google_compute_region_backend_service can fail google name validation

[yoshiotu]

https://github.com/banyansecurity/terraform-google-banyan-accesstier2/blob/main/main.tf#L206

The name of the external address is constructed from the access tier name, but the result may fail google provider's regex validation if the access tier name contains "." or various other characters that we allow for the access tier name.

[danhiris]

should we just replace the dots with underscores or dashes in the hostname?

[yoshiotu]

"." is not the only problematic character. Maybe we could strip out anything non-alphanumeric and use the resulting string as the external address name.