plugin/kubernetes: Handle endpoint tombstones (#3887)

* check for nil
Signed-off-by: Chris O'Haver <cohaver@infoblox.com>

* handle tombstone
Signed-off-by: Chris O'Haver <cohaver@infoblox.com>

* move casting to caller. add comments.
Signed-off-by: Chris O'Haver <cohaver@infoblox.com>

* more sanding
Signed-off-by: Chris O'Haver <cohaver@infoblox.com>

* more scrubbing
Signed-off-by: Chris O'Haver <cohaver@infoblox.com>

* move object unwraping to switch cases
Signed-off-by: Chris O'Haver <cohaver@infoblox.com>

* oops remove debug
Signed-off-by: Chris O'Haver <cohaver@infoblox.com>

* remove cruft
Signed-off-by: Chris O'Haver <cohaver@infoblox.com>

plugin/kubernetes/controller.go

@@ -141,11 +141,14 @@ func newdnsController(ctx context.Context, kubeClient kubernetes.Interface, opts
 			func(clientState cache.Indexer, h cache.ResourceEventHandler) cache.ProcessFunc {
 				return func(obj interface{}) error {
 					for _, d := range obj.(cache.Deltas) {
-
-						apiEndpoints, obj := object.ToEndpoints(d.Object)
-
 						switch d.Type {
 						case cache.Sync, cache.Added, cache.Updated:
+							apiEndpoints, ok := d.Object.(*api.Endpoints)
+							if !ok {
+								return errors.New("got non-endpoint add/update")
+							}
+							obj := object.ToEndpoints(apiEndpoints)
+
 							if old, exists, err := clientState.Get(obj); err == nil && exists {
 								if err := clientState.Update(obj); err != nil {
 									return err
@@ -163,19 +166,39 @@ func newdnsController(ctx context.Context, kubeClient kubernetes.Interface, opts
 								h.OnAdd(d.Object)
 								dns.updateModifed()
 								recordDNSProgrammingLatency(dns.getServices(obj), apiEndpoints)
+								if !opts.skipAPIObjectsCleanup {
+									*apiEndpoints = api.Endpoints{}
+								}
 							}
 						case cache.Deleted:
+							apiEndpoints, ok := d.Object.(*api.Endpoints)
+							if !ok {
+								// Assume that the object must be a cache.DeletedFinalStateUnknown.
+								// This is essentially an indicator that the Endpoint was deleted, without a containing a
+								// up-to date copy of the Endpoints object. We need to use cache.DeletedFinalStateUnknown
+								// object so it can be properly deleted by store.Delete() below, which knows how to handle it.
+								tombstone, ok := d.Object.(cache.DeletedFinalStateUnknown)
+								if !ok {
+									return errors.New("expected tombstone")
+								}
+								apiEndpoints, ok = tombstone.Obj.(*api.Endpoints)
+								if !ok {
+									return errors.New("got non-endpoint tombstone")
+								}
+							}
+							obj := object.ToEndpoints(apiEndpoints)
+
 							if err := clientState.Delete(obj); err != nil {
 								return err
 							}
 							h.OnDelete(d.Object)
 							dns.updateModifed()
 							recordDNSProgrammingLatency(dns.getServices(obj), apiEndpoints)
-						}
 							if !opts.skipAPIObjectsCleanup {
 								*apiEndpoints = api.Endpoints{}
 							}
 						}
+					}
 					return nil
 				}
 			})

plugin/kubernetes/object/endpoint.go

@@ -44,12 +44,7 @@ type EndpointPort struct {
 func EndpointsKey(name, namespace string) string { return name + "." + namespace }
 
 // ToEndpoints converts an api.Endpoints to a *Endpoints.
-func ToEndpoints(obj interface{}) (*api.Endpoints, *Endpoints) {
-	end, ok := obj.(*api.Endpoints)
-	if !ok {
-		return nil, nil
-	}
-
+func ToEndpoints(end *api.Endpoints) *Endpoints {
 	e := &Endpoints{
 		Version:   end.GetResourceVersion(),
 		Name:      end.GetName(),
@@ -93,7 +88,7 @@ func ToEndpoints(obj interface{}) (*api.Endpoints, *Endpoints) {
 		}
 	}
 
-	return end, e
+	return e
 }
 
 // CopyWithoutSubsets copies e, without the subsets.