Configuring an AWS Elastic Load Balancer with Terraform to Distribute Traffic

Setting up an AWS Elastic Load Balancer (ELB) using Terraform is an essential step in ensuring your application scales seamlessly and efficiently handles traffic. In this comprehensive guide, we will walk you through the process of deploying an ELB and configuring it to distribute traffic across EC2 instances. We will also cover the necessary steps to set up a security group, launch EC2 instances, and configure health checks.

Prerequisites

Before we dive into the configuration, make sure you have the following prerequisites in place:

AWS Access Key ID and Secret Access Key Terraform installed on your machine A running VPC on AWS A set of instances ready to receive traffic

Setting Up Terraform Provider Configuration

To get started, you need to configure the AWS provider in your Terraform code. Here’s how you can set it up:

provider aws {
  region   your-region
  access_key  your-access-key
  secret_key  your-secret-key
}

Creating a Security Group

A security group in AWS is a virtual firewall that controls the traffic to and from your EC2 instances. Let's create a security group that allows HTTP traffic on port 80:

resource aws_security_group example {
  cidr_block  0.0.0.0/0
  ingress {
    from_port    80
    to_port      80
    protocol     tcp
    cidr_blocks  [0.0.0.0/0]
  }
  egress {
    from_port    0
    to_port      0
    protocol     -1
    cidr_blocks  [0.0.0.0/0]
  }
  vpc_id  your-vpc-id
  tags  {
    Name  Example-Security-Group
  }
}

Launching EC2 Instances

You need to launch EC2 instances that will be part of your load balancing setup. Here’s an example:

resource aws_instance example {
  ami  your-ami-id
  instance_type  t2.micro
  security_groups  [aws_security_]
  subnet_id  your-subnet-id
  tags  {
    Name  Example-EC2-Instance
  }
}

Creating the Load Balancer and Target Group

Now, we will create the Elastic Load Balancer (ELB) and the target group. The target group will be responsible for routing incoming traffic to your EC2 instances based on their health status.

resource aws_lb example {
  name                example-elb
  internal            false
  load_balancer_type  application
  security_groups     [aws_security_]
  subnets             [for subnet in aws_subnet.example : ]
  enable_deletion_protection  true
  tags  {
    Environment  production
  }
}
resource aws_lb_target_group example {
  name      example-tg
  port      80
  protocol  http
  vpc_id    your-vpc-id
}
resource aws_lb_listener example {
  load_balancer_arn  aws_
  port               80
  protocol           http
  ssl_policy         ELBSecurityPolicy-2016-08
  certificate_arn    your-certificate-arn
  default_action {
    type             forward
    target_group_arn  aws_lb_target_
  }
}
resource aws_lb_target_group_attachment example {
  target_group_arn  aws_lb_target_
  target_id         aws_
}
resource aws_lb_target_health example {
  target_group_arn  aws_lb_target_
  target_id         aws_
  health_check {
    enabled       true
    healthy_threshold  3
    interval      10
    matcher       200
    path          /
    protocol      http
    timeout       3
    unhealthy_threshold  2
  }
}

Conclusion

By configuring an AWS Elastic Load Balancer with Terraform, you can ensure your infrastructure is scalable, resilient, and cost-effective. In this guide, we have covered the steps to set up the necessary resources, including a security group, EC2 instances, and the load balancer itself. Additionally, we have demonstrated how to configure health checks to ensure the load balancer routes traffic only to healthy instances.

For more details and additional customization options, refer to the Terraform AWS provider documentation.