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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-ArgumentKey CharacteristicBest Use Case
countInteger-based, zero-indexedCreate a fixed number of identical resources
for_eachKey-based, uses a set or map of valuesStable addressing of dynamic or named items

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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.

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