Manage git repositories, provide access to them over SSH, with tight access control and not needing shell accounts.

Note

Documentation is still lacking, and non-default configurations (e.g. config file, repositories, installing in a location that is not in PATH) basically have not been tested at all. Basic usage should be very reliable -- the project has been hosting itself for a long time. Any help is welcome.

gitosis aims to make hosting git repos easier and safer. It manages multiple repositories under one user account, using SSH keys to identify users.
End users do not need shell accounts on the server, they will talk to one shared account that will not let them run arbitrary commands.

gitosis is licensed under the GPL, see the file COPYING for more information.

You can get gitosis via git by saying:

git clone https://github.com/voretaq7/gitosis.git

And install it via:

python setup.py install

Though you may want to use e.g. --prefix=.

First, we will create the user that will own the repositories. This is usually named git, but any name will work, and you can have more than one per system if you really want to. The user does not need a password, but does need a valid shell (otherwise, SSH will refuse to work).
Create a dedicated service account. DO NOT use a normal user account.

The git repositories will be stored in the service account user's home directory, so a location such as /srv/example.com/git or /var/git is recommended. Create the user with :

sudo adduser \
    --system \
    --shell /bin/sh \
    --gecos 'git version control' \
    --group \
    --disabled-password \
    --home /srv/example.com/git \
    git

or equivalent commands on your system.

You will need an SSH public key to continue. If you don't have one, you need to generate one. See the man page for ssh-keygen, and you may also be interested in ssh-agent.
Create the SSH key on your personal computer and protect the private key well -- that includes not transferring it over the network.

Next, we need to set things up for the newly-created git user.
The following command will create a ~/repositories that will hold the git repositories, a ~/.gitosis.conf that will be a symlink to the actual configuration file, and it will add the SSH public key to ~/.ssh/authorized_keys with a command= option that restricts it to running gitosis-serve.
Run:

sudo -H -u git gitosis-init <FILENAME.pub
# (or just copy-paste the public key when prompted)

You can now git clone git@SERVER:gitosis-admin.git, and you get a repository with SSH keys as keys/USER.pub and a gitosis.conf where you can configure who has access to what.

warning

For now, gitosis uses the HOME environment variable to locate where to write its files. If you use sudo -u without -H, sudo will leave the old value of HOME in place, and this will cause trouble. There will be a workaround for that later on, but for now, always remember to use -H if you're sudoing to the account.

You should always edit the configuration file via git.
The file symlinked to ~/.gitosis.conf on the server will be overwritten when pushing changes to the gitosis-admin.git repository.

Edit the settings as you wish, commit and push. That's pretty much it! Once you push, gitosis will immediately make your changes take effect on the server.

The gitosis system and managed repositories will be available using your system's regular SSH daemon. This may be what you want, however if you don't expose SSH publicly you may wish to set up a dedicated SSH daemon exclusively for gitosis.
For best security this should run on an alternate port, only allow the git user to log in, and not allow the use of interactive passwords.

Some recommended sshd_config settings:

AllowUsers git
AllowAgentForwarding no
AllowTcpForwarding no
X11Fordwarding no
PermitRootLogin no
PasswordAuthentication no
ChallengeResponseAuthentication no

To add new users:

• add a keys/USER.pub file
• authorize them to read/write repositories as needed
  (or just authorize the group @all)

To create new repositories, just authorize writing to them and push. It's that simple!
For example: let's assume your username is jdoe and you want to create a repository myproject. In your clone of gitosis-admin, edit gitosis.conf and add:

[group myteam]
members = jdoe
writable = myproject

Commit that change and push, then create the initial commit in your local repository and push it:

mkdir myproject
cd mypyroject
git init
git remote add myserver git@MYSERVER:myproject.git
# do some work, git add and commit files
git push myserver master:refs/heads/master

That's it. If you now add others to members, they can write to that repository too.

Anonymous read-only access to git repositories is provided by git daemon, which is distributed as part of git. But gitosis will still help you manage it: setting daemon = yes in your gitosis.conf, either globally in [gitosis] or per-repository under [repo REPOSITORYNAME], makes gitosis create the git-daemon-export-ok files in those repository, thus telling git daemon that publishing those repositories is ok.

To actually run git daemon refer to your operating system's instructions for running daemons at startup.

Note that this short snippet is not a substitute for reading and understanding the relevant documentation.

gitweb is a CGI script that lets one browse git repositories on the web. It is most commonly used anonymously, but you could also require authentication in your web server, before letting people use it.

gitosis can help here by generating a list of projects that are publicly visible. Simply add a section [repo REPOSITORYNAME] to your gitosis.conf, and allow publishing with gitweb = yes (or globally under [gitosis]). You should also set description and owner for each repository.