Remove terminating pods from endpoints

The standard endpoint controller removes, by default, terminating pods
from an endpoint: kubernetes/kubernetes@2aaf8bd#diff-a1a9c0efe93384ed9a010e65e8ad4604R316

This behaviour let the service clients time to react to stop sending
traffic to the terminating pods while finishing processing current
requests, as pods in "terminating" state are technically still able to
accept connections and handle requests.

It allows to smoothly replace the pods by the activator when all pods
are entering the terminating state, for the reason described above.

pkg/endpoints/controller/endpoints_manager.go

@@ -5,6 +5,7 @@ import (
 	"encoding/base64"
 	"encoding/json"
 	"fmt"
+	"strconv"
 	"sync"
 
 	"github.com/deislabs/osiris/pkg/kubernetes"
@@ -18,6 +19,14 @@ import (
 	endpointsv1 "k8s.io/kubernetes/pkg/api/v1/endpoints"
 )
 
+const (
+
+	// tolerateAnnoration backport annotation
+	// TolerateUnreadyEndpointsAnnotation definition from
+	// k8s.io/kubernetes/pkg/controller/endpoint
+	tolerateAnnoration = "service.alpha.kubernetes.io/tolerate-unready-endpoints"
+)
+
 // endpointsManager is a controller responsible for the on-going management of
 // the endpoints resource corresponding to a single Osiris-enabled service
 type endpointsManager struct {
@@ -127,6 +136,27 @@ func (e *endpointsManager) syncAppPod(obj interface{}) {
 			break
 		}
 	}
+
+	// If the user specified the older (deprecated) annotation,
+	// we have to respect it.
+	tolerateUnreadyEndpoints := e.service.Spec.PublishNotReadyAddresses
+	v, ok := e.service.Annotations[tolerateAnnoration]
+	if ok {
+		b, err := strconv.ParseBool(v)
+		if err == nil {
+			tolerateUnreadyEndpoints = b
+		} else {
+			glog.Errorf(
+				"Failed to parse annotation %v: %v",
+				tolerateAnnoration,
+				err,
+			)
+		}
+	}
+
+	if !tolerateUnreadyEndpoints && pod.DeletionTimestamp != nil {
+		ready = false
+	}
 	glog.Infof(
 		"Informed about pod %s for service %s in namespace %s; its IP is %s and "+
 			"its ready condition is %t",