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.

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"

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.

Links and References

• OpenTofu Documentation
• AWS EC2 Instance Resource
• Terraform count Meta-Argument
• Terraform for_each Meta-Argument