Bump the minimum kubeadm control plane version to v1.6.0-alpha.2

cmd/kubeadm/app/cmd/defaults.go

@@ -60,7 +60,7 @@ func setInitDynamicDefaults(cfg *kubeadmapi.MasterConfiguration) error {
 		return fmt.Errorf("couldn't parse kubernetes version %q: %v", cfg.KubernetesVersion, err)
 	}
 	if k8sVersion.LT(minK8sVersion) {
-		return fmt.Errorf("this version of kubeadm only supports deploying clusters with the control plane version >= v1.6.0-alpha.1. Current version: %s", cfg.KubernetesVersion)
+		return fmt.Errorf("this version of kubeadm only supports deploying clusters with the control plane version >= v%s. Current version: %s", kubeadmconstants.MinimumControlPlaneVersion, cfg.KubernetesVersion)
 	}
 
 	fmt.Printf("[init] Using Kubernetes version: %s\n", cfg.KubernetesVersion)

cmd/kubeadm/app/constants/constants.go

@@ -44,7 +44,7 @@ const (
 	AuthzModeWebhook     = "Webhook"
 
 	// Important: a "v"-prefix shouldn't exist here; semver doesn't allow that
-	MinimumControlPlaneVersion = "1.6.0-alpha.1"
+	MinimumControlPlaneVersion = "1.6.0-alpha.2"
 
 	// Constants for what we name our ServiceAccounts with limited access to the cluster in case of RBAC
 	KubeDNSServiceAccountName   = "kube-dns"