CI/CD stands for Continuous Integration and Continuous Delivery (or Deployment). It represents a set of practices and tools that automate the process of integrating code changes, testing them, and delivering or deploying them to production environments.
Continuous Integration (CI)
Continuous Integration is the practice of automatically building and testing code changes as soon as they are committed to a shared repository. This helps detect and fix integration issues quickly.
Key components of CI:
- Automated Builds: Code is automatically compiled and packaged when changes are committed
- Automated Testing: Unit, integration, and other tests are run automatically
- Fast Feedback: Developers receive immediate feedback on the quality of their changes
- Version Control: All code changes are tracked in a version control system
Continuous Delivery/Deployment (CD)
Continuous Delivery ensures that code changes are automatically tested and prepared for deployment to production. Continuous Deployment goes further by automatically deploying all changes that pass the tests to production.
Types of CD:
- Continuous Delivery: Code is automatically tested and prepared for release, but deployment to production requires manual approval
- Continuous Deployment: Code changes are automatically deployed to production without manual intervention
Key Benefits
- Faster Time to Market: Reduces the time between writing code and deploying it to production
- Improved Quality: Automated testing catches bugs early in the development cycle
- Reduced Risk: Smaller, more frequent releases reduce the impact of potential issues
- Increased Productivity: Automation reduces manual work and human errors
- Better Collaboration: Frequent integration reduces conflicts between team members
- Reliability: Consistent deployment processes reduce production incidents
Common Practices
- Automated Testing: Comprehensive test suites covering unit, integration, and end-to-end tests
- Infrastructure as Code: Managing infrastructure through code and version control
- Feature Flags: Enabling/disabling features without deploying new code
- Blue-Green Deployments: Running two identical production environments for zero-downtime deployments
- Canary Releases: Gradually rolling out changes to a subset of users
- Rollback Mechanisms: Ability to quickly revert to previous versions if needed
Popular CI/CD Tools
- Cloud-based: GitHub Actions, GitLab CI/CD, CircleCI, Travis CI, Jenkins X
- Self-hosted: Jenkins, TeamCity, Bamboo, GoCD
- Platform-specific: AWS CodePipeline, Azure DevOps, Google Cloud Build
CI/CD Pipeline Stages
- Source: Code is committed to version control
- Build: Code is compiled and packaged
- Test: Automated tests are run
- Package: Artifacts are created and stored
- Deploy: Code is deployed to staging/production
- Monitor: Applications and infrastructure are monitored