Terraform & AWS: How to deploy a cluster of web servers

Overview

In this tutorial, we’ll embark on a journey through the basics of Terraform, a powerful infrastructure as code software tool, and demonstrate how to deploy a cluster of web servers on AWS. By combining Terraform with Amazon Web Services (AWS), you can automate the provisioning of a scalable and reliable web server cluster.

Prerequisites

• Basic knowledge of AWS services, particularly EC2 and VPC.
• Familiarity with Terraform syntax and concepts.
• An AWS account and the AWS CLI installed and configured.
• Terraform installed on your local machine.

Step-by-Step Instructions

Step 1: Terraform Installation and Setup

First, ensure that Terraform is installed on your machine. You can download it from the Terraform website. After installation, verify it by running terraform -v in your terminal. This should return the version of Terraform you’ve installed.

Step 2: Creating Your Terraform Configuration

To deploy a cluster of web servers in AWS, you’ll need to write a Terraform configuration file. This file defines the AWS resources you wish to provision.

Begin by creating a file named main.tf. Your initial Terraform configuration might look like this:

provider "aws" {
  region = "us-east-1"
}

resource "aws_instance" "web" {
  ami           = "ami-12345"
  instance_type = "t2.micro"
  count         = 3

  tags = {
    Name = "WebServerCluster"
  }
}

This configuration specifies that you want to deploy three t2.micro instances in the AWS region US-east-1, tagged with the name “WebServerCluster”. The ami parameter should be replaced with the AMI ID of your choice, suitable for your web server.

Step 3: Initializing Terraform

With your configuration file in place, it’s time to initialize Terraform, which will prepare your directory for other commands. Run terraform init in your project directory. This command sets up Terraform to run and downloads necessary provider plugins.

Step 4: Planning Your Deployment

Before applying your configuration, it’s wise to run terraform plan. This command shows you what Terraform will do without making any actual changes. It’s an excellent opportunity to review and confirm your configuration.

Step 5: Deploying Your Web Server Cluster

Once you’re satisfied with the plan, deploy your cluster with terraform apply. After confirming the action, Terraform will create the specified AWS resources. You can monitor the progress in your terminal.

After deployment, Terraform will output the details of the instances it has created, including their public IPs. You can use these IPs to access your web servers.

Step 6: Automating Load Balancing

With your servers up and running, you might want to add a load balancer to distribute incoming traffic evenly. Extending your main.tf file, you could add:

resource "aws_elb" "web" {
  name               = "web-elb"
  availability_zones = ["us-east-1a", "us-east-1b", "us-east-1c"]
  listener {
    instance_port     = 80
    instance_protocol = "HTTP"
    lb_port           = 80
    lb_protocol       = "HTTP"
  }

  health_check {
    target              = "HTTP:80/"
    interval            = 30
    timeout             = 5
    healthy_threshold   = 2
    unhealthy_threshold = 2
  }

  instances                   = aws_instance.web.*.id
}

This configuration sets up an Elastic Load Balancer to distribute traffic among your instances based on their availability zones. Understanding and adjusting these parameters based on your specific requirements is crucial for efficiency and cost-effectiveness.

Step 7: Scaling Your Configuration

As your application grows, you may need to adjust the number of instances in your cluster. With Terraform, scaling is as simple as changing the count parameter in your aws_instance resource and reapplying your configuration.

Conclusion

By following these steps, you’ve successfully deployed a cluster of web servers on AWS using Terraform. This approach not only simplifies infrastructure management but also ensures consistency and repeatability across deployments. The power of Terraform lies in its ability to define infrastructure as code, making it an indispensable tool in the era of cloud computing.