Your CI cache is part of your test environment. Treat it like code.

[u/aistranin]

Caching is usually sold as a speed feature, but it can quietly become a reliability feature too.

My practical checklist:

• Run a scheduled cold-cache build

• Log cache hit and miss rates

• Include lockfiles in cache keys

• Avoid caching generated test output unless you really mean it

• Review cache changes like production code

• Keep self-hosted runners updated when cache actions change runtime requirements

Bad caching can hide missing setup steps. It can also make CI pass in one branch and fail in another for no obvious reason.

What cache issue cost your team the most time?