Terraform Tutorial — Meta-Arguments Overview

Meta-arguments are special arguments that work on ANY resource type. They change how Terraform handles the resource itself, not what the resource looks like.

---

count — Create N Identical Resources

resource "aws_instance" "web" {
  count         = 3
  ami           = "ami-0c55b159cbfafe1f0"
  instance_type = "t3.micro"

  tags = {
    Name = "web-server-${count.index}"
  }
}

This creates three EC2 instances: web-server-0, web-server-1, web-server-2.

Reference by index: aws_instance.web[0].public_ip

---

for_each — Create Resources from a Collection

variable "buckets" {
  default = {
    logs    = "private"
    assets  = "private"
    backups = "private"
  }
}

resource "aws_s3_bucket" "buckets" {
  for_each = var.buckets
  bucket   = "myapp-${each.key}"
}

Creates three buckets, each identified by its key: aws_s3_bucket.buckets["logs"], aws_s3_bucket.buckets["assets"], etc.

count vs for_each

Aspect	count	for_each
Input	A number	A set or map
Identify instances	By index [0], [1]	By key ["logs"], ["assets"]
Removing middle item	Shifts all subsequent indexes	Only removes that key
Best for	Identical copies	Distinct items with meaningful keys

💡 Tip: Prefer for_each over count. If you remove item [1] from a count of 3, Terraform wants to destroy [2] and rename [1] — causing unnecessary changes. With for_each, removing "assets" only affects that one resource.

---

depends_on — Explicit Dependencies

resource "aws_instance" "web" {
  ami           = "ami-0c55b159cbfafe1f0"
  instance_type = "t3.micro"

  depends_on = [aws_iam_role_policy_attachment.web_policy]
}

Use when Terraform can’t detect the dependency from references alone.

---

provider — Use a Specific Provider

resource "aws_s3_bucket" "eu_bucket" {
  provider = aws.eu
  bucket   = "myapp-eu-data"
}

Selects which provider configuration to use (for aliased providers).

---

lifecycle — Control Create/Update/Destroy Behavior

resource "aws_db_instance" "main" {
  # ... arguments ...

  lifecycle {
    prevent_destroy       = true
    create_before_destroy = true
    ignore_changes        = [password]
  }
}

---

Summary Table

Meta-Argument	Purpose
count	Create N copies of a resource
for_each	Create one resource per item in a set/map
depends_on	Declare explicit dependencies
provider	Choose which provider configuration to use
lifecycle	Control create/update/destroy behavior

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What’s Next?

You now have a complete picture of Terraform resources. Time to test your knowledge with the practice exercises.

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← Resource Lifecycle Practice Exercises →