How to use number variable terraform

TerraformHow-ToBeginner · 3 min read

How to Use Number Variables in Terraform: Simple Guide

In Terraform, you define a number variable using variable block with type = number. You can then reference this variable in your configuration by using var.variable_name to use numeric values in your infrastructure code.

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Syntax

To declare a number variable in Terraform, use the variable block with type = number. You can optionally set a default value or leave it to be provided during runtime.

variable "name": declares the variable name.
type = number: specifies the variable holds numeric values.
default: optional default numeric value.

Use the variable in your Terraform code by referencing var.name.

terraform

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

resource "aws_instance" "example" {
  count = var.instance_count
  ami           = "ami-12345678"
  instance_type = "t2.micro"
}

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Example

This example shows how to declare a number variable and use it to set the number of AWS EC2 instances to create.

terraform

variable "instance_count" {
  type    = number
  default = 2
}

provider "aws" {
  region = "us-east-1"
}

resource "aws_instance" "example" {
  count         = var.instance_count
  ami           = "ami-0c55b159cbfafe1f0"
  instance_type = "t2.micro"
}

output "created_instances" {
  value = aws_instance.example.*.id
}

Output

Apply complete! Resources: 2 added, 0 changed, 0 destroyed. Outputs: created_instances = ["i-0abcd1234efgh5678", "i-0abcd1234efgh5679"]

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Common Pitfalls

Common mistakes when using number variables include:

Not specifying type = number, which can cause Terraform to treat the variable as a string.
Passing string values instead of numbers when providing variable input.
Using number variables in places expecting strings without conversion.

Always ensure numeric inputs are numbers, not quoted strings.

terraform

variable "wrong_number" {
  default = "3"  # Incorrect: string instead of number
}

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

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Quick Reference

Concept	Example	Description
Declare number variable	variable "count" { type = number }	Defines a variable that holds a number.
Set default value	default = 5	Provides a default number if none is given.
Reference variable	count = var.count	Uses the number variable in resource configuration.
Input number value	terraform apply -var='count=4'	Passes a number value during apply.

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Key Takeaways

Declare number variables with type = number to ensure numeric handling.

Reference number variables using var.variable_name in your Terraform code.

Avoid passing numbers as quoted strings to prevent type errors.

Use default values to provide fallback numbers for variables.

Pass number variables at runtime with -var flag for flexible configuration.