Ability to use existing DNS custom resolver ID

[nupurg-ibm]

Description

We want to support both the below cases in our solution:

Existing custom resolver + New DNS instance ID
Existing custom resolver + Existing DNS instance ID

New or affected modules

landing-zone
landing-zone-vpc

---

By submitting this issue, you agree to follow our Code of Conduct

[imprateeksh]

As of now, a PR in landing zone VPC module has been raised. Once the changes are merged, will be raising another PR to consume changes in terraform-ibm-landing-zone

[nupurg-ibm]

@imprateeksh Do let us know once we have any update on this please.

CC @bksagar @jayeshh123 @manirtm

[imprateeksh]

@nupurg-ibm - We have modified the logic slightly to now incorporate the list of custom resolver ids instead of just one resolver id to future proof the solution.
PR is ready for another round of review and should be merged soon in landing-zone-vpc module.
Once it is merged, I will raise another PR here in landing-zone to consume the latest changes.

[nupurg-ibm]

Thanks for the update @imprateeksh

[nupurg-ibm]

As per @imprateeksh The DNS resolver ID changes are done, but he encountered some failures during testing. He tested with some combinations though tests passed.

[imprateeksh]

Update: I faced few issues like the existing resolver id was not getting assigned in all approaches I tried.
I checked in console there is no provision to include the existing custom resolver ids. I have also asked the same query here. It seems this is not supported.

So what we have with new custom resolver ids are already part of the code.

S.No	Scenario	Status
1	New custom resolver ids with New DNS instance	Already supported in current code
2	New custom resolver ids with Existing DNS instance	Already supported in current code
3	Existing custom resolver ids with New DNS instance	As per DNS team, not possible
4	Existing custom resolver ids with Existing DNS instance	As per DNS team, not possible

[imprateeksh]

As per latest conversation with @nupurg-ibm and @rajatagarwal-ibm the change is not about supporting the existing custom resolver ids but we need to introduce a flag to allow skipping the creation of custom resolver.

@nupurg-ibm can you please confirm ?

[nupurg-ibm]

Thats correct @imprateeksh

[imprateeksh]

As the ask has now been changed to only provide a flag to skip custom resolver creation instead of providing existing custom resolver ids.
But we already have a flag for that in the current code base which is used while creating the resource here
Same variable exists in landing-zone module as well.

@nupurg-ibm - Please let us know if this is what you were looking for.
cc: @Rajat-Agrawal

[imprateeksh]

@nupurg-ibm - Are we good to close the issue if there is no other change required here?

[imprateeksh]

As mentioned over slack, closing the issue.