5.1GitHub Actions and Automation

GitHub Actions is a workflow platform for automating work, starting with CI/CD.

■ What CI/CD means • CI (continuous integration) = frequently integrate changes and catch issues early with automated builds/tests. • CD (continuous delivery/deployment) = keep software releasable and automate distribution/deployment.

■ Workflow structure (see the diagram) Workflows are defined as YAML in the .github/workflows folder. The on key specifies triggers (push, pull_request, schedule (cron), workflow_dispatch (manual), and more). The hierarchy is Workflow > Jobs > Steps, with jobs running on runners. Runners are either GitHub-hosted (provided/managed by GitHub) or self-hosted (provided/managed by you). Use needs: to express job ordering (dependencies).

■ Common features • Secrets = store secrets like API keys encrypted and reference them as ${{ secrets.NAME }} (masked in logs). • Artifacts = save/share build outputs (test reports, binaries, etc.). • matrix = run a job across combinations of OSes/language versions in parallel. • Environments = set per-target (staging/production) protections like required reviewers and wait timers. • reusable workflows (workflow_call) = define a common workflow and reuse it. Find community reusable Actions on the GitHub Marketplace and include them with uses: (pin a version for safety).