Type conversion functions in Terraform - Mini Project: Build & Apply

Type Conversion Functions in Terraform

📖 Scenario: You are setting up a Terraform configuration to manage cloud resources. Some input variables come as strings, but you need to convert them to other types to use them correctly in your resource definitions.

🎯 Goal: Build a Terraform configuration that demonstrates converting string variables to number, boolean, and list types using Terraform's type conversion functions.

📋 What You'll Learn

Create input variables with string values

Add variables to hold converted types using Terraform type conversion functions

Use tonumber() to convert string to number

Use tobool() to convert string to boolean

Use tolist() to convert a tuple to a list

💡 Why This Matters

🌍 Real World

Cloud infrastructure often requires converting input data types to match resource argument expectations. This project shows how to handle string inputs and convert them properly in Terraform.

💼 Career

Understanding type conversion in Terraform is essential for cloud engineers and DevOps professionals to write flexible and error-free infrastructure code.

1

Create string input variables

Create three Terraform input variables with the exact names and string values: var_string_number with value "42", var_string_bool with value "true", and var_string_list with value ["a", "b", "c"] as a tuple of strings.

Terraform

# Define three input variables with string values
# Your code here

Need a hint?

Use variable blocks with default set to the exact string or tuple values.

2

Add variables for converted types

Create three local variables named number_value, bool_value, and list_value to hold the converted values from the input variables. Initialize them with the input variables but do not convert yet.

Terraform

variable "var_string_number" {
  default = "42"
}

variable "var_string_bool" {
  default = "true"
}

variable "var_string_list" {
  default = ["a", "b", "c"]
}

locals {
  number_value = var.var_string_number
  bool_value = var.var_string_bool
  list_value = var.var_string_list
  # Your code here
}

Need a hint?

Use a locals block and assign each local variable to the corresponding input variable.

3

Convert string variables to correct types

Update the local variables number_value, bool_value, and list_value to convert the input variables using Terraform's type conversion functions: use tonumber() for number_value, tobool() for bool_value, and tolist() for list_value.

Terraform

variable "var_string_number" {
  default = "42"
}

variable "var_string_bool" {
  default = "true"
}

variable "var_string_list" {
  default = ["a", "b", "c"]
}

locals {
  number_value = tonumber(var.var_string_number)
  bool_value = tobool(var.var_string_bool)
  list_value = tolist(var.var_string_list)
  # Your code here
}

Need a hint?

Use the functions tonumber(), tobool(), and tolist() around the input variables.

4

Use converted variables in a resource

Add a Terraform null_resource named example that uses the converted local variables in its triggers argument: set number_trigger to local.number_value, bool_trigger to local.bool_value, and list_trigger to local.list_value.

Terraform

variable "var_string_number" {
  default = "42"
}

variable "var_string_bool" {
  default = "true"
}

variable "var_string_list" {
  default = ["a", "b", "c"]
}

locals {
  number_value = tonumber(var.var_string_number)
  bool_value = tobool(var.var_string_bool)
  list_value = tolist(var.var_string_list)
}

resource "null_resource" "example" {
  triggers = {
    number_trigger = local.number_value
    bool_trigger = local.bool_value
    list_trigger = local.list_value
  }
  # Your code here
}

Need a hint?

Use a null_resource with a triggers map that references the converted local variables.