The plugin repeater maven plugin allows you to follow the DRY principal when writing your POM files.
If you've ever had to write a very similar plugin execution dozens of times then this is the plugin for you.
The plugin repeater plugin lets you repeat a plugin execution with different variables substituted.
All the examples in this README assume that we have a fictional plugin, adder-maven-plugin, that adds numbers. Anywhere you see <!-- Boilerplate omitted -->
means that we've left out the plugin GAV as well as any tags that aren't necessary. This may mean it is in the contentPlugin section of a repeater plugin
configuration or a plugin inside a pom's plugins section. The context should provide that information for you.
Say we wanted to add 5 sets of two numbers. Normally you'd have to write something like this:
<plugin>
<groupId>fake.plugin.group</groupId>
<artifactId>adder-maven-plugin</artifactId>
<version>0.0.0</version>
<executions>
<execution>
<id>first-number-add</id>
<goals>
<goal>add</goal>
</goals>
<configuration>
<numberOne>1</numberOne>
<numberTwo>2</numberTwo>
</configuration>
</execution>
<execution>
<id>second-number-add</id>
<goals>
<goal>add</goal>
</goals>
<configuration>
<numberOne>3</numberOne>
<numberTwo>4</numberTwo>
</configuration>
</execution>
<execution>
<id>third-number-add</id>
<goals>
<goal>add</goal>
</goals>
<configuration>
<numberOne>5</numberOne>
<numberTwo>6</numberTwo>
</configuration>
</execution>
<execution>
<id>four-number-add</id>
<goals>
<goal>add</goal>
</goals>
<configuration>
<numberOne>7</numberOne>
<numberTwo>8</numberTwo>
</configuration>
</execution>
<execution>
<id>fifth-number-add</id>
<goals>
<goal>add</goal>
</goals>
<configuration>
<numberOne>9</numberOne>
<numberTwo>10</numberTwo>
</configuration>
</execution>
</executions>
</plugin>
With the plugin repeater maven plugin you can just write:
<plugin>
<groupId>com.nlocketz.plugins</groupId>
<artifactId>plugin-repeater-maven-plugin</artifactId>
<!-- Check maven central for latest version -->
<version>LATEST</version>
<executions>
<execution>
<id>run-addings</id>
<goals>
<goal>repeat</goal>
</goals>
<configuration>
<repetitions>
<!-- Each repetition corresponds to a single run of contentPlugin -->
<!-- The values mapped in the repetition are subbed in @ surrounded tags -->
<repetition>
<nOne>1</nOne>
<nTwo>2</nTwo>
</repetition>
<repetition>
<nOne>3</nOne>
<nTwo>4</nTwo>
</repetition>
<repetition>
<nOne>5</nOne>
<nTwo>6</nTwo>
</repetition>
<repetition>
<nOne>7</nOne>
<nTwo>8</nTwo>
</repetition>
<repetition>
<nOne>9</nOne>
<nTwo>10</nTwo>
</repetition>
</repetitions>
<contentPlugin>
<groupId>fake.plugin.group</groupId>
<artifactId>adder-maven-plugin</artifactId>
<version>0.0.0</version>
<executions>
<execution>
<id>repeat-add</id>
<goals>
<!-- Every goal will be run. -->
<!-- the adder-maven-plugin only has one goal -->
<goal>add</goal>
</goals>
<!-- NOTE: Due to a limitation of the maven plugin API -->
<!-- this doesn't support the phase tag. All the executions -->
<!-- are run in the same phase as your plugin-repeator-maven-plugin -->
<configuration>
<!-- These @ surrounded variables are replaced with their -->
<!-- corresponding values during each repetition. -->
<numberOne>@nOne@</numberOne>
<numberTwo>@nTwo@</numberTwo>
</configuration>
</execution>
</executions>
</contentPlugin>
</configuration>
</execution>
</executions>
</plugin>
If you have some repetitions that all use a certain variable with a certain value, except 1, you'd have to repeat that variable in the repetitions (violating the DRY principal).
Fear not! We have thought of this, and added a feature called repetitionGroups that allow you to set defaults for certain repetitions, and override it for others.
Here is an example:
<!-- Boilerplate omitted -->
<execution>
<id>run-addings</id>
<goals>
<goal>repeat</goal>
</goals>
<configuration>
<repetitions>
<repetitionGroup>
<!-- Here we set a default for 'nOne'. -->
<!-- If any repetitions nested inside this repetitionGroup -->
<!-- *don't* declare 'nOne', it will be supplied by the most recent default. -->
<!-- In this case that is the top level repetition group, and 2. -->
<nOne>2</nOne>
<repetition>
<nTwo>2</nTwo>
</repetition>
<repetition>
<nTwo>3</nTwo>
</repetition>
<repetition>
<nTwo>4</nTwo>
<nOne>4</nOne>
</repetition>
</repetitionGroup>
</repetitions>
...
<!-- Same as before ... -->
...
</configuration>
</execution>
which is equivalent to:
<!-- Boilerplate omitted -->
<executions>
<execution>
<!-- NOTE: even though these have the same execution ID -->
<!-- they will all be run inside the plugin-repeater-maven-plugin -->
<id>repeat-add</id>
<goals>
<goal>add</goal>
</goals>
<configuration>
<numberOne>2</numberOne>
<numberTwo>2</numberTwo>
</configuration>
</execution>
<execution>
<id>repeat-add</id>
<goals>
<goal>add</goal>
</goals>
<configuration>
<numberOne>2</numberOne>
<numberTwo>3</numberTwo>
</configuration>
</execution>
<execution>
<id>repeat-add</id>
<goals>
<goal>add</goal>
</goals>
<configuration>
<numberOne>4</numberOne>
<numberTwo>4</numberTwo>
</configuration>
</execution>
</executions>
You can even nest these as deeply as you want!
<!-- Boilerplate omitted -->
<execution>
<id>run-addings</id>
<goals>
<goal>repeat</goal>
</goals>
<configuration>
<repetitions>
<repetitionGroup>
<nOne>2</nOne>
<repetitionGroup>
<nTwo>2</nTwo>
<repetition>
<nOne>10</nOne>
</repetition>
</repetitionGroup>
<repetition>
<nTwo>-1</nTwo>
</repetition>
</repetitionGroup>
</repetitions>
...
<!-- Same as before ... -->
...
</configuration>
</execution>
is equivalent to:
<!-- Boilerplate omitted -->
<executions>
<execution>
<id>repeat-add</id>
<goals>
<goal>add</goal>
</goals>
<configuration>
<numberOne>10</numberOne>
<numberTwo>2</numberTwo>
</configuration>
</execution>
<execution>
<id>repeat-add</id>
<goals>
<goal>add</goal>
</goals>
<configuration>
<numberOne>2</numberOne>
<numberTwo>-1</numberTwo>
</configuration>
</execution>
<executions>
Due to limitations on maven's XML, you cannot currently do something like this:
<!-- Boilerplate omitted -->
<execution>
<id>run-addings</id>
<goals>
<goal>repeat</goal>
</goals>
<configuration>
<repetitions>
<repetitionGroup>
<nOne>2</nOne>
<repetitionGroup>
<nTwo>2</nTwo>
<!-- neither of the following tags will be recognized! -->
<!-- Even though they are unambiguous in terms of their intention -->
<repetition/>
<repetition>
</repetition>
</repetitionGroup>
</repetitionGroup>
</repetitions>
...
<!-- Same as before ... -->
...
</configuration>
</execution>
The plugin-repeater-maven-plugin also supports conditional inclusion of XML for content plugins. Currently you can only make the decision based on whether a filter variable is defined for the current repetition or not.
In order to conditionally include a tag, myTag inside the configuration of your content plugin you can do the following:
<configuration>
<myTag if="myVar">@myVar@</myTag>
</configuration>
This includes <myTag>myVarValue</myTag> if myVar has a definition for the current repetition.
An important note for this is that a failed condition excludes everything within the failing tag.
Any nested XML tags will also be excluded as well as any attributes or string contents.
The plugin-repeater-maven-plugin also supports the unless attribute.
Here is a toy usage:
<!-- Boilerplate omitted -->
<execution>
<id>run-addings</id>
<goals>
<goal>repeat</goal>
</goals>
<configuration>
<repetitions>
<repetition>
<nOne>1</nOne>
<nTwo>2</nTwo>
</repetition>
<repetition>
<nTwo>5</nTwo>
</repetition>
</repetitions>
<contentPlugin>
<groupId>fake.plugin.group</groupId>
<artifactId>adder-maven-plugin</artifactId>
<version>0.0.0</version>
<executions>
<execution>
<id>repeat-add</id>
<goals>
<goal>add</goal>
</goals>
<configuration>
<numberOne if="nOne">@nOne@</numberOne>
<numberOne unless="nOne">0</numberOne>
<numberTwo>@nTwo@</numberTwo>
</configuration>
</execution>
</executions>
</contentPlugin>
</execution>
</executions>
which equivalent to:
<!-- Boilerplate omitted -->
<executions>
<execution>
<id>repeat-add</id>
<goals>
<goal>add</goal>
</goals>
<configuration>
<numberOne>1</numberOne>
<numberTwo>2</numberTwo>
</configuration>
</execution>
<execution>
<id>repeat-add</id>
<goals>
<goal>add</goal>
</goals>
<configuration>
<numberOne>0</numberOne>
<numberTwo>5</numberTwo>
</configuration>
</execution>
<executions>