Blue/Green Deployment on AWS Using CodeDeploy and CodePipeline

When you're learning AWS in depth, nothing teaches you better than building a real-world pipeline. In this project, I created a highly available and automated deployment architecture using EC2, CodeDeploy, Load Balancer, Auto Scaling Group, Launch Templates, GitHub, and CodePipeline.

This blog walks you through the exact process — every IAM role, installation, configuration, and deployment — so you can rebuild it on your own or use it as a learning reference.

This setup ensures:

High availability
Automated deployments
Auto-healing servers
CI/CD with zero manual intervention

1️⃣ Creating IAM Roles

"IAM Role for EC2"

This EC2 role needs permissions for:

Administrator Access
AmazonS3FullAccess
AWSCodeDeployFullAccess
AWSCodePipelineFullAccess
AutoScaling Full Access
ELB Full Access

Create IAM Role → AWS Service → EC2 → Attach Policies above → Create Role
Attach this role later when launching the EC2 instance.

"IAM Role for CodeDeploy"

CodeDeploy uses this role to interact with your EC2 instances.

AdministratorAccess
AmazonS3FullAccess
Service: CodeDeploy

2️⃣ Launching an EC2 Instance (Amazon Linux)

• AMI: Amazon Linux 2
• Instance Type: t2.micro (Free tier)
• IAM Role: attach the EC2 role you created
• Security Group: open HTTP (80) + SSH (22)

SSH into the instance:

sudo yum install httpd -y
sudo systemctl start httpd
sudo systemctl enable httpd

3️⃣ Installing the CodeDeploy Agent

sudo yum install ruby -y
sudo yum install wget -y
cd /home/ec2-user
wget https://aws-codedeploy-us-east-1.s3.us-east-1.amazonaws.com/latest/install
chmod +x ./install
sudo ./install auto
sudo systemctl start codedeploy-agent
sudo systemctl enable codedeploy-agent

Verify:

sudo systemctl status codedeploy-agent

4️⃣ Creating an AMI from the EC2 Instance

Now that the EC2 instance has a proper role attached:

Apache
CodeDeploy agent

→ Create an AMI:

Actions → Image and Templates → Create Image (AMI)
Include:

Root volume
OS

This AMI becomes your base image for Auto Scaling.

5️⃣ Creating a Launch Template

• Go to EC2 → Launch Templates → Create Template
• Use the AMI you just created
• Attach the same IAM role
• Set Auto Scaling Guidance = Enabled
• Save template

After this → Terminate the original EC2 instance
(Your ASG will take over from here.)

6️⃣ Create a Load Balancer

• Use Application Load Balancer (ALB):
• Scheme: Internet-facing
• Listeners: HTTP (80)
• Target Group: Register later by ASG
• Health Check Path: /

7️⃣ Creating the Auto Scaling Group (ASG)

Go to EC2 → Auto Scaling Groups → Create
Select the Launch Template

• Select 2 AZs
• Attach the Load Balancer Target Group
• Desired Capacity: 2
• Min: 2
• Max: 3

Your ASG will launch 2 EC2 instances from the AMI → both have CodeDeploy agent → both are healthy behind ALB.

8️⃣ Setting Up CodeDeploy

• Create Application → Type: EC2/On-premises
• Create Deployment Group:
• Select Service Role (CodeDeploy IAM Role)
• Deployment Type: In-place
• Environment: Amazon EC2 Auto Scaling Group
• Choose your ASG
• Install during deployment: Enable
• Load Balancer: Select Target Group

9️⃣ Creating Your App Files on GitHub

Repo structure:

/index.html
/appspec.yml

index.html

<h1>Welcome to my AWS CI/CD Project!</h1>
<p>This deployment was automated using AWS CodeDeploy & CodePipeline.</p>

appspec.yml

version: 0.0
os: linux

files:
  - source: index.html
    destination: /var/www/html

🔟 Creating CodePipeline

Now connect the whole workflow:

• Source Stage → GitHub
• Connect to your repo
• Detect changes automatically
• Deploy Stage → CodeDeploy
• Select Application
• Select Deployment Group

Whenever you push changes to the main branch:

Pipeline is triggered
CodeDeploy pushes the latest files
ASG instances receive an update
ALB routes traffic to healthy updated instances

🎉 Full CI/CD and Auto Scaling setup is complete!