How to Write an if, else, elsif Conditional Statement in Terraform

TLDR

Terraform supports if, else, and elsif (via nested conditionals) for creating dynamic configurations. These are implemented using conditional expressions.

---

Writing Conditional Statements in Terraform

Terraform does not have traditional if, else, or elsif statements like programming languages. Instead, it uses conditional expressions to achieve similar functionality.

Basic if Statement

A basic if statement in Terraform is written as a conditional expression:

variable "is_production" {
  default = false
}

output "environment" {
  value = var.is_production ? "production" : "development"
}

In this example, if is_production is true, the output will be "production". Otherwise, it will be "development".

if-else Statement

The if-else logic is implemented using the same conditional expression:

variable "enable_feature" {
  default = true
}

output "feature_status" {
  value = var.enable_feature ? "enabled" : "disabled"
}

Here, the feature_status output will be "enabled" if enable_feature is true, and "disabled" otherwise.

if-elsif-else Statement

Terraform does not have a direct elsif keyword, but you can achieve this using nested conditionals:

variable "environment" {
  default = "staging"
}

output "env_message" {
  value = var.environment == "production" ? "Live Environment" : (var.environment == "staging" ? "Testing Environment" : "Development Environment")
}

In this example:

• If environment is "production", the output will be "Live Environment".
• If environment is "staging", the output will be "Testing Environment".
• Otherwise, it will be "Development Environment".

Best Practices

• Keep It Simple: Avoid deeply nested conditionals. Use variables to simplify complex logic.
• Use Descriptive Variable Names: Make your conditions self-explanatory.
• Test Your Logic: Use terraform console to validate your expressions before applying them.

By mastering conditional expressions, you can create highly dynamic and adaptable Terraform configurations.