Stop 05 · Git & GitHubTopics · 11/11

GitHub Actions basics

In short

What if every push automatically ran your tests and checked your code? GitHub Actions does that, so broken code gets caught before it reaches main.

GitHub's built-in CI/CD system — YAML workflow files that automatically run tests, builds or deployments on events like pushes and pull requests. Workflows can run tests, linting, builds, security checks, releases, and deployments automatically, making them a foundation for repeatable engineering processes.

The jaadu mascot works an airport x-ray scanner as suitcases roll past on a belt.

Think of it like this

Airport security check

Every passenger goes through the same scanner before boarding, no exceptions. GitHub Actions is your project's scanner. Every push or PR goes through the same checks, and anything suspicious gets flagged before it flies.

Watch it happen

What happens when you push

Push

Workflow

Runner

Steps

Result

1/5You push a commit or open a PR. GitHub receives a push or pull_request event.

The big ideas

What you need to know

A YAML file

Workflows live in .github/workflows/ as .yml files. GitHub finds and runs them on its own.

Triggered by events

The on: key says when to run, like on every push, on pull requests or on a schedule.

Jobs and steps

A job runs on a fresh virtual machine. Steps inside it run one after another, like commands.

Green tick or red cross

Results show on your commits and PRs. Teams often block merging until checks pass.

See it in code

Walk through the code

yaml

1# .github/workflows/ci.yml2name: CI3on: [push, pull_request]4 5jobs:6  build:7    runs-on: ubuntu-latest8    steps:9      - uses: actions/checkout@v410      - uses: actions/setup-node@v411        with:12          node-version: 2213          cache: npm14      - run: npm ci15      - run: npm run lint16      - run: npm test

1/4The file's location makes it a workflow. on: runs it for every push and pull request.

uses: runs a ready-made action from the marketplace. run: runs a shell command. npm ci installs exactly what's in your lock file.

Save yourself the pain

Common mistakes

Oops

Pasting API keys straight into the workflow file.

Do this instead

Store them under Settings, Secrets and variables, Actions, and read them in the workflow as secrets.

Oops

Ignoring a red cross and merging anyway.

Do this instead

Open the failed run, read the logs of the red step, and fix it before merging.

Your mission

Your first green tick

~30 min

Quick check

In a workflow file, what decides when the workflow runs?

Go deeper

1Add a simple workflow that runs `npm test` on every push. Test the result on both a successful path and an invalid or unexpected input.
2Learn the basic YAML structure: triggers, jobs, and steps. Focus on understanding the underlying reason it works, not only memorizing the definition.
3Explore the GitHub Actions marketplace for prebuilt actions (deploy, lint, etc.).