+git-mirror - Sync your git repositories
+=======================================
+
+Introduction
+------------
+
+git-mirror_ is a tool to keep multiple git repositories of the same project in
+sync. Whenever something is pushed to any repository, the commits will
+immediately be forwarded to all the others. The tool assumes to run on a server
+hosting one of these repositories - so there has to be at least one you can
+control. A typical use-case would be your own gitolite_ installation, that you
+want to keep in sync with GitHub_.
+
+.. _git-mirror: https://www.ralfj.de/projects/git-mirror
+.. _gitolite: http://gitolite.com/gitolite/index.html
+.. _GitHub: https://github.com/
+
+Setup (gitolite)
+----------------
+
+This describes how you set up git-mirror on a server running gitolite. For other
+git hosting software, please consult the respective documentation on adding git
+hooks. I will assume that gitolite is installed to ``/home/git/gitolite``, that
+the repositories are sitting in ``/home/git/repositories``, and that git-mirror
+has been cloned to ``/home/git/git-mirror``.
+
+First of all, you need to create a file called ``git-mirror.conf`` in the
+``git-mirror`` directory. For now, it only needs to contain a single line::
+
+ mail-sender = git@example.com
+
+We will also need to add hooks to the git repositories you want to sync. The
+easiest way to manage these hooks is to put them into your ``gitolite-admin``
+repository, so enable the following line in ``/home/git/.gitolite.rc``::
+
+ LOCAL_CODE => "$rc{GL_ADMIN_BASE}/local",
+
+Make sure you read the `security note
+<http://gitolite.com/gitolite/non-core.html#pushcode>`_ concerning this
+configuration.
+
+Now add a file called ``local/hooks/repo-specific/git-mirror`` to your
+``gitolite-admin`` repository, make ii executable, and give it the following
+content::
+
+ #!/bin/sh
+ exec ~/git-mirror/githook.py
+
+For every repository you want to be synced, you can enable the hook by adding
+the following line to its configuration in ``conf/gitolite.conf``::
+
+ option hook.post-receive = git-mirror
+
+(If you need multiple hooks here, you can separate them by spaces.)
+
+Finally, you need to tell git-mirror where to sync incoming changes to this
+repository to. Add a block like the following to ``git-mirror.conf``::
+
+ [repo-name]
+ owner = post@ralfj.de
+ local = /home/git/repositories/repo-name.git
+ deploy-key = ssh-key
+ mirror-a = git@server2.example.com:repo-name.git
+ mirror-b = git@server2.example.org:the-repo.git
+
+Here, ``local`` has to be set to the path where the repository is stored
+locally. ``deploy-key`` is the name of the SSH key used for pushing the changes
+to other repositories. ``owner`` is the e-mail-address that error messages
+occurring during synchronization are sent to. And finally, the URLs to push to
+are given by ``mirror-<something>``. If these other servers also run gitolite
+and have a symmetric setup, then no matter where a change is pushed, git-mirror
+will forward it to all the other repositories.
+
+Setup (GitHub)
+--------------
+
+This explains how to configure a GitHub repository that should be part of a
+synchronized set. I will assume that one of the copies of the repository lives
+on a gitolite server you control.
+
+Since you cannot install a normal git hook on GitHub, syncing changes that are
+sent to GitHub has to be done with a webhook. First of all, you will have to
+configure your webserver to run ``webhook.py`` as CGI script. Consult the
+webserver documentation for more details.
+
+Secondly, ``webhook.py`` needs to be able to find the main git-mirror scripts,
+and it needs to be able to execute them as the ``git`` user. For the first
+point, open ``webhook.py`` and change ``webhook_core`` to point to the file
+``webhook-core.py`` in your git-mirror clone. If your installation matches the
+paths I used above, that should already be the case. For the second point,
+``webhook.py`` is using ``sudo`` to elevate its privileges. You need to tell
+``sudo`` that this is all right, by creating a file
+``/etc/sudoers.d/git-mirror`` with content::
+
+ www-data ALL=(git) NOPASSWD: /home/git/git-mirror/webhook-core.py
+
+Now, if you visit ``https://example.com/git-mirror/webhook.py`` (replace with
+your URL), the script should run and tell you ``Repository missing or not
+found.``.
+
+The next step is to add this as a webhook to the GitHub repository you want to
+sync with, to create a fresh SSH key and configure it as deployment key for the
+repository, and to configure git-mirror accordingly. For additional security,
+one shouldalso configure a shared HMAC secret, such that the webhook can verify
+that the data indeed comes from GitHub.
+
+To make your job easier, there is a script ``github-add-hooks.py`` that can do
+all this for you. It assumes that the repository exists on the GitHub side, but
+has not yet been configure for git-mirror, neither locally nor remotely.
+
+To give the script access to your repositories, you need to create an access
+token for it. Go to "Personal Access Tokens" in your GitHub configuration, and
+create a new token with the permissions ``admin:repo_hook`` and ``public_repo``.
+Add the token and the webhook URL to the top part of ``git-mirror.conf`` (right
+below ``mail-sender``)::
+
+ github-token = pastethetokenhere
+ webhook-url = https://example.com/git-mirror/webhook.py
+
+Now you can call the automatic setup script as follows::
+
+ ./github-add-hooks.py -o UserName -e email@ddress.com -l ~/repositories/repo-name.git/ -n github-repo-name
+
+Notice that the username is case-sensitive! This will do all the setup on the
+GitHub side, and it will add an appropriate configuration block to your local
+``git-mirror.conf``. You will still have to manually add the local git hook to
+gitolite.
+
+Source, License
+---------------
+
+You can find the sources in the `git repository`_ (also available `on GitHub`_).
+They are provided under a `2-clause BSD license`_. See the file ``LICENSE-BSD``
+for more details.
+
+.. _git repository: http://www.ralfj.de/git/git-mirror.git
+.. _on GitHub: https://github.com/RalfJung/git-mirror
+.. _2-clause BSD license: http://opensource.org/licenses/bsd-license.php
+
+Contact
+-------
+
+If you found a bug, or want to leave a comment, please
+`send me a mail <mailto:post-AT-ralfj-DOT-de>`_. I'm also happy about pull
+requests :)
projects / git-mirror.git / commitdiff