Fast Forward Bot

A GitHub bot allowing for quick and easy fast-forward merges triggered by PR comments.

You may want to use this application if you want to rebase your commits to your master branch from within GitHub whilst preserving author signature information and avoiding the rewriting of commits.

Deployment

Creating the application

Follow the guide here to create a new GitHub app.

The following permissions are required:

• Contents: Read & Write
• Issues: Read & Write
• Pull Requests: Read & Write

The following webhook events must be selected:

• Issue comment

Set the webhook URL to https://your-prod-domain.com/hook and select a secure client secret.

Once created, generate a client secret and keep a hold of this value for later.

Deployment

A Docker image is published at ghcr.io/jb3/ff_bot:latest which can be used to deploy this application.

The following environment variables must be set:

Variable	Description
GITHUB_WEBHOOK_SECRET	A secure secret configured in GitHub and your app to validate webhook payloads. Same as the preference set earlier.
GITHUB_CLIENT_ID	The client ID of your created GitHub app
GITHUB_CLIENT_SECRET	The client secret certificate of your GitHub app used to sign token requests.

You can also optionally set these variables:

Variable	Description	Default
FF_POLICY_FILE	The file to read for policy on who can perform merges	.github/ff-bot.yml
FF_LISTEN_PORT	The HTTP port for the service to listen on	4000
FF_NO_PROPAGANDA	Disable all team encouragement messages generated by the bot.

Usage

Once deployed, follow GitHub's instructions to install to your own account/organisation and select the repositories to use.

For a repository to use it, it must have a review policy at .github/ff-bot.yml (or whatever you have set FF_POLICY_FILE to).

An example policy looks like this:

users:
- jb3
teams:
- python-discord/devops

Once a user wants to merge a PR, all they have to do is run /merge in the PR comments. If the branch is up to date the merge will take place, if not then the bot will reply with the branch status.

For the merge to complete, the user must be in the policy file directly or in a team mentioned in the policy file.

Providing the user is in the policy file and the branch in question is up to date with main (i.e. is only "ahead" of main, no divergence), the merge will take place and GitHub will automatically close the Pull Request as all commits are now present on your primary branch.