While git is a completely distributed revision control system, sometimes the lack of a central canonical repository can be annoying. For example, you might want to make your repository published publically, so other people can fork your code, or you might want all your developers to push into (or have code pulled into) a central "golden" tree, that you then use for automated building and continuous integration. This entry should explain how to get this all working on Ubuntu 9.04 (Jaunty).

Gitosis is a very useful git repository manager, which adds support like ACLs in pre-commits and gitweb and git-daemon management. While it's possible to set all these things up by hand, gitosis does everything for you. It is nicely configured via git; to make configuration changes, you push the config file changes into gitosis repository on the server.

Gitosis is available in Jaunty, but unfortunately there is a bug in the version in Jaunty, which means it doesn't work out of the box. Fortunately there is a fixed version in jaunty-proposed that fixes the main problem. This does mean that you need to add the following to your sources.list:

deb http://gb.archive.ubuntu.com/ubuntu/ jaunty-proposed universe

Run apt-get update && apt-get install gitosis. You should install 0.2+20080825-2ubuntu0.1 or later. There is another small bug in the current version too, as a result of git removing the git-$command scripts out of /usr/bin. Edit /usr/share/python-support/gitosis/gitosis/templates/admin/hooks/post-update and replace

git-update-server-info

with

git update-server-info

With these changes in place, we can now set up our gitosis repository. On the server you are going to use to host your central repositories, run:

sudo -H -u gitosis gitosis-init < id_rsa.pub

The id_rsa.pub file is a public ssh key. As I mentioned, gitosis is managed over git, so you need an initial user to clone and then push changes back into the gitosis repo, so make sure this key belongs to a keypair you have available to the remote user you're going to configure gitosis.

Now, on your local computer, you can clone the gitosis-admin repo using:

git clone gitosis@gitserver.example.com:gitosis-admin.git

If you look inside the gitosis-admin directory, you should find a file called gitosis.conf and a directory called keydir. The directory is where you can add ssh public keys for your users. The file is the configuration file for gitosis.

[gitosis]
loglevel = INFO

[group gitosis-admin]
writable = gitosis-admin
members = david@david

[group developers]
members = david@david
writable = publicproject privateproject

[group contributors]
members = george@wilber
writable = publicproject

[repo publicproject]
daemon = yes
gitweb = yes

[repo privateproject]
daemon = no
gitweb = no

This sets up two repositories, called publicproject and privateproject. It enables the public project to be available via the git protocol and in gitweb if you have that installed. We also create two groups, developers and contributors. David has access to both projects, but George only has access to change the publicproject. David can also modify the gitosis configuration. The users are the names of ssh keys (the last part of the line in id_dsa.pub or id_rsa.pub).

Once you've changed this file, you can run git add gitosis.conf to add it to the commit, git commit -m "update gitosis configuration to commit it to your local repository, and finally git push to push your commits back up into the central repository. Gitosis should now update the configuration on the server to match the config file.

One last thing to do is to enable git-daemon, so people can anonymously clone your projects. Create /etc/event.d/git-daemon with the following contents:

start on startup
stop on shutdown

exec /usr/bin/git daemon \
   --user=gitosis --group=gitosis \
   --user-path=public-git \
   --verbose \
   --syslog \
   --reuseaddr \
   --base-path=/srv/gitosis/repositories/ 
respawn

You can now start this using start git-daemon

So now, you need to start using your repository. You can either start with an existing project or an empty directory. Start by running git init and then git add $file to add each of the files you want in your project, and finally git commit to commit them to your local repository. The final task is to add a remote repository and push your code into it.

git remote add origin gitosis@gitserver.example.com:privateproject.git
git push origin master:refs/heads/master

In future, you should be able to do git push to push your changes back into the central repository. You can also clone a project using git or ssh, providing you have access, using the following commands. The first is for read-write access over ssh and the second uses the git protocol for read-only access. The git protocol uses TCP port 9418, so make sure that's available externally, if you want the world to be able to clone your repos.

git clone gitosis@gitserver.example.com:publicproject.git
git clone git://gitserver.example.com/publicproject.git

Setting up GitWeb is left as an exercise for the reader (and myself because I am yet to attempt to set that up).