Terraform Associate: Build Infrastructure

Building infrastructure with Terraform means creating resources like virtual machines, networks, databases, and other services in cloud environments (such as AWS, Azure, GCP, etc.) using declarative configuration files. After defining the infrastructure, Terraform sets it up and manages it by interacting with the cloud provider APIs.

Here’s a step-by-step guide to building infrastructure with Terraform:

1. Install Terraform

First, you need to install Terraform on your system. You can download it from the official website: Terraform Downloads.

To check if Terraform is installed correctly, run:

terraform --version

2. Set Up Your Project Directory

Create a new directory for your Terraform project and navigate to it:

mkdir my-terraform-infrastructure
cd my-terraform-infrastructure

3. Create Terraform Configuration Files

Terraform configuration files are written in HCL (HashiCorp Configuration Language) and typically have an .tf extension.

Let’s say you want to build infrastructure in AWS (Amazon Web Services). The first step is to configure the AWS provider and define the resources you want to create, such as an EC2 instance and a security group.

Example of Terraform Configuration

Here’s a simple Terraform configuration to create an AWS EC2 instance with a security group.

1. Define the AWS Provider (providers.tf): This file specifies the cloud provider (AWS in this case) and the region.

    provider "aws" {
      region = "us-west-2"  # Specify your desired region
    }
   

2. Define Resources (main.tf): In this file, you define the actual resources you want to create. For example, an EC2 instance and a security group.

    resource "aws_security_group" "allow_ssh" {
      name        = "allow_ssh"
      description = "Allow SSH inbound traffic"
   
      ingress {
        from_port   = 22
        to_port     = 22
        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"]
      }
    }
   
    resource "aws_instance" "example" {
      ami           = "ami-0c55b159cbfafe1f0"  # Replace with a valid AMI ID
      instance_type = "t2.micro"
      key_name      = "my-key-pair"  # Replace with your SSH key name
   
      security_groups = [aws_security_group.allow_ssh.name]
    }
   

In this configuration:

• We define an AWS provider that specifies which region to use.

• We define a security group (aws_security_group.allow_ssh) that allows SSH traffic on port 22.

• We create an EC2 instance (aws_instance.example) with a specified AMI and instance type (t2.micro). The instance is also associated with the security group we created.

3. Create a terraform.tfvars file (optional): If you want to pass variables like AWS credentials, region, or instance type, you can define a terraform.tfvars file.

    region = "us-west-2"
    ami_id = "ami-0c55b159cbfafe1f0"
    instance_type = "t2.micro"
   

4. Initialize the Terraform Project

Before you can use Terraform to manage your infrastructure, you need to initialize your project. Run the following command to initialize the working directory and download the necessary provider plugins:

terraform init

This command sets up the environment and prepares Terraform to interact with your cloud provider.

5. Preview the Infrastructure Changes

Use the terraform plan command to preview the changes Terraform will make. It will show you which resources will be created, updated, or deleted based on your configuration.

terraform plan

This will display a detailed output, like:

+ aws_security_group.allow_ssh
+ aws_instance.example

6. Apply the Changes (Build Infrastructure)

After reviewing the plan, you can apply the configuration to create the infrastructure:

terraform apply

Terraform will ask for confirmation before proceeding with the infrastructure creation. Type yes to proceed.

Terraform will then proceed to create the resources specified in your configuration file. It will interact with the AWS API (or your chosen provider) to create the infrastructure.

7. Verify the Infrastructure

Once the terraform apply command finishes, Terraform will output information about the created resources. You can verify your infrastructure by logging into your AWS Console (or your respective cloud provider console) and confirming that the resources (like EC2 instances, security groups, etc.) are created.

For instance, you should be able to see the EC2 instance under the "Instances" section and the security group under "Security Groups" in AWS.

8. Managing Infrastructure State

Terraform manages the current state of your infrastructure in a file called terraform.tfstate. This file keeps track of the resources you have created and their state in the cloud. It is crucial to manage this state file properly. Terraform uses this state to compare your current infrastructure with your desired state when you run commands like terraform plan and terraform apply.

9. Updating Infrastructure

If you want to modify your infrastructure, simply update the configuration files. For example, if you want to change the instance type, modify the instance_type in the aws_instance block and then run:

terraform plan
terraform apply

Terraform will calculate the changes and apply the necessary updates to your infrastructure.

10. Destroying Infrastructure

If you want to tear down the infrastructure you’ve built, you can use the terraform destroy command. This will remove all resources defined in the configuration files.

terraform destroy

Again, Terraform will prompt for confirmation before it deletes the resources. Type yes to destroy them.

Conclusion

Building infrastructure with Terraform involves defining your resources in configuration files, initializing the Terraform project, running terraform plan to preview changes, and applying those changes with terraform apply. Terraform automates the process of provisioning infrastructure, ensuring consistency, repeatability, and version control.

By following these steps, you can easily build, manage, and scale infrastructure on any cloud platform supported by Terraform, all while keeping infrastructure management as code.

Reference

1. https://learn.hashicorp.com/tutorials/terraform/install-cli
   Official guide for installing Terraform on different operating systems and checking if the installation is successful.

2. https://www.terraform.io/docs/language/index.html
   Complete documentation on Terraform's HashiCorp Configuration Language (HCL) for writing infrastructure as code.

3. https://aws.amazon.com/blogs/infrastructure-and-automation/introducing-terraform-quick-starts-for-aws/
   A useful introduction to using Terraform on AWS, including key concepts and examples for creating cloud resources.

4. https://www.terraform.io/docs/cli/index.html
   A detailed reference for all Terraform commands like terraform init, terraform plan, and terraform apply, which are essential for managing your infrastructure.

5. https://www.terraform.io/docs/language/state/index.html
   A guide on understanding and managing Terraform state files, ensuring consistent and reliable infrastructure management across different environments.