CI/CD

Definitions

• CI (Continuous Integration) — merge frequently; every push triggers build + test to catch issues early.
• CD (Continuous Delivery) — every change is release-ready; deploy is a manual approval.
• Continuous Deployment — every green change auto-deploys to production.

Typical pipeline stages

checkout → build → unit tests → static analysis (SonarQube) → package (jar/image) → integration tests → publish artifact → deploy → smoke tests

Tools

• Jenkins (pipelines as Jenkinsfile), GitHub Actions, GitLab CI, CircleCI, Argo CD (GitOps).
• Artifacts: Nexus/Artifactory; images: container registry.

Deployment strategies

• Rolling — replace instances gradually.
• Blue-green — two environments; switch traffic; instant rollback.
• Canary — release to a small % first, then ramp up.

GitOps

Declarative desired state in git; a controller (Argo CD/Flux) syncs the cluster to match. Git is the source of truth.

Good practices

• Fast, reliable pipelines; fail fast; quality gates (coverage, security scans).
• Immutable artifacts promoted across envs (dev → UAT → prod); no rebuild per env.
• Automated rollback; secrets from a vault, never in the pipeline config.

Diagrams