Application Load Balancer Module

Deploy an AWS Application Load Balancer with configurable listeners, target groups, and security group management.

What You'll Build

• Application Load Balancer with HTTP/HTTPS listeners
• Target groups with health checks
• Listener rules for advanced routing
• Optional WAF integration
• Security group for ALB inbound/egress rules

How to Use

module "alb" {
  source = "github.com/nnthanh101/terraform-aws/modules/alb"

  name            = "app-alb"
  load_balancer_type = "application"
  internal        = false
  subnets         = var.public_subnets
  security_groups = [aws_security_group.alb.id]

  listeners = {
    http = {
      port            = 80
      protocol        = "HTTP"
      forward = {
        target_group_key = "app"
      }
    }
  }

  target_groups = {
    app = {
      name            = "app-tg"
      port            = 8080
      protocol        = "HTTP"
      target_type     = "instance"
      health_check = {
        healthy_threshold   = 2
        unhealthy_threshold = 2
        timeout             = 3
        interval            = 30
        path                = "/"
        matcher             = "200"
      }
    }
  }

  tags = {
    Environment = "prod"
    Service     = "api"
  }
}

Key Variables

Variable	Type	Purpose
name	string	Load balancer name (max 32 chars, alphanumeric + hyphens)
load_balancer_type	string	Type: "application", "network", or "gateway"
internal	bool	Internal vs internet-facing LB
subnets	list(string)	Subnets for LB deployment
security_groups	list(string)	Security group IDs for network rules
listeners	map(object)	Listener configurations (port, protocol, rules)
target_groups	map(object)	Target group definitions (health check, routing)
enable_deletion_protection	bool	Prevent accidental deletion (default: true)

Outputs

Output	Use Case
id	Load balancer ID for resource references
arn	ARN for CloudWatch metrics, WAF association
dns_name	DNS CNAME for Route53 alias records
zone_id	ALB zone ID for Route53 alias setup
listeners	Map of created listener resources
target_groups	Map of created target group resources

Integration

• EC2 Instances: Register instances in additional_target_group_attachments
• CloudWatch: Use arn_suffix for ALB metrics and alarms
• WAF: Attach Web ACL via web_acl_arn variable
• Route53: Create alias record pointing to dns_name
• Auto Scaling: Attach ASG to target group via create_attachment

Source Reference

Module: terraform-aws/modules/alb