Question

Your enterprise runs a fleet of self-hosted Linux runners for a large monorepo. Builds frequently call actions/setup-node and actions/setup-python, but you notice these steps download and compile the requested versions on every run, adding several minutes per job. On GitHub-hosted runners these same steps complete almost instantly. What is the most effective way to make the setup-* actions resolve versions instantly on your self-hosted runners?

Accepted Answer

Pre-populate the runner tool cache directory (RUNNER_TOOL_CACHE / hostedtoolcache) with the required Node and Python versions so the setup-* actions find and restore them without downloading

Answer

Add actions/cache steps before each setup-* action to cache the downloaded language runtimes across runs

Answer

Set the fail-fast strategy to false so slow setup steps do not block the rest of the matrix

Answer

Configure an organization allow list that only permits the pinned versions of setup-node and setup-python