Terraform IaC Infrastructure as Code

🏗️ What is Terraform?

With Terraform, you can manage complex infrastructures across different providers. It separates the planning phase (what needs to be done) from the application phase (actual execution), allowing you to review and approve changes before they are applied.

🧩 Core Concepts

Terraform is based on several key concepts that form the foundation for managing your infrastructure.

# Example: AWS Provider Configuration
terraform {
  required_providers {
    aws = {
      source  = "hashicorp/aws"
      version = "~> 5.0"
    }
  }
}

provider "aws" {
  region = "eu-central-1"
}

# Example: AWS EC2 Instance Resource
resource "aws_instance" "web_server" {
  ami           = "ami-0c55b31ad2c455052" # Example AMI ID
  instance_type = "t2.micro"

  tags = {
    Name = "HelloWorld"
  }
}

# Example: Variable Definition
variable "instance_type" {
  description = "The type of EC2 instance"
  type        = string
  default     = "t2.micro"
}

# Example: Output Definition
output "instance_ip_addr" {
  value = aws_instance.web_server.public_ip
}

💾 State Management

Terraform stores the state of your managed infrastructure and configuration. This state is used to map real resources to your configuration, track metadata, and improve performance for large infrastructures. By default, the state is stored locally in a file called \`terraform.tfstate\`, but for teamwork and better management, it can be stored in a remote backend (e.g., AWS S3, Terraform Cloud).

⚙️ Terraform Workflow

The core workflow of Terraform consists of three main steps:

• Init: Initializes the working directory, downloads provider plugins, and configures the backend. (`terraform init`)
• Plan: Creates an execution plan. Terraform determines which actions are required to achieve the desired state. (`terraform plan`)
• Apply: Applies the changes described in the plan to create, update, or delete the infrastructure. (`terraform apply`)
• Destroy: Destroys all resources managed by Terraform. (`terraform destroy`)

🌟 Best Practices

• Use remote state backends for teamwork and security.
• Structure your code with modules for reusability and readability.
• Version your Terraform code with Git or a similar system.
• Use variables for configurable values and avoid hardcoding.
• Format your code consistently with `terraform fmt`.
• Validate your configuration with `terraform validate`.
• Implement a "least privilege" strategy for provider credentials.
• Always plan changes before you apply them and check the plan carefully.

☁️ Terraform Cloud & Enterprise

HashiCorp offers Terraform Cloud as a hosted service that facilitates collaboration, governance, and state management. For larger organizations, there is Terraform Enterprise, a self-hosted version with additional features.