Make it easy for projects to automate homebrew PRs

[mdiep]

I'm one of the maintainers of Carthage. Every time we release a new version, someone needs to manually open a PR against homebrew to update to the latest version. It'd be really great if this was easily automatable for project maintainers as part of deployment. Carthage already uploads a new installer from Travis as part of the deployment process when a new tag is created. I'd love for updating homebrew to be just another automated step in that process.

I think this could be either:

1. A webhook/service that's configurable on GitHub and listens to tags/releases and responds by creating a new PR against Homebrew.
2. Some documentation and/or example scripts that project maintainers can add to Travis' deploy steps to automate opening a Homebrew PR.

At least in Carthage's case, updating homebrew means changing a SHA and a tag name. That seems like a great thing for a computer to do for us. ☺️

[MikeMcQuaid]

CC @mislav and @FooBarWidget if you could elaborate how you've scripted this.

[FooBarWidget]

The Passenger release script performs the following operations (simplified explanation):

1. It creates a tarball.
2. It clones the Homebrew repository.
3. It modifies the Passenger formula, replacing the filename and SHA hash with that of the new tarball.
4. It installs the locally-modified formula and the newly generated tarball, and runs brew install passenger to automatically test whether the formula works.
5. If the test passes, it force-pushes to a Phusion-specific Homebrew fork repo.
6. It uses the hub command to automatically send a pull request from phusion/homebrew to Homebrew/homebrew.
7. It uploads the tarball to our file server.

[mislav]

One of my scripts is here. Basically:

1. Obtain the checksum for the tagged archive on GitHub
2. Checkout Homebrew at the latest state of master branch
3. Edit Library/Formula/NAME.rb by:
   • Substituting url field with new tarball location
   • Substituting sha256 field with new checksum
4. Push the change to a new branch of your fork
5. Open a PR for Homebrew. I use hub for this, but a generic script could use a manual approach. See below.

curl -H 'content-type: application/json' \
  -H "authorization: token $GITHUB_TOKEN" \
  https://api.github.com/repos/OWNER/REPO/pulls -d @- <<JSON
{ "title": "${program_name} ${version}",
  "head": "${fork_name}:${tmp_branch}",
  "base": "master" ]}
JSON

[mislav]

I'd love to see a web service for this that could be triggered by CI or webhooks.

[zbeekman]

👍

[luzpaz]

👍

[MikeMcQuaid]

PR opened in #46580 #49848 for the command. We'll consider a web service in future.

[zbeekman]

I think you meant #49848

[MikeMcQuaid]

@zbeekman I did, thanks.

[MikeMcQuaid]

Added as brew bump-formula-pr in #49848.