Ephemeral macOS builds with Buildkite, Nix, and Tailscale

Determinate Systems is working on making Nix, an extremely powerful but often tricky language, build tool, and package manager, easier to use for everyone, including macOS users. The company uses Buildkite's unique feature set to achieve this goal. While GitHub Actions is used for straightforward CI logic, Buildkite is employed when needs go beyond what Actions can offer. One area where GitHub Actions does not shine is in support for macOS machines, particularly Apple Silicon runners. Determinate Systems has built an internal tool called bonk that erases the machines and shuts them down using the Mosyle API, making each Buildkite job run on a “fresh” machine. The company's setup of ephemeral macOS machines has been hugely beneficial, providing cost savings compared to cloud-based solutions and faster turnaround times for CI jobs.