Fix nat_gateway_enabled=false Invalid index error

[paulrob-100]

what

• Fix Setting the nat_gateway_enabled=false results in Invalid index error #44
• Same test from Fix nat_gateway_enabled=false InvalidNatGatewayId.Malformed error  #45 applied and still fails
• Readded test after merge of Fix variable enabled=false results in errors #47 and using us-east-2 as advised
• Tried to retain the output_map AZ => null design choice when nat_gateway_enabled=false. However:-
  • I get an aws_route ExactlyOne error if the nat_gw_id is null when nat_gateway_enabled=false
  • When I filter out null ngw_ids in private.tf then I get value depends on resource attributes that cannot be determined until apply when nat_gateway_enabled=true
• Hence changed output_map AZ => null design choice to an empty map

why

• Users should be able to create subnets without NAT gateways

references

• closes Setting the nat_gateway_enabled=false results in Invalid index error #44

[paulrob-100]

@Nuru resubmitted as per description. I kept the tests in the us-east-2 region as advised in #45
I couldn't see a way to keep the mapping to null, but if you can please update. Thanks

[Nuru]

Thank you for this submission, once again, @paulrob-100

We are not going to support the use case of private subnets without NAT gateways, at least not in this module.

I have a bunch if stylistic issues with this PR, but rather than bother you with them, I am going to try to fix this issue in a new PR, taking this PR as inspiration. I hope you don't mind.

[paulrob-100]

Thanks again for your review and fix @Nuru.
I'm just checking the new implementation.

Private subnets without routes to NAT gateways are going to be reasonably common especially considering the more modern network architectures permitted by the gateway load balancer.

Certainly it was one of the reasons I selected this module.

I'll perhaps join your sweetops slack group to see if I can find any more context behind this decision.