CI/CD Pipeline: Continuous Integration and Continuous Deployment

What is CI/CD?

CI (Continuous Integration): Developers frequently (several times a day) merge code changes into the main branch and run automated tests.

CD (Continuous Deployment/Delivery): Code changes are automatically tested and deployed to production. Delivery requires manual approval, Deployment is fully automated.

Benefits: Faster release cycle, fewer bugs, more reliable deploys, increased developer productivity.

Pipeline: Automated workflow consisting of code commit → Build → Test → Deploy steps.

CI Pipeline Stages

Source: Pull changes from code repository (GitHub, GitLab, Bitbucket). Automatic triggering via webhook.

Build: Compile code and install dependencies. npm install, npm run build. Create build artifacts (Docker image, binary).

Test: Run unit tests, integration tests, and end-to-end tests. Generate test coverage report. Check coverage threshold.

Code quality: Linting (ESLint), type checking (TypeScript), security scanning (Snyk, Dependabot). Define code quality gates.

Artifact: Push build artifacts to registry (Docker Hub, npm registry, S3). Add version tags.

CD Pipeline Stages

Staging deploy: Deploy artifact to staging environment. Run automated smoke tests.

Manual approval: Manual approval for production deploy (Continuous Delivery). Automatic deploy after approval.

Production deploy: Zero-downtime deploy with blue-green deployment, canary release, or rolling update.

Post-deploy: Health check, monitoring, alerting. Automatic rollback if deploy fails.

Notification: Deploy status notification via Slack, email, or Teams. Different channels for successful/failed deploys.

Popular CI/CD Tools

GitHub Actions: Native CI/CD in GitHub repositories. Configured with YAML workflow files. Free tier available.

GitLab CI: Native CI/CD in GitLab repositories. Configured with .gitlab-ci.yml. Docker runner support.

Jenkins: Self-hosted, open-source CI/CD. Configured with Groovy pipeline scripts. Very wide plugin ecosystem.

CircleCI: Cloud-based CI/CD. Fast builds and parallel test support. Configured with config.yml.

ArgoCD: GitOps CD tool for Kubernetes. Uses Git repository as source of truth. Automatic sync and rollback.

Best Practices

Pipeline as Code: Store pipeline configuration as code (YAML). Track with version control.

Fast feedback: Keep pipeline fast (under 10 minutes). Run tests in parallel. Use caching (node_modules, Docker layers).

Security: Manage secrets (API key, password) with environment variables or secret manager (Vault, AWS Secrets Manager). Don't hardcode in code.

Idempotency: Running pipeline multiple times should produce same result. Deploy scripts must be idempotent.

Monitoring: Monitor pipeline metrics: build time, test success rate, deploy frequency, MTTR (Mean Time to Recovery).

GitOps and Infrastructure as Code

GitOps: Use Git repository as single source of truth. All infrastructure and application changes managed through Git.

Terraform: Infrastructure as Code tool. Define and manage cloud resources (VM, database, network) as code.

Kubernetes: Container orchestration platform. Define resources like Deployment, Service, Ingress with YAML.

Helm: Package manager for Kubernetes. Parameterize application deploys with Charts.

ArgoCD/Flux: Monitor Git repository and auto-sync to Kubernetes cluster. Drift detection and auto-healing.