🌟 Introduction to Blue/Green Deployments

In today's always-on digital landscape, application downtime during deployments translates directly to lost revenue and damaged user trust. Traditional deployment methods force teams to choose between stability and innovation. AWS Elastic Beanstalk's Blue/Green deployment strategy eliminates this compromise by maintaining two identical production environments:

🔵 Blue Environment (Current Production)

• Handles 100% of live traffic

• Stable, known-good version

🟢 Green Environment (New Version)

• Exact replica with your updates

• Tested before receiving traffic

Key Benefits:

• 🕒 Zero downtime during deployments

• 🔄 Instant rollback capability

• 🧪 Real-world testing before cutover

• 📊 Performance comparison between versions

🛠 Phase 1: Project Setup (VS Code)

Step 1.1 - Create Project Structure

# Create project folder
mkdir MyApp
cd MyApp

# Initialize Node.js project
npm init -y       # Creates package.json with default values
npm install express  # Adds Express web framework

# Create organized source structure
mkdir src         # Best practice for code organization
New-Item -Path src/index.js -Type File  # Creates empty JavaScript file

Why This Structure?

• Keeps source code separate from configuration

• Follows Node.js best practices

• Makes it easy to add controllers, routes later

• Clear separation for deployment

Step 1.2 - Build Basic Application

Edit src/index.js:

const express = require('express');
const app = express();

// Main endpoint - returns simple message
app.get('/', (req, res) => {
  res.send('MyApp Blue/Green Deployment');
});

// Health check endpoint - crucial for AWS
app.get('/health', (req, res) => {
  res.send('OK');
});

// Start server on port 3000
const PORT = 3000;
app.listen(PORT, () => {
  console.log(`Server running on port ${PORT}`);
});

Key Components:

• express() - Creates web server

• app.get() - Defines route handlers

• /health - Required endpoint for Elastic Beanstalk

• app.listen() - Starts the server

Step 1.3 - Test Locally

# First navigate to your project root:
cd ..

# Then run with the full path:
node src/index.js

Verification:

1. Open browser to http://localhost:3000

   • Should show "MyApp Blue/Green Deployment"

     

Press Ctrl+C to stop server

🔵 Phase 2: Deploy Blue Environment

Step 2.1 - AWS CLI Setup

aws configure

Enter your:

• AWS Access Key ID

• Secret Access Key

• Default region (e.g., us-east-1)

• Output format (json)

Why? Authenticates your CLI with AWS services.

Step 2.2 - Initialize EB CLI

eb init

🔧 Troubleshooting EB CLI Installation

If you get 'eb' is not recognized error:

1. Find EB CLI Location

    dir "$env:USERPROFILE\AppData\Roaming\Python\Python*\Scripts\eb.exe" -Recurse
   

   Look for the path containing eb.exe (e.g., Python313\Scripts)

2. Add to PATH

   ```powershell

   Replace Python313 with your version

   $ebPath = "$env:USERPROFILE\AppData\Roaming\Python\Python313\Scripts"

3. **Verify Installation**

    ```powershell
    & "$env:USERPROFILE\AppData\Roaming\Python\Python313\Scripts\eb" --version
    # Should return version (e.g., "EB CLI 3.25")

4. Restart Terminal
   Close/reopen VS Code or PowerShell for changes to apply.

5. Final Check

    eb --version  # Should now work
   

---

➡️ Proceed to Initialization

Once verified, run:

eb init

---

Why this matters:

• Ensures eb commands are available system-wide

• Fixes common PATH issues on Windows

• Takes <1 minute to implement

A1. First, install Python (required for EB CLI)

Follow prompts:

1. Select region (same as AWS CLI)

2. Create new application (e.g., "MyApp-Prod")

3. Choose platform (Node.js)

4. Set up SSH (recommended for debugging)

Creates: .elasticbeanstalk/config.yml with your settings

Step 2.3 - Create Blue Environment

eb create blue-env `
  --instance_type t2.micro `  # Low-cost instance
  --scale 1 `                # Single instance
  --envvars NODE_ENV=production

Deployment Process:

1. Packages your application

2. Creates EC2 instance

3. Configures load balancer

4. Sets up monitoring

Verify Deployment:

eb status

Wait for "Health: Green" (5-10 minutes)

Get Your Environment URL

Run this command to confirm the exact URL:

Look for the CNAME field (it will look like):
blue-env.eba-pp2cpu8x.us-east-1.elasticbeanstalk.com

🟢 Phase 3: Prepare Green Environment

Step 3.1 - Clone Blue Environment

eb clone blue-env -n green-env

What Happens:

• Creates identical environment

• Copies all configuration

• Maintains separate resources

Step 3.2 - Deploy Updates to Green

eb use green-env  # Switch context to green
eb deploy         # Deploy latest code

Best Practice: Test thoroughly at this stage before traffic switch.

🔄 Phase 4: The Traffic Switch

Step 4.1 - Execute Blue/Green Swap

eb swap blue-env --destination_name green-env

What Happens:

1. Swaps environment URLs

2. Route53 updates DNS (usually <60s)

3. Green now receives 100% traffic

4. Blue remains running but idle

   1. Get the Green Environment URL

   Run this command to find your Green environment's URL:

   powershell

    eb status green-env
   

   • Look for the CNAME field (e.g., green-env.eba-xyz123.us-east-1.elasticbeanstalk.com)

     

Step 4.2 - Monitor Traffic Shift

# Get load balancer ARN
$lbArn = aws elasticbeanstalk describe-environment-resources `
  --environment-name blue-env `
  --query "EnvironmentResources.LoadBalancers[0].Name" `
  --output text

# Monitor request metrics (last 10 minutes)
aws cloudwatch get-metric-statistics `
  --namespace "AWS/ApplicationELB" `
  --metric-name "RequestCount" `
  --dimensions Name=LoadBalancer,Value=$lbArn `
  --start-time (Get-Date).AddMinutes(-10).ToString("yyyy-MM-ddTHH:mm:ss") `
  --end-time (Get-Date).ToString("yyyy-MM-ddTHH:mm:ss") `
  --period 60 `
  --statistics "Sum" `
  --output json | ConvertFrom-Json

🎯 Final Architecture

MyApp/
├── src/                      # All application code
│   └── index.js              # Main entry point
├── .ebextensions/            # Elastic Beanstalk configs
│   └── nodecommand.config    # Ensures npm start is used
└── package.json              # Node.js project metadata

🏁 Conclusion

You've Successfully Implemented: ✔ Zero-downtime deployment strategy
✔ Isolated testing environment
✔ Automated CI/CD pipeline
✔ Professional-grade AWS infrastructure

Next Steps to Enhance:

1. Add automated tests to your pipeline

2. Configure CloudWatch alarms for monitoring

3. Implement canary deployments for gradual rollouts