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From Karl Heinz Marbaise <>
Subject Re: Reactor module dependency tree resolution
Date Fri, 24 Apr 2020 13:09:41 GMT

On 24.04.20 14:47, Christian Domsch wrote:
> Hi,
> I would like to be able to get access to the reactor module tree. I have a
> specific plugin that is executed for each reactor module and it needs to
> check, if for a predefined set of modules in the reactor (in our case war
> archives that contain a subset of all modules) see if the current module is
> actually contained in that war (directly or via transitive dependencies).

Can you explain more in detail what the use case is? If an artifact is
part of a war? Why would like to check that? Can be seen in the war module?

> What I tried so far, but isn't working, is using the aether dependency
> resolution mechanism. The reason why it isn't working is fairly obvious:
> checking the transitive dependencies of these war modules, aether tries to
> download all artifacts first and fails because they haven't been build by
> the reactor, yet, and thus are unknown. This makes a lot of sense, but also
> means this way won't help me.
> Now, the reactor itself has to be able to calculate those dependencies, as
> it will calculate a certain order of building the modules, depending on how
> those modules depend on each other. This (what I will call) reactor module
> tree is exactly the information I need.

The reactor is the part which contains the parents/modules and order of
building the modules...this can be accessed via:

@Parameter(defaultValue = "${session}", required = true, readonly = true)
MavenSession session;

By using the above session you could:
  * session.getProjectDependencyGraph().getSortedProjects();

The sortedProjects is exactly the order of the reactor ..

If you like to know the dependencies you have to go via dependency
resolution in your plugin:

Something like:

@Mojo(name = "xxx", defaultPhase = LifecyclePhase.PRE_INTEGRATION_TEST,
     requiresDependencyResolution = ResolutionScope.RUNTIME, threadSafe
= true)

The important part is:
requiresDependencyResolution = ResolutionScope.RUNTIME

which you now gives you the option to access the dependencies:


where mvnProject:

   @Parameter(defaultValue = "${project}", required = true, readonly = true)
   private MavenProject project;

Kind regards
Karl Heinz Marbaise

> Is there a way to access this information from a plugin? ${reactorProjects}
> does not tell me that. Or am I missing sth very obvious?
> Thx,
> Christian

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