Git Plugin

This plugin allows use of GIT as a build SCM.

Changelog

 Version 0.3

• Add support for pre-build branch merges

 Version 0.2

• Improve handling of git repositories (use local tags to identify up to date versions rather than the wc HEAD)
• Don't have to specify a branch, in which case all branches are examined for changes and built
• Includes a publisher which can be used to push build success/failure tags back up to the upstream repository

 Version 0.1

• Initial Release

Using Git, Hudson and pre-build branch merging

Continuous Integration tools such as Hudson are useful on projects as they give users early indication that a particular codebase is 'unstable' - and that if a developer checks it out, there will be trouble ahead (they won't be able to work on their own code, because someone else has broken something).

Unfortunately, by the time the build completes, this is often too late (particularly if the build cycle time is very long), as a developer has updated their working copy to the latest, unstable code in the repository and has begun work.

This can lead to the code base remaining unstable as developers tread on each others toes steadily fixing one thing, but breaking something else.

Some environments (e.g. TeamCity) attempt to fix this by making commits into SVN only 'really' happen once they have been tested. These kinds of 'delayed-commits' are problematic, because local SCM tools assume that commits will be immediately available, which can confuse them. In many ways this mechanism is a hack to get around the fact that branch management in SVN is very heavyweight.

Fortunately, with GIT and Hudson, you can achieve the same 'stable branches' with minimal effort.

Set up your hudson project, and leave the 'branch' field in the Git SCM blank. This will cause Hudson to consider any change on any branch for building.

Next, pick a particular branch name as the integration target in the 'Advanced' section - (e.g. 'master', or 'stable'), and select 'Merge before build'.

Select 'Push GIT tags back to origin repository' from the post-build actions (this is required to update your centralised git repo with the results of the build).

Now, developers should never commit directly to your integration branch (the 'master' or 'stable'). Instead, they should either use feature branches, or create new remote branches on commit (e.g : "git push origin HEAD:refs/heads/myNewFeature"). You could also set up your GIT repository to only accept commits onto the integration branch from Hudson.

You're done. Commits should now be automatically merged with the integration branch (they will fail if they do not merge cleanly), and built. If the build succeeds, the result of the merge will be pushed back to the remote git repository.