gitlab-ci

# GitLab CI/CD ## What I Do I am GitLab's integrated CI/CD platform that automates building, testing, and deploying your code. I use YAML configuration files to define pipelines, with tight integration into GitLab's repository, issue tracking, and deployment features. ## When to Use Me - Projects hosted on GitLab - Requiring native container registry integration - Using GitLab for both source control and CI/CD - Implementing Auto DevOps - Kubernetes-native deployments - Security scanning in the pipeline - Multi-project pipeline dependencies ## Core Concepts - **.gitlab-ci.yml**: Pipeline configuration file - **Jobs**: Smallest units of execution - **Pipelines**: Collection of jobs grouped into stages - **Stages**: Groups of jobs that run in parallel - **Runners**: Executors that run jobs - **Artifacts**: Files passed between stages - **Cache**: Preserved files between runs - **Variables**: Environment variables for jobs - **Rules**: Conditional job execution - **Include**: External YAML configuration - **Templates**: Reusable job definitions ## Code Examples **Basic .gitlab-ci.yml:** ```yaml stages: - build - test - deploy variables: DOCKER_DRIVER: overlay2 DOCKER_TLS_CERTDIR: "" MAVEN_OPTS: "-Dmaven.repo.local=$CI_PROJECT_DIR/.m2/repository" build: stage: build image: maven:3.8.6-openjdk-17 script: - mvn clean compile -DskipTests cache: key: ${CI_COMMIT_REF_SLUG} paths: - .m2/repository artifacts: paths: - target/ expire_in: 1 hour test: stage: test image: maven:3.8.6-openjdk-17 script: - mvn test coverage: '/Total.*?([0-9]{1,3})%/' artifacts: reports: junit: target/surefire-reports/*.xml coverage_report: coverage_format: cobertura path: target/site/jacoco/jacoco.xml integration-test: stage: test image: maven:3.8.6-openjdk-17 services: - postgres:14 variables: POSTGRES_DB: testdb POSTGRES_USER: testuser POSTGRES_PASSWORD: testpass script: - mvn verify -Pintegration-tests artifacts: reports: junit: target/failsafe-reports/*.xml deploy_staging: stage: deploy environment: name: staging url: https://staging.example.com script: - helm upgrade --install myapp ./chart --namespace staging --values ./values-staging.yaml only: - develop deploy_production: stage: deploy environment: name: production url: https://example.com script: - helm upgrade --install myapp ./chart --namespace production --values ./values-prod.yaml when: manual only: - main ``` **Advanced Matrix Builds:** ```yaml stages: - build - test - deploy variables: DOCKER_REGISTRY: registry.example.com build: stage: build image: docker:20.10 services: - docker:20.10-dind script: - docker build -t $CI_REGISTRY_IMAGE:$CI_COMMIT_SHA . - docker push $CI_REGISTRY_IMAGE:$CI_COMMIT_SHA only: changes: - Dockerfile - src/**/* .test_template: &test_template stage: test script: - npm ci - npm test coverage: '/All files[^|]*\|[^|]*\s+([\d\.]+)/' artifacts: reports: junit: junit.xml test:linux: <<: *test_template image: node:18-alpine tags: - linux test:macos: <<: *test_template tags: - macos before_script: - brew install node@18 test:windows: <<: *test_template tags: - windows only: changes: - "**/*.ts" - "package.json" ``` **Auto DevOps with Customization:** ```yaml include: - template: Auto-DevOps.gitlab-ci.yml variables: AUTO_DEVOPS_BUILD_IMAGE: Dockerfile AUTO_DEVOPS_BUILD_STRATEGY: docker DOCKER_DRIVER: overlay2 KUBERNETES_VERSION: "1.25" HELM_VERSION: "3.10" stages: - build - test - deploy test:unit: extends: .test:unit allow_failure: false test:integration: extends: .test:integration services: - postgres:14 - redis:7 variables: POSTGRES_DB: test DATABASE_URL: "postgresql://test:test@postgres:5432/test" REDIS_URL: "redis://redis:6379" after_script: - echo "Running additional cleanup" review: environment: name: review/$CI_COMMIT_REF_NAME url: https://$CI_ENVIRONMENT_SLUG.example.com on_stop: stop_review script: - helm upgrade --install myapp ./chart --namespace $CI_ENVIRONMENT_SLUG --set image.tag=$CI_COMMIT_SHA --set replicaCount=1 when: manual stop_review: stage: deploy variables: GIT_STRATEGY: none script: - helm uninstall myapp --namespace $CI_ENVIRONMENT_SLUG || true environment: name: review/$CI_COMMIT_REF_NAME action: stop when: manual ``` **Pipeline with Dependencies:** ```yaml stages: - build - test - package - deploy build:library: stage: build script: - make build-library artifacts: paths: - dist/ - package.json rules: - if: $CI_COMMIT_TAG - if: $CI_MERGE_REQUEST_IID changes: - library/**/* build:service: stage: build script: - make build-service dependencies: - build:library artifacts: paths: - bin/ rules: - if: $CI_COMMIT_TAG - if: $CI_MERGE_REQUEST_IID changes: - service/**/* package:docker: stage: package image: docker:20.10 services: - docker:20.10-dind script: - docker build -t $CI_REGISTRY_IMAGE:$CI_COMMIT_SHA ./service - docker push $CI_REGISTRY_IMAGE:$CI_COMMIT_SHA dependencies: - build:service deploy:prod: stage: deploy environment: production script: - kubectl set image deployment/myapp myapp=$CI_REGISTRY_IMAGE:$CI_COMMIT_SHA only: - main ``` ## Best Practices 1. **Use extends for DRY configs** - Avoid duplication with YAML anchors 2. **Implement proper caching** - Speed up build times significantly 3. **Use rules for conditional execution** - Only run necessary jobs 4. **Include external templates** - Share configurations across projects 5. **Set appropriate timeouts** - Prevent stuck jobs 6. **Use artifacts for outputs** - Pass files between stages 7. **Implement security scanning** - SAST, DAST, dependency scanning 8. **Use environments for deployments** - Track deployments visually 9. **Keep pipelines fast** - Parallelize, cache, optimize scripts 10. **Document pipeline structure** - Comments for complex logic