CI/CD
Continuous Integration and Continuous Deployment/Delivery. A set of practices that automate the building, testing, and deployment of applications.
Detailed Explanation
CI/CD is the backbone of modern software development. Continuous Integration (CI) ensures that code changes are automatically built and tested when merged to a shared branch, catching integration issues early. Continuous Delivery extends this by automatically preparing releases for deployment. Continuous Deployment goes further by automatically deploying every passing change to production.
A typical CI/CD pipeline: developer pushes code → pipeline triggers → code is built (compilation, bundling) → tests run (unit, integration, e2e) → code is analyzed (linting, security scanning) → artifacts are built (Docker images, bundles) → deployment happens (to staging or production). Popular CI/CD tools include GitHub Actions, GitLab CI, Jenkins, CircleCI, and Travis CI.
Why It Matters
CI/CD dramatically reduces deployment risk, accelerates release cycles, and improves code quality. It is essential for any team shipping software regularly.
Real-World Example
A team pushes code at 5 PM. CI runs tests and catches a breaking change. The developer fixes it before it reaches production. The next day, the fixed code is deployed automatically through CD.
When to Use
Any team shipping code should use CI/CD. Even solo developers benefit from automated testing and deployment pipelines.
Advantages
- Faster, more reliable releases
- Early detection of integration issues
- Reduced manual errors in deployment
- Consistent and repeatable processes
- Faster feedback loops for developers
Disadvantages
- Initial setup requires investment
- Pipeline maintenance adds overhead
- Flaky tests can block deployments
- Requires good test coverage to be effective
- Complex deployment scenarios need careful pipeline design
Related Terms
Frequently Asked Questions
What is the difference between CI and CD?
CI (Continuous Integration) automates building and testing code when changes are merged. CD can mean Continuous Delivery (automated release preparation) or Continuous Deployment (automatic production deployment). Together, they automate the path from code to production.
What tool should I use for CI/CD?
GitHub Actions is the most popular for GitHub projects. GitLab CI is built into GitLab. Jenkins is powerful but complex. For simple projects, start with GitHub Actions or Vercel/Netlify's built-in CI/CD.
How do I handle database migrations in CI/CD?
Run migrations as a separate step before deploying application code. In Kubernetes, use init containers. In serverless, run migrations as a pre-deploy step. Always make migrations backward-compatible.
What is a deployment strategy?
Common strategies: rolling deployment (gradually replace instances), blue-green (switch traffic from old to new), canary (deploy to small percentage first), and recreate (stop old, start new). Choose based on downtime tolerance and risk.
How fast should a CI pipeline be?
Aim for under 10 minutes for the core build and test suite. Longer pipelines reduce developer productivity. Use parallel execution, caching, and test splitting to keep pipelines fast.