Chapter 9: GitHub Actions Hands-On

9.7b Matrix and reuse (awareness only)

By Ravindra Bagale · Last updated: 1 October 2026

Matrix builds run the same job across Python/Node versions. Useful later; do not enable a huge matrix on day one (minutes and minutes of Actions usage).

Reusable workflows and composite actions help large orgs share YAML. For badge API course work, one clear ci.yml you understand beats five abstract includes.

Concurrency.

concurrency:
  group: badge-api-main
  cancel-in-progress: true

Cancels outdated runs on the same branch so you are not waiting on yesterday's push.