terraform/website/docs/configuration/expressions/function-calls.html.md

layout	page_title
language	Function Calls - Configuration Language

Function Calls

Hands-on: Try the Perform Dynamic Operations with Functions tutorial on HashiCorp Learn.

The Terraform language has a number of built-in functions that can be used in expressions to transform and combine values. These are similar to the operators but all follow a common syntax:

<FUNCTION NAME>(<ARGUMENT 1>, <ARGUMENT 2>)

The function name specifies which function to call. Each defined function expects a specific number of arguments with specific value types, and returns a specific value type as a result.

Some functions take an arbitrary number of arguments. For example, the min function takes any amount of number arguments and returns the one that is numerically smallest:

min(55, 3453, 2)

A function call expression evaluates to the function's return value.

Expanding Function Arguments

If the arguments to pass to a function are available in a list or tuple value, that value can be expanded into separate arguments. Provide the list value as an argument and follow it with the ... symbol:

min([55, 2453, 2]...)

The expansion symbol is three periods (...), not a Unicode ellipsis character (…). Expansion is a special syntax that is only available in function calls.

Available Functions

For a full list of available functions, see the function reference.