Obtaining git.commit.id.abbrev from the command line via mvn-plugin:exec possible?

[leonroy]

We have our tagged docker images being pushed to Docker hub with the following custom property app.docker.version.

<project>
    <artifactId>api-server</artifactId>
    <version>0.6.31-SNAPSHOT</version>

    <properties>
        <app.docker.version>${version}-${git.commit.id.abbrev}</app.docker.version>
    </properties>
...
</project>

We wanted to grab this property from the command line and pass it to our deploy step on the CI/CD server.

Running mvn -f api-server/pom.xml -q -Dexec.executable="echo" -Dexec.args='${app.docker.version}' --non-recursive org.codehaus.mojo:exec-maven-plugin:1.3.1:exec from the command line however returns null.

We can get the project.version just fine but not app.docker.version. Any ideas? (thanks)

[TheSnoozer]

Hello,
thank you for creating this issue.

Let me try to understand this correctly:
When trying to get the app.docker.version it returns null and not any variable (e.g. the outcome of ${version}-${git.commit.id.abbrev})?

If this is the case then that sounds like an issue with the org.codehaus.mojo:exec-maven-plugin and not this plugin. In general my suspect is that sounds related to running maven with a it's Plugin's Prefix (e.g. instead of mvn clean package you run with mvn clean org.codehaus.mojo:exec-maven-plugin:1.3.1:exec...). Within maven that might yield to surprises and the plugin properly needs to obtain the properties (e.g. checking System.getProperty). I can't recall the details what this plugin did, but as reference I'd point to

#413 (comment)
#444
#287

If this is not a bug in the plugin I'd suggest to open an issue for org.codehaus.mojo:exec-maven-plugin.

[TheSnoozer]

Just tested this locally and indeed this is a classical 'plugin' prefix problem.
Try running without the -q option to see what tasks are executed.

When running with mvn -Dexec.executable="echo" -Dexec.args='${app.docker.version}' --non-recursive org.codehaus.mojo:exec-maven-plugin:1.3.1:exec only the exec-task is being executed:

[INFO] Scanning for projects...
[INFO] 
[INFO] ---------< pl.project13.maven:git-commit-id-plugin-debugging >----------
[INFO] Building Git Commit Id Plugin Maven Mojo Debugging 0.0.3-SNAPSHOT
[INFO] --------------------------------[ pom ]---------------------------------
[INFO] 
[INFO] --- exec-maven-plugin:1.3.1:exec (default-cli) @ git-commit-id-plugin-debugging ---
0.0.3-SNAPSHOT-null
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  0.824 s
[INFO] Finished at: 2020-07-14T22:15:43+02:00
[INFO] ------------------------------------------------------------------------

Where should the ${git.commit.id.abbrev} come from when the plugin is not even run?

You also need to add this plugin to the execution graph:

$ mvn -q -Dexec.executable="echo" -Dexec.args='${app.docker.version}' --non-recursive pl.project13.maven:git-commit-id-plugin:4.0.0:revision org.codehaus.mojo:exec-maven-plugin:1.3.1:exec
0.0.3-SNAPSHOT-beef4e9

or invoke it via the initialize lifecycle as such:

$ mvn -q -Dexec.executable="echo" -Dexec.args='${app.docker.version}' --non-recursive initialize org.codehaus.mojo:exec-maven-plugin:1.3.1:exec
0.0.3-SNAPSHOT-beef4e9

Since this is how maven is intended to work (by specifying the plugin prefix you want to run a specific mojo/task as outlined in https://maven.apache.org/guides/introduction/introduction-to-plugin-prefix-mapping.html) I'm going ahead and close this.

Feel free to reopen if you still have trouble getting this sorted.