ikiwiki/ rcs/ Git

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

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

Normally you can just follow the instructions in setup to create the git repositories and get started. To understand the details, read on.

## git repository setup

The suggested setup for git has a bare repository, and various working clones (with working directories). The bare repository is pushed to and pulled from the various working clones.

One of the clones is special; it is the srcdir which is used to compile the wiki, and is also used by the cgi to commit changes made via the web interface. It is special since the `post-update` 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) clones are meant for you to work on, and commit to, changes should then be pushed to the bare root repository.

Using three or more repositories isn't the most obvious set up, but it works the best for typical ikiwiki use. ikiwiki-makerepo can automate setting this up for the common case where there is no pre-existing wiki. Laptop wiki with git describes a different way to set up ikiwiki and git.

## 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 be pushed 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 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.)

## git repository with untrusted committers

By default, anyone who can commit to the git repository can modify any file on the wiki however they like. A `pre-receive` hook can be set up to limit incoming commits from untrusted users. Then the same limits that are placed on edits via the web will be in effect for commits to git for the users. They will not be allowed to edit locked pages, they will only be able to delete pages that the remove configuration allows them to remove, and they will only be allowed to add non-page attachments that the attachment configuration allows.

To enable this, you need to set up the git repository to have multiple committers. Trusted committers, including the user that ikiwiki runs as, will not have their commits checked by the `pre-receive` hook. Untrusted committers will have their commits checked. The configuration settings to enable are `git_test_receive_wrapper`, which enables generation of a `pre-receive` hook, and `untrusted_committers`, which is a list of usernames of the untrusted committers.

Note that when the `pre-receive` hook is checking incoming changes, it ignores the git authorship information, and uses the username of the unix user who made the commit. Then tests including the `locked_pages` PageSpec are checked to see if that user can edit the pages in the commit.

You can even set up an anonymous user, to allow anyone to push changes in via git rather than using the web interface.

## Optionally using a local wiki to preview changes

When working on your wiki, it is common (but optional) practice to preview your changes using a private wiki on the local host before publishing the updates by sending it to the root repository. If you do want to setup a private wiki, you will have to have another setup file and and an ikiwiki installation on your local machine. You will need all the packages this implies -- a web server, git, ikiwiki, etc. However, there is a caveat: by default, ikiwiki pulls and pushes from `origin`. This is not ideal for the working clones on the local machine, since you might go through several iterations of a page before pushing to the bare root of the repository tree (and thus publishing it on your public wiki). You do not want the action of refreshing the local wiki in order to review your work to accidentally publish the contents before you are ready. In order to prevent the git push that is the normal behaviour of ikiwiki, set the configuration of the local wiki:

      gitorigin_branch => "",
      ## git post-commit wrapper
      git_wrapper => "/working/dir/.git/hooks/post-commit",

Then just committing should refresh the private ikiwiki on the local host. Now just run `ikiwiki --setup localwiki.setup --gettime` and you should be good to go. (You only need the slow `--gettime` option the first time you run setup.) Use standard git commands to handle pulling from and pushing to the server. Note: After pulling changes from the bare root repository, you will need to manually update the local wiki, with a command such as `ikiwiki --setup localwiki.setup --refresh`. You could use git's `post-merge` hook to automate that command.

## Using ikiwiki with Gerrit

Gerrit Code Review manages a set of Git repositories and provides a web interface to review and merge commits. You can configure ikiwiki to work with a Gerrit-managed repository, allowing you to review and merge commits to your wiki.

First, create your initial wiki repository with Gerrit. On the server, as the user that will own the wiki, clone that repository to create a working directory for ikiwiki, such as /srv/wiki/ikiwiki-checkout. Create a setup file and target directory as usual, referencing that working directory path, and creating a post-update hook in Gerrit's repository. You'll need to set appropriate permissions on the hook directory for the repository so that the user running ikiwiki can compile and install the post-update hook. Also note that you must disable web editing by disabling the editpage plugin, and you must not enable any other plugin that commits to the repository, since ikiwiki will not have permission to push to the repository. (Allowing web edits to have such permission would bypass Gerrit's code review, defeating the purpose.)

Gerrit does not run per-repository hooks, such as the post-update hook ikiwiki installs to update the wiki after pushes. However, Gerrit has site-wide hooks, including a ref-updated hook that runs whenever a ref changes. You can use that hook to trigger ikiwiki's post-update hook. The following script, installed as Gerrit's ref-updated hook, will run the post-update hook on any repository that has a "gerrit-run-post-update-hook" file in it:

    #!/bin/sh
    if [ -e "$GIT_DIR/gerrit-run-post-update-hook" ] ; then
        exec "$GIT_DIR/hooks/post-update"
    fi

Then just create gerrit-run-post-update-hook in the wiki repository, run ikiwiki --setup on the setup file, add your wiki to /etc/ikiwiki/wikilist, and start reviewing and committing wiki changes via Gerrit.