Terraform Learning Repository

This repository documents my journey of learning and practicing Terraform. It includes various exercises, examples, and modules to understand Infrastructure as Code (IaC) concepts and Terraform's capabilities.

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Project Structure

The repository is divided into multiple projects and modules, each focusing on specific Terraform concepts:

1. tf-module-final-project

• Goal: Create a scalable infrastructure with Terraform modules.

• Features:

  • Compute Module:

    • Creates a golden AMI with Apache pre-installed using aws_ami_from_instance.
    • Configures an Auto Scaling Group (ASG) with 3 instances using aws_autoscaling_group.
    • Uses local-exec provisioner to terminate temporary instances after AMI creation.

  • Network Module:

    • Sets up a VPC with public and private subnets.
    • Configures an Application Load Balancer (ALB) with health checks.
    • Implements security groups to restrict access to specific IP ranges and ports.

  • Key Concepts:

    • Terraform modules for resource segregation.
    • Dynamic tagging using merge function.
    • High availability with ASG and ALB.

2. tf-utils-lab

• Goal: Experiment with Terraform utilities and validation tools.
• Features:
  • Pre-commit hooks for linting and validation (tflint, tfsec, terraform-docs).
  • Validation blocks in variables to enforce input constraints.
  • Example EC2 instance with encrypted root volume and metadata options.
• Key Concepts:
  • Using pre-commit for code quality.
  • Validation blocks for input constraints.
  • Provisioners like local-exec for custom commands.

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Key Terraform Concepts Used

1. Modules

• Resources are segregated into modules (compute, network, etc.) for better organization and reusability.

2. Provisioners

• local-exec: Used to execute shell commands, e.g., terminating temporary EC2 instances after creating a golden AMI.

• Example:

  resource "null_resource" "delete_tmp_instance" {
      provisioner "local-exec" {
          command = "aws ec2 terminate-instances --instance-ids ${aws_instance.tmp_golden_instance.id}"
      }
  }

3. Dynamic Tagging

• Tags are dynamically generated using the merge function to combine static and variable-based values.

• Example:

  tags = merge(
      var.instance_tags,
      {
          Name = "${var.project_name}-${var.environment}-instance"
      }
  )

4. Validation Blocks

• Enforce constraints on variable inputs to ensure correctness.

• Example:

  variable "ami" {
      validation {
          condition     = can(regex("^ami-[a-zA-Z0-9]+$", var.ami))
          error_message = "AMI ID must follow the format 'ami-xxxxxx'."
      }
  }

5. Auto Scaling and Load Balancing

• Configured an Auto Scaling Group (ASG) with a Launch Template.
• Integrated an Application Load Balancer (ALB) with health checks for high availability.

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Tools and Utilities

1. Pre-commit Hooks

• Tools used:

• tflint: Linting for Terraform code.

• tfsec: Security scanning for Terraform configurations.

• terraform-docs: Automatically generate module documentation.

• Setup:

  pre-commit install --install-hooks
  pre-commit run --all-files

2. Validation Tools

• checkov, terrascan, and tfsec were used to validate security and compliance.

3. Golden AMI Creation

• Used aws_ami_from_instance to create a reusable AMI with pre-installed software.

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How to Use

1. Setup:

   • Install Terraform: Terraform CLI.
   • Configure AWS CLI with credentials.

2. Run Terraform:

   terraform init
   terraform plan
   terraform apply