For_each for map-based instances in Terraform - Mini Project: Build & Apply

For_each for map-based instances

📖 Scenario: You are setting up multiple virtual machines (instances) in the cloud. Each instance has a unique name and a specific size. You want to create these instances efficiently using Terraform.

🎯 Goal: Create a Terraform configuration that uses for_each to deploy multiple instances from a map of instance names and sizes.

📋 What You'll Learn

Define a map variable with instance names as keys and sizes as values

Use for_each in the resource block to create instances from the map

Assign the instance name and size from the map values

Output the instance IDs after creation

💡 Why This Matters

🌍 Real World

Cloud engineers often need to deploy multiple similar resources with different configurations. Using for_each with maps helps manage these resources efficiently.

💼 Career

Understanding for_each with maps in Terraform is essential for infrastructure as code roles, enabling scalable and maintainable cloud deployments.

1

Define the instances map variable

Create a Terraform variable called instances of type map(string) with these exact entries: "web1" = "small", "web2" = "medium", "db1" = "large".

Terraform

# Your code here

Need a hint?

Use variable block with type = map(string) and set default to the given map.

2

Add a local variable for instance configuration

Create a local variable called instance_config that references the var.instances variable.

Terraform

variable "instances" {
  type = map(string)
  default = {
    web1 = "small"
    web2 = "medium"
    db1  = "large"
  }
}

# Your code here

Need a hint?

Use a locals block to assign instance_config to var.instances.

3

Create instances using for_each

Create a resource block resource "aws_instance" "example" that uses for_each = local.instance_config. Set the instance_type to each.value and the tags with a Name key set to each.key.

Terraform

variable "instances" {
  type = map(string)
  default = {
    web1 = "small"
    web2 = "medium"
    db1  = "large"
  }
}

locals {
  instance_config = var.instances
}

# Your code here

Need a hint?

Use for_each with local.instance_config. Set instance_type to each.value and tag the instance with Name = each.key.

4

Output the instance IDs

Create an output called instance_ids that outputs a map of instance names to their IDs using aws_instance.example and for_each.

Terraform

variable "instances" {
  type = map(string)
  default = {
    web1 = "small"
    web2 = "medium"
    db1  = "large"
  }
}

locals {
  instance_config = var.instances
}

resource "aws_instance" "example" {
  for_each = local.instance_config

  instance_type = each.value

  ami           = "ami-12345678"

  tags = {
    Name = each.key
  }
}

# Your code here

Need a hint?

Use an output block with a for expression to map instance names to their IDs.