Development / Git

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Development on the MusicBrainz Server source code is coordinated using Git. We use GitHub for hosting our repositories, see http://github.com/metabrainz for all the repositories.

Checking out source code

To create a local copy of the MusicBrainz Server source code, clone the repository using:

git clone https://github.com/metabrainz/musicbrainz-server.git musicbrainz-server
cd musicbrainz-server

And to stay up to date with the latest changes use:

git pull

The above will clone the latest development version. Alternatively, if you're looking for a stable live release of the MusicBrainz Server, all official releases we make are tagged and accessible using:

git tag -l
git checkout <tag name>

If you need help or are confused send an email to support@musicbrainz.org, or drop by the #metabrainz IRC channel.

Development with Git

If you want to help contribute to MusicBrainz - it's really simple! First, go to the musicbrainz-server repository and click 'fork' - you'll need a GitHub account to do this. Afterwards, you just need to clone your repository, and you're good to go!

git clone https://github.com/<YOUR USER NAME HERE>/musicbrainz-server.git musicbrainz-server
cd musicbrainz-server
git checkout -b my-cool-feature beta

You probably also want to do git remote add upstream https://github.com/metabrainz/musicbrainz-server.git once you're in your new clone, to be able to fetch/pull the most recent code.

This will give you a local branch to work on your feature. Note, this is a slightly different model than you may be used to. This type of development is called "topical branches" - each branch of the code deals with a single isolated feature. This helps us develop by reviewing individual features and bug fixes, without being confused by other possibly unimportant changes.

When you are ready to share your work with us, you should submit a patch; read the instructions for submitting a patch below.

For more information on any of this, please drop by the #metabrainz IRC channel, and someone will give you more details.

Submitting a patch

If you make changes to MusicBrainz Server, they'll need to go through our code review process. We use GitHub's pull request system to handle this—if you've already forked the project on GitHub per the above section, all you'll need to do is follow GitHub's documentation on "Proposing changes to a project with pull requests". The target branch will usually be 'master' (though you should have branched off from 'beta').

Be sure to mention other details, such as the JIRA tickets you're fixing (if there isn't a relevant ticket, you may be asked to create one) and what testing you have done -- those reviewing your code will want to know. If your code is running anywhere that it can be tested by reviewers, such as on a sandbox, mention this.

Ultimately, you should get some "Ship It"s or comments to fix; fix anything that needs fixing, and discuss with those who comment on your review. Once it's satisfactory, someone with access will merge your code and it'll get released!

The MusicBrainz Workflow

MusicBrainz uses a simple workflow to get work out for testing, marking it as stable, and deploying the work. There are 3 eternal branches: production, beta and master. 'production' contains a released version of the code (a tag to be specific), plus possibly a few more commits to fix urgent issues on the production servers. 'master' contains work that has passed testing and code review and will be included in one of the next versions of MusicBrainz. Finally, the 'beta' branch follows 'master', but is frozen one week before the next release (the code in this branch is deployed for live testing at https://beta.musicbrainz.org/). At release time, what was in 'beta' is released and becomes the new 'production'; 'beta' is unfrozen and once more follows the latest code from 'master'.

Let's look at an imaginary example of a small release: MusicBrainz has just released a new version, lets call it v-2015-11-30. At this point 'production' has a tag, v-2015-11-30. 'beta' and 'master' are equivalent. Two bugs are reported, so we create separate branches for them: 'mbs-1' and 'mbs-2' for example. When they are deemed ready by the owner, pull requests are opened for them and testing and reviewing is requested. After testing, 'mbs-1' is fine and passes review, but 'mbs-2' isn't good enough yet. At this point, 'mbs-1' is merged into 'master' and will soon continue to 'beta', and more work can happen on 'mbs-2'. A new or revised pull request for 'mbs-2' is placed, and testing and reviewing is requested once more. Testers are now happy with this branch, and it passes review, so now 'mbs-2' also gets merged to 'master'. However, one week has passed since the release and 'beta' is already frozen, so the new code doesn't move on yet. Next time we release, 'beta' is merged into 'production', so the code of 'beta' and 'production' are roughly equivalent again. Finally, a release happens which means 'production' is tagged with a new version, a blog post is posted, and customers can now check this new tag out. Then 'beta' is unfrozen and 'master', which includes 'mbs-2', is merged into it.

Git Resources

If you're new to Git, don't worry - there is plenty of excellent documentation about how to use it: