🚀 Multi-Application CI/CD on AWS (Production-Style)

#devops #aws #cicd #softwareengineering

🎯 Project Goal
Host multiple web applications on AWS where:

Developers push code to GitHub
GitHub Actions automatically:
Tests code
Builds Docker images
Pushes images to AWS ECR
Deploys to AWS ECS (Fargate) or EC2 + Docker
End users access apps via HTTPS (ALB + ACM)
Logs & monitoring via CloudWatch
Supports rolling / blue-green deployment

🏗️ High-Level Architecture

Developer
   |
   v
GitHub Repo (App1, App2, App3)
   |
GitHub Actions (CI/CD)
   |
   |-- Test
   |-- Docker Build
   |-- Push to ECR
   v
AWS ECR (Images)
   |
AWS ECS (Fargate)
   |
Application Load Balancer
   |
   v
End Users (HTTPS)

📁 Repository Structure

multi-app-devops/
├── app1/
│   ├── Dockerfile
│   └── src/
├── app2/
│   ├── Dockerfile
│   └── src/
├── app3/
│   ├── Dockerfile
│   └── src/
└── .github/
    └── workflows/
        └── deploy.yml

Each app is independent but deployed via same pipeline logic.

🔐 STEP 1: AWS ACCOUNT & IAM
Create IAM User (DevOpsUser)
Permissions:

AmazonEC2FullAccess
AmazonECS_FullAccess
AmazonEC2ContainerRegistryFullAccess
CloudWatchFullAccess
IAMReadOnlyAccess

⚠️ Create Access Key (Programmatic)

🌐 STEP 2: Networking (VPC)

Create VPC
2 Public Subnets
Internet Gateway
Route Table
Security Groups:
ALB: 80, 443
ECS: 3000/5000/80 (app ports)

📦 STEP 3: Create ECR Repositories
Create one ECR per app:

app1-ecr
app2-ecr
app3-ecr

Save:

AWS Account ID
Region
Repository URI Example:

123456789012.dkr.ecr.us-east-1.amazonaws.com/app1

🐳 STEP 4: Dockerize Applications
Example Dockerfile (Node.js / Python)

FROM node:18-alpine
WORKDIR /app
COPY package*.json .
RUN npm install
COPY . .
EXPOSE 3000
CMD ["npm", "start"]

Repeat per app.

⚙️ STEP 5: ECS Cluster (Fargate)

Create ECS Cluster
Create Task Definition per App

Container Image: ECR URI
Port Mapping
CPU & Memory

Create Service

Launch Type: FARGATE
Attach ALB
Desired Tasks: 2 (HA)

🌍 STEP 6: Application Load Balancer
Create ALB
Listener:
HTTP → Redirect HTTPS
HTTPS → Target Groups
Path-based routing:

/app1 → app1-service
/app2 → app2-service
/app3 → app3-service

🔑 STEP 7: GitHub Secrets
In GitHub Repo → Settings → Secrets
AWS_ACCESS_KEY_ID AWS_SECRET_ACCESS_KEY AWS_REGION AWS_ACCOUNT_ID ECR_REPO_APP1 ECR_REPO_APP2

🔄 STEP 8: GitHub Actions CI/CD Pipeline
.github/workflows/deploy.yml

name: CI-CD Pipeline

on:
  push:
    branches: [ "main" ]

env:
  AWS_REGION: us-east-1

jobs:
  deploy:
    runs-on: ubuntu-latest

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

    - name: Configure AWS Credentials
      uses: aws-actions/configure-aws-credentials@v4
      with:
        aws-access-key-id: ${{ secrets.AWS_ACCESS_KEY_ID }}
        aws-secret-access-key: ${{ secrets.AWS_SECRET_ACCESS_KEY }}
        aws-region: ${{ env.AWS_REGION }}

    - name: Login to Amazon ECR
      run: |
        aws ecr get-login-password --region $AWS_REGION \
        | docker login --username AWS --password-stdin \
        ${{ secrets.AWS_ACCOUNT_ID }}.dkr.ecr.$AWS_REGION.amazonaws.com

    - name: Build & Push App1
      run: |
        docker build -t app1 ./app1
        docker tag app1:latest ${{ secrets.ECR_REPO_APP1 }}:latest
        docker push ${{ secrets.ECR_REPO_APP1 }}:latest

    - name: Deploy to ECS
      run: |
        aws ecs update-service \
          --cluster devops-cluster \
          --service app1-service \
          --force-new-deployment

✔ Repeat build steps for app2 & app3.