Terraform timestamp() to numbers only string

Question

The timestamp() function in the interpolation syntax will return an ISO 8601 formatted string, which looks like this 2019-02-06T23:22:28Z. However, I want to have a string which looks like this 20190206232240706500000001. A string with only numbers (integers) and no hyphens, white spaces, colon, Z or T. What is a simple and elegant way to achieve this?

It works if I replace every a single character class at the time hyphens, white spaces, colon Z and T:

locals {
  timestamp = "${timestamp()}"
  timestamp_no_hyphens = "${replace("${local.timestamp}", "-", "")}"
  timestamp_no_spaces = "${replace("${local.timestamp_no_hyphens}", " ", "")}"
  timestamp_no_t = "${replace("${local.timestamp_no_spaces}", "T", "")}"
  timestamp_no_z = "${replace("${local.timestamp_no_t}", "Z", "")}"
  timestamp_no_colons = "${replace("${local.timestamp_no_z}", ":", "")}"
  timestamp_sanitized = "${local.timestamp_no_colons}"
}

output "timestamp" {
  value = "${local.timestamp_sanitized}"
}

The resulting output is in the desired format, except the string is significantly shorter:

Outputs:

timestamp = 20190207000744

However, this solution is very ugly. Is there another way of doing the same thing in a more elegant way as well as producing a string with the same length as the example string 20190206232240706500000001?

Answer 1

Terraform 0.12.0 introduced a new function formatdate which can make this more readable:

output "timestamp" {
  value = formatdate("YYYYMMDDhhmmss", timestamp())
}

At the time of writing, formatdate's smallest supported unit is whole seconds, so this won't give exactly the same result as the regexp approach, but can work if the nearest second is accurate enough for the use-case.