5.8 KiB
delegating access control responsibilities
[Thanks to jeromeag for forcing me to think through this...]
lots of repos, lots of users
Gitolite tries to make it easy to manage access to lots of users and repos, exploiting commonalities wherever possible. (The example under "simpler, more powerful syntax" here should give you an idea). As you can see, it lets you specify bits and pieces of the access control separately -- i.e., all the access specs for a certain repo need not be together; they can be scattered, which makes it easier to manage the sort of slice and dice needed in that example.
But eventually the config file will become too big. If you let only one person have control, he could become a bottleneck. If you give it to multiple people, they might make mistakes or stomp on each others' work accidentally.
The best way is to divide up the config file and give parts of it to different people. Ideally, we would delegate authority for groups of repos, not individual repos, otherwise it doesn't scale.
It would also be nice if we could specify what repos can be delegated to a particular admin, and prevent him/her from specifying access control for any other repos. This would be a nice "security" feature.
splitting up the config file into fragments
To start with, recall that gitolite allows you to specify groups (of users
or repos, same syntax). So the basic idea is that the main config file
(~/.gitolite/conf/gitolite.conf
by default) will specify some repo groups:
# group your projects/repos however you want
@webbrowser_repos = firefox lynx
@webserver_repos = apache nginx
@malware_repos = conficker storm
# any other config as usual, including access control lines for any of the
# above projects or groups
Now just create these files (assuming default $GL_ADMINDIR
location):
~/.gitolite/conf/fragments/webbrowser_repos.conf
~/.gitolite/conf/fragments/webserver_repos.conf
~/.gitolite/conf/fragments/malware_repos.conf
Within each of those files put in whatever access control rules you want for the repos that are members of that group. Notice that the basenames of the files must be exactly the same as the name of the corresponding repo group in the main config file.
For instance, ~/.gitolite/conf/fragments/webbrowser_repos.conf
would only
contain access control for firefox and lynx. If it referenced any other repo
(say "storm") those lines would be ignored (and a warning message generated).
When you run the compile script (src/gl-compile-conf
), the net effect is
as if you appended the contents of all the "fragment" files, in alphabetical
order, to the bottom of the main file.
(Except of course, while processing a fragment, it will ignore attempts to set permissions for repos that are not members of the same-named "repo group").
And that's basically it, in the simplest usage.
delegating ownership of fragments
Splitting up the file does help, but there's also that little security issue -- anyone can make any change to any "fragment", unless you (once again) go back to Unix permissions to keep them separate.
Fixing that requires using "push-to-admin".
The page on push-to-admin explains clearly how to set it up. Unlike gitosis, I refuse to make it the default because it's a support nightmare. Don't get me wrong -- it's a great feature, and I use it myself, but the learning curve is too steep to make it required.
So, having setup push-to-admin, you add these lines to the main config file, assuming Alice is in charge of all web browser development projects, Bob takes care of web servers, and Mallory, as tradition dictates, is in charge of malware ;-)
# you probably added these two lines while setting up push-to-admin
repo gitolite-admin
RW+ = sitaram
# now add these 3 lines
RW webbrowser_repos = alice
RW webserver_repos = bob
RW malware_repos = mallory
As you can see, for each repo group you want to delegate authority over,
there's a branch in the gitolite-admin
repo with the same name. Whoever
has write access to that branch, is allowed to define rules for repos in the
corresponding "repo group".
In other words, we use gitolite's per-branch permissions to "enforce" the separation between the delegated configs!
Here's how to use this in practice:
-
Alice clones the
gitolite-admin
repo, creates (if not already created) and checks out a new branch calledwebbrowser_repos
, and adds a file calledconf/fragments/webbrowser_repos.conf
in that branch- (the rest of the contents of that branch do not matter; she can keep all the other files or delete all of them -- it doesn't make any difference. Only that one specific file is used).
-
she writes in this file any access control rules for the "firefox" and "lynx" repos. She should not write access rules for any other project -- they will be ignored
-
Alice then commits and pushes this branch to the
gitolite-admin
repo
Naturally, a successful push invokes the post-update hook that you installed (while setting up push-to-admin). Here's what it does:
-
for each branch, say
br
, of thegitolite-admin
repo, it checks if there is a file calledconf/fragments/br.conf
-
if there is, it extracts it and copies it with the exact same name and path, into the
$GL_ADMINDIR
directory (~/.gitolite
by default)
After that, it runs the compile script, and things work the same as described in the previous section.