Add warn if kvm driver version is old

Author: josedonizetti

Diff for: cmd/minikube/cmd/start.go

@@ -26,6 +26,7 @@ import (
 	"os/exec"
 	"os/user"
 	"path/filepath"
+	"regexp"
 	"runtime"
 	"strconv"
 	"strings"
@@ -210,6 +211,8 @@ func runStart(cmd *cobra.Command, args []string) {
 		exit.WithError("Failed to save config", err)
 	}
 
+	validateDriverVersion(viper.GetString(vmDriver))
+
 	m, err := machine.NewAPIClient()
 	if err != nil {
 		exit.WithError("Failed to get machine client", err)
@@ -850,3 +853,50 @@ func saveConfig(clusterConfig cfg.Config) error {
 	}
 	return nil
 }
+
+func validateDriverVersion(vmDriver string) {
+	if vmDriver == constants.DriverKvm2 {
+		cmd := exec.Command("docker-machine-driver-kvm2", "version")
+		output, err := cmd.Output()
+
+		// we don't want to fail if an error was returned, libmachine has a nice message for the user if
+		// the driver isn't present
+		if err != nil {
+			console.Warning("Error checking driver version: %v", err)
+		}
+
+		v := extractVMDriverVersion(string(output))
+
+		if len(v) == 0 {
+			exit.WithCode(exit.Failure, "Please upgrade the 'docker-machine-driver-kvm2'.")
+		}
+
+		vmDriverVersion, err := semver.Make(v)
+		if err != nil {
+			console.Warning("Error parsing vmDriver version: %v", err)
+			return
+		}
+
+		minikubeVersion, err := version.GetSemverVersion()
+		if err != nil {
+			console.Warning("Error parsing minukube version: %v", err)
+			return
+		}
+
+		if vmDriverVersion.LT(minikubeVersion) {
+			console.Warning("The 'docker-machine-driver-kvm2' version is old. Please consider upgrading.")
+		}
+	}
+}
+
+func extractVMDriverVersion(s string) string {
+	versionRegex := regexp.MustCompile(`version:(.*)`)
+	matches := versionRegex.FindStringSubmatch(s)
+
+	if len(matches) != 2 {
+		return ""
+	}
+
+	v := strings.TrimSpace(matches[1])
+	return strings.TrimPrefix(v, version.VersionPrefix)
+}

Diff for: cmd/minikube/cmd/start_test.go

@@ -0,0 +1,45 @@
+/*
+Copyright 2016 The Kubernetes Authors All rights reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package cmd
+
+import (
+	"testing"
+)
+
+func Test_extractVMDriverVersion(t *testing.T) {
+	v := extractVMDriverVersion("")
+	if len(v) != 0 {
+		t.Error("Expected empty string")
+	}
+
+	v = extractVMDriverVersion("random text")
+	if len(v) != 0 {
+		t.Error("Expected empty string")
+	}
+
+	expectedVersion := "1.2.3"
+
+	v = extractVMDriverVersion("version: v1.2.3")
+	if expectedVersion != v {
+		t.Errorf("Expected version: %s, got: %s", expectedVersion, v)
+	}
+
+	v = extractVMDriverVersion("version: 1.2.3")
+	if expectedVersion != v {
+		t.Errorf("Expected version: %s, got: %s", expectedVersion, v)
+	}
+}