Automatic Deployment

Robots do the work for you

Right now it works like this: you change the code → commit → push → GitHub Pages updates. That’s already automation! But the pros go further – GitHub Actions is a robot that, after every push, does whatever you tell it to: build the website, check for errors, deploy.

This is called CI/CD (continuous integration / continuous deployment). It sounds complicated, but it’s really just: “Robots check and deploy everything after every change.”

Show me: your first workflow

Tasks for robots are written into a file inside the .github/workflows/ folder. For example, deploy.yml:

name: Check and deploy

on:
  push:
    branches: [main]   # run after every push to main

jobs:
  check:
    runs-on: ubuntu-latest   # the robot gets a clean Linux computer
    steps:
      - uses: actions/checkout@v4      # download my code
      - name: Check HTML
        run: |
          echo "Checking that index.html exists…"
          test -f index.html && echo "OK ✅"

After a push, a running robot shows up on GitHub under the Actions tab. A green checkmark means everything passed; a red X means something’s wrong, and the robot will tell you what.

Now it’s your turn 💪

1. Create .github/workflows/deploy.yml following the example, push it, and watch the Actions tab.
2. Break something on purpose: rename index.html to index2.html, push – the workflow turns red. Fix it and watch it turn green. (This is the most important experience of this lesson!)
3. Add a second step to the workflow – checking that no localhost was left in the HTML:

      - name: No localhost in the code
        run: |
          if grep -r "localhost:3000" *.html; then
            echo "WARNING: localhost was left in the code!" && exit 1
          fi
          echo "OK ✅"

4. Write in LAUNCH.md: “The website deploys automatically, a robot checks every push.”

What to take away from this lesson

• CI/CD = robots check and deploy after every push.
• Workflows are written into .github/workflows/*.yml.
• A red X is your friend: it stops a mistake before visitors ever see it.

© 2026 Ing. Martin Polak / AlgoRhino · Content usage terms