GitHub Actions Basics: One CI Check You Can Trust

CI only matters if it runs something real. Most tutorials show either bloated pipelines or toy examples that verify nothing. I prefer one workflow, one runner, two commands, and a green check.

This post is the workflow file I use as a baseline.

Why I set this up first

Without CI, I am the only person verifying the build. The moment another OS, another Node version, or another contributor enters the picture, assumptions break. CI gives me feedback in a clean environment every time I push.

GitHub Actions is just the platform. It spins up a temporary machine, checks out my code, runs the commands I tell it to run, and reports pass or fail. Nothing more mysterious than that.

The workflow file

Create .github/workflows/ci.yml:

name: CI

on:
  push:
    branches: ["main"]
  pull_request:
    branches: ["main"]

jobs:
  build:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: actions/setup-node@v4
        with:
          node-version: 20
      - run: npm install
      - run: npm run lint
      - run: npm run build

That is it. actions/checkout pulls the repo. actions/setup-node installs Node. The three run lines execute the same commands I run locally. If any exit non-zero, the workflow fails.

How I verify it works

I commit the file, push to GitHub, then open the Actions tab. If the run is green, CI is working. If it fails, the log tells me exactly which command failed. I fix it locally, commit again, and CI re-runs.

Common failures I have hit

• Workflow never runs: the default branch is not named main.
• Install fails: package-lock.json is missing or out of sync.
• Passes locally, fails in CI: local environment hides an assumption, like a different Node version or a missing env var.

The fix is always to make local and CI more similar, not to weaken the checks.

Closing

A CI setup is not measured by complexity. It is measured by whether it runs my real build in a clean environment and tells me when something breaks. If I have a workflow file, a visible run, and a green check, CI is doing its job.