GitLab CI/CD Pipeline Writing

Name: gitlab-ci
Rating: 92
Author: mikeparcewski

Write production-ready GitLab CI/CD pipelines with security and optimization built in.

When to Use

•Creating new CI/CD pipelines
•Optimizing slow or expensive pipelines
•Setting up multi-environment deployments
•Debugging pipeline failures

Core Structure

yaml

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

variables:
  NODE_VERSION: "20"

build:
  stage: build
  script:
    - npm ci
    - npm run build
  artifacts:
    paths:
      - dist/

GitLab vs GitHub Actions

Concept	GitHub Actions	GitLab CI
Config	`.github/workflows/*.yml`	`.gitlab-ci.yml`
Grouping	`jobs:`	`stages:`
Triggers	`on:`	`rules:`
Secrets	`${{ secrets.X }}`	`$VARIABLE`
Artifacts	`actions/upload-artifact`	Built-in
Caching	`actions/cache`	Built-in

Security

Protected Variables

yaml

deploy:
  script:
    - deploy --token $DEPLOY_TOKEN
  # Set DEPLOY_TOKEN as protected in GitLab UI

Restrict Execution

yaml

deploy:
  rules:
    - if: $CI_COMMIT_BRANCH == "main"
      when: manual  # Require approval
    - when: never

Performance

Caching

yaml

default:
  cache:
    key:
      files:
        - package-lock.json
    paths:
      - node_modules/

DAG (Parallel Dependencies)

yaml

deploy:
  needs:
    - build-frontend
    - build-backend
  # Starts when both complete, skips waiting for whole stage

Path Filtering

yaml

build:
  rules:
    - changes:
        - src/**/*
        - package.json

Parallel Jobs

yaml

test:
  parallel: 4
  script:
    - npm test -- --shard=$CI_NODE_INDEX/$CI_NODE_TOTAL

Common Patterns

Include Templates

yaml

include:
  - local: .gitlab/ci/build.yml
  - template: Security/SAST.gitlab-ci.yml

Services

yaml

test:
  services:
    - postgres:15
  variables:
    DATABASE_URL: postgresql://postgres@postgres/test

Multi-Environment

yaml

.deploy: &deploy
  script: deploy.sh
  when: manual

deploy-staging:
  <<: *deploy
  environment: staging
  rules:
    - if: $CI_COMMIT_BRANCH == "develop"

deploy-production:
  <<: *deploy
  environment: production
  rules:
    - if: $CI_COMMIT_BRANCH == "main"

References

•refs/templates.md - Copy-paste templates for Node.js, Python, Docker, K8s
•refs/troubleshooting.md - Common errors and fixes