Setting Up the Third Group of Resources EC2

• Build a reusable Terraform module that provisions EC2 instances and exposes inputs for AMI, instance type, key pair, networking, and security groups.
• Create a Terragrunt configuration for each environment that supplies environment-specific inputs to the module.
• Initialize, plan, and apply the Terragrunt configuration to provision the instances.

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Architecture and layout (conceptual)

• Create a reusable Terraform module at infrastructure/modules/ec2 that contains the EC2 resources and supporting pieces (for example aws_instance, optional aws_ebs_volume, tags, and outputs).
• Create a Terragrunt folder per environment that references the module and injects environment-specific inputs. Example layout:
  • live/account/dev/third-group/terragrunt.hcl
  • live/account/prod/third-group/terragrunt.hcl

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Example Terragrunt configuration

terraform {
  source = "../../../modules/ec2"
}

inputs = {
  name                = "web-server-dev"
  instance_type       = "t3.micro"
  ami                 = "ami-0abcdef1234567890" # replace with a region-correct AMI
  key_name            = "my-ssh-key"
  subnet_id           = "subnet-0123456789abcdef0"
  security_group_ids  = ["sg-0123456789abcdef0"]
  tags = {
    Environment = "dev"
    Project     = "demo"
  }
}

​

Common module variables (example)

variable "name" {
  type        = string
  description = "Name tag for the instance"
}

variable "instance_type" {
  type        = string
  description = "EC2 instance type"
  default     = "t3.micro"
}

variable "ami" {
  type        = string
  description = "AMI ID to use for the instance"
}

variable "key_name" {
  type        = string
  description = "Existing EC2 key pair name for SSH access"
  default     = ""
}

variable "subnet_id" {
  type        = string
  description = "Subnet ID for the instance"
}

variable "security_group_ids" {
  type        = list(string)
  description = "List of security group IDs to attach to the instance"
  default     = []
}

​

Deployment steps with Terragrunt

1. Change directory to the target environment folder (for example live/account/dev/third-group).
2. Initialize the configuration:

terragrunt init

3. Preview the planned changes:

terragrunt plan

4. Apply the configuration to create resources:

terragrunt apply

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Key considerations (best practices)

• Security groups: follow least-privilege principles. Avoid opening SSH (port 22) to 0.0.0.0/0 in production—restrict to known IPs or use AWS Systems Manager Session Manager.
• Key pairs: key_name must reference an existing EC2 key pair in the selected region unless you use a different access mechanism (for example, SSM).
• AMI IDs are region-specific: ensure the AMI exists in the target region.
• Networking: confirm subnet_id and security_group_ids are valid for the target VPC/account.
• IAM permissions: the AWS credentials used must have permissions to create EC2 instances, attach networking resources, and tag resources.

• Proceed to the AWS For Beginners with Hands-On Labs to set up a full demo project and apply these patterns.
• References:
  • Terragrunt docs: https://terragrunt.gruntwork.io/
  • Terraform EC2 resource: https://registry.terraform.io/providers/hashicorp/aws/latest/docs/resources/instance