Define Environment Name Variable with Allowed Values

Environment Name Variable

The environment variable is a cornerstone of multi-environment Terraform setups. It controls resource naming, sizing, feature toggles, and tag values across your infrastructure.

Variable Definition

variable "environment" {
  type        = string
  description = "Deployment environment name"
  default     = "dev"

  validation {
    condition     = contains(["dev", "staging", "prod"], var.environment)
    error_message = "Environment must be one of: dev, staging, prod."
  }
}

Usage in Resource Naming

resource "aws_s3_bucket" "data" {
  bucket = "${var.project_name}-${var.environment}-data"
}

resource "aws_instance" "app" {
  instance_type = var.environment == "prod" ? "m5.large" : "t3.micro"

  tags = {
    Name        = "${var.project_name}-${var.environment}-app"
    Environment = var.environment
  }
}

Conditional Configuration

The environment variable drives many infrastructure decisions:

locals {
  is_prod = var.environment == "prod"

  instance_count = local.is_prod ? 3 : 1
  multi_az       = local.is_prod ? true : false
  backup_enabled = local.is_prod ? true : false
  log_level      = local.is_prod ? "warn" : "debug"
}

Per-Environment tfvars Files

terraform plan -var-file="environments/dev.tfvars"
terraform plan -var-file="environments/staging.tfvars"
terraform plan -var-file="environments/prod.tfvars"

Each tfvars file sets the environment along with environment-specific overrides:

# environments/prod.tfvars
environment   = "prod"
instance_type = "m5.large"
min_capacity  = 3
max_capacity  = 10