[Documentation]: Add example for specifying p12 certificate with `aws_sns_platform_application`

Terraform Core Version

OpenTofu v1.8.7

AWS Provider Version

v5.81.0

Affected Resource(s)

• aws_sns_platform_application APNS

The platform_principal needs to be the contents of a p12 file for APNS. Since that is a binary file and terraform expects all strings to be utf-8 (see e.g. https://developer.hashicorp.com/terraform/language/functions/base64decode), we have a bit of a problem.

I guess one option would be to add a mutually exclusive platform_principal_base64 that would eat bas64 encoded data instead.

Expected Behavior

resource "aws_sns_platform_application" "apns_application" {
  name                = "APNS-01"
  platform            = "APNS"
  platform_credential = data.onepassword_item.sns_apns_cert_key.password
  platform_principal  = base64decode(data.onepassword_item.sns_apns_cert.file[0].content_base64)
}

Should apply correctly.

Actual Behavior

│ Call to function "base64decode" failed: the result of decoding the provided string is not valid UTF-8.

Relevant Error/Panic Output Snippet

No response

Terraform Configuration Files

resource "aws_sns_platform_application" "apns_application" {
  name                = "APNS-01"
  platform            = "APNS"
  platform_credential = data.onepassword_item.sns_apns_cert_key.password
  platform_principal  = base64decode(data.onepassword_item.sns_apns_cert.file[0].content_base64)
}

Steps to Reproduce

tofu apply

Debug Output

No response

Panic Output

No response

Important Factoids

No response

References

No response

Would you like to implement a fix?

I might be able to implement the suggested fix