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CI/CD — Practical Overview & Commands

CI/CD (Continuous Integration and Continuous Deployment) automates the building, testing, and delivery of software to production environments. Its primary goals include:

  • Faster release cycles
  • Consistent, repeatable deployments
  • Reduced manual errors
  • Higher developer productivity

1. Source Control & Repository Setup

Command / Tool Purpose
git init Initialize a Git repository
git add . Stage all changes
git commit -m "message" Commit staged changes
git remote add origin <repo_url> Connect local repo to remote
git push origin main Push commits to main branch
gh workflow list Display GitHub Actions workflows
gh workflow run <name> Trigger a workflow manually
gh run watch Stream workflow execution logs

2. Continuous Integration (CI)

Continuous Integration focuses on automatic building and testing of code changes before merging into mainline branches.

Typical CI Pipeline Stages

Stage Tool / Command Purpose
Build docker build -t <image> . Package or compile the application
Dependency Installation npm install / pip install -r requirements.txt Install dependencies
Automated Testing npm test / pytest / mvn test Validate correctness
Linting / Static Analysis eslint . / flake8 Ensure formatting and code quality
Artifact Creation CI-generated build output Used for deployment
Pipeline Triggers on: [push, pull_request] Automatically run on commit events

Common GitHub Actions CI Components

Component Purpose
actions/checkout@v4 Clone repository source
actions/setup-node@v4 / setup-python Setup runtime environment
actions/cache@v4 Cache dependencies for faster builds

3. Continuous Deployment (CD)

Continuous Deployment automates delivery of application artifacts to runtime environments like virtual machines, containers, or Kubernetes clusters.

Deployment Sequence

Stage Command / Tool Purpose
Build Image docker build -t <image> . Build container image
Push Image docker push <repo>/<image>:tag Push to registry
Deploy to K8s kubectl apply -f k8s/ Apply deployment manifests
Verify Deployment kubectl get pods / kubectl get svc Validate deployment state
Monitor Rollout kubectl rollout status deployment/<name> Track deployment progress
Rollback kubectl rollout undo deployment/<name> Revert unsuccessful releases

Supported Container Registries

Registry Provider
DockerHub Docker
ECR AWS
GCR Google
ACR Azure

4. Secrets & Security Considerations

Common secrets required in CI/CD pipelines include:

  • Docker credentials
  • Kubernetes configuration
  • API keys or tokens

These should be stored securely via:

GitHub → Repository → Settings → Secrets & Variables

5. Example: GitHub Actions CI/CD Workflow

name: CI/CD Pipeline

on:
  push:
    branches: [ "main" ]

jobs:
  build-and-deploy:
    runs-on: ubuntu-latest

    steps:
      - name: Checkout Source Code
        uses: actions/checkout@v4

      - name: Setup Node Environment
        uses: actions/setup-node@v4
        with:
          node-version: 18

      - name: Install Dependencies
        run: npm install

      - name: Run Tests
        run: npm test

      - name: Build Docker Image
        run: docker build -t ${{ secrets.DOCKER_USERNAME }}/devops-app:latest .

      - name: Authenticate to DockerHub
        uses: docker/login-action@v3
        with:
          username: ${{ secrets.DOCKER_USERNAME }}
          password: ${{ secrets.DOCKER_PASSWORD }}

      - name: Push Image to Docker Registry
        run: docker push ${{ secrets.DOCKER_USERNAME }}/devops-app:latest

      - name: Deploy to Kubernetes Cluster
        env:
          KUBE_CONFIG_DATA: ${{ secrets.KUBE_CONFIG_DATA }}
        run: |
          echo "$KUBE_CONFIG_DATA" | base64 --decode > $HOME/.kube/config
          kubectl apply -f k8s/
          kubectl rollout status deployment/devops-app

6. Deployment Flow (End-to-End)

Commit → CI (Build/Test) → Container Registry → CD → Kubernetes → Service Exposure