HashiCorp Configuration Language (HCL) supports user-denned functions.

HashiCorp Configuration Language (HCL) does not support user-defined functions. You can only use the built-in functions that are provided by the language. The built-in functions allow you to perform various operations and transformations on values within expressions. The general syntax for function calls is a function name followed by comma-separated arguments in parentheses, such as max(5, 12, 9). You can find the documentation for all of the available built-in functions in the Terraform Registry orthe Packer Documentation, depending on which tool you are using. References = : Functions - Configuration Language | Terraform : Functions - Configuration Language | Packer