Use a Github Action workflow to build "universal" Rust binaries that work for both MacOS chip architectures.

Issue

With MacOS's new M1 chip architecture, there are now two build targets for MacOS: x86_64-apple-darwin and aarch64-apple-darwin. Rather than ask our users to identify their chip architecture on a product installation page, I prefer to have one binary that works for all installation targets.

Apple's happy path uses XCode, but detest using a vendor-specific GUI to ship software on each release. That leaves us with lipo, which ships with MacOS. MacOS Runners are expensive, but it's a good start.

Along the way, we need to notarize the binary with Apple so our users don't get a scary installation popup warning that our application might be malware.

Solution

This Github Workflow creates two binaries, x86_64-apple-darwin and aarch64-apple-darwin and "smushes them together" with lipo. Then it signs and notarizes the resulting binary and bundles it into a .app that's ready to be installed. There are some other goodies in here, such as a minor SemVer bump and some build caching to speed things up.

Kudos

Credit to Federico Terzi's blog post on signing and notarizing MacOS apps with GitHub Actions.