Variables & Outputs

Parameterize configurations with input variables and expose values with outputs

Variables & Outputs

What Are Variables?

Variables let you parameterize your Terraform config so it works for different environments (dev, staging, production) without copying files.

Input Variables

hcl

variable "location" {
  description = "Azure region for resources"
  type        = string
  default     = "East US"
}

variable "environment" {
  description = "Environment name (dev/staging/prod)"
  type        = string
}

variable "tags" {
  description = "Common resource tags"
  type        = map(string)
  default = {
    managed_by = "terraform"
  }
}

Using Variables

hcl

resource "azurerm_resource_group" "main" {
  name     = "app-${var.environment}"
  location = var.location
  tags     = var.tags
}

Syntax	What it does
`var.variable_name`	References a variable value
`"app-${var.environment}"`	String interpolation
`variable "name" {}`	Declares a variable block

Setting Variable Values

bash

# Via command-line
terraform apply -var="environment=dev" -var="location=West US"

# Via .tfvars file
echo 'environment = "prod"
location = "North Europe"' > terraform.tfvars

# Via environment variable
export TF_VAR_environment=staging

Outputs

Outputs expose information about your infrastructure after creation:

hcl

output "resource_group_name" {
  description = "Name of the created resource group"
  value       = azurerm_resource_group.main.name
}

output "storage_account_endpoint" {
  value = azurerm_storage_account.data.primary_blob_endpoint
}

After apply, outputs are displayed:

Apply complete! Resources: 3 added.
Outputs:
resource_group_name = "app-prod"
storage_account_endpoint = "https://proddata123.blob.core.windows.net"

Common Mistakes

Wrong	Why	Right
`variable name` without quotes around default string	HCL requires strings in quotes	`default = "East US"`
Referencing `variable.name` instead of `var.name`	Variables use `var.` prefix	`var.location`
Hard-coding values across resources	Breaks reusability	Use variables for anything that changes

Your Turn!

Create a variable block for environment (string, no default) and instance_count (number, default 2). Then create an output that displays the values.

💡Need a hint? (3 available)

#1Variables use the var. prefix (like var.location)

#2Use string interpolation: ${var.name} inside double-quoted strings

#3Outputs display values after apply

🔑Show solution (try it yourself first!)

variable "environment" {
  description = "Environment name"
  type        = string
}

variable "instance_count" {
  description = "Number of instances"
  type        = number
  default     = 2
}

output "env_name" {
  value = var.environment
}

output "count" {
  value = var.instance_count
}

✏️ Code Editor

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📤 Output

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