AutoMirror

Purpose

AutoMirror is a Git post-receive hook designed to automatically mirror a self-hosted Git repository to a remote location when a push to the original repository occurs. The utility is especially useful for mirroring repositories to standard cloud platforms like GitHub. AutoMirror was designed to facilitate the publication of specific releases or branches to publicly accessible repositories to supports standard fork and pull-request workflows for newcomers. However, pull requests should be manually applied and pushed to the original remote. AutoMirror is activated after a git receive operation in the source repository, enabling the mirroring of specific Git references (refs) such as entire repositories, specific branches, or tags. Additionally, when provided with a GitHub Access Token, it can create GitHub repositories and configure remotes automatically.

Scope and Limitations

• AutoMirror requires that the user executing git-receive-pack has push access to the specified remote repository. The utility is compatible with all standard Git protocols (ssh, git, https, file, and ftps). ssh keys or other automatic authentication methods should be configured in advance.

• Installation of a Git post-receive hook is necessary for using AutoMirror.

• AutoMirror is limited to creating repositories on GitHub. For other Git providers, repository setup must be done manually. Contributions through pull requests are welcome.

Installation

Dependencies

AutoMirror is developed for systems with Python 3.x and the python3-requests package. The required dependencies can be installed using the following distro-specific commands:

For Ubuntu/Debian:

sudo apt install python3 python3-requests git

For Arch Linux:

sudo pacman -S python git python-requests

Installing a Key File

Automatic authentication is required for ssh. The standard method to accomplish this is to setup SSH key for pushing to the remote repository and to specify the key should be used in the ~/.ssh/config file:

Match host github.com
    IdentityFile ~/.ssh/github-mirror

Installing in a Single Repository

To activate AutoMirror for a single repository, copy the post-receive script into the repository's hooks directory:

cp post-receive /some/repo.git/hooks/post-receive
chmod +x /some/repo.git/hooks/post-receive

Global Installation

For a global installation, the following steps are required (which are compatible with newer Git versions):

mkdir -p /etc/git/hooks
git config --global core.hooksPath /etc/git/hooks
cp post-receive /etc/git/hooks/post-receive
chmod +x /etc/git/hooks/post-receive

Gitolite Installation

For Gitolite installations:

cp post-receive ~/.gitolite/hooks/common/post-receive
gitolite setup --hooks
chmod +x ~/.gitolite/hooks/common/post-receive

Append the following keys to the GIT_CONFIG_KEYS variable in /etc/gitolite3/gitolite.rc:

automirror.refs automirror.remote automirror.gh-create automirror.gh-desc automirror.gh-homepage

Per-repository AutoMirror settings can be configured through git config entries in the gitolite.conf file:

repo example
  config automirror.remote ssh://git.example.com:/example

Configuration

Remote and Refs

A remote must be specified to enable mirroring. When this setting is configured through automirror.remote, AutoMirror mirrors the repository to the specified remote following a git receive operation. Optionally, you can specify which refs to mirror using automirror.refs:

git config --local --set automirror.remote <REMOTE_URL>
git config --local --set automirror.refs <REF_SPEC>

The <REMOTE_URL> is the URL of the Git remote repository to which updates will be pushed. The <REF_SPEC> is a set of refs that will be synchronized. If automirror.refs is not set, the remote symbolic ref "HEAD" will be mirrored. By default, HEAD is set to git config --get init.defaultbranch which is typically either master or main.

For example, <REF_SPEC> could be:

refs/heads/*                       # all heads
refs/tags/*                        # all tags
refs/{heads,tags}/*                # all heads and tags
refs/heads/main,refs/heads/release # main and release branches
refs/tags/*,refs/heads/main        # all tags and main branch

GitHub Integration

GitHub integration is optional but offers automated repository creation via GitHub's API. If you set automirror.gh-create to true and leave automirror.remote unspecified, AutoMirror will automatically create a GitHub repository. This feature requires AutoMirror to have access to a GitHub personal access token stored in automirror.gh-token-file. It's important to secure this file with restricted permissions (chmod 600 <file>).

git config --local  --add automirror.gh-create true

After the repository is successfully created, the value of automirror.remote is automatically set to the repository's ssh_url.

Configuring the Repository Description and Homepage

You can optionally specify the repository description and homepage. Use the automirror.gh-desc and automirror.gh-homepage settings, respectively. These strings utilize Python's string.format method, allowing you to use {repo_name} as a placeholder in your templates.

git config --global --add automirror.gh-desc '{repo_name} Mirror - This is an automatically maintained mirror of https://git.flu0r1ne.net/{repo_name}.'
git config --global --add automirror.gh-homepage 'https://git.flu0r1ne.net/{repo_name}/'

Obtaining and Configuring a Personal Access Token

For this feature to work, a personal access token from GitHub is required. This token must have read and write access to the Administration scope, as well as read access to Metadata. You can obtain such a token as follows:

1. Navigate to GitHub and go to Settings -> Developer settings -> Personal access tokens -> Fine-grained tokens.
2. Click Generate new token.
3. In the account permissions section, enable read and write access to Administration and read access to Metadata.
4. Generate and copy the token.

Once obtained, store this token in a file and set its permissions. You can use cat to echo the token without it being added to your bash history. Press Ctrl-D to exit:

cat </dev/stdin >/path/to/token_file
chmod 600 /path/to/token_file

Finally, configure AutoMirror to use this token file:

git config --global --add automirror.gh-token-file '/path/to/token_file'

This completes the setup for GitHub integration.

GitHub integration is optional. If automirror.gh-create is set to true and automirror.remote is not defined, AutoMirror will create the GitHub repository using the GitHub API. The API requires a personal access token stored in automirror.gh-token-file, which should have restricted permissions (chmod 600 file).

For optional GitHub integration:

git config --local  --add automirror.gh-create true

The description and homepage templates:

git config --global --add automirror.gh-desc '{repo_name} Mirror - This is an automatically maintained mirror of https://git.flu0r1ne.net/{repo_name}.'
git config --global --add automirror.gh-homepage 'https://git.flu0r1ne.net/{repo_name}/'

Example Usage

To mirror all heads and tags from a local repository to a remote repository:

1. Configure the remote URL: bash git config --local --set automirror.remote ssh://git.example.com:/example

2. Specify the refs to mirror: bash git config --local --set automirror.refs "refs/{heads,tags}/*"

For additional queries or issues, consult the project documentation or contact the maintainers.