The Chronicle

of a ColdFusion Expatriate

Run Your Own Private Shared Git Repository

January 14, 2013

So everyone uses Github now, and that’s cool, because Github is awesome. But what if Github goes down, even just for a short time, and you’re sitting there trying to get your stuff deployed or whatever? You’re basically screwed. Though Github is a fantastically stable service, it does have the occasional availability hiccup and the only real solution to that problem is redundancy.

So what’s a guy (or gal) to do? Run your own private git repository somewhere else!

Push your changes to Github and to your own repository and you’ll never be without a version-controlled source. You may know that git itself is able to operate over several protocols:

  • HTTP(S)
  • SSH
  • Git

The HTTP and SSH protocols are obvious and they give you exactly the capabilities that you would expect. But who wants to have to type in:

$ git push ssh://username@domain.com:/var/git/repos/myrepo.git

That’s silly. On top of that, you want to have centralized access to repositories across a few users rather than spread all around on the remote system. In short, you want what Github provides. You want this:

$ git push git@github.com:username/repository.git

Well, you can have it, and I’m going to tell you how.

The trick is to use git-shell and the so-called “git protocol.” In reality, the git protocol wraps around SSH and SCP; it transfers the actual data to the remote system through an SSH tunnel and doesn’t require running any additional daemons or servers on the remote host. It does require that git is installed on the remote host, of course, so do that first.

When you use a URL like `git@github.com:this/is/a/path.git`, it actually logs into the remote host via SSH using the username “git” and makes changes to the repository found at “this/is/a/path.git”, which will most likely reside in the “git” user’s home directory. I did a very simple setup, so that directory is actually “/home/git”.

To make all of this work, you need the following:

  1. A “git” user and group on the remote host.
  2. The git user’s home directory contains a directory called “git-shell-commands,” which is empty.
  3. The git user’s shell is set to /usr/bin/git-shell (or wherever it is on your system; try which git-shell).
  4. Your own public key on your local system is appended to /home/git/.ssh/authorized_keys2.

To see it work, you will first need to create a bare repository on the remote system into which you will push some changesets. To create it, simply do this:

$ cd /home/git
$ mkdir -p username/new-repository.git
$ cd username/new-repository.git
$ git init --bare
$ sudo chown -R git:git /home/git/username

All of this is assuming that your username is username, which I’m using here just as a way to separate one user’s repositories from another in the way that Github does. You don’t need to do this; you could place each repository directly into git’s home directory if you wanted to.

The important part is git init --bare, which creates an empty git repository without placing it into a .git folder; it simply dumps all of the repository metadata files right into the named path (or your current directory if no path is specified, as above). Now it is ready to receive data!

To push to it, just use the same familiar syntax you would use with Github. I like to add actual remotes by name because it makes it easier later on:

$ git remote add my-server git@mydomain.com:username/new-repository.git
$ git push --all my-server

You probably wouldn’t use the --all switch every time, but that tells git to push all refs and heads, not just the one(s) named. You could also just do:

$ git push my-server master

To push only the master head out to your new server. If you have an SSH agent available already, it should start pushing those files out with no trouble. If not, you may be prompted to enter your private key passphrase.

Was this helpful? Let me know.

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