Added TF DNS config options to prevent Autopilot destroy / create on existing cluster

[abmarcum]

What type of PR is this?
/kind bug

What this PR does / Why we need it:
Prevents re-creating Autopilot clusters if they already exist.

Special notes for your reviewer:

[markmandel]

Deferring to @zmerlynn and @gongmax who have been doing more of the autopilot work than I have.

[zmerlynn]

@abmarcum Thanks for the contribution! Can you describe the problem in more detail? Is our TF config recreating DNS settings? This seems like a flaw in the Google TF module, if so - if not, could you explain why not? Thanks!

[abmarcum]

After creating a cluster using the Agones GKE Autopilot module, if I re-run terraform, I get the following on the cluster:

  - dns_config { # forces replacement
      - cluster_dns        = "CLOUD_DNS" -> null
      - cluster_dns_domain = "cluster.local" -> null
      - cluster_dns_scope  = "CLUSTER_SCOPE" -> null
    }

This indicates to me that Google is adding this configuration after the cluster is installed but because Terraform does not know about it, trys resets the configuration values to zero when run again. This then forces Terraform to destroy and re-create the Autopilot GKE cluster.

By adding these values to the Terraform code, this prevents Terraform for destroying/creating the cluster.

This may be an issue with what Terraform is expecting from Google (and should not destroy the cluster) but I tried this out on the latest Google Provider 4.78.0 and the issue still persists.

[agones-bot]

Build Succeeded 👏

Build Id: 05319555-bc49-4aca-ba7f-ca13bf9d6177

The following development artifacts have been built, and will exist for the next 30 days:

• image: us-docker.pkg.dev/agones-images/ci/agones-controller:1.35.0-dev-85b1d1f-amd64
• image: us-docker.pkg.dev/agones-images/ci/agones-extensions:1.35.0-dev-85b1d1f-amd64
• image: us-docker.pkg.dev/agones-images/ci/agones-sdk:1.35.0-dev-85b1d1f-linux-amd64
• image: us-docker.pkg.dev/agones-images/ci/agones-ping:1.35.0-dev-85b1d1f-amd64
• image: us-docker.pkg.dev/agones-images/ci/agones-allocator:1.35.0-dev-85b1d1f-amd64
• Linux C++ SDK (build): agonessdk-1.35.0-dev-85b1d1f-amd64-linux-arch_64.tar.gz
• SDK Server: agonessdk-server-1.35.0-dev-85b1d1f-amd64.zip

A preview of the website (the last 30 builds are retained):

• https://85b1d1f-dot-preview-dot-agones-images.appspot.com/

To install this version:

• git fetch https://github.com/googleforgames/agones.git pull/3330/head:pr_3330 && git checkout pr_3330
• helm install agones ./install/helm/agones --namespace agones-system --set agones.image.registry=us-docker.pkg.dev/agones-images/ci --set agones.image.tag=1.35.0-dev-85b1d1f-amd64

[abmarcum]

Note: I do not see this on a non-Autopilot GKE Cluster but I did see it on a non Agones GKE Autopilot cluster (the same changes fixed the issue.)

I did not check immediately after I first creating the cluster but I did see the error after I deployed workloads to the Autopilot clusters and ran terraform apply. The spinning up of nodes for workloads may be where those settings are being added to the GKE cluster.

You should be able to replicate this issue if you re-run Terraform against a GKE Autopilot cluster with existing workloads.

[zmerlynn]

I see the issue on my desktop now as well. LGTM.

[google-oss-prow]

New changes are detected. LGTM label has been removed.

[google-oss-prow]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: abmarcum, zmerlynn
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[agones-bot]

Build Succeeded 👏

Build Id: 4ffa4c1c-016e-4e91-a94a-5b060edb369e

The following development artifacts have been built, and will exist for the next 30 days:

• image: us-docker.pkg.dev/agones-images/ci/agones-controller:1.35.0-dev-9b27097-amd64
• image: us-docker.pkg.dev/agones-images/ci/agones-extensions:1.35.0-dev-9b27097-amd64
• image: us-docker.pkg.dev/agones-images/ci/agones-sdk:1.35.0-dev-9b27097-linux-amd64
• image: us-docker.pkg.dev/agones-images/ci/agones-ping:1.35.0-dev-9b27097-amd64
• image: us-docker.pkg.dev/agones-images/ci/agones-allocator:1.35.0-dev-9b27097-amd64
• Linux C++ SDK (build): agonessdk-1.35.0-dev-9b27097-amd64-linux-arch_64.tar.gz
• SDK Server: agonessdk-server-1.35.0-dev-9b27097-amd64.zip

A preview of the website (the last 30 builds are retained):

• https://9b27097-dot-preview-dot-agones-images.appspot.com/

To install this version:

• git fetch https://github.com/googleforgames/agones.git pull/3330/head:pr_3330 && git checkout pr_3330
• helm install agones ./install/helm/agones --namespace agones-system --set agones.image.registry=us-docker.pkg.dev/agones-images/ci --set agones.image.tag=1.35.0-dev-9b27097-amd64