This brings over the work done by @apparentlymart and @radeksimko in
PR #3124, and converts it into a data source for the AWS provider:
This commit adds a helper to construct IAM policy documents using
familiar Terraform concepts. It makes Terraform-style interpolations
easier and resolves the syntax conflict between Terraform interpolations
and IAM policy variables by changing the latter to use &{...} for its
interpolations.
Its use is completely optional and users are free to go on using literal
heredocs, file interpolations or whatever else; this just adds another
option that fits more naturally into a Terraform config.
James Nugent