Chapter Eleven

GitHub Actions in Depth

The patterns that turn Actions from a single workflow file into real CI/CD — matrices, caching, secrets, environments, reusable units, and the runners jobs execute on.

7 topics

The fundamentals chapter covered what a workflow, job, step, and trigger are. This one is about using them well: building a CI pipeline that actually blocks bad merges, fanning a job across a matrix of platforms, moving files across the ephemeral-VM boundary with caches and artifacts, and handling secrets so they never end up in a log.

From there it climbs to delivery — environments with approval gates that turn CI into controlled CD, reusable workflows and composite actions that kill copy-pasted YAML, and the self-hosted runners you reach for only when specific hardware or a private network demands it. Each topic is a decision you will make on real pipelines, with the failure modes that make the wrong choice expensive.

From CI gate to gated deploy
PR checksrequired
Build once
Test
Deploy stagingon merge
Deploy productiongated

Topics in This Chapter