git-ssh-server

Description

This software is designed to be an (almost) entirely ssh-based public git hosting server; think GitHub or Gitorious without the web server. This offers three main advantages: the administrator doesn't need to set up a web server, the end user can do everything through the command line, and I (the author) don't have to do any web programming (at which I suck). The only part you must do out-of-band (e.g. through a web server) is signing up users; I will add this feature soon.

Repository Types

Repositories are broken into three types, which specify the permissions of the repository: user, group, and public.

User Repositories

User repositories are owned by a particular user and are of the following form:

u/owner.git

That is, user repositories begin with "u/", followed by the username of the owner of the repository, and end with ".git". The "u" denotes that it is a user repository (as opposed to group and public, below), and all repository paths end in ".git".

Additionally, user repositories may be nested arbitrarily within subdirectories. Examples:

u/owner/repo.git
u/owner/dir/repo.git
u/owner/dir/subdir/repo.git

... and so on. Anyone may read a user repository, but only the owner may write to one. Also, only the owner may create, delete, or rename repositories within the owner's directory.

There is one exception: any repositories located within a subdirectory named "private" are readable only by the owner. For example, "u/mark/pub.git" will be readable by all, but "u/mark/private/secret.git" will be readable only by "mark".

Group Repositories

Group repositories act just like user repositories, except the "owner" is a group of users, rather than a single user, and the prefix is "g/" instead of "u/". Examples:

g/group.git
g/group/repo.git

and so on. Just like user repositories, anyone may read from group repositories (except those in a "private" subdirectory). Any member of the group may write to, create, delete, and rename repositories within the group's directory.

Unfortunately, group management is not yet implemented in the user interface. This will hopefully come soon.

Public Repositories

Public repositories follow the same naming scheme as user and group repositories, but begin with "p/". Examples:

p/project.git
p/project/devel.git
p/project/subproject/foo.git

Unlike user and group repositories, public repositories are not owned by anyone and, therefore, are readable and writable by all. In the public name space, "private" directories are not allowed.

Though there are no owners of public repositories, the second component of the path ("project" in the above examples) is suggested to be a project name. In that way, related repositories can be grouped together. We suggest having the "official" (or stable) repository be "p/project.git", while any development repositories or related side projects be within the "p/project/" directory structure.

Package Layout

This package contains the following scripts:

git_ssh_server.py: The main "server" that interacts with users. The manual page is below.
generate_cgitrc.py: Scans the repository directory and generates a configuration file suitable for inclusion by cgit. Currently it is designed to be run as a cron job; in the future, I may incorporate this functionality directly into git_ssh_server.py.
authorized_keys_update.py: A script/module for atomically updating the ~/.git/authorized_keys file.

In addition, there exist the following support files:

atomicfile.py: A module that performs file locking and/or atomic writes.
odict.py: An implementation of an ordered dictionary.
COPYING: A copy of the AGPL3.
README.rst: This file.

Manual Page for git_ssh_server.py

NAME

git_ssh_server.py - A more useful git-shell.

SYNOPSIS

git_ssh_server.py user

git_ssh_server.py (--help | --man)

DESCRIPTION

Run commands from $SSH_ORIGINAL_COMMAND as a git restricted shell, allowing access only to the directories accessible by given user.

This script is usually run automatically by ssh. Suppose the user jsmith runs the following:

ssh git@server create foo

On server, ~git/.ssh/authorized_keys is configured to run the following:

SSH_ORIGINAL_COMMAND='create foo' git_ssh_server.py jsmith

This is the same basic model as git-shell(1), except that many more commands are available to the user, and permissions are checked for various operations.

AVAILABLE COMMANDS

To use this server, run one of the following commands on the ssh command line. For example: ssh git@hostname list mine.

help [command]: If command is given, print out the help for that command. Otherwise, list the available commands.
list [--mine|--writable] [[--] pattern]: List all available repositories. If the regular expression pattern is given, only print repositories that match. If --mine or --writable are given, only print repostories owned by you or only those that you can write to, respectively. Use -- if patterns starts with a dash.
create path: Create a new repository located at path. The path must end in ".git", must not be contained in another repository, and must not already exist.
fork existing-path new-path: Fork (make a copy of) an existing repository. The same rules for create apply to new-path.
rename existing-path new-path: Change the path an existing repository. The same rules for create apply to new-path. WARNING: Once you perform this operation, users who have set up a remote to this repository will have to change their configuration to point to the new path.

In addition, the following commands are called indirectly by the end user's git program.

git-upload-pack path: Called by git fetch and git clone.
git-receive-pack path: Called by git push.

CONFIGURATION

The following directions were modified from http://eagain.net/blog/2007/03/22/howto-host-git.html.

Create a git user. :

sudo adduser \
    --system \
    --home /var/www/git \
    --no-create-home \
    --shell /bin/sh \
    --gecos 'git version control' \
    --group \
    --disabled-password \
    git

For each user, add an authorized_keys entry to ~git/.ssh/authorized_keys. Replace "jdoe" with the user's id, and "..." with the user's public SSH key. Each entry must be on a single line. :
```
command="/path/to/git_ssh_server.py jdoe",no-port-forwarding,no-X11-forwarding,no-agent-forwarding ssh-rsa ... jdoe@example.com
```

BUGS

$SSH_ORIGINAL_COMMAND strips quotes and mashes all the arguments together, so if any argument has a space in it, it is parsed as a separate argument. Unless you allow paths with spaces in them, this is not a problem.

There is no checking of lock files, so if you delete or rename a repository while someone is fetching, bad stuff may happen.

TODO

Add group management stuff.

Call git update-server-info after a push?

Add a way of setting the project description for cgit/gitweb.

Ideas for future commands:

show - display project info
cat - cat file of HEAD
ls - directory list of HEAD
find - like find(1) command?
follow - like github's follow?
config - set project meta-data?

AUTHOR

Mark Lodato <lodatom-at-gmail>

LICENSE

GNU Affero General Public License, Version 3

Contact the author if you wish to obtain a different license.

zuantianyang/git-ssh-server