Feature Request: Update CoreDNS and the CoreDNS Addon's Default's that eks blueprints uses

[neoakris]

Describe the feature

Problem Statement: AWS's EKS Upstream has poor default values for CoreDNS
Feature Request: Have future version of EKS Blueprints default to better defaults, specifically:

• have a hard requirement to spread replicas of coredns across nodes
• have CoreDNS autoscaling on by default

Use Case

EKS Blueprints is supposed to implement best practices by default.
Best practice is

1. hard requirement to spread coredns replicas across nodes, vs a soft preference.
2. coredns autoscaling enabled by default.

Just because EKS upstream has poor default values doesn't mean this project should.

Proposed Solution

Have a future version of EKS Blueprints use the following default values for CoreDNS
Note: "auto" would have to map to a supported version of the addon. (like "v1.11.1-eksbuild.11")

new blueprints.addons.CoreDnsAddOn( "v1.11.1-eksbuild.11", {
    configurationValues: {
            "autoScaling": {
              "enabled": true,
              "minReplicas": 2,
              "maxReplicas": 100
            },
            "affinity": {
              "nodeAffinity": {
                "requiredDuringSchedulingIgnoredDuringExecution": {
                  "nodeSelectorTerms": [
                    {
                      "matchExpressions": [
                        {
                          "key": "kubernetes.io/os",
                          "operator": "In",
                          "values": [
                            "linux"
                          ]
                        },
                        {
                          "key": "kubernetes.io/arch",
                          "operator": "In",
                          "values": [
                            "amd64",
                            "arm64"
                          ]
                        }
                      ]
                    }
                  ]
                }
              },
              "podAntiAffinity": {
                "requiredDuringSchedulingIgnoredDuringExecution": [
                  {
                    "labelSelector": {
                      "matchExpressions": [
                        {
                          "key": "k8s-app",
                          "operator": "In",
                          "values": [
                            "kube-dns"
                          ]
                        }
                      ]
                    },
                    "topologyKey": "kubernetes.io/hostname"
                  }
                ]
              }
            }
    } //end CoreDNS configurationValues override
  }) //end CoreDNS AddOn

Other Information

aws eks describe-addon-configuration --addon-name coredns --addon-version v1.11.1-eksbuild.8 --query configurationSchema --output text | jq .
^-- shows autoscaling is not available on the older version
(the above shows a shema, with autoscaling missing)

aws eks describe-addon-configuration --addon-name coredns --addon-version v1.11.1-eksbuild.11 --query configurationSchema --output text | jq .
^-- shows autoscaling is available in the newer version
aws eks describe-addon-configuration --addon-name coredns --addon-version v1.11.1-eksbuild.11 --query configurationSchema --output text | jq . | grep auto

        "autoScaling": {
          "description": "autoScaling configurations",

Useful Note about cdk-eks-blueprints v1.15.1:

• "auto" currently results in DEBUG Core add-on coredns has autoselected version v1.11.1-eksbuild.8 (which doesn't support the above config)
• "v1.11.1-eksbuild.11" results in DEBUG Core add-on coredns is at version v1.11.1-eksbuild.11
  (which does support the above config)

Acknowledgements

• I may be able to implement this feature request

CDK version used

2.133.0

EKS Blueprints Version

1.15.1

Node.js Version

v20.15.0

Environment details (OS name and version, etc.)

Mac OS Sonoma 14.5

[neoakris]

ugh ok, nvm I'll edit this, there's no upstream bug. I just typo'd the auto scaling part
"autoscaling" --> "autoScaling", that said the feature request is still valid.

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