CI/CD Interview Questions for DevOps and Developers

1. What is CI/CD?

CI/CD stands for Continuous Integration and Continuous Deployment. It automates testing and deployment of code, ensuring faster and more reliable releases.

2. What is a CI/CD pipeline?

A CI/CD pipeline is a set of automated steps that run after code is pushed — such as installing dependencies, testing, building, and deploying the app.

3. What tools have you used for CI/CD?

I’ve used GitHub Actions for automating CI/CD. For deployment, I’ve used Vercel, Render, and Docker on VPS.

4. What is the role of the .yml file in CI/CD?

The .yml file defines the CI/CD workflow steps (e.g., install, test, deploy) that the CI/CD tool (like GitHub Actions) should execute.

5. How do you deploy a MERN app using CI/CD?

Deploying a MERN (MongoDB, Express, React, Node.js) application using a CI/CD pipeline involves automating the build, testing, and deployment process whenever changes are pushed to the repository.

Typical Workflow

1. Code Push
   • Developers push code to a Git repository such as GitHub or GitLab.
2. Continuous Integration (CI)
   • A CI tool (e.g., GitHub Actions, GitLab CI, Jenkins) automatically:
     • Installs dependencies
     • Runs tests
     • Builds the application
3. Frontend Deployment (React)
   • The React application is built using:

   npm run build
   

CI runs tests and build first, then deploys if everything passes.
The build output is deployed to hosting platforms such as Vercel, Netlify, or AWS S3 + CloudFront.
4. **Backend Deployment (Node.js / Express)**
   The backend API is deployed to a server or cloud platform such as:
   - Render
   - AWS EC2
   - Docker containers
   - VPS using SSH deployment via GitHub Actions
Database Connection
The backend connects to MongoDB (e.g., MongoDB Atlas) using environment variables stored securely in the deployment platform.
## 6. What are GitHub Actions Secrets?
Secrets are encrypted variables (e.g., API keys, DB URIs) stored securely in GitHub and used in workflows via ${{ secrets.MY_SECRET }}.
## 7. How do you prevent broken code from being deployed?
By running tests and lint checks in the CI step. If any step fails, the deployment is skipped automatically.