GitLab CI Fundamentals

GitLab CI runs automated pipelines defined in .gitlab-ci.yml.

Core Concepts

• Pipeline: Full CI/CD execution for a commit or merge request.
• Stage: Logical phase (build, test, deploy).
• Job: Individual task executed by a runner.
• Runner: Agent that executes jobs.
• Artifacts: Files passed between jobs/stages.
• Variables: Config/secrets used by jobs.

Basic .gitlab-ci.yml Shape

stages: [build, test, deploy]

build:
  stage: build
  script:
    - echo "build"

test:
  stage: test
  script:
    - echo "test"

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

Best Practices

• Keep jobs fast and deterministic.
• Cache dependencies carefully.
• Use protected branches and protected variables.
• Separate environments (dev, staging, prod).
• Add security scans (SAST/Dependency/Container scanning).