[Maven + Git] Releasing and Branching done right…

Maven is really awful. I hate it.

But it is by far the best tool available… Therefore I am using it for several years now. And since it is a tool one has to struggle with, I have invested a lot of time into optimizing my build environment. So I know Maven quite well now – better than I wanted…

And of course I am using Git. And I really love it. But unfortunately Git is just a second class citizen in Maven land. The basic things work, but other things don’t (like mvn release:branch).

I have created this checklist for doing a release. Just take a look and compare it with the steps you are doing. I’d like to hear some opinions and ideas for improvements.

Small scripts

I use some scripts that make my life easier:

The setup

The version numbers

The upcoming release will be 1.0.0 (the first release for this project). Therefore no maintenance branches exist yet.

Currently the master branch is set to 1.0.0-SNAPSHOT.

The branches

Branch Description
master Contains the current development version (that will be released as next major release).

(I have an additional pu branch that is merged to master automatically when all tests have been run successfully, but that doesn’t matter for this entry)

next Contains some experimental code (that will be merged to master one day)
maint-[VERSION] Maintenance branches for every version. Just bugfixes are commited here and merged up.

Release: What has to be done

The master branch contains the latest peace of software that shall be released (that means that all bugfixes have been merged in from the maint* branches).

  • Tag for the release
  • Creating a new maint-* branch with updated version number
  • Updating the version number for master
  • Probably updated the version number for next, too

And: Of course release one version of our software…

The Checklist

1: Ensure all bugfixes have been merged into master

git log master..maint-[VERSION]

2: Creating the maint-branch

git checkout master
git checkout -b maint-1.0.0
git publish-branch

3: Releasing on maint

mvn release:prepare
mvn release:perform

4: Merging maint to master

git checkout master
git merge maint-1.0.0

5: Updating the version on master

mvn versions:set -DnewVersion=1.1.0-SNAPSHOT -DgenerateBackupPoms=false
git commit -a -m "preparing for next major release: updated version in master"

6: Merging master to next

git checkout next
git merge master

That merge has probably one merge conflict: The version in the pom.xml. Just keep the value of the next branch.

7: Updating the version for next (optional/if necessary)

mvn versions:set -DnewVersion=2.0.0-SNAPSHOT -DgenerateBackupPoms=false
git commit -a -m "preparing release: updated version in next"

8: Pushing the changes

git push

The result

Now there are three branches with different version numbers:

Branch Version
maint-1.0.0 1.0.1-SNAPSHOT
master 1.1.0-SNAPSHOT
next 2.0.0-SNAPSHOT

6 Responses to “[Maven + Git] Releasing and Branching done right…”

  • Andrey Paramonov Says:

    Hi Johannes,

    Thanks for the nice post. Can you show me the SCM section of your POM? I’m wondering what’s the standard (or conventional) way of configuring scm-plugin for local Git repository.

    Thanks,
    Andrey

    P.S. You should vote on http://jira.codehaus.org/browse/MRELEASE-579. Maybe it will wake up release plugin developers :-)

  • johannes Says:

    Usually I am using a central Git repository – connected by ssh. But for that example I used a local one.

    The URLs are described here:
    http://maven.apache.org/scm/git.html

    So for local repository it might look like that:
    scm:git:file:////home/johannes/tmp/…

  • Simon Says:

    And how do you manage the conflict of versions in step 6 ? Manually editing pom is annoying when there are many modules. Moreover it does not help for automating the release.
    Thank you

  • Ron Says:

    What is the naming convention for your version #’s? For example: [major release].[minor release].[patch #]. Do you track this with each specific app, or globally?

    I’m new to the whole ‘release’ business, and it seems a bit confusing to keep track of.

    I have a parent-pom.xml and many child-pom.xml’s for specific applications. Are you releasing each application here, or globally for the whole thing.

  • Johannes Schneider Says:

    I don’t have a “nice” solution for this step. I merge it manually every time. This isn’t too difficult – just the version numbers…
    But of course that step should be automated…

  • Marcus Linke Says:

    There is a dedicated maven gitflow plugin from Atlassian now:

    https://bitbucket.org/atlassian/maven-jgitflow-plugin

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