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Introduction to GitHub Actions

Table of contents​

  1. What is GitHub Actions?
  2. Key concepts
  3. Benefits of GitHub Actions
  4. First workflow
  5. GitHub Actions interface
  6. Practical exercises

1 - What is GitHub Actions?​

Definition​

GitHub Actions is a CI/CD automation platform integrated directly into GitHub. It lets you automate tasks in response to events on your repository.

Use cases​

CategoryExamples
CIAutomated tests, linting, build
CDStaging/production deployment
AutomationRelease notes, automatic labels
SecurityVulnerability scanning, audit
DevOpsInfrastructure as Code, backups

Comparison with other tools​

ToolTypeAdvantagesDrawbacks
GitHub ActionsIntegratedFree, native to GitHubLimited to GitHub
JenkinsSelf-hostedVery flexibleMaintenance
GitLab CIIntegratedCompleteGitLab ecosystem
CircleCISaaSPerformanceCost

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2 - Key concepts​

Essential vocabulary​

Definitions​

TermDescription
WorkflowYAML file that defines the automation
EventTrigger (push, PR, schedule...)
JobA set of steps run on a runner
StepAn individual task (action or command)
ActionA reusable block (from the Marketplace or custom)
RunnerThe machine that runs the jobs
ArtifactA file produced by a workflow

File structure​

.github/
└── workflows/
    ├── ci.yml          # Tests et build
    ├── cd.yml          # Déploiement
    └── release.yml     # Publication

Types of runners​

RunnerOSSpecsUsage
ubuntu-latestLinux2 CPU, 7GB RAMDefault
windows-latestWindows2 CPU, 7GB RAMWindows apps
macos-latestmacOS3 CPU, 14GB RAMiOS/macOS apps
Self-hostedCustomYour hardwareSpecific needs

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3 - Benefits of GitHub Actions​

Why choose GitHub Actions?​

BenefitDescription
IntegratedNo external configuration
Free2000 min/month for public repos
Marketplace+15000 ready-to-use actions
YAMLVersioned Configuration as Code
Multi-OSLinux, Windows, macOS
CommunityRich documentation and support

Pricing​

PlanMinutes/monthStorage
Free2,000500 MB
Team3,0002 GB
Enterprise50,00050 GB
Tip

Public repos have unlimited free minutes!

Ecosystem​

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4 - First workflow​

Hello World​

# .github/workflows/hello.yml
name: Hello World

on:
  push:
    branches: [main]
  workflow_dispatch:  # Permet l'exécution manuelle

jobs:
  greet:
    runs-on: ubuntu-latest
    
    steps:
      - name: Say Hello
        run: echo "Hello, GitHub Actions! 🚀"
      
      - name: Show date
        run: date
      
      - name: Show system info
        run: |
          echo "OS: $(uname -a)"
          echo "User: $(whoami)"
          echo "Directory: $(pwd)"

Line-by-line explanation​

name: Hello World          # Nom affiché dans l'interface
on:                        # Événements déclencheurs
  push:
    branches: [main]       # Seulement sur la branche main
jobs:                      # Liste des jobs
  greet:                   # Nom du job
    runs-on: ubuntu-latest # Runner à utiliser
    steps:                 # Liste des étapes
      - name: Say Hello    # Nom de l'étape
        run: echo "..."    # Commande shell

Create the workflow​

# Dans votre repo
mkdir -p .github/workflows
nano .github/workflows/hello.yml
# Collez le contenu ci-dessus

git add .github/workflows/hello.yml
git commit -m "Add first workflow"
git push

Workflow with checkout​

name: Build Project

on: [push]

jobs:
  build:
    runs-on: ubuntu-latest
    
    steps:
      - name: Checkout code
        uses: actions/checkout@v4
      
      - name: List files
        run: ls -la
      
      - name: Show README
        run: cat README.md || echo "No README"

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5 - GitHub Actions interface​

Access the workflows​

  1. Go to your GitHub repository
  2. Click the Actions tab
  3. See the available workflows
  4. Click a run for the details

Interface elements​

ElementDescription
WorkflowsList of defined workflows
RunsExecution history
JobsJobs of a specific run
LogsDetailed output of each step
ArtifactsProduced files
SummaryRun summary

Statuses​

StatusIconMeaning
Success✅All jobs succeeded
Failure❌At least one job failed
Cancelled⚪Cancelled manually
Skipped⏭️Job skipped (condition)
In progress🟡Currently running
Queued⏳Waiting for a runner

Status badges​

<!-- Dans votre README.md -->
![CI](https://github.com/USER/REPO/actions/workflows/ci.yml/badge.svg)

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6 - Practical exercises​

Exercise 1: First workflow​

Create a workflow that displays "Hello from GitHub Actions!" on every push:

Solution
# .github/workflows/hello.yml
name: Hello

on: [push]

jobs:
  hello:
    runs-on: ubuntu-latest
    steps:
      - run: echo "Hello from GitHub Actions!"

Exercise 2: Workflow with system information​

Create a workflow that displays the runner's information:

Solution
name: System Info

on: [push]

jobs:
  info:
    runs-on: ubuntu-latest
    steps:
      - name: OS Info
        run: |
          echo "OS: $(uname -s)"
          echo "Kernel: $(uname -r)"
          echo "Architecture: $(uname -m)"
      
      - name: Disk Space
        run: df -h
      
      - name: Memory
        run: free -h

Quiz​

Q1. Where are workflow files stored?

Answer

In .github/workflows/ at the root of the repository.

Q2. Which runner is recommended by default?

Answer

ubuntu-latest - It is the fastest and cheapest.

Q3. Which action retrieves the repo's code?

Answer

actions/checkout@v4

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Key takeaways​

  • GitHub Actions = CI/CD integrated into GitHub
  • Workflows defined in YAML in .github/workflows/
  • Triggered by events (push, PR, schedule...)
  • Run on runners (ubuntu, windows, macos)
  • actions/checkout to retrieve the code
  • Free for public repos

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Next chapter: Workflow syntax →