This allows variables to have explicit types, similar to Terraform
variables. It uses HCL's `typeexpr` extension for the specification.
For conversion of overrides to complex types (when explicit typing is
provided), HCL's native JSON-based unmarshalling is used.
Typing is independent of any default, but if a default is provided, it
will be validated. Similarly, if an override is provided, it will be
converted to that type.
When typing is not provided, previous behavior is used, namely
passing through as a string when no default, converting to primitives if
the default was primitive, and failing otherwise (complex types).
For complex types, the happy path is lists of primitives, but in theory
any complex/composite type can be used provided they are expressed
correctly in JSON. In the interest of simplicity and correctness, there
are no shortcuts for lists. There *is* a shortcut for strings as users
don't provide them for untyped variables and would be unintuitive.
Signed-off-by: Roberto Villarreal <rrjjvv@yahoo.com>
Roberto Villarreal
5b8a3b3728