GitLab CI/CD Pipelines: Writing .gitlab-ci.yml, Using rules and Artifacts, and Registering a Runner

# .gitlab-ci.yml

stages:
  - test
  - build
  - deploy

variables:
  NODE_VERSION: "20"
  IMAGE_NAME: $CI_REGISTRY_IMAGE

# Job definitions
lint:
  stage: test
  image: node:20-alpine
  script:
    - npm ci
    - npm run lint

test:
  stage: test
  image: node:20-alpine
  script:
    - npm ci
    - npm test
  coverage: '/Liness*:s*(d+.d+)%/'
  artifacts:
    reports:
      coverage_report:
        coverage_format: cobertura
        path: coverage/cobertura-coverage.xml

stages:
  - test       # run in parallel
  - build      # after test completes
  - staging    # after build completes
  - production # after manual approval

build-image:
  stage: build
  image: docker:24
  services:
    - docker:24-dind
  script:
    - docker login -u $CI_REGISTRY_USER -p $CI_REGISTRY_PASSWORD $CI_REGISTRY
    - docker build -t $IMAGE_NAME:$CI_COMMIT_SHORT_SHA .
    - docker push $IMAGE_NAME:$CI_COMMIT_SHORT_SHA
  only:
    - main
    - develop

deploy-staging:
  stage: staging
  environment:
    name: staging
    url: https://staging.example.com
  script:
    - kubectl set image deployment/myapp myapp=$IMAGE_NAME:$CI_COMMIT_SHORT_SHA
  only:
    - develop

deploy-production:
  stage: production
  environment:
    name: production
    url: https://example.com
  script:
    - kubectl set image deployment/myapp myapp=$IMAGE_NAME:$CI_COMMIT_TAG
  when: manual           # requires manual approval
  only:
    - tags

# Cache — reused across jobs (e.g. node_modules)
cache:
  key: $CI_COMMIT_REF_SLUG
  paths:
    - node_modules/
    - .npm/

# Artifacts — pass files between jobs + available for download
build:
  script:
    - npm run build
  artifacts:
    paths:
      - dist/
    expire_in: 1 week    # retention period

# Using artifacts
deploy:
  dependencies:
    - build
  script:
    - ls dist/           # artifacts from the build job are available

test:
  script: npm test
  rules:
    - if: '$CI_PIPELINE_SOURCE == "merge_request_event"'
    - if: '$CI_COMMIT_BRANCH == "main"'
    - if: '$CI_COMMIT_TAG'
      when: never        # do not run on tags

# Run only when files change
backend-test:
  script: npm test
  rules:
    - changes:
        - src/**/*
        - package.json

# Install Runner (Ubuntu)
curl -L https://packages.gitlab.com/install/repositories/runner/gitlab-runner/script.deb.sh | sudo bash
sudo apt install -y gitlab-runner

# GitLab project → Settings → CI/CD → Runners — copy the token
sudo gitlab-runner register   --url https://gitlab.com   --registration-token YOUR_TOKEN   --executor docker   --docker-image alpine:latest   --description "my-runner"

# Check status
sudo gitlab-runner status
sudo gitlab-runner list