timestamp returns a UTC timestamp string in RFC 3339 format.
In the Terraform language, timestamps are conventionally represented as
strings using RFC 3339
"Date and Time format" syntax, and so
timestamp returns a string
in this format.
The result of this function will change every second, so using this function
directly with resource attributes will cause a diff to be detected on every
Terraform run. We do not recommend using this function in resource attributes,
but in rare cases it can be used in conjunction with
ignore_changes lifecycle meta-argument
to take the timestamp only on initial creation of the resource. For more stable
time handling, see the Time Provider.
Due to the constantly changing return value, the result of this function cannot be predicted during Terraform's planning phase, and so the timestamp will be taken only once the plan is being applied.
> timestamp() 2018-05-13T07:44:12Z