Use better error var name in kube-proxy code (#72849)

cmd/kube-controller-manager/app/core.go

@@ -211,7 +211,7 @@ func startPersistentVolumeBinderController(ctx ControllerContext) (http.Handler,
 
 func startAttachDetachController(ctx ControllerContext) (http.Handler, bool, error) {
 	if ctx.ComponentConfig.AttachDetachController.ReconcilerSyncLoopPeriod.Duration < time.Second {
-		return nil, true, fmt.Errorf("Duration time must be greater than one second as set via command line option reconcile-sync-loop-period.")
+		return nil, true, fmt.Errorf("Duration time must be greater than one second as set via command line option reconcile-sync-loop-period")
 	}
 	csiClientConfig := ctx.ClientBuilder.ConfigOrDie("attachdetach-controller")
 	// csiClient works with CRDs that support json only

cmd/kube-proxy/app/conntrack.go

@@ -43,7 +43,7 @@ type Conntracker interface {
 
 type realConntracker struct{}
 
-var readOnlySysFSError = errors.New("readOnlySysFS")
+var errReadOnlySysFS = errors.New("readOnlySysFS")
 
 func (rct realConntracker) SetMax(max int) error {
 	if err := rct.setIntSysCtl("nf_conntrack_max", max); err != nil {
@@ -70,14 +70,14 @@ func (rct realConntracker) SetMax(max int) error {
 	// issue (https://github.com/docker/docker/issues/24000). Setting
 	// conntrack will fail when sysfs is readonly. When that happens, we
 	// don't set conntrack hashsize and return a special error
-	// readOnlySysFSError here. The caller should deal with
-	// readOnlySysFSError differently.
+	// errReadOnlySysFS here. The caller should deal with
+	// errReadOnlySysFS differently.
 	writable, err := isSysFSWritable()
 	if err != nil {
 		return err
 	}
 	if !writable {
-		return readOnlySysFSError
+		return errReadOnlySysFS
 	}
 	// TODO: generify this and sysctl to a new sysfs.WriteInt()
 	klog.Infof("Setting conntrack hashsize to %d", max/4)
@@ -126,7 +126,7 @@ func isSysFSWritable() (bool, error) {
 		}
 		klog.Errorf("sysfs is not writable: %+v (mount options are %v)",
 			mountPoint, mountPoint.Opts)
-		return false, readOnlySysFSError
+		return false, errReadOnlySysFS
 	}
 
 	return false, errors.New("No sysfs mounted")

cmd/kube-proxy/app/server.go

@@ -550,10 +550,10 @@ func (s *ProxyServer) Run() error {
 		if max > 0 {
 			err := s.Conntracker.SetMax(max)
 			if err != nil {
-				if err != readOnlySysFSError {
+				if err != errReadOnlySysFS {
 					return err
 				}
-				// readOnlySysFSError is caused by a known docker issue (https://github.com/docker/docker/issues/24000),
+				// errReadOnlySysFS is caused by a known docker issue (https://github.com/docker/docker/issues/24000),
 				// the only remediation we know is to restart the docker daemon.
 				// Here we'll send an node event with specific reason and message, the
 				// administrator should decide whether and how to handle this issue,