Replace string comparison with class method

cmd/minikube/cmd/start.go

@@ -209,7 +209,8 @@ func runStart(cmd *cobra.Command, args []string) {
 	selectedEnableDefaultCNI := viper.GetBool(enableDefaultCNI)
 
 	// default network plugin (cni)
-	if selectedContainerRuntime != "" {
+	r, err := cruntime.New(cruntime.Config{Type: selectedContainerRuntime})
+	if err == nil && r.DefaultCNI() {
 		if !cmd.Flags().Changed(networkPlugin) {
 			selectedNetworkPlugin = "cni"
 			if !cmd.Flags().Changed(enableDefaultCNI) {

pkg/minikube/cruntime/containerd.go

@@ -41,6 +41,11 @@ func (r *Containerd) SocketPath() string {
 	return "/run/containerd/containerd.sock"
 }
 
+// DefaultCNI returns whether to use CNI networking by default
+func (r *Containerd) DefaultCNI() bool {
+	return true
+}
+
 // Active returns if containerd is active on the host
 func (r *Containerd) Active() bool {
 	err := r.Runner.Run("systemctl is-active --quiet service containerd")

pkg/minikube/cruntime/crio.go

@@ -41,6 +41,11 @@ func (r *CRIO) SocketPath() string {
 	return "/var/run/crio/crio.sock"
 }
 
+// DefaultCNI returns whether to use CNI networking by default
+func (r *CRIO) DefaultCNI() bool {
+        return true
+}
+
 // Available returns an error if it is not possible to use this runtime on a host
 func (r *CRIO) Available() error {
 	return r.Runner.Run("command -v crio")

pkg/minikube/cruntime/cruntime.go

@@ -49,6 +49,8 @@ type Manager interface {
 	KubeletOptions() map[string]string
 	// SocketPath returns the path to the socket file for a given runtime
 	SocketPath() string
+	// DefaultCNI returns whether to use CNI networking by default
+	DefaultCNI() bool
 
 	// Load an image idempotently into the runtime on a host
 	LoadImage(string) error

pkg/minikube/cruntime/docker.go

@@ -40,6 +40,11 @@ func (r *Docker) SocketPath() string {
 	return r.Socket
 }
 
+// DefaultCNI returns whether to use CNI networking by default
+func (r *Docker) DefaultCNI() bool {
+	return false
+}
+
 // Available returns an error if it is not possible to use this runtime on a host
 func (r *Docker) Available() error {
 	_, err := exec.LookPath("docker")