Count vs for_each decision in Terraform - Hands-On Comparison

Count vs for_each decision

📖 Scenario: You are setting up cloud resources using Terraform. You want to create multiple virtual machines (VMs) in a cloud environment. Some VMs are identical, and some have unique names and settings.

🎯 Goal: Learn when to use count and when to use for_each in Terraform to create multiple resources efficiently.

📋 What You'll Learn

Create a variable with a list of VM names

Create a variable with the number of identical VMs

Use count to create identical VMs

Use for_each to create uniquely named VMs

💡 Why This Matters

🌍 Real World

Cloud engineers often need to create multiple resources that are either identical or unique. Knowing when to use <code>count</code> or <code>for_each</code> helps manage infrastructure efficiently.

💼 Career

Understanding <code>count</code> and <code>for_each</code> is essential for Terraform users to write scalable and maintainable infrastructure code.

1

Create a list variable with VM names

Create a Terraform variable called vm_names with the list ["web1", "web2", "db1"].

Terraform

# Create a variable called vm_names with the list ["web1", "web2", "db1"]
# Your code here

Need a hint?

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

2

Create a variable for identical VM count

Create a Terraform variable called vm_count with the default value 3.

Terraform

variable "vm_names" {
  type    = list(string)
  default = ["web1", "web2", "db1"]
}

# Create a variable called vm_count with default 3
# Your code here

Need a hint?

Use a variable block with type = number and default = 3.

3

Use count to create identical VMs

Create a resource block resource "azurerm_virtual_machine" "identical_vm" that uses count = var.vm_count and sets name = "vm-${count.index + 1}".

Terraform

variable "vm_names" {
  type    = list(string)
  default = ["web1", "web2", "db1"]
}

variable "vm_count" {
  type    = number
  default = 3
}

# Create resource azurerm_virtual_machine identical_vm with count = var.vm_count
# Set name = "vm-${count.index + 1}"
# Your code here

Need a hint?

Use count = var.vm_count and name = "vm-${count.index + 1}" inside the resource block.

4

Use for_each to create uniquely named VMs

Create a resource block resource "azurerm_virtual_machine" "unique_vm" that uses for_each = toset(var.vm_names) and sets name = each.key.

Terraform

variable "vm_names" {
  type    = list(string)
  default = ["web1", "web2", "db1"]
}

variable "vm_count" {
  type    = number
  default = 3
}

resource "azurerm_virtual_machine" "identical_vm" {
  count = var.vm_count

  name = "vm-${count.index + 1}"
  # Other required properties would go here
}

# Create resource azurerm_virtual_machine unique_vm with for_each = toset(var.vm_names)
# Set name = each.key
# Your code here

Need a hint?

Use for_each = toset(var.vm_names) and name = each.key inside the resource block.