bug fix #45156. Make cloud-provider flag mandatory

cmd/cloud-controller-manager/app/options/options.go

@@ -69,7 +69,7 @@ func NewCloudControllerManagerServer() *CloudControllerManagerServer {
 func (s *CloudControllerManagerServer) AddFlags(fs *pflag.FlagSet) {
 	fs.Int32Var(&s.Port, "port", s.Port, "The port that the cloud-controller-manager's http service runs on")
 	fs.Var(componentconfig.IPVar{Val: &s.Address}, "address", "The IP address to serve on (set to 0.0.0.0 for all interfaces)")
-	fs.StringVar(&s.CloudProvider, "cloud-provider", s.CloudProvider, "The provider of cloud services. Empty for no provider.")
+	fs.StringVar(&s.CloudProvider, "cloud-provider", s.CloudProvider, "The provider of cloud services. Cannot be empty.")
 	fs.StringVar(&s.CloudConfigFile, "cloud-config", s.CloudConfigFile, "The path to the cloud provider configuration file.  Empty string for no configuration file.")
 	fs.DurationVar(&s.MinResyncPeriod.Duration, "min-resync-period", s.MinResyncPeriod.Duration, "The resync period in reflectors will be random between MinResyncPeriod and 2*MinResyncPeriod")
 	fs.DurationVar(&s.NodeMonitorPeriod.Duration, "node-monitor-period", s.NodeMonitorPeriod.Duration,

cmd/cloud-controller-manager/controller-manager.go

@@ -52,6 +52,10 @@ func main() {
 
 	verflag.PrintAndExitIfRequested()
 
+	if s.CloudProvider == "" {
+		glog.Errorf("--cloud-provider cannot be empty")
+	}
+
 	cloud, err := cloudprovider.InitCloudProvider(s.CloudProvider, s.CloudConfigFile)
 	if err != nil {
 		glog.Fatalf("Cloud provider could not be initialized: %v", err)