ci-friendly-flatten-maven-plugin

This is the ci-friendly-flatten-maven-plugin.

Why another flatten plugin?

Having a large (> 350 modules) reactor with multiple daily releases, we encountered two issues:

1. Commit history littered with maven release plugin commits.
2. Race between committers pushing to the main branch, and the release plugin pushing its own pom changes.

When we found out about ci friendly versions, we were ecstatic - finally we can avoid having versions in poms and achieve zero commits release process!

The only problem was that the flatten plugin coupled with the resolveCiFriendliesOnly option does not work. As adherers of the unix philosophy, we decided to create a plugin that truly, really, only replaces the revision, sha and changelist properties.

Quickstart

This plugin flattens a pom by replacing ${revision}, ${sha1}, ${changelist} to values you set by passing them as args. It then writes the resulting pom to a file named .ci-friendly-pom.xml and sets it as the new reactor. For example, installing version 2.0.0:

mvn -Drevision=2.0.0 clean install

Plugin setup

   <build>
        <plugins>
          <plugin>
            <groupId>com.outbrain.swinfra</groupId>
            <artifactId>ci-friendly-flatten-maven-plugin</artifactId>
            <!--<version>INSERT LATEST VERSION HERE</version>-->
            <executions>
              <execution>
                <goals>
                  <!-- Ensure proper cleanup. Will run on clean phase-->
                  <goal>clean</goal>
                  <!-- Enable ci-friendly version resolution. Will run on process-resources phase-->
                  <goal>flatten</goal>
                </goals>
              </execution>
            </executions>
          </plugin>
        </plugins>
   </build>

Plugin Goals

• ci-friendly-flatten:flatten Replaces revision, sha1, changelist, writes the resolved pom file to .ci-friendly-pom.xml and sets it as the new reactor (Default maven phase binding: process-resources).
• ci-friendly-flatten:clean Removes any files created by ci-friendly-flatten:flatten (Default maven phase binding: clean).
• ci-friendly-flatten:version Fetches the latest git tag, increments it and writes it to revision.txt, relies on scm configuration.
• ci-friendly-flatten:scmTag Tags the commit with the updated version and pushes the tag, relies on scm configuration.

Installing artifacts

1. To avoid having to type -Drevision=<version> when installing locally, define a default revision property.

     <properties>
        <revision>5.0.0-SNAPSHOT</revision>
     </properties>
   

mvn clean install

Will install all artifacts with 5.0.0-SNAPSHOT version.

2. Provide the version with revision arg

mvn clean install -Drevision=<VERSION>

Will install all artifacts with your provided VERSION

Deploying artifacts

Same as above, just use mvn clean deploy -Drevision=<VERSION>

How we configured it ?

1. We added ci-friendly-flatten-maven-plugin to our pom.xml.

2. TeamCity Configuration:

   • Added a project system param system.version.

   • The project build steps:

     • Step #0 New project should tag their project before step 1 (git tag)

       git tag -a "1.0.0" -m "my version '1.0.0'"

       git push origin "1.0.0"

     • Step #1 - (Maven step) Fetch the latest git tag, increment it and write the result to revision.txt. This is the version we are going to release.

       mvn ci-friendly-flatten:version

     • Step #2 - (Command line step) Set a system.version TeamCity parameter with our soon to be released version, in order to use it in the next steps

       #!/bin/bash -x
       VER_PATH="%teamcity.build.checkoutDir%/revision.txt"
       REV=`cat $VER_PATH`
       set +x
       echo "##teamcity[setParameter name='system.version' value='$REV']"
       

     • Step #3 - (Maven step) deploy

       mvn clean deploy -Drevision=%system.version%

     • Step #4 - (Maven step) Tag the current commit with the updated version and push the tag

       mvn ci-friendly-flatten:scmTag -Drevision=%system.version%