How can I find out the default phase a Maven goal binds to?

Question

In Maven, how can I find out the default phase of a goal (if any default phase exists at all for this particular goal)?

Example

I am using a Maven plugin called Jetty Maven Plugin. It contains a goal jetty:run. Running the command mvn jetty:run (notice this command only contains a goal, not a phase) first builds a pom.xml-specified web application up to the default test-compile phase, then deploys it inside a Jetty server.

As pointed out in the Mojo API Specification, a goal can have a default phase assigned to it in its source code (via @phase or via @execute phase). In case of jetty:run, the default phase is @execute phase="test-compile".

But finding the source code file can get quite complicated. Is there an easier way for finding out the default phase?

Answer 1

The simplest solution is to use the maven-help-plugin like the following:

mvn help:describe -DartifactId=maven-compiler-plugin -DgroupId=org.apache.maven.plugins -Dgoal=compile -Ddetail

which will printout many information but in the first lines:

[INFO] Mojo: 'compiler:compile'
compiler:compile
  Description: Compiles application sources
  Implementation: org.apache.maven.plugin.CompilerMojo
  Language: java
  Bound to phase: compile

  Available parameters:
  ....

If you try that for jetty:run like this:

mvn help:describe -DartifactId=jetty-maven-plugin -DgroupId=org.mortbay.jetty -Dgoal=run -Ddetail

You will get a large output but you won't see a default phase, cause it's intended to be called from command line:

[INFO] Mojo: 'jetty:run'
jetty:run
  Description: This goal is used in-situ on a Maven project without first
    ....
    redeploying.
     .....

  Implementation: org.mortbay.jetty.plugin.JettyRunMojo
  Language: java
  Before this mojo executes, it will call:
    Phase: 'test-compile'

  Available parameters:
      ....