Fixes validation on image repository URL when it contains port but not schema

Refactor the way validations are done to use regular expression
Explicitly use "auto" as the imageRepo instead of an empty string when URL received is invalid

cmd/minikube/cmd/start.go

@@ -1408,32 +1408,39 @@ func validateRegistryMirror() {
 // args match the format of registry.cn-hangzhou.aliyuncs.com/google_containers
 // also "<hostname>[:<port>]"
 func validateImageRepository(imageRepo string) (validImageRepo string) {
+	expression := regexp.MustCompile(`^(?:(\w+)\:\/\/)?([-a-zA-Z0-9]{1,}(?:\.[-a-zA-Z]{1,}){0,})(?:\:(\d+))?(\/.*)?$`)
 
 	if strings.ToLower(imageRepo) == "auto" {
-		validImageRepo = "auto"
+		imageRepo = "auto"
 	}
-	URL, err := url.Parse(imageRepo)
 
-	if err != nil {
-		klog.Errorln("Error Parsing URL: ", err)
+	if !expression.MatchString(imageRepo) {
+		klog.Errorln("Provided repository is not a valid URL. Defaulting to \"auto\"")
+		imageRepo = "auto"
 	}
 
 	var imageRepoPort string
+	groups := expression.FindStringSubmatch(imageRepo)
 
-	if URL.Port() != "" && strings.Contains(imageRepo, ":"+URL.Port()) {
-		imageRepoPort = ":" + URL.Port()
+	scheme := groups[1]
+	hostname := groups[2]
+	port := groups[3]
+	path := groups[4]
+
+	if port != "" && strings.Contains(imageRepo, ":"+port) {
+		imageRepoPort = ":" + port
 	}
 
 	// tips when imageRepo ended with a trailing /.
 	if strings.HasSuffix(imageRepo, "/") {
-		out.Infof("The --image-repository flag your provided ended with a trailing / that could cause conflict in kuberentes, removed automatically")
+		out.Infof("The --image-repository flag your provided ended with a trailing / that could cause conflict in kubernetes, removed automatically")
 	}
 	// tips when imageRepo started with scheme such as http(s).
-	if URL.Scheme != "" {
-		out.Infof("The --image-repository flag your provided contains Scheme: {{.scheme}}, which will be removed automatically", out.V{"scheme": URL.Scheme})
+	if scheme != "" {
+		out.Infof("The --image-repository flag you provided contains Scheme: {{.scheme}}, which will be removed automatically", out.V{"scheme": scheme})
 	}
 
-	validImageRepo = URL.Hostname() + imageRepoPort + strings.TrimSuffix(URL.Path, "/")
+	validImageRepo = hostname + imageRepoPort + strings.TrimSuffix(path, "/")
 
 	return validImageRepo
 }

cmd/minikube/cmd/start_test.go

@@ -346,6 +346,14 @@ func TestValidateImageRepository(t *testing.T) {
 			imageRepository:      "auto",
 			validImageRepository: "auto",
 		},
+		{
+			imageRepository:      "$$$$invalid",
+			validImageRepository: "auto",
+		},
+		{
+			imageRepository:      "",
+			validImageRepository: "auto",
+		},
 		{
 			imageRepository:      "http://registry.test.com/google_containers/",
 			validImageRepository: "registry.test.com/google_containers",
@@ -370,6 +378,10 @@ func TestValidateImageRepository(t *testing.T) {
 			imageRepository:      "https://registry.test.com:6666/google_containers",
 			validImageRepository: "registry.test.com:6666/google_containers",
 		},
+		{
+			imageRepository:      "registry.test.com:6666/google_containers",
+			validImageRepository: "registry.test.com:6666/google_containers",
+		},
 	}
 
 	for _, test := range tests {