Cheatsheet for Terraform as Infrastructure as code

• Definition: Terraform is an open-source tool created by HashiCorp. It allows you to define and provision infrastructure using a high-level configuration language.
• Purpose: It is used to manage cloud services and resources with code, allowing for the automation of deployment and maintenance tasks.

Key Concepts

• Infrastructure as Code (IaC): Manage your physical infrastructure through code similar to how software is managed.
• Providers: Plugins for accessing and managing resources in a specific cloud provider (e.g., AWS, Azure, Google Cloud).
• Resources: Components of your infrastructure, like virtual machines, networks, or databases.
• Modules: Reusable, encapsulated Terraform configurations for organizing and packaging code.
• State: Terraform tracks the state of your managed infrastructure and configuration.

Basic File Structure

• main.tf: Main file for Terraform configurations.
• variables.tf: Optional file to define variables.
• outputs.tf: Optional file to define outputs.
• provider.tf: Optional file to define providers.

Core Terraform Commands

• terraform init: Initialize a Terraform working directory by installing necessary providers.
• terraform plan: Create an execution plan, showing what Terraform will do when you apply changes.
• terraform apply: Apply changes required to reach the desired state of the configuration.
• terraform destroy: Destroy the Terraform-managed infrastructure.

Commonly Used Commands

• terraform fmt: Automatically formats Terraform code to a canonical format.
• terraform validate: Validates the configuration for syntax and consistency.
• terraform output: Read outputs from your state file.

Best Practices for Beginners

1. Version Control: Always store your Terraform configurations in version control systems like Git.
2. Module Use: Use modules to organize and reuse code, which can simplify management of larger infrastructures.
3. Automate: Use automation tools like Terraform Cloud or CI/CD pipelines to apply Terraform changes safely.
4. Secure State Files: Protect and back up your Terraform state files, which contain sensitive data.
5. Review Plans: Always review the plan before applying to avoid unintended changes to your infrastructure.

provider "aws" {
  region = "us-west-2"
}

resource "aws_instance" "example" {
  ami           = "ami-0c55b159cbfafe1f0"
  instance_type = "t2.micro"

  tags = {
    Name = "ExampleInstance"
  }
}

Tips for Debugging

• Use terraform plan to see changes without applying them.
• Check Terraform’s detailed logs by setting the TF_LOG environment variable (e.g., export TF_LOG=DEBUG).