Finding the root directory of a multi module maven reactor project

Question

I want to use the maven-dependency-plugin to copy EAR-files from all sub-modules of my multi-module project to a directory that is relative to the root directory of the entire project.

That is, my layout looks similar to this, names changed:

to-deploy/
my-project/
    ear-module-a/
    ear-module-b/
    more-modules-1/
        ear-module-c/
        ear-module-d/
    more-modules-2/
        ear-module-e/
        ear-module-f/
    ...

And i want all the EAR-files to be copied from the target-directories of their respective modules to my-project/../to-deploy so i end up with

to-deploy/
    ear-module-a.ear
    ear-module-b.ear
    ear-module-c.ear
    ear-module-d.ear
    ear-module-e.ear
    ear-module-f.ear
my-project/
    ...

I could do it with a relative path in each ear-module, like so:

        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-dependency-plugin</artifactId>
            <executions>
                <execution>
                    <id>copy</id>
                    <phase>install</phase>
                    <goals>
                        <goal>copy</goal>
                    </goals>
                    <configuration>
                        <artifactItems>
                            <artifactItem>
                                <groupId>${project.groupId}</groupId>
                                <artifactId>${project.artifactId}</artifactId>
                                <version>${project.version}</version>
                                <type>ear</type>
                                <outputDirectory>../../to-deploy</outputDirectory>
                            </artifactItem>
                        </artifactItems>
                    </configuration>
                </execution>
            </executions>
        </plugin>

But i'd rather not specify a relative path in the <outputDirectory> element. I'd prefer something like ${reactor.root.directory}/../to-deploy, but i can't find anything like this.

Also, i'd prefer if there was some way to inherit this maven-dependency-plugin configuration so i don't have to specify it for each EAR-module.

I also tried inheriting a custom property from the root pom:

<properties>
    <myproject.root>${basedir}</myproject.root>
</properties>

But when i tried to use ${myproject.root} in the ear-module POM's, the ${basedir} would resolve to the basedir of the ear-module.

Also, i found http://labs.consol.de/lang/de/blog/maven/project-root-path-in-a-maven-multi-module-project/ where it's suggested that each developer and presumably the continuous integration server should configure the root directory in a profiles.xml file, but i don't consider it a solution.

So is there an easy way to find the root of a multi-module project?

Answer 1

I'm not aware of a "nice" way to find the root of a multi-module project. But you can maybe improve a bit your current approach.

A first alternative would be to create an additional module directly under the root project, to declare all EARs as dependencies in it and to use dependency:copy-dependencies to copy the dependencies of the module to the to-deploy directory (relatively). Yes the path would still be relative but since the dependency plugin configuration would be centralized, I don't find it that annoying.

A second alternative would be to use the Maven Assembly Plugin instead of the Maven Dependency Plugin to create a distribution using the dir format (this will create a distribution in a directory). This is actually what I would do.