GitHub Actions

What it is

GitHub Actions is GitHub’s built-in CI/CD automation engine. You define workflows as YAML files under .github/workflows/ in your repository; each workflow runs jobs containing steps that execute actions when triggered by repository events.

Why it exists

It keeps CI/CD inside the repository host — no separate tool — so “code + automation live together.” Events like push, pull_request, and schedule drive workflows, and the action ecosystem (actions/checkout, actions/upload-artifact) makes steps composable.

Key ideas

• Workflow = the automation unit; one YAML file = one workflow.
• Events drive it (push, pull_request, workflow_dispatch, schedule); see ci-trigger.
• Jobs run in parallel by default; steps within a job run sequentially and share a runner’s filesystem.
• Runners execute jobs — GitHub-hosted (ubuntu/windows/macos) or self-hosted.
• Actions are reusable building blocks (community or actions/* official).
• Artifacts — actions/upload-artifact / actions/download-artifact share build output between jobs; see build-artifact.
• Reusable workflows & composite actions enable reuse; see pipeline-templates.

Exam notes

• Workflow file lives at .github/workflows/<name>.yml.
• GitHub-hosted runner pricing/free minutes for private repos vs free for public.
• GitHub Actions can deploy to Azure (Azure login action, service principals); common in AZ-400.
• Runs (like Azure Pipelines runs) are the execution of a workflow on an event.

Related

azure-pipelines · ci-trigger · build-artifact · pipeline-templates · self-hosted-agent

📘 Source: Microsoft Learn — Github Actions