added reverse lookup feature to module dns #1042

[chemapolo]

#1042

I've missed reverse lookup feature at dns modules while using cloud foundation fabric.

Basically i've added a new type in variables.tf file called reverse and I've changed google_dns_managed_zone. non-public adding reverse_lookup attribute set to var.type=="reverse" in that way if type is differente to reverse it will be false and only when setting it to reverse the value will be true and will create the required reverse zone.

I've modified as well README.md file to add an example and new type.

I've run already tfdoc and tests as per your contributing guide.

Regards

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[ludoo]

Super-clean PR, thanks a lot!

One trivial doubt: should we use reverse-managed instead of reverse, to indicate that custom reverse zones are a different thing and use the private type?

[chemapolo]

Super-clean PR, thanks a lot!

One trivial doubt: should we use reverse-managed instead of reverse, to indicate that custom reverse zones are a different thing and use the private type?

No prob ill change it, i've seen that by mistake I left ${reverse-ip}.in-addr.arpa. in the readme example instead of an ip. im going to change it and commit with your suggestion 'reverse-managed' Thanks a lot!