Collaborating Using git-svn

I like Git, and I'm using it everywhere. It gives you so much power that once you taste it, you won't want to come back to traditional source control systems. One of the Git benefits is collaboration friendliness. Git encourages collaboration, ideas exchange, and code review. If your team is using Git then you know how easy it is to share your code with your co-workers. But sometimes you are the only person in the team who uses Git, and everybody else is on Subversion. Don't worry, you still can share your ideas by means of git-svn tool, and here I want to show you how. The process is not as simple as native Git (via pull/push or patch/apply) but it's better than nothing.

Suppose you have an idea and you are eager to try it. You don't want to create a branch in Subversion because you don't know if your idea will work out, and committing all your crazy stuff in Subversion can easily pollute it. So you create a local Git branch and start working.

$ git checkout -b topic/great-idea

You code, test, git-add, git-commit, code, test, etc. At some point you see that your idea was great indeed and it's time to show the amazing results to your teammates. Now you need to "push" your Git branch to Subversion. To do this you have to create Subversion brunch first

$ svn copy http://svn.repo.path/project-name/trunk \
http://svn.repo.path/project-name/branches/great-idea \
-m "Created branch for my cool stuff"

Next step is to add this Subversion branch as a remote branch to Git configuration. Open .git/config file with a text editor. You should see something like this

[core]
       repositoryformatversion = 0
       filemode = true
       bare = false
       logallrefupdates = true
[svn-remote "svn"]
       url = http://svn.repo.path
       fetch = project-name/trunk:refs/remotes/trunk

If you built your Git repository by cloning Subversion repository (which you most likely did), you will have one or more svn-remote sections in this configuration file. You need to add another one for new Subversion branch.

[core]
       repositoryformatversion = 0
       filemode = true
       bare = false
       logallrefupdates = true
[svn-remote "svn"]
       url = http://svn.repo.path
       fetch = project-name/trunk:refs/remotes/trunk
[svn-remote "svn-great-idea"]
       url = http://svn.repo.path
       fetch = project-name/branches/great-idea:refs/remotes/great-idea

Next step is to fetch Subversion branch, but first you need to know revision number when this branch was created. Run this command

$ svn log --stop-on-copy http://svn.repo.path/project-name/branches/great-idea

You should get something like this:

------------------------------------------------------------------------
r2165 | andy | 2009-07-03 14:36:59 -0400 (Fri, 03 Jul 2009) | 1 line
 
Created branch for my cool stuff
------------------------------------------------------------------------

The first number of the output is what we are looking for:

$ git svn fetch svn-great-idea -r2165

Now you have the Subversion branch in you Git. If you run git branch -a command you will see "great-idea" branch in the list.

 master
* topic/great-idea
 great-idea
 trunk

You shouldn't work on remote branch, so let's create local one:

$ git branch svn-branch/great-idea remotes/great-idea

I put it in svn-branch namespace just to make it visually clear that this branch is in synch with Subversion. The next set of commands is a standard way to bring your work from one local branch to another. In our case: from initial topic/great-idea to svn-branch/great-idea

$ git rebase svn-branch/great-idea
$ git checkout svn-branch/great-idea
$ git rebase topic/great-idea

That's it. Now you are ready to commit your code to Subversion:

$ git svn dcommit

Done. As an option, you can delete initial branch because you have a Subversion backed copy of it:

$ git branch -D topic/great-idea

Resources

• Ian Boston's post explaining how to add Subversion branches to Git.