steward

A GitHub App built with Probot that helps you manage PR flow.

Intro

If you have a fairly long build + CI process that runs on every PR, and you rerun all PRs against the latest master (e.g. you re-merge PRs onto the latest head), this bot is for you.

In these cases, every merge to master causes all PRs to rebuild, which means if you strictly merge only PRs that are green and up to date against master, you must wait build time between each merge. In a repo with high activity and large PR rate, such as a monorepo or monolithic, this quickly becomes extremely limiting and also a terrible developer experience.

Steward merges PRs for you, and attempts to build merge trains, where multiple ready PRs are merged at once optimistically. It does not merge all PRs in a merge train into a proposed branch, which is what something like bors (or bors-ng) does. Instead, Steward assumes that merge conflict of this nature happens fairly infrequently, and that you have build + CI against master that also runs.

In some sense, this is more complicated then a simple merge bot that merges when CI is green on a per PR basis, but less intelligent then a bors style bisecting merge-manager, or GitLab's merge trains (which build the combined diff set).

Features

• A UI on /merge which enables and disables merging, e.g. in cases like production hotfixes or master breaking, so that the bot stops merging PRs.

• Cached github responses: fast and never hits the rate limit

Development

Dev notes

Node 12, yarn, prettier.

Testing

Add tests. There is a variety of fixtures to nock and fire the events.

Next++

• Read from a .github/config instead of hard coded labels
• Better /merge UI
• Allow custom predictors to better choose PRs in a train, e.g. by checking CI predicted build time left, for example.

License

MIT