GitLab CI

TL;DR

What: Built-in CI/CD system integrated with GitLab repositories.

Why: Native GitLab integration, YAML config, auto DevOps, container registry included.

Quick Start

Create .gitlab-ci.yml in repository root:

stages:
  - build
  - test
  - deploy

build:
  stage: build
  script:
    - npm install
    - npm run build

test:
  stage: test
  script:
    - npm test

deploy:
  stage: deploy
  script:
    - echo "Deploying..."
  only:
    - main

Trigger: Push to repository. View at CI/CD → Pipelines.

Cheatsheet

Concept	Description
stages	Define pipeline stages
script	Commands to run
only/except	Branch filtering
rules	Advanced conditions
artifacts	Save build outputs
cache	Speed up builds
services	Linked containers

Gotchas

Complete pipeline example

stages:
  - build
  - test
  - deploy

variables:
  NODE_VERSION: "18"

default:
  image: node:${NODE_VERSION}
  cache:
    paths:
      - node_modules/

build:
  stage: build
  script:
    - npm ci
    - npm run build
  artifacts:
    paths:
      - dist/
    expire_in: 1 hour

test:
  stage: test
  script:
    - npm ci
    - npm test
  coverage: '/Coverage: \d+\.\d+%/'

deploy_staging:
  stage: deploy
  script:
    - ./deploy.sh staging
  environment:
    name: staging
    url: https://staging.example.com
  rules:
    - if: $CI_COMMIT_BRANCH == "develop"

deploy_production:
  stage: deploy
  script:
    - ./deploy.sh production
  environment:
    name: production
    url: https://example.com
  rules:
    - if: $CI_COMMIT_BRANCH == "main"
  when: manual

Using services (Docker in Docker)

build_image:
  image: docker:24
  services:
    - docker:24-dind
  variables:
    DOCKER_TLS_CERTDIR: "/certs"
  script:
    - docker build -t myapp:$CI_COMMIT_SHA .
    - docker push myapp:$CI_COMMIT_SHA

Matrix jobs

test:
  stage: test
  parallel:
    matrix:
      - NODE_VERSION: ["16", "18", "20"]
  image: node:${NODE_VERSION}
  script:
    - npm test

Using secrets

deploy:
  stage: deploy
  script:
    - echo "$DEPLOY_KEY" > key.pem
    - chmod 600 key.pem
    - scp -i key.pem dist/* user@server:/var/www/
  variables:
    DEPLOY_KEY: $CI_DEPLOY_KEY  # Set in CI/CD Settings

Include templates

include:
  - template: Security/SAST.gitlab-ci.yml
  - local: .gitlab/ci/build.yml
  - remote: https://example.com/ci-template.yml

Next Steps

• GitLab CI Documentation - Official docs
• CI/CD YAML Reference - Complete syntax
• Predefined Variables - Built-in vars
• CI/CD Examples - Sample configs