14. Target Groups

Target Groups

---

Prerequisites

---

1. Target Groups

Target Group is a core component used with Load Balancers. It defines Where incoming traffic should be sent

User → Load Balancer → Target Group → EC2

A Target Group is:

• A logical group of backend resources
• Used by a Load Balancer to route traffic

👉 Targets can be:

• EC2 instances
• IP addresses
• Lambda functions

Load Balancer does NOT directly send traffic to EC2. Instead, Load Balancer → Target Group → Targets

Without Target Group:

• Load Balancer must manage instances directly
• No flexibility
• No grouping

With Target Group:

• Logical grouping of instances
• Easy scaling
• Flexible routing
• High availability
• Fault tolerance
• Clean architecture

1-1. Relationship with ASG

Auto Scaling Group → Target Group → Load Balancer

ASG automatically:

• Adds instances to Target Group
• Removes terminated instances

1-2. Routing Logic

Target Group allows:

• Decoupling Load Balancer and EC2
• Flexible scaling
• Service-based routing

User
 ↓
[ Load Balancer ]
   ↓
[ Target Group ]
   ├── EC2 (Instance A)
   ├── EC2 (Instance B)
   └── EC2 (Instance C)

Load Balancer uses Target Group to:

• Distribute traffic
• Apply routing rules

/api → Target Group A
/web → Target Group B

• Path-based routing
• Microservices architecture

Target Types

Type	Description
Instance	EC2 instance ID
IP	Private IP address
Lambda	Serverless function

2. Components of Template

2-1. Health Check

Target Group performs health checks.

GET /health

Behavior

• Healthy → receives traffic
• Unhealthy → removed from routing

Only healthy instances receive traffic

3. How to create Target Groups

3-1. Search EC2

3-2. Click Navigation pane → “Target Groups”

3-3. Click Button → “Create Auto Scaling group”

3-4. Step 1. Create target group

3-5. Step 2. Register targets - recommended

4. Related Concepts

• Components
  • Load Balancing
  • Auto Scaling Groups