fix: Do not replace NAT gateways when additional subnets are added #1055
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manuelmazzuola changed the title manuelmazzuola force-pushed the fix-nat-gateway-replacement branch 2 times, most recently from e8bfc7c to 4dff716 Compare 
manuelmazzuola force-pushed the fix-nat-gateway-replacement branch from 4dff716 to 2ded1dd Compare manuelmazzuola changed the title 
| tf-controller plan output: No changes. Your infrastructure matches the configuration. Terraform has compared your real infrastructure against your configuration and found no differences, so no changes are needed. To apply this plan, please merge this pull request. |
bryantbiggs reviewed Apr 25, 2024
| locals { | ||
| nat_gateway_count = var.single_nat_gateway ? 1 : var.one_nat_gateway_per_az ? length(var.azs) : local.max_subnet_length | ||
| nat_gateway_ips = var.reuse_nat_ips ? var.external_nat_ip_ids : try(aws_eip.nat[*].id, []) | ||
| nat_gateway_ips = var.reuse_nat_ips ? var.external_nat_ip_ids : aws_eip.nat[*].id |
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why would this change make a difference?
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because the try statement can't be evaluated while planning, so the nat gateways are all replaced, despite the fact that they are not changed
bryantbiggs changed the title bryantbiggs approved these changes Apr 26, 2024
antonbabenko pushed a commit that referenced this pull request Apr 26, 2024
## [5.8.1](v5.8.0...v5.8.1) (2024-04-26) ### Bug Fixes * Do not replace NAT gateways when additional subnets are added ([#1055](#1055)) ([cf18c37](cf18c37))
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| This PR is included in version 5.8.1 🎉 |
| I'm going to lock this pull request because it has been closed for 30 days ⏳. This helps our maintainers find and focus on the active issues. If you have found a problem that seems related to this change, please open a new issue and complete the issue template so we can capture all the details necessary to investigate further. |
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Description
Adding new private subnets to an already deployed vpc module leads to the replacement of the nat gateways for all the subnets that already existing.
There is no reason to use the try function in that case.
Motivation and Context
Breaking Changes
none
How Has This Been Tested?
examples/*to demonstrate and validate my change(s)examples/*projectspre-commit run -aon my pull requestBefore the change
After the change