GitLab CI Generator

What is GitLab CI?

GitLab CI/CD is a tool built into GitLab for software development through the continuous methodologies: Continuous Integration, Continuous Delivery, and Continuous Deployment.

Configurations are defined in a file named .gitlab-ci.yml, which sits at the root of your repository.

Key Concepts

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Stages and Jobs

A pipeline is composed of independent jobs that run scripts, grouped into stages. Stages run sequentially, while jobs within the same stage run in parallel.

build: Compile code or build Docker images.

test: Run unit, integration, and security tests.

deploy: Push code to staging or production environments.

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Artifacts and Caching

Artifacts: Used to pass intermediate build results between stages (e.g., passing a compiled binary from the build stage to the deploy stage).

Cache: Used to speed up the execution of jobs by storing dependencies (e.g., node_modules) that can be reused in subsequent pipeline runs.

Best Practices for GitLab CI

Use Docker-in-Docker Carefully: When building images, DIND is useful but can be insecure if not configured with TLS.

Pin Image Tags: Never use latest for job images. Always pin to specific versions to avoid unexpected pipeline breakages.

Use Rules: The rules keyword replaces the older only/except syntax and provides powerful logic for deciding when a job should run.