packer functions not recognized in map variables

[youngturk2]

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Overview of the Issue

I am trying to use Packer's formatdate and timestamp functions to create a variable, eg.:

formatdate("YYYY-MM-DD", timestamp())

However, I can't seem to get these functions to work when using them to declare a variable. Attempting to declare the below variable:

variable testfunc {
    default = formatdate("YYYY-MM-DD", timestamp())
}

Results in the below error message:

Error: Call to unknown function
  on variables.pkr.hcl line 48, in variable "testfunc":
  48:     default = formatdate("YYYY-MM-DD", timestamp())


  on variables.pkr.hcl line 48, in variable "testfunc":
There is no function named "formatdate".
  48:     default = formatdate("YYYY-MM-DD", timestamp())

I only seem to be able to use packer's built-in functions if they are utilized in a local or locals block, so the below locals block works perfectly fine:

locals {
  tags = {
    createdon = formatdate("YYYY-MM-DD", timestamp())
  }
}

Can't imagine that this is by design, as I have seen other past issues that appear to also reference this issue, but are now closed (eg #9430 ). Not sure why the issue was closed, as the issue does not appear to have been fixed.

Reproduction Steps

1. Create a packer config file
2. define a variable and set the default value to use the timestamp function
3. run packer init .

Packer version

packer -version
1.9.2

Simplified Packer Template

variable testfunc {
    default = formatdate("YYYY-MM-DD", timestamp())
}

Operating system and Environment details

Windows server 2016 x64

Log Fragments and crash.log files

Error: Call to unknown function
  on variables.pkr.hcl line 48, in variable "testfunc":
  48:     default = formatdate("YYYY-MM-DD", timestamp())


  on variables.pkr.hcl line 48, in variable "testfunc":
There is no function named "formatdate".
  48:     default = formatdate("YYYY-MM-DD", timestamp())


2023/08/07 20:14:51 [INFO] (telemetry) Finalizing.
There is no function named "formatdate".


2023/08/07 20:14:52 waiting for all plugin processes to complete...

[Stromweld]

This is actually by design of the HCL language. In the issue you linked in your description the reason why that one was closed is found in this comment #9430 (comment). Variables are meant to be constant values and local variables are meant for computing a value. This separation is meant to keep it clear what is generated and what is provided by the caller.

[nywilken]

Thanks for the assist @Stromweld. @youngturk2 I'm going to close this as it is not an issue with variables. But please feel free to reach out if you run into any other unexpected variable questions or behaviors.

[github-actions]

I'm going to lock this issue because it has been closed for 30 days ⏳. This helps our maintainers find and focus on the active issues.
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