Clase 08 — YAML en CI/CD (GitHub Actions & GitLab CI)

GitHub Actions

Estructura básica

# .github/workflows/ci.yml
name: CI Pipeline

on:
  push:
    branches: [main, develop]
  pull_request:
    branches: [main]

jobs:
  nombre_job:
    runs-on: ubuntu-latest
    steps:
      - name: Paso 1
        run: echo "Hola"

Eventos (triggers)

on:
  push:
    branches:
      - main
      - 'release/**'
    paths:
      - 'src/**'
      - '!src/**/*.md'            # Ignorar cambios en .md
    tags:
      - 'v*'

  pull_request:
    branches: [main]
    types: [opened, synchronize, reopened]

  schedule:
    - cron: '0 6 * * 1-5'         # Lun-Vie a las 6AM UTC

  workflow_dispatch:
    inputs:
      environment:
        description: 'Ambiente de deploy'
        required: true
        default: 'staging'
        type: choice
        options:
          - staging
          - production

Ejemplo completo: CI/CD para API Python

name: CI/CD Pipeline

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

env:
  PYTHON_VERSION: "3.11"
  REGISTRY: ghcr.io
  IMAGE_NAME: ${{ github.repository }}

jobs:
  # ─── LINT ───
  lint:
    name: Lint & Format
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - name: Setup Python
        uses: actions/setup-python@v5
        with:
          python-version: ${{ env.PYTHON_VERSION }}
      - name: Verificar formato
        run: |
          pip install flake8 black isort
          black --check .
          isort --check-only .
          flake8 .

  # ─── TEST ───
  test:
    name: Tests
    runs-on: ubuntu-latest
    needs: lint
    services:
      postgres:
        image: postgres:16-alpine
        env:
          POSTGRES_DB: test_db
          POSTGRES_USER: test
          POSTGRES_PASSWORD: test
        ports:
          - 5432:5432
        options: >-
          --health-cmd pg_isready
          --health-interval 10s
          --health-timeout 5s
          --health-retries 5
    steps:
      - uses: actions/checkout@v4
      - uses: actions/setup-python@v5
        with:
          python-version: ${{ env.PYTHON_VERSION }}
          cache: pip
      - name: Ejecutar tests
        env:
          DATABASE_URL: postgresql://test:test@localhost:5432/test_db
        run: |
          pip install -r requirements.txt
          pip install pytest pytest-cov
          pytest tests/ --cov=app --cov-report=xml -v

  # ─── BUILD ───
  build:
    name: Build & Push Docker
    runs-on: ubuntu-latest
    needs: test
    if: github.event_name == 'push' && github.ref == 'refs/heads/main'
    permissions:
      contents: read
      packages: write
    steps:
      - uses: actions/checkout@v4
      - name: Login al registry
        uses: docker/login-action@v3
        with:
          registry: ${{ env.REGISTRY }}
          username: ${{ github.actor }}
          password: ${{ secrets.GITHUB_TOKEN }}
      - name: Build y Push
        uses: docker/build-push-action@v5
        with:
          context: .
          push: true
          tags: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}:${{ github.sha }}

  # ─── DEPLOY ───
  deploy-staging:
    name: Deploy Staging
    runs-on: ubuntu-latest
    needs: build
    environment:
      name: staging
      url: https://staging.mi-app.com
    steps:
      - uses: actions/checkout@v4
      - name: Deploy a staging
        run: echo "Deploying to staging..."

  deploy-production:
    name: Deploy Production
    runs-on: ubuntu-latest
    needs: deploy-staging
    environment:
      name: production
      url: https://mi-app.com
    steps:
      - uses: actions/checkout@v4
      - name: Deploy a producción
        run: echo "Deploying to production..."

Matrix Strategy

jobs:
  test:
    runs-on: ${{ matrix.os }}
    strategy:
      matrix:
        os: [ubuntu-latest, macos-latest]
        python-version: ["3.10", "3.11", "3.12"]
        exclude:
          - os: macos-latest
            python-version: "3.10"
    steps:
      - uses: actions/checkout@v4
      - uses: actions/setup-python@v5
        with:
          python-version: ${{ matrix.python-version }}
      - run: |
          pip install -r requirements.txt
          pytest tests/

---

GitLab CI/CD

Estructura básica

# .gitlab-ci.yml
stages:
  - test
  - build
  - deploy

variables:
  APP_NAME: mi-app

test:
  stage: test
  image: python:3.11
  script:
    - pip install -r requirements.txt
    - pytest tests/

Ejemplo completo: GitLab CI/CD

stages:
  - lint
  - test
  - build
  - deploy

variables:
  PYTHON_VERSION: "3.11"
  REGISTRY: $CI_REGISTRY
  IMAGE: $CI_REGISTRY_IMAGE

# ─── Templates reutilizables ───
.python_template: &python_template
  image: python:${PYTHON_VERSION}
  before_script:
    - pip install --upgrade pip
    - pip install -r requirements.txt

.docker_template: &docker_template
  image: docker:24
  services:
    - docker:24-dind
  before_script:
    - docker login -u $CI_REGISTRY_USER -p $CI_REGISTRY_PASSWORD $CI_REGISTRY

.deploy_template: &deploy_template
  image: bitnami/kubectl:latest
  before_script:
    - kubectl config set-cluster k8s --server=$K8S_SERVER
    - kubectl config set-credentials deployer --token=$K8S_TOKEN
    - kubectl config use-context default

# ─── LINT ───
lint:
  <<: *python_template
  stage: lint
  script:
    - pip install flake8 black
    - black --check .
    - flake8 .

# ─── TEST ───
test:
  <<: *python_template
  stage: test
  services:
    - postgres:16-alpine
  variables:
    POSTGRES_DB: test_db
    POSTGRES_USER: test
    POSTGRES_PASSWORD: test
    DATABASE_URL: "postgresql://test:test@postgres:5432/test_db"
  script:
    - pip install pytest pytest-cov
    - pytest tests/ --cov=app --cov-report=xml -v

# ─── BUILD ───
build:
  <<: *docker_template
  stage: build
  script:
    - docker build -t $IMAGE:$CI_COMMIT_SHA -t $IMAGE:latest .
    - docker push $IMAGE:$CI_COMMIT_SHA
    - docker push $IMAGE:latest
  rules:
    - if: '$CI_COMMIT_BRANCH == "main"'

# ─── DEPLOY ───
deploy_staging:
  <<: *deploy_template
  stage: deploy
  script:
    - kubectl set image deployment/$CI_PROJECT_NAME app=$IMAGE:$CI_COMMIT_SHA
    - kubectl rollout status deployment/$CI_PROJECT_NAME --timeout=180s
  environment:
    name: staging
  rules:
    - if: '$CI_COMMIT_BRANCH == "main"'

deploy_production:
  <<: *deploy_template
  stage: deploy
  script:
    - kubectl set image deployment/$CI_PROJECT_NAME app=$IMAGE:$CI_COMMIT_SHA
    - kubectl rollout status deployment/$CI_PROJECT_NAME --timeout=300s
  environment:
    name: production
  rules:
    - if: '$CI_COMMIT_BRANCH == "main"'
      when: manual

Comparación rápida

Concepto	GitHub Actions	GitLab CI
Archivo	.github/workflows/*.yml	.gitlab-ci.yml
Ejecución	jobs	stages + jobs
Runner	runs-on	image / tags
Variables	env / secrets	variables
Condicional	if	rules / only
Caché	actions/cache	cache
Artefactos	actions/upload-artifact	artifacts
Manual	workflow_dispatch	when: manual
Reutilizar	Reusable workflows	include / anclas

Ejercicios

1. Creá un GitHub Actions workflow para una app Node.js con: lint, test y build de Docker
2. Creá un .gitlab-ci.yml con stages de test, build y deploy usando anclas para evitar duplicación
3. Agregá una matrix strategy para testear en múltiples versiones de Node.js