# GitLab CI/CD Quick Reference

*Pipelines, jobs, stages, variables, artifacts, environments*

> Source: GitLab Documentation (docs.gitlab.com) · MIT

## Pipeline Basics

### How Pipelines Work

| Command | Description |
|---------|-------------|
| `Pipeline` | Top-level container; one per commit/trigger |
| `Stage` | Group of jobs that run in parallel |
| `Job` | Single task (script) within a stage |
| `Runner` | Agent that executes jobs |

### Triggering Pipelines

| Command | Description |
|---------|-------------|
| `Push to branch` | Automatic (default) |
| `Merge request` | Via workflow:rules or only: merge_requests |
| `Schedule` | CI/CD → Schedules in project settings |
| `API` | POST /projects/:id/trigger/pipeline |
| `Manual` | Run Pipeline button in CI/CD menu |

## .gitlab-ci.yml

### Minimal Config

```
stages: [build, test, deploy]
build-job:
  stage: build
  script: echo "Compiling..."
```

### Global Keywords

| Command | Description |
|---------|-------------|
| `stages` | Define stage order |
| `default` | Default values for all jobs |
| `variables` | Global CI/CD variables |
| `workflow` | Control when pipelines are created |
| `include` | Import external YAML files |

### Include Templates

```
include:
  - template: Auto-DevOps.gitlab-ci.yml
  - local: .ci/lint.yml
  - project: 'group/shared-ci'
    file: '/templates/deploy.yml'
```

## Jobs

### Job Definition

```
test-unit:
  stage: test
  image: node:20
  script:
    - npm ci
    - npm test
```

### Job Keywords

| Command | Description |
|---------|-------------|
| `script` | Shell commands to run (required) |
| `before_script` | Commands before main script |
| `after_script` | Commands after (even on failure) |
| `image` | Docker image for the job |
| `rules` | Conditions for job inclusion |
| `needs` | DAG dependencies (skip stage order) |
| `allow_failure` | Pipeline continues if job fails |
| `retry` | Auto-retry count (0-2) |
| `timeout` | Max job duration |

### Rules

```
deploy:
  rules:
    - if: '$CI_COMMIT_BRANCH == "main"'
      when: manual
    - if: '$CI_PIPELINE_SOURCE == "merge_request_event"'
      when: never
    - when: on_success
```

## Stages

### Stage Order

```
stages:
  - lint
  - build
  - test
  - deploy
```

### Default Stages

| Command | Description |
|---------|-------------|
| `.pre` | Always runs first |
| `build` | Default stage 1 |
| `test` | Default stage 2 |
| `deploy` | Default stage 3 |
| `.post` | Always runs last |

### DAG with needs

```
test-api:
  stage: test
  needs: ["build-api"]    # skip waiting for full stage
test-web:
  stage: test
  needs: ["build-web"]    # runs as soon as build-web done
```

## Variables

### Defining Variables

```
variables:
  NODE_ENV: "production"
  DB_HOST: "postgres"
job:
  variables:
    NODE_ENV: "test"      # job-level override
```

### Predefined Variables

| Command | Description |
|---------|-------------|
| `CI_COMMIT_SHA` | Full commit hash |
| `CI_COMMIT_BRANCH` | Branch name |
| `CI_COMMIT_TAG` | Tag name (if tag pipeline) |
| `CI_PIPELINE_ID` | Unique pipeline ID |
| `CI_PROJECT_DIR` | Repo checkout path |
| `CI_MERGE_REQUEST_IID` | MR number (MR pipelines only) |
| `CI_REGISTRY_IMAGE` | Container registry image path |

### Protected & Masked

| Command | Description |
|---------|-------------|
| `Protected` | Only available on protected branches/tags |
| `Masked` | Hidden in job logs |
| `File` | Written to a temp file; path in variable |

## Artifacts

### Saving Artifacts

```
build:
  script: npm run build
  artifacts:
    paths: [dist/]
    expire_in: 1 week
```

### Artifact Types

| Command | Description |
|---------|-------------|
| `paths` | Files/dirs to store |
| `exclude` | Patterns to skip |
| `expire_in` | Auto-delete after duration |
| `reports:junit` | JUnit XML for MR test summary |
| `reports:coverage_report` | Cobertura coverage visualization |

### JUnit Report

```
test:
  script: pytest --junitxml=report.xml
  artifacts:
    reports:
      junit: report.xml
```

## Cache

### Caching Dependencies

```
test:
  cache:
    key: ${CI_COMMIT_REF_SLUG}
    paths: [node_modules/]
  script: npm ci && npm test
```

### Cache vs Artifacts

| Command | Description |
|---------|-------------|
| `Cache` | Speed up jobs; not guaranteed; same key reuse |
| `Artifacts` | Pass files between jobs/stages; guaranteed |

### Cache Policies

| Command | Description |
|---------|-------------|
| `pull-push` | Download + upload (default) |
| `pull` | Download only (faster for consumers) |
| `push` | Upload only (for producers) |

## Environments

### Defining Environments

```
deploy-staging:
  stage: deploy
  environment:
    name: staging
    url: https://staging.example.com
  script: ./deploy.sh staging
```

### Environment Features

| Command | Description |
|---------|-------------|
| `name` | Environment name (shown in UI) |
| `url` | Link to deployed app |
| `on_stop` | Job to run when environment is stopped |
| `auto_stop_in` | Auto-stop after duration |
| `action: stop` | Marks job as the stop action |

### Review Apps

```
review:
  environment:
    name: review/$CI_COMMIT_REF_SLUG
    url: https://$CI_COMMIT_REF_SLUG.example.com
    on_stop: stop-review
    auto_stop_in: 1 week
```

## Docker

### Build & Push Image

```
build-image:
  image: docker:24
  services: [docker:24-dind]
  script:
    - docker login -u $CI_REGISTRY_USER -p $CI_REGISTRY_PASSWORD $CI_REGISTRY
    - docker build -t $CI_REGISTRY_IMAGE:$CI_COMMIT_SHA .
    - docker push $CI_REGISTRY_IMAGE:$CI_COMMIT_SHA
```

### Services (Sidecar Containers)

```
test:
  image: python:3.12
  services:
    - postgres:16
    - redis:7
  variables:
    POSTGRES_DB: testdb
    POSTGRES_PASSWORD: secret
```

### Docker-in-Docker

| Command | Description |
|---------|-------------|
| `docker:24-dind` | DinD service image |
| `DOCKER_TLS_CERTDIR` | Set to '/certs' or '' for TLS config |
| `DOCKER_HOST` | tcp://docker:2376 (TLS) or :2375 |

## Common Patterns

### Monorepo (changes)

```
test-api:
  rules:
    - changes: [api/**/*]
test-web:
  rules:
    - changes: [web/**/*]
```

### Manual Deploy Gate

```
deploy-prod:
  stage: deploy
  when: manual
  rules:
    - if: '$CI_COMMIT_BRANCH == "main"'
```

### Parallel Matrix

```
test:
  parallel:
    matrix:
      - PYTHON: ["3.10", "3.11", "3.12"]
        DB: ["postgres", "sqlite"]
  script: tox -e py${PYTHON}-${DB}
```