, the goals run-war and run-exploded will work on unassembled webapps.

Run an unassembled webapp as an exploded WAR with mvn jetty:run-exploded

The run-exploded goal assembles your webapp into an exploded WAR and automatically deploys it to Jetty.

More actions

Stop the plugin from another terminal window with mvn jetty:stop

You can terminate the plugin from another terminal window by executing the stop goal. If you wish to be able to use mvn jetty:stop then you need to configure the plugin with a special port number and key that you also supply on the stop command:

<plugin>
  <groupId>org.mortbay.jetty</groupId>
  <artifactId>jetty-maven-plugin</artifactId>
  <configuration>
    <stopPort>9966</stopPort>
    <stopKey>foo</stopKey>
  </configuration>
</plugin>

Then, while Jetty is running, type:

   mvn jetty:stop

The <stopPort> must be free on the machine you are running on. If this is not the case, you will get an "Address already in use" error message after the "Started SelectedChannelConnector ..." message.

Get more help with mvn jetty:help

mvn jetty:help prints out the list of goals for the jetty-maven-plugin, with a description of each goal.

mvn jetty:help -Ddetail=true -Dgoal=<goal-name> will print out a list of the settable properties for that goal, in addition to its description, which is useful to get quick information about a goal.

Automatic plugin execution during unit testing with mvn jetty:run

One useful feature of the plugin is its automatic plugin execution. You can automatically have your webapp started at the beginning of the tests, and stopped at the end rather than manually executing mvn jetty:run on the command line.

To do this, you need to set up a couple of <execution> scenarios for the Jetty plugin and use the <daemon>true</daemon> configuration option to force Jetty to only execute while Maven is running, instead of running indefinitely.

The pre-integration-test and post-integration-test Maven build phases can be used to trigger the execution and termination of Jetty:

<plugin>
  <groupId>org.mortbay.jetty</groupId>
  <artifactId>jetty-maven-plugin</artifactId>
  <configuration>
    <scanIntervalSeconds>10</scanIntervalSeconds>
    <stopKey>foo</stopKey>
    <stopPort>9999</stopPort>
  </configuration>
  <executions>
    <execution>
      <id>start-jetty</id>
      <phase>pre-integration-test</phase>
      <goals>
        <goal>run</goal>
      </goals>
      <configuration>
       <scanIntervalSeconds>0</scanIntervalSeconds>
       <daemon>true</daemon>
      </configuration>
    </execution>
    <execution>
      <id>stop-jetty</id>
      <phase>post-integration-test</phase>
      <goals>
        <goal>stop</goal>
      </goals>
    </execution>
  </executions>
</plugin>

Setting the groupId
Maven by default looks for plugins with a groupId of org.apache.maven.plugins, even if the groupId is declared differently as above. In order to instruct Maven to look for the plugin in the groupId as defined, set a plugin group in a profile in settings.xml like so:

<profile>
  ...
  <pluginGroups>
    <pluginGroup>org.mortbay.jetty</pluginGroup>
  </pluginGroups>
</profile>