Contents:

Overview

The Application Load Balancer (ALB) will distribute incoming traffic to multiple services (microservices) running on ECS Fargate.
ALB supports path-based routing and host-based routing, allowing requests to be directed to the correct service.

Benefits:

  • Load balances traffic across multiple service instances
  • Ensures high availability and fault tolerance
  • Easily scales to handle increased traffic

Create an Application Load Balancer (ALB)

  1. Go to EC2 Console → Load Balancers → Create Load Balancer
  2. Select Application Load Balancer
  3. Name: fargate-alb
  4. Scheme: Internet-facing (for public access)
  5. IP address type: IPv4
  6. Select your VPC and at least 2 subnets in different Availability Zones (Multi-AZ)
  7. Security Group:
    • Allow HTTP (80) and HTTPS (443) if using SSL
  8. Skip Target Group creation for now (will create later)
  9. Click Create Load Balancer

Create Target Groups

  1. Go to EC2 Console → Target Groups → Create target group
  2. Target type: IP addresses
  3. Name: api-target-group
  4. Protocol: HTTP, Port: 8080 (or your API service port)
  5. Select your VPC
  6. Health check path: /health
  7. Create an additional target group for the Frontend:
    • Name: frontend-target-group
    • Port: 80
    • Health check path: /

Attach Services to Target Groups

  1. Go to ECS Console → Cluster → Service → Select the service you want to configure
  2. Edit the service → In the Load balancing section:
    • Select Application Load Balancer
    • Listener: HTTP 80 (or HTTPS 443 if SSL is enabled)
    • Choose the corresponding Target Group (API → api-target-group, Frontend → frontend-target-group)
  3. Save and redeploy the service

Test the Setup

  1. Go to EC2 Console → Load Balancers → Select fargate-alb
  2. Copy the ALB DNS name
  3. Access it in your browser:
    • http://<ALB_DNS>/ → should display the frontend
    • http://<ALB_DNS>/api/health → should return the API health check response
  4. Ensure that the Target Group status shows healthy