HCL Language - 20 - Math Functions in HCL

Math Functions in HCL

HCL (HashiCorp Configuration Language) is a powerful configuration language used in tools like Terraform and Packer. While it primarily focuses on defining infrastructure as code, it also provides a set of math functions to perform calculations within your configurations. In this guide, we’ll explore the math functions available in HCL and how to use them effectively.

Basic Math Functions

HCL provides a range of basic math functions, such as addition, subtraction, multiplication, and division. These functions allow you to perform arithmetic operations within your configurations.


variable "num1" {
  type    = number
  default = 10
}

variable "num2" {
  type    = number
  default = 5
}

output "sum" {
  value = "${var.num1 + var.num2}"
}

output "product" {
  value = "${var.num1 * var.num2}"
}

In this example, we define two variables, “num1” and “num2,” and use basic math functions to calculate their sum and product. The results are then exposed as outputs.

Math Functions for Rounding

HCL includes functions to round numbers, which can be useful when working with real-world data or precision requirements.


variable "price" {
  type    = number
  default = 15.75
}

output "rounded_price" {
  value = floor("${var.price}")
}

In this example, we have a price with a decimal value, and we use the “floor” function to round it down. You can also use “ceil” to round up and “round” for standard rounding.

Math Functions for Randomization

HCL offers functions for generating random numbers and shuffling lists. These can be valuable when you need to introduce variability into your configurations.


resource "random_pet" "example" {
  length = 2
}

resource "random_shuffle" "example" {
  input = ["apple", "banana", "cherry", "date", "fig"]
}

output "random_name" {
  value = random_pet.example.id
}

output "shuffled_list" {
  value = random_shuffle.example.result
}

In this example, we use the “random_pet” and “random_shuffle” resources to generate random pet names and shuffle a list of fruits.

Math Functions for Trigonometry

HCL includes trigonometric functions, like sine and cosine, which can be useful for certain types of calculations, such as when dealing with geographic coordinates.


variable "angle" {
  type    = number
  default = 45
}

output "sin_value" {
  value = sin("${radians(var.angle)}")
}

output "cos_value" {
  value = cos("${radians(var.angle)}")
}

In this example, we calculate the sine and cosine of a given angle in degrees. We convert the angle to radians using the “radians” function before applying trigonometric functions.

Benefits of Math Functions in HCL

Utilizing math functions in HCL offers several advantages:

Dynamic Configurations: Math functions allow you to create dynamic configurations that adapt to changing values.
Precision Control: Rounding functions enable control over the precision of numbers in your infrastructure definitions.
Randomization: Randomization functions introduce variability, which is useful for load balancing and generating unique identifiers.

Summary

Math functions in HCL provide a robust set of tools for performing calculations and introducing variability into your infrastructure configurations. Whether you need to perform basic arithmetic, round numbers, generate random values, or work with trigonometric functions, HCL’s math functions empower you to create flexible and dynamic infrastructure as code.

HCL Language – 20 – Math Functions in HCL