Scaling Golang CI by Replacing actions/setup-go

We've found a new way to speed up parallel Golang continuous integration workflows by taking advantage of the Golang build cache. Replacing GitHub's official actions/setup-go action with a drop-in equivalent cut our test job runtimes by 69%. We're open-sourcing cloudx-io/setup-go (opens in a new tab) so you can do the same.

GitHub's official actions/setup-go step makes parallel jobs interfere with each other's performance, and it continuously loads stale cache values. Backtesting in our monorepo, which has the common situation of a few parallel Golang test jobs (one for lints, one for tests, one for builds), suggests that 86% of the work the default action does is completely unnecessary.

If you manage a moderately complex Go project, you can expect similar performance improvements; see our CI measurement methodology or just try it for yourself.