stan / gitlab-shell

GitLab Shell

GitLab Shell handles git commands for GitLab

GitLab Shell handles git commands for GitLab and modifies the list of authorized keys. GitLab Shell is not a Unix shell nor a replacement for Bash or Zsh.

When you access the GitLab server over ssh then GitLab Shell will:

1. Limits you to predefined git commands (git push, git pull).
2. Call the GitLab Rails API to check if you are authorized
3. It will execute the pre-receive hooks (called Git Hooks in GitLab Enterprise Edition)
4. It will execute the action you requested
5. Process the GitLab post-receive actions
6. Process any custom post-receive actions

If you access a GitLab server over http(s) what happens depends on if you pull from or push to the git repository. If you pull from git repositories over http(s) the GitLab Rails app will completely handle the authentication and execution. If you push to git repositories over http(s) the GitLab Rails app will not handle any authentication or execution but it will delegate the following to GitLab Shell:

1. Call the GitLab Rails API to check if you are authorized
2. It will execute the pre-receive hooks (called Git Hooks in GitLab Enterprise Edition)
3. It will excute the action you requested
4. Process the GitLab post-receive actions
5. Process any custom post-receive actions

Maybe you wonder why in the case of git push over http(s) the Rails app doesn't handle authentication before delegating to GitLab Shell. This is because GitLab Rails doesn't have the logic to interpret git push commands. The idea is to have these interpretation code in only one place and this is GitLab Shell so we can reuse it for ssh access. Actually GitLab Shell executes all git push commands without checking authorizations and relies on the pre-receive hooks to check authorizations. When you do a git pull command the authorizations are checked before executing the commands (either in GitLab Rails or GitLab Shell with an API call to GitLab Rails). The authorization checks for git pull are much simpler since you only have to check if a user can access the repo (no need to check branch permissions).

An overview of the four cases described above:

1. git pull over ssh -> gitlab-shell -> API call to gitlab-rails (Authorization) -> accept or decline -> execute git command
2. git pull over http -> gitlab-rails (Authorization) -> accept or decline -> execute git command
3. git push over ssh -> gitlab-shell (git command is not executed yet) -> execute git command -> gitlab-shell pre-receive hook -> API call to gitlab-rails (authorization) -> accept or decline push
4. git push over http -> gitlab-rails (git command is not executed yet) -> execute git command -> gitlab-shell pre-receive hook -> API call to gitlab-rails (authorization) -> accept or decline push

Code status

Requirements

GitLab shell will always use your system ruby (normally located at /usr/bin/ruby) and will not use the ruby your installed with a ruby version manager (such as RVM). It requires ruby 2.0 or higher. Please uninstall any old ruby versions from your system:

sudo apt-get remove ruby1.8

Download Ruby and compile it with:

mkdir /tmp/ruby && cd /tmp/ruby
curl -L --progress http://cache.ruby-lang.org/pub/ruby/2.1/ruby-2.1.5.tar.gz | tar xz
cd ruby-2.1.5
./configure --disable-install-rdoc
make
sudo make install

To install gitlab-shell you also need a Go compiler version 1.8 or newer. https://golang.org/dl/

Setup

./bin/install
./bin/compile

Check

./bin/check

Keys

Add key:

./bin/gitlab-keys add-key key-782 "ssh-rsa AAAAx321..."

Remove key:

./bin/gitlab-keys rm-key key-23 "ssh-rsa AAAAx321..."

List all keys:

./bin/gitlab-keys list-keys

Remove all keys from authorized_keys file:

./bin/gitlab-keys clear

Git LFS remark

Starting with GitLab 8.12, GitLab supports Git LFS authentication through ssh.

Releasing a new version

GitLab Shell is versioned by git tags, and the version used by the Rails application is stored in GITLAB_SHELL_VERSION.

For each version, there is a raw version and a tag version:

• The raw version is the version number. For instance, 15.2.8.
• The tag version is the raw version prefixed with v. For instance, v15.2.8.

To release a new version of GitLab Shell and have that version available to the Rails application:

1. Update the CHANGELOG with the tag version and the VERSION file with the raw version.
2. Add a new git tag with the tag version.
3. Update GITLAB_SHELL_VERSION in the Rails application to the raw version. (Note: this can be done as a separate MR to that, or in and MR that will make use of the latest GitLab Shell changes.)

Updating VCR fixtures

In order to generate new VCR fixtures you need to have a local GitLab instance running and have next data:

1. gitlab-org/gitlab-test project.
2. SSH key with access to the project and ID 1 that belongs to Administrator.
3. SSH key without access to the project and ID 2.

You also need to modify secret variable at spec/gitlab_net_spec.rb so tests can connect to your local instance.

Contributing

See CONTRIBUTING.md.

License

See LICENSE.