Initial proptotyping for kubernetes#2570

Author: nanikjava

cmd/minikube/cmd/start.go

@@ -179,7 +179,7 @@ func initMinikubeFlags() {
 
 // initKubernetesFlags inits the commandline flags for kubernetes related options
 func initKubernetesFlags() {
-	startCmd.Flags().String(kubernetesVersion, constants.DefaultKubernetesVersion, "The kubernetes version that the minikube VM will use (ex: v1.2.3)")
+	startCmd.Flags().String(kubernetesVersion, "", "The kubernetes version that the minikube VM will use (ex: v1.2.3)")
 	startCmd.Flags().Var(&extraOptions, "extra-config",
 		`A set of key=value pairs that describe configuration that may be passed to different components.
 		The key should be '.' separated, and the first part before the dot is the component to apply the configuration to.
@@ -1063,6 +1063,9 @@ func getKubernetesVersion(old *cfg.Config) (string, bool) {
 	isUpgrade := false
 	if rawVersion == "" {
 		rawVersion = constants.DefaultKubernetesVersion
+		if ( old.KubernetesConfig.KubernetesVersion != "" ) {
+			rawVersion = old.KubernetesConfig.KubernetesVersion
+		}
 	}
 
 	nvs, err := semver.Make(strings.TrimPrefix(rawVersion, version.VersionPrefix))
@@ -1107,7 +1110,7 @@ func getKubernetesVersion(old *cfg.Config) (string, bool) {
 * Reuse the existing cluster with Kubernetes v{{.old}} or newer: Run "minikube start {{.profile}} --kubernetes-version={{.old}}"`, out.V{"new": nvs, "old": ovs, "profile": profileArg})
 
 	}
-	if nvs.GT(ovs) {
+	if ( nvs.GT(ovs) && viper.GetString(kubernetesVersion)!="") {
 		out.T(out.ThumbsUp, "Upgrading from Kubernetes {{.old}} to {{.new}}", out.V{"old": ovs, "new": nvs})
 		isUpgrade = true
 	}