Using the count Meta Argument

The count meta-argument in Terraform lets you create multiple instances of the same resource from a single resource block. It uses a zero-based numeric index (count.index) that you can reference inside the resource to produce unique names, tags, or other per-instance values. This makes count ideal when you need several identical or nearly-identical resources, or when the number of instances should be driven by a variable.

Use count when you want to scale identical resources by number. For stable identities or keyed collections, consider for_each instead (see the comparison below).

The image explains the count meta-argument in Terraform, which allows creating multiple instances of a resource using a single block, assigns an index to each instance, and describes how to reference the resource.

How `count` works

Set count to a number or a numeric variable (for example, var.vm_count).
Terraform creates that many instances and assigns each a numeric index starting at 0.
Inside the resource you can reference count.index to create unique values per instance.
To address an individual instance from another resource or an output, use an index on the resource address (for example: aws_instance.example[1]).

Example: create multiple Azure VMs driven by a variable and use count.index to generate unique names.

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

resource "azurerm_virtual_machine" "example" {
  count               = var.vm_count
  name                = "vm-${count.index}"
  location            = "East US"
  resource_group_name = "my-resource-group"
  vm_size             = "Standard_D2s_v3"

  os_profile {
    computer_name  = "vm-${count.index}"
    admin_username = "adminuser"
  }
}

With vm_count = 3, Terraform will create VMs named vm-0, vm-1, and vm-2.

Referencing instances

Address the first instance: azurerm_virtual_machine.example[0]
Get the name of the second instance: azurerm_virtual_machine.example[1].name
Collect all names into an output:

output "vm_names" {
  value = azurerm_virtual_machine.example[*].name
}

Common uses and tips

Use count.index inside name, tags, or properties that accept strings to ensure uniqueness.
Combine count with other functions (for example, count = var.vm_count > 0 ? var.vm_count : 0) to handle conditional creation.
Avoid using count with resources that require stable identity across changes if individual items will be added/removed frequently — the numeric indexing can shift.

count vs for_each

Feature	`count`	`for_each`
Indexing	Numeric, zero-based `count.index`	Keyed by element value or map keys
Stable identity	No — indices shift if items are inserted/removed	Yes — each key maps to a stable instance
Use-case	Create N identical instances, scale by a number	Create instances from a set/map where identity matters
Example	`count = var.vm_count`	`for_each = toset(["a","b","c"])`

When to prefer for_each

If you need stable, predictable identities for each instance (for example, when adding/removing single items), for_each is usually safer because it keys resources by a set or map value instead of a shifting numeric index.

Because count is index-based, changing the number or ordering of instances can shift indices and cause Terraform to delete and recreate resources. If you need stable identities for resources, prefer for_each.

Course Introduction

Preparing Your Environment

Terraform Foundations

The Core Terraform Workflow

Terraform CLI

Terraform File Structure and Organization

Terraform Configuration - Fundamentals

Understading and Managing Terraform State

Marking Code Reusable

Refactoring Terraform State

Terraform Modules

Securing Terraform Configurations

Terraform Troubleshooting

HCP Terraform

Using the count Meta Argument

How `count` works

Referencing instances

Common uses and tips

count vs for_each

When to prefer for_each

References

Watch Video

Practice Lab

​How count works

​Referencing instances

​Common uses and tips

​count vs for_each

​When to prefer for_each

​References

Watch Video

Practice Lab

How `count` works

Referencing instances

Common uses and tips

count vs for_each

When to prefer for_each

References