Meta Arguments amp Count and for each

In this guide, you’ll learn how to provision multiple EC2 instances with the count and for_each meta-arguments in OpenTofu. Both approaches let you duplicate a single resource block, but differ in indexing and lifecycle behavior.

Meta-Argument	Key Characteristic	Best Use Case
count	Integer-based, zero-indexed	Create a fixed number of identical resources
for_each	Key-based, uses a set or map of values	Stable addressing of dynamic or named items

1. Using `count`

The count meta-argument accepts an integer and creates that many instances of a resource.

resource "aws_instance" "web" {
  ami           = var.ami
  instance_type = var.instance_type
  count         = 3
}

variable "ami" {
  default = "ami-06178cf087598769c"
}

variable "instance_type" {
  default = "m5.large"
}

Run:

tofu apply

Then verify:

tofu state list
# aws_instance.web[0]
# aws_instance.web[1]
# aws_instance.web[2]

Dynamic `count` with `length()`

Instead of hardcoding an integer, drive count from a list:

variable "webservers" {
  type    = list(string)
  default = ["web1", "web2", "web3"]
}

resource "aws_instance" "web" {
  ami           = var.ami
  instance_type = var.instance_type
  count         = length(var.webservers)

  tags = {
    Name = var.webservers[count.index]
  }
}

variable "ami" {
  default = "ami-06178cf087598769c"
}

variable "instance_type" {
  default = "m5.large"
}

Here, each instance tag is assigned by its count.index:

count.index = 0 → Name = "web1"
count.index = 1 → Name = "web2"
count.index = 2 → Name = "web3"

Removing or reordering items in the webservers list causes all subsequent resources to be reindexed. This can lead to unintended in-place updates instead of only removing the orphaned resource.

Example plan when deleting "web1":

# aws_instance.web[0] will be updated (web1 → web2)
# aws_instance.web[1] will be updated (web2 → web3)
# aws_instance.web[2] will be destroyed (web3)

2. Using `for_each`

The for_each meta-argument uses a set or map, giving each resource a stable key based on its value.

variable "webservers" {
  type    = set(string)
  default = ["web1", "web2", "web3"]
}

resource "aws_instance" "web" {
  ami           = var.ami
  instance_type = var.instance_type
  for_each      = var.webservers

  tags = {
    Name = each.value
  }
}

Run and list state:

tofu apply
tofu state list
# aws_instance.web["web1"]
# aws_instance.web["web2"]
# aws_instance.web["web3"]

If you remove "web1" from the set and run tofu plan, only that resource is destroyed:

# aws_instance.web["web1"] will be destroyed
Plan: 0 to add, 0 to change, 1 to destroy.

This ensures stable resource addressing and prevents unnecessary updates.

Course Introduction

Introduction to Infrastructure as Code

OpenTofu Basics

OpenTofu State

Working with OpenTofu

Remote State

OpenTofu Provisioners

OpenTofu Import, Tainting Resources and Deubugging

OpenTofu Modules

OpenTofu Functions and Conditional Expressions

OpenTofu: Beyond Basics

Course Conclusion

Getting Started with OpenTofu

Meta Arguments amp Count and for each

1. Using `count`

Dynamic `count` with `length()`

2. Using `for_each`

Links and References

Watch Video

​1. Using count

​Dynamic count with length()

​2. Using for_each

​Links and References

Watch Video

1. Using `count`

Dynamic `count` with `length()`

2. Using `for_each`

Links and References