Upgrade to Kubernetes 1.20

[roberthbailey]

List of items to do for upgrading to 1.20:

• Update terraform submodules
  • GKE
  • Azure
  • EKS
• Update prow cluster to use 1.20 (even though we aren't using it yet, we should keep it in sync)
  • Recreate cluster with new scripts: cd build/terraform/prow; terraform apply -var project=agones-images
• Update e2e cluster to run against 1.20
  • Recreate cluster with new scripts: cd build/terraform/e2e; terraform apply -var project=agones-images
• Update kubectl in dev tooling
  • Update kubectl in build/build-image/Dockerfile
  • Update kubectl in build/e2e-image/Dockerfile
• Update documentation for creating clusters to 1.20
  • Config.toml supported_k8s and related (do dev_ before main)
• Update the dev tooling to create 1.20 clusters
  • Minikube
  • Kind
• Update client-go
• Update CRD API reference
  • Update links to k8s documentation in site/assets/templates/crd-doc-config.json
  • Regenerate crd api reference docs - make gen-api-docs
• Regenerate Kubernetes resource includes (e.g. ObjectMeta, PodTemplateSpec)
  • Start a cluster with make gcloud-test-cluster, uninstall agones using helm uninstall, and then run make gen-embedded-openapi and make gen-install

[roberthbailey]

I checked the 3 public cloud providers to see whether we meet the criteria to upgrade our Kubernetes version for the 1.17 release:

AKS: https://github.com/Azure/AKS/releases/tag/2021-07-15 says Kubernetes 1.21 is now Generally Available (GA), estimated to roll out the week of 2021-07-19 (so this week).

EKS: https://docs.aws.amazon.com/eks/latest/userguide/kubernetes-versions.html shows that Kubernetes version 1.21.2 is currently available for new clusters in Amazon EKS.

GKE: https://cloud.google.com/kubernetes-engine/docs/release-notes#May_28_2021 shows that 1.21 is available in the Rapid channel.

Everyone has 1.20 - so according to our guidelines, it is time to upgrade to 1.20.

[roberthbailey]

Current Azure versions:

# az aks get-versions --location eastus --output table
KubernetesVersion    Upgrades
-------------------  ------------------------
1.21.1(preview)      None available
1.20.7               1.21.1(preview)
1.20.5               1.20.7, 1.21.1(preview)
1.19.11              1.20.5, 1.20.7
1.19.9               1.19.11, 1.20.5, 1.20.7
1.18.19              1.19.9, 1.19.11
1.18.17              1.18.19, 1.19.9, 1.19.11

[markmandel]

Here's some nice news - just confirmed, that issue with Helm + changes to CRDs: No longer present on 1.20 😄