Pod watch: keep it low volume

Addressing PR kubernetes-sigs#1214 comments: bubbling up all (ingress backing)
pods events to main reconcile loop might trigger an excessive AWS
API calls volume. Let's keep that pod watch noise to the minimum
requiered for readiness gates: catching changes in `ContainerReady`.

internal/ingress/backend/endpoint.go

@@ -182,15 +182,10 @@ func (resolver *endpointResolver) resolveIP(ingress *extensions.Ingress, backend
 					continue
 				}
 
-				// check if all containers are ready
-				for _, condition := range pod.Status.Conditions {
-					if condition.Type == api.ContainersReady {
-						if condition.Status == api.ConditionTrue {
-							addresses = append(addresses, epAddr)
-						}
-						break
-					}
+				if IsPodSuitableAsIPTarget(pod) {
+					addresses = append(addresses, epAddr)
 				}
+
 			}
 			for _, epAddr := range addresses {
 				result = append(result, &elbv2.TargetDescription{
@@ -226,6 +221,17 @@ func IsNodeSuitableAsTrafficProxy(node *corev1.Node) bool {
 	return false
 }
 
+// IsPodSuitableAsIPTarget check whether pod is suitable as a TargetGroup's target
+// (currently tested: are all pod's containers ready?).
+func IsPodSuitableAsIPTarget(pod *corev1.Pod) bool {
+	for _, condition := range pod.Status.Conditions {
+		if condition.Type == api.ContainersReady {
+			return condition.Status == api.ConditionTrue
+		}
+	}
+	return false
+}
+
 // findServiceAndPort returns the service & servicePort by name
 func findServiceAndPort(store store.Storer, namespace string, serviceName string, servicePort intstr.IntOrString) (*corev1.Service, *corev1.ServicePort, error) {
 	serviceKey := namespace + "/" + serviceName

internal/ingress/controller/handlers/pod.go

@@ -2,11 +2,11 @@ package handlers
 
 import (
 	"context"
-	"reflect"
 
 	"github.com/golang/glog"
 	"github.com/kubernetes-sigs/aws-alb-ingress-controller/internal/alb/tg"
 	"github.com/kubernetes-sigs/aws-alb-ingress-controller/internal/ingress/annotations/class"
+	"github.com/kubernetes-sigs/aws-alb-ingress-controller/internal/ingress/backend"
 	corev1 "k8s.io/api/core/v1"
 	extensions "k8s.io/api/extensions/v1beta1"
 	"k8s.io/apimachinery/pkg/types"
@@ -27,14 +27,17 @@ type EnqueueRequestsForPodsEvent struct {
 
 // Create is called in response to an create event - e.g. Pod Creation.
 func (h *EnqueueRequestsForPodsEvent) Create(e event.CreateEvent, queue workqueue.RateLimitingInterface) {
-	h.enqueueImpactedIngresses(e.Object.(*corev1.Pod), queue)
 }
 
 // Update is called in response to an update event -  e.g. Pod Updated.
 func (h *EnqueueRequestsForPodsEvent) Update(e event.UpdateEvent, queue workqueue.RateLimitingInterface) {
 	podOld := e.ObjectOld.(*corev1.Pod)
 	podNew := e.ObjectNew.(*corev1.Pod)
-	if !reflect.DeepEqual(podOld, podNew) {
+
+	// we only enqueue reconcile events for pods whose containers changed state
+	// (ContainersReady vs not ContainersReady).
+	if backend.IsPodSuitableAsIPTarget(podNew) != backend.IsPodSuitableAsIPTarget(podOld) {
+		// ... and only for pods referenced by an endpoint backing an ingress:
 		h.enqueueImpactedIngresses(podNew, queue)
 	}
 }
@@ -96,6 +99,7 @@ func (h *EnqueueRequestsForPodsEvent) enqueueImpactedIngresses(pod *corev1.Pod,
 						Name:      ingress.Name,
 					},
 				})
+				break
 			}
 		}
 	}