$ cat .github/workflows/ci.yml
CI/CD Pipeline Explained: Complete Guide for DevOps Engineers
Everything about CI/CD pipelines - from basic concepts to advanced patterns. Learn GitHub Actions, GitLab CI, Jenkins, and best practices.
Key Takeaways
- ▹CI automates testing on every code push
- ▹CD automates deployment to staging/production
- ▹Use matrix builds for multi-environment testing
- ▹Implement quality gates: tests, security scans, approvals
CI vs CD vs CT
CI: Automatically build and test code on every commit.
CD: Automatically deploy to staging after CI passes.
CT: Automated testing throughout the pipeline.
CI Pipeline Stages
1. Checkout - Clone repository
2. Install - Install dependencies
3. Build - Compile code
4. Test - Run unit & integration tests
5. Security Scan - Scan for vulnerabilities
6. Artifact - Package the application
GitHub Actions Example
Triggers on push to main. Runs npm install, tests, security scans, and build.
GitLab CI Example
Defines stages: build, test, deploy. Artifacts passed between stages.
Jenkins Pipeline
Declarative pipeline with build, test, and deploy stages.
Best Practices
Fail fast - run fastest tests first.
Parallelize - split tests across runners.
Quality gates - block merges on failures.
Artifact retention - keep builds for rollback.
Advanced Patterns
Blue-Green: Two identical environments, switch traffic.
Canary: Gradual rollout to small percentage.
Feature Flags: Toggle features without deployment.
GitOps: Git-based deployment strategy.