Disable ETCD Learner Mode in v1.29

ETCD Learner Mode went to Beta in k8s 1.29 and is now default enabled.

When a new stacked etcd instance comes up, it joins the cluster in learner mode.

The API Server cannot perform rpc calls against its etcd instance, and fails to come online.

In theory the etcd instance should be promoted to a full member and this issue should
be resolved, but for some reason this is not happening.

While we investigate a root cause, we are disabling this new feature flag explicitly.

pkg/providers/cloudstack/config/template-cp.yaml

@@ -67,6 +67,10 @@ spec:
       name: {{.controlPlaneTemplateName}}
   kubeadmConfigSpec:
     clusterConfiguration:
+{{- if (ge (atoi $kube_minor_version) 29) }}
+      featureGates:
+        EtcdLearnerMode: false
+{{- end }}
       imageRepository: {{.kubernetesRepository}}
       etcd:
 {{- if .externalEtcd }}

pkg/providers/cloudstack/testdata/expected_results_encryption_config_cp_1_29.yaml

@@ -59,6 +59,8 @@ spec:
       name: test-control-plane-template-1234567890000
   kubeadmConfigSpec:
     clusterConfiguration:
+      featureGates:
+        EtcdLearnerMode: false
       imageRepository: public.ecr.aws/eks-distro/kubernetes
       etcd:
         local:

pkg/providers/snow/apibuilder.go

@@ -55,6 +55,9 @@ func KubeadmControlPlane(log logr.Logger, clusterSpec *cluster.Spec, snowMachine
 	joinConfigKubeletExtraArg["provider-id"] = "aws-snow:////'{{ ds.meta_data.instance_id }}'"
 
 	addStackedEtcdExtraArgsInKubeadmControlPlane(kcp, clusterSpec.Cluster.Spec.ExternalEtcdConfiguration)
+	if versionsBundle.KubeVersion == "1.29" {
+		disableEtcdLearnerMode(kcp)
+	}
 
 	machineConfig := clusterSpec.SnowMachineConfig(clusterSpec.Cluster.Spec.ControlPlaneConfiguration.MachineGroupRef.Name)
 

pkg/providers/snow/apibuilder_test.go

@@ -108,7 +108,7 @@ func wantKubeadmControlPlane(kubeVersion v1alpha1.KubernetesVersion) *controlpla
 	wantReplicas := int32(3)
 	wantMaxSurge := intstr.FromInt(1)
 	versionBundles := givenVersionsBundle(kubeVersion)
-	return &controlplanev1.KubeadmControlPlane{
+	kcp := &controlplanev1.KubeadmControlPlane{
 		TypeMeta: metav1.TypeMeta{
 			APIVersion: "controlplane.cluster.x-k8s.io/v1beta1",
 			Kind:       "KubeadmControlPlane",
@@ -200,6 +200,14 @@ func wantKubeadmControlPlane(kubeVersion v1alpha1.KubernetesVersion) *controlpla
 			Version:  versionBundles.KubeDistro.Kubernetes.Tag,
 		},
 	}
+
+	if kubeVersion == "1.29" {
+		kcp.Spec.KubeadmConfigSpec.ClusterConfiguration.FeatureGates = map[string]bool{
+			"EtcdLearnerMode": false,
+		}
+	}
+
+	return kcp
 }
 
 func wantKubeadmControlPlaneUnstackedEtcd() *controlplanev1.KubeadmControlPlane {

pkg/providers/snow/etcd.go

@@ -15,3 +15,11 @@ func addStackedEtcdExtraArgsInKubeadmControlPlane(kcp *controlplanev1.KubeadmCon
 	stackedEtcdExtraArgs["listen-peer-urls"] = "https://0.0.0.0:2380"
 	stackedEtcdExtraArgs["listen-client-urls"] = "https://0.0.0.0:2379"
 }
+
+func disableEtcdLearnerMode(kcp *controlplanev1.KubeadmControlPlane) {
+	if kcp.Spec.KubeadmConfigSpec.ClusterConfiguration.FeatureGates == nil {
+		kcp.Spec.KubeadmConfigSpec.ClusterConfiguration.FeatureGates = map[string]bool{}
+	}
+
+	kcp.Spec.KubeadmConfigSpec.ClusterConfiguration.FeatureGates["EtcdLearnerMode"] = false
+}

pkg/providers/tinkerbell/config/template-cp.yaml

@@ -37,6 +37,11 @@ metadata:
 spec:
   kubeadmConfigSpec:
     clusterConfiguration:
+{{- $kube_minor_version := (index (splitList "." (trimPrefix "v" .kubernetesVersion)) 1) }}
+{{- if (ge (atoi $kube_minor_version) 29) }}
+      featureGates:
+        EtcdLearnerMode: false
+{{- end }}
       imageRepository: {{.kubernetesRepository}}
       etcd:
 {{- if .externalEtcd }}

pkg/providers/vsphere/config/template-cp.yaml

@@ -86,6 +86,10 @@ spec:
       name: {{.controlPlaneTemplateName}}
   kubeadmConfigSpec:
     clusterConfiguration:
+{{- if (ge (atoi $kube_minor_version) 29) }}
+      featureGates:
+        EtcdLearnerMode: false
+{{- end }}
       imageRepository: {{.kubernetesRepository}}
       etcd:
 {{- if .externalEtcd }}

pkg/providers/vsphere/testdata/expected_results_ubuntu_etcd_encryption_cp_1_29.yaml

@@ -78,6 +78,8 @@ spec:
       name: test-control-plane-template-1234567890000
   kubeadmConfigSpec:
     clusterConfiguration:
+      featureGates:
+        EtcdLearnerMode: false
       imageRepository: public.ecr.aws/eks-distro/kubernetes
       etcd:
         external: