BZ1714769: fix kubeletconfig zero MCP errors

Do not requeue the key if there are zero MCPs. Prevents multiple status
updates and will not succeed.

ref: https://bugzilla.redhat.com/show_bug.cgi?id=1714769

pkg/controller/kubelet-config/kubelet_config_controller.go

@@ -2,6 +2,7 @@ package kubeletconfig
 
 import (
  "encoding/json"
+ "errors"
  "fmt"
  "reflect"
  "time"
@@ -12,7 +13,7 @@ import (
  "github.com/vincent-petithory/dataurl"
 
  v1 "k8s.io/api/core/v1"
- "k8s.io/apimachinery/pkg/api/errors"
+ macherrors "k8s.io/apimachinery/pkg/api/errors"
  metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
  "k8s.io/apimachinery/pkg/labels"
  "k8s.io/apimachinery/pkg/types"
@@ -59,6 +60,8 @@ var updateBackoff = wait.Backoff{
  Jitter: 1.0,
 }
 
+var errCouldNotFindMCPSet = errors.New("could not find any MachineConfigPool set for KubeletConfig")
+
 // A list of fields a user cannot set within the KubeletConfig CR. If a user
 // were to set these values, then the system may become unrecoverable (ie: not
 // recover after a reboot).
@@ -156,7 +159,7 @@ func New(
 
  ctrl.featLister = featInformer.Lister()
  ctrl.featListerSynced = featInformer.Informer().HasSynced
- 
+
  ctrl.patchKubeletConfigsFunc = ctrl.patchKubeletConfigs
 
  return ctrl
@@ -236,7 +239,7 @@ func (ctrl *Controller) cascadeDelete(cfg *mcfgv1.KubeletConfig) error {
  }
  mcName := cfg.GetFinalizers()[0]
  err := ctrl.client.Machineconfiguration().MachineConfigs().Delete(mcName, &metav1.DeleteOptions{})
- if err != nil && !errors.IsNotFound(err) {
+ if err != nil && !macherrors.IsNotFound(err) {
  return err
  }
  if err := ctrl.popFinalizerFromKubeletConfig(cfg); err != nil {
@@ -284,7 +287,7 @@ func (ctrl *Controller) processNextWorkItem() bool {
 }
 
 func (ctrl *Controller) handleErr(err error, key interface{}) {
- if err == nil {
+ if err == nil || err == errCouldNotFindMCPSet {
  ctrl.queue.Forget(key)
  return
  }
@@ -373,7 +376,7 @@ func (ctrl *Controller) syncKubeletConfig(key string) error {
 
  // Fetch the KubeletConfig
  cfg, err := ctrl.mckLister.Get(name)
- if errors.IsNotFound(err) {
+ if macherrors.IsNotFound(err) {
  glog.V(2).Infof("KubeletConfig %v has been deleted", key)
  return nil
  }
@@ -415,7 +418,7 @@ func (ctrl *Controller) syncKubeletConfig(key string) error {
  }
 
  features, err := ctrl.featLister.Get(clusterFeatureInstanceName)
- if errors.IsNotFound(err) {
+ if macherrors.IsNotFound(err) {
  features = createNewDefaultFeatureGate()
  } else if err != nil {
  glog.V(2).Infof("%v", err)
@@ -434,10 +437,10 @@ func (ctrl *Controller) syncKubeletConfig(key string) error {
  // Get MachineConfig
  managedKey := getManagedKubeletConfigKey(pool)
  mc, err := ctrl.client.Machineconfiguration().MachineConfigs().Get(managedKey, metav1.GetOptions{})
- if err != nil && !errors.IsNotFound(err) {
+ if err != nil && !macherrors.IsNotFound(err) {
  return ctrl.syncStatusOnly(cfg, err, "could not find MachineConfig: %v", managedKey)
  }
- isNotFound := errors.IsNotFound(err)
+ isNotFound := macherrors.IsNotFound(err)
  // Generate the original KubeletConfig
  originalKubeletIgn, err := ctrl.generateOriginalKubeletConfig(role)
  if err != nil {
@@ -502,7 +505,7 @@ func (ctrl *Controller) syncKubeletConfig(key string) error {
 func (ctrl *Controller) popFinalizerFromKubeletConfig(kc *mcfgv1.KubeletConfig) error {
  return retry.RetryOnConflict(updateBackoff, func() error {
  newcfg, err := ctrl.mckLister.Get(kc.Name)
- if errors.IsNotFound(err) {
+ if macherrors.IsNotFound(err) {
  return nil
  }
  if err != nil {
@@ -538,7 +541,7 @@ func (ctrl *Controller) patchKubeletConfigs(name string, patch []byte) error {
 func (ctrl *Controller) addFinalizerToKubeletConfig(kc *mcfgv1.KubeletConfig, mc *mcfgv1.MachineConfig) error {
  return retry.RetryOnConflict(updateBackoff, func() error {
  newcfg, err := ctrl.mckLister.Get(kc.Name)
- if errors.IsNotFound(err) {
+ if macherrors.IsNotFound(err) {
  return nil
  }
  if err != nil {
@@ -586,7 +589,7 @@ func (ctrl *Controller) getPoolsForKubeletConfig(config *mcfgv1.KubeletConfig) (
  }
 
  if len(pools) == 0 {
- return nil, fmt.Errorf("could not find any MachineConfigPool set for KubeletConfig %s", config.Name)
+ return nil, errCouldNotFindMCPSet
  }
 
  return pools, nil