ikiwiki/doc/rcs/git.mdwn

[[meta title="Git"]]

[Git][git] is a distributed revison control system originally developed for
the Linux kernel. Ikiwiki supports storing a wiki in git.

[git]: http://git.or.cz/

Ikiwiki can run as a `post-update` hook to update a wiki whenever commits
come in. When running as a [[cgi]] with Git, ikiwiki automatically
commits edited pages, and uses the Git history to generate the
[[RecentChanges]] page.

## git repository setup

The suggested setup for git is a set of repositories setup like a
shallow, single level tree, with a bare repository (meaning that it
does not have a working tree checked out) at the root, and various
working clones (with working directories) as leaf nodes.  The root
(bare) repository is meant to be pushed to and pulled from the various
working clones. 

One of the leaf node clone repositories is special; it has working
directory which is used to compile the wiki from, and is also used by the
[[cgi]] to commit changes made via the web interface. It is special
since the `post-commit` hook for the bare root repository is used to
trigger an update of this repository, and then an ikiwiki refresh
updates the published  wiki itself.

The other (optional) leaf node repositories are meant for you to work
on, and commit to, changes should then be pushed to the bare root
repository.  In theory, you could work on the same leaf node repository
that ikiwiki uses to compile the wiki from, and the [[cgi]] commits
to, as long as you ensure that permissions and ownership don't hinder
the working of the [[cgi]]. This can be done, for example, by using
ACL's, in practice, it is easier to just setup separate clones for
yourself.

So, to reiterate, when using Git, you probably want to set up three
repositories:

* The root repository. This should be a bare repository (meaning that it does not have a working tree checked out), which the other repositories will push to/pull from.  It is a bare repository, since there are problems pushing to a repository that has a working directory. This is called _repository_ in [[ikiwiki-makerepo]]'s  manual page. Nominally, this bare repository has a `post-commit` hook that would change directory to the ikiwiki leaf node repository below (the working directory for ikiwiki), do a _git pull_, and refresh ikiwiki to regenerate the wiki with any new content.
* The second repository is a clone of the bare root repository, and has a working tree which is used as ikiwiki's srcdir for compiling the wiki. **Never** push to this repository. When running as a [[cgi]], the changes are committed to this repository, and pushed to the master repository above. This is called _srcdir_ in [[ikiwiki-makerepo]]'s manual page.
* The other (third, fourth, fifth, sixth -- however many pleases you) repositories are also clones of the bare root repository above -- and these have a working directory for you to work on. Use either the `git` transport (if available), or `ssh`. These repositories may be on remote machines, your laptop, whereever you find convenient to hack on your wiki. Any new content should be pushed to the bare master repository when you are ready to publish it, and then the post-commit hook of the bare repository will ensure that the ikiwiki's source directory is updated, and the ikiwiki refreshed with the new content.

[[ikiwiki-makerepo]] can automate setting this up. Using three or more of repositories isn't the most obvious set up, but it works the best for typical ikiwiki use.  [[tips/Laptop_wiki_with_git]] describes a different way to set up ikiwiki and git.

It is **paramount** that you **never** push to the non-bare repository
([this FAQ entry explains why](http://git.or.cz/gitwiki/GitFaq#head-b96f48bc9c925074be9f95c0fce69bcece5f6e73)).
Instead, clone the bare repository as mentioned above, and push **only** to the bare repository.

The ikiwiki `post-commit` hook should be put in the bare repository.

## git repository with multiple committers

It can be tricky to get the permissions right to allow multiple people to
commit to an ikiwiki git repository. As the [[security]] page mentions,
for a secure ikiwiki installation, only one person should be able to write
to ikiwiki's srcdir. When other committers make commits, their commits
should go to the bare repository, which has a `post-update` hook that uses
ikiwiki to pull the changes to the srcdir.

One setup that will work is to put all committers in a group (say,
"ikiwiki"), and use permissions to allow that group to commit to the bare git
repository. Make both the post-update hook and ikiwiki.cgi be setgid
to the group, as well as suid to the user who admins the wiki. The
`wrappergroup` [[setup_file_option|usage]] can be used to make the wrappers
be setgid to the right group. Then the srcdir, including its git
repository, should only be writable by the wiki's admin, and *not* by the
group. Take care that ikiwiki uses a umask that does not cause files in
the srcdir to become group writable. (umask 022 will work.)