Gitlab CI

GitLab CI/CD

GitLab CI/CD is known for its robust pipeline definition (.gitlab-ci.yml) and Auto DevOps capabilities. In 2025, CI Components replace legacy templates for modular pipeline composition.

When to Use

• GitLab Users: It's integrated and excellent.
• Complex Pipelines: The DAG (Directed Acyclic Graph) capabilities are sophisticated (needs keyword).
• On-Prem: Excellent support for air-gapped instances.

Quick Start

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

build-job:
  stage: build
  image: node:20
  script:
    - npm ci
    - npm run build
  artifacts:
    paths:
      - dist/

test-job:
  stage: test
  image: node:20
  script:
    - npm test
  needs: [build-job]

Core Concepts

.gitlab-ci.yml

The heart of the pipeline. Defines stages, jobs, and environment variables.

Runners

The agents that run jobs. Unique feature: Docker-in-Docker support is first-class (using services: docker:dind).

CI Components (2025)

Reusable pipeline parts listed in the CI Catalog. Replaces the old include: template method with versioned, input-driven components.

Best Practices (2025)

Do:

• Use CI Components: Adopt the module catalog.
• Use rules: Control when jobs run (e.g., only on Merge Requests, or only when package.json changes).
• Use cache vs artifacts: Use cache for dependencies (node_modules) and artifacts for output binaries passed between stages.

Don't:

• Don't use only/except: They are deprecated. Use rules.

References

• GitLab CI/CD Documentation