Updating TopologyCache to disregard unready endpoints in calculations

pkg/controller/endpointslice/reconciler_test.go

@@ -516,7 +516,7 @@ func TestReconcile1EndpointSlicePublishNotReadyAddresses(t *testing.T) {
 	endpointSlices := fetchEndpointSlices(t, client, namespace)
 	for _, endpointSlice := range endpointSlices {
 		for i, endpoint := range endpointSlice.Endpoints {
-			if !*endpoint.Conditions.Ready {
+			if !endpointsliceutil.EndpointReady(endpoint) {
 				t.Errorf("Expected endpoints[%d] to be ready", i)
 			}
 		}

pkg/controller/endpointslice/topologycache/sliceinfo.go

@@ -30,16 +30,16 @@ type SliceInfo struct {
 	Unchanged   []*discovery.EndpointSlice
 }
 
-func (si *SliceInfo) getTotalEndpoints() int {
+func (si *SliceInfo) getTotalReadyEndpoints() int {
 	totalEndpoints := 0
 	for _, slice := range si.ToCreate {
-		totalEndpoints += len(slice.Endpoints)
+		totalEndpoints += numReadyEndpoints(slice.Endpoints)
 	}
 	for _, slice := range si.ToUpdate {
-		totalEndpoints += len(slice.Endpoints)
+		totalEndpoints += numReadyEndpoints(slice.Endpoints)
 	}
 	for _, slice := range si.Unchanged {
-		totalEndpoints += len(slice.Endpoints)
+		totalEndpoints += numReadyEndpoints(slice.Endpoints)
 	}
 	return totalEndpoints
 }

pkg/controller/endpointslice/topologycache/sliceinfo_test.go

@@ -21,13 +21,15 @@ import (
 	"testing"
 
 	discovery "k8s.io/api/discovery/v1"
+	utilpointer "k8s.io/utils/pointer"
 )
 
-func TestGetTotalEndpoints(t *testing.T) {
+func Test_getTotalReadyEndpoints(t *testing.T) {
 	testCases := []struct {
 		name               string
 		si                 *SliceInfo
-		expectedTotal int
+		expectedTotalReady int
+		expectedTotal      int // this is really just testing the test helper
 	}{{
 		name:          "empty",
 		si:            &SliceInfo{},
@@ -35,30 +37,49 @@ func TestGetTotalEndpoints(t *testing.T) {
 	}, {
 		name: "empty slice",
 		si: &SliceInfo{
-			ToCreate: []*discovery.EndpointSlice{sliceWithNEndpoints(0)},
+			ToCreate: []*discovery.EndpointSlice{sliceWithNEndpoints(0, 0)},
 		},
+		expectedTotalReady: 0,
 		expectedTotal:      0,
 	}, {
 		name: "multiple slices",
 		si: &SliceInfo{
-			ToCreate: []*discovery.EndpointSlice{sliceWithNEndpoints(15), sliceWithNEndpoints(8)},
+			ToCreate: []*discovery.EndpointSlice{sliceWithNEndpoints(15, 0), sliceWithNEndpoints(8, 0)},
 		},
+		expectedTotalReady: 23,
 		expectedTotal:      23,
 	}, {
 		name: "slices for all",
 		si: &SliceInfo{
-			ToCreate:  []*discovery.EndpointSlice{sliceWithNEndpoints(15), sliceWithNEndpoints(8)},
+			ToCreate:  []*discovery.EndpointSlice{sliceWithNEndpoints(15, 0), sliceWithNEndpoints(8, 0)},
-			ToUpdate:  []*discovery.EndpointSlice{sliceWithNEndpoints(2)},
+			ToUpdate:  []*discovery.EndpointSlice{sliceWithNEndpoints(2, 0)},
-			Unchanged: []*discovery.EndpointSlice{sliceWithNEndpoints(100), sliceWithNEndpoints(90)},
+			Unchanged: []*discovery.EndpointSlice{sliceWithNEndpoints(100, 0), sliceWithNEndpoints(90, 0)},
 		},
+		expectedTotalReady: 215,
 		expectedTotal:      215,
+	}, {
+		name: "slices for all with some unready",
+		si: &SliceInfo{
+			ToCreate:  []*discovery.EndpointSlice{sliceWithNEndpoints(15, 3), sliceWithNEndpoints(5, 4)},
+			ToUpdate:  []*discovery.EndpointSlice{sliceWithNEndpoints(3, 8)},
+			Unchanged: []*discovery.EndpointSlice{sliceWithNEndpoints(98, 2), sliceWithNEndpoints(90, 6)},
+		},
+		expectedTotalReady: 211,
+		expectedTotal:      234,
 	}}
 
 	for _, tc := range testCases {
 		t.Run(tc.name, func(t *testing.T) {
-			actualTotal := tc.si.getTotalEndpoints()
+			actualTotal := countEndpoints(tc.si.ToCreate) + countEndpoints(tc.si.ToUpdate) + countEndpoints(tc.si.Unchanged)
+
 			if actualTotal != tc.expectedTotal {
-				t.Errorf("Expected %d, got %d", tc.expectedTotal, actualTotal)
+				// This likely means that sliceWithNEndpoints or countEndpoints are not working as expected
+				t.Errorf("Problem with test or test helper. Expected %d total endpoints, got %d", tc.expectedTotal, actualTotal)
+			}
+
+			actualTotalReady := tc.si.getTotalReadyEndpoints()
+			if actualTotalReady != tc.expectedTotalReady {
+				t.Errorf("Expected %d, got %d", tc.expectedTotalReady, actualTotalReady)
 			}
 		})
 	}
@@ -66,14 +87,32 @@ func TestGetTotalEndpoints(t *testing.T) {
 
 // helpers
 
-func sliceWithNEndpoints(n int) *discovery.EndpointSlice {
+func sliceWithNEndpoints(ready, unready int) *discovery.EndpointSlice {
-	endpoints := []discovery.Endpoint{}
+	endpoints := make([]discovery.Endpoint, ready+unready)
 
-	for i := 0; i < n; i++ {
+	for i := 0; i < ready; i++ {
-		endpoints = append(endpoints, discovery.Endpoint{Addresses: []string{fmt.Sprintf("10.1.2.%d", i)}})
+		endpoints[i] = discovery.Endpoint{
+			Addresses:  []string{fmt.Sprintf("10.1.2.%d", i)},
+			Conditions: discovery.EndpointConditions{Ready: utilpointer.BoolPtr(true)},
+		}
+	}
+
+	for i := 0; i < unready; i++ {
+		endpoints[ready+i] = discovery.Endpoint{
+			Addresses:  []string{fmt.Sprintf("10.1.2.%d", ready+i)},
+			Conditions: discovery.EndpointConditions{Ready: utilpointer.BoolPtr(false)},
+		}
 	}
 
 	return &discovery.EndpointSlice{
 		Endpoints: endpoints,
 	}
 }
+
+func countEndpoints(slices []*discovery.EndpointSlice) int {
+	total := 0
+	for _, slice := range slices {
+		total += len(slice.Endpoints)
+	}
+	return total
+}

pkg/controller/endpointslice/topologycache/topologycache.go

@@ -24,6 +24,7 @@ import (
 	discovery "k8s.io/api/discovery/v1"
 	"k8s.io/apimachinery/pkg/api/resource"
 	"k8s.io/klog/v2"
+	endpointsliceutil "k8s.io/kubernetes/pkg/controller/util/endpointslice"
 )
 
 const (
@@ -84,7 +85,7 @@ func (t *TopologyCache) GetOverloadedServices() []string {
 // AddHints adds or updates topology hints on EndpointSlices and returns updated
 // lists of EndpointSlices to create and update.
 func (t *TopologyCache) AddHints(si *SliceInfo) ([]*discovery.EndpointSlice, []*discovery.EndpointSlice) {
-	totalEndpoints := si.getTotalEndpoints()
+	totalEndpoints := si.getTotalReadyEndpoints()
 	allocations := t.getAllocations(totalEndpoints)
 
 	if allocations == nil {
@@ -103,6 +104,10 @@ func (t *TopologyCache) AddHints(si *SliceInfo) ([]*discovery.EndpointSlice, []*
 	// step 1: assign same-zone hints for all endpoints as a starting point.
 	for _, slice := range allocatableSlices {
 		for i, endpoint := range slice.Endpoints {
+			if !endpointsliceutil.EndpointReady(endpoint) {
+				endpoint.Hints = nil
+				continue
+			}
 			if endpoint.Zone == nil || *endpoint.Zone == "" {
 				klog.InfoS("Endpoint found without zone specified, removing hints from service", "serviceKey", si.ServiceKey)
 				t.RemoveHints(si.ServiceKey, si.AddressType)

pkg/controller/endpointslice/topologycache/topologycache_test.go

@@ -55,6 +55,7 @@ func TestAddHints(t *testing.T) {
 				Endpoints: []discovery.Endpoint{{
 					Addresses:  []string{"10.1.2.3"},
 					Zone:       utilpointer.StringPtr("zone-a"),
+					Conditions: discovery.EndpointConditions{Ready: utilpointer.BoolPtr(true)},
 				}},
 			}},
 		},
@@ -63,6 +64,7 @@ func TestAddHints(t *testing.T) {
 			Endpoints: []discovery.Endpoint{{
 				Addresses:  []string{"10.1.2.3"},
 				Zone:       utilpointer.StringPtr("zone-a"),
+				Conditions: discovery.EndpointConditions{Ready: utilpointer.BoolPtr(true)},
 			}},
 		}},
 		expectedSlicesToUpdate: []*discovery.EndpointSlice{},
@@ -80,9 +82,11 @@ func TestAddHints(t *testing.T) {
 				Endpoints: []discovery.Endpoint{{
 					Addresses:  []string{"10.1.2.3"},
 					Zone:       utilpointer.StringPtr("zone-a"),
+					Conditions: discovery.EndpointConditions{Ready: utilpointer.BoolPtr(true)},
 				}, {
 					Addresses:  []string{"10.1.2.4"},
 					Zone:       utilpointer.StringPtr("zone-b"),
+					Conditions: discovery.EndpointConditions{Ready: utilpointer.BoolPtr(true)},
 				}},
 			}},
 		},
@@ -91,9 +95,11 @@ func TestAddHints(t *testing.T) {
 			Endpoints: []discovery.Endpoint{{
 				Addresses:  []string{"10.1.2.3"},
 				Zone:       utilpointer.StringPtr("zone-a"),
+				Conditions: discovery.EndpointConditions{Ready: utilpointer.BoolPtr(true)},
 			}, {
 				Addresses:  []string{"10.1.2.4"},
 				Zone:       utilpointer.StringPtr("zone-b"),
+				Conditions: discovery.EndpointConditions{Ready: utilpointer.BoolPtr(true)},
 			}},
 		}},
 		expectedSlicesToUpdate: []*discovery.EndpointSlice{},
@@ -110,9 +116,59 @@ func TestAddHints(t *testing.T) {
 				Endpoints: []discovery.Endpoint{{
 					Addresses:  []string{"10.1.2.3"},
 					Zone:       utilpointer.StringPtr("zone-a"),
+					Conditions: discovery.EndpointConditions{Ready: utilpointer.BoolPtr(true)},
 				}, {
 					Addresses:  []string{"10.1.2.4"},
 					Zone:       utilpointer.StringPtr("zone-b"),
+					Conditions: discovery.EndpointConditions{Ready: utilpointer.BoolPtr(true)},
+				}},
+			}},
+		},
+		expectedEndpointsByAddrType: map[discovery.AddressType]EndpointZoneInfo{
+			discovery.AddressTypeIPv4: {
+				"zone-a": 1,
+				"zone-b": 1,
+			},
+		},
+		expectedSlicesToCreate: []*discovery.EndpointSlice{{
+			Endpoints: []discovery.Endpoint{{
+				Addresses:  []string{"10.1.2.3"},
+				Zone:       utilpointer.StringPtr("zone-a"),
+				Hints:      &discovery.EndpointHints{ForZones: []discovery.ForZone{{Name: "zone-a"}}},
+				Conditions: discovery.EndpointConditions{Ready: utilpointer.BoolPtr(true)},
+			}, {
+				Addresses:  []string{"10.1.2.4"},
+				Zone:       utilpointer.StringPtr("zone-b"),
+				Hints:      &discovery.EndpointHints{ForZones: []discovery.ForZone{{Name: "zone-b"}}},
+				Conditions: discovery.EndpointConditions{Ready: utilpointer.BoolPtr(true)},
+			}},
+		}},
+		expectedSlicesToUpdate: []*discovery.EndpointSlice{},
+	}, {
+		name: "slice to create with 2 ready, 1 unready, 1 unknown endpoints, zone ratios only require 2",
+		cpuRatiosByZone: map[string]float64{
+			"zone-a": 0.45,
+			"zone-b": 0.55,
+		},
+		sliceInfo: &SliceInfo{
+			ServiceKey:  "ns/svc",
+			AddressType: discovery.AddressTypeIPv4,
+			ToCreate: []*discovery.EndpointSlice{{
+				Endpoints: []discovery.Endpoint{{
+					Addresses:  []string{"10.1.2.3"},
+					Zone:       utilpointer.StringPtr("zone-a"),
+					Conditions: discovery.EndpointConditions{Ready: utilpointer.BoolPtr(true)},
+				}, {
+					Addresses:  []string{"10.1.2.4"},
+					Zone:       utilpointer.StringPtr("zone-b"),
+					Conditions: discovery.EndpointConditions{Ready: utilpointer.BoolPtr(true)},
+				}, {
+					Addresses:  []string{"10.1.2.5"},
+					Zone:       utilpointer.StringPtr("zone-b"),
+					Conditions: discovery.EndpointConditions{Ready: utilpointer.BoolPtr(false)},
+				}, {
+					Addresses: []string{"10.1.2.6"},
+					Zone:      utilpointer.StringPtr("zone-b"),
 				}},
 			}},
 		},
@@ -127,10 +183,21 @@ func TestAddHints(t *testing.T) {
 				Addresses:  []string{"10.1.2.3"},
 				Zone:       utilpointer.StringPtr("zone-a"),
 				Hints:      &discovery.EndpointHints{ForZones: []discovery.ForZone{{Name: "zone-a"}}},
+				Conditions: discovery.EndpointConditions{Ready: utilpointer.BoolPtr(true)},
 			}, {
 				Addresses:  []string{"10.1.2.4"},
 				Zone:       utilpointer.StringPtr("zone-b"),
 				Hints:      &discovery.EndpointHints{ForZones: []discovery.ForZone{{Name: "zone-b"}}},
+				Conditions: discovery.EndpointConditions{Ready: utilpointer.BoolPtr(true)},
+			}, {
+				Addresses:  []string{"10.1.2.5"},
+				Zone:       utilpointer.StringPtr("zone-b"),
+				Hints:      nil,
+				Conditions: discovery.EndpointConditions{Ready: utilpointer.BoolPtr(false)},
+			}, {
+				Addresses: []string{"10.1.2.6"},
+				Zone:      utilpointer.StringPtr("zone-b"),
+				Hints:     nil,
 			}},
 		}},
 		expectedSlicesToUpdate: []*discovery.EndpointSlice{},
@@ -148,40 +215,50 @@ func TestAddHints(t *testing.T) {
 				Endpoints: []discovery.Endpoint{{
 					Addresses:  []string{"10.1.2.3"},
 					Zone:       utilpointer.StringPtr("zone-a"),
+					Conditions: discovery.EndpointConditions{Ready: utilpointer.BoolPtr(true)},
 				}, {
 					Addresses:  []string{"10.1.2.4"},
 					Zone:       utilpointer.StringPtr("zone-b"),
+					Conditions: discovery.EndpointConditions{Ready: utilpointer.BoolPtr(true)},
 				}},
 			}, {
 				Endpoints: []discovery.Endpoint{{
 					Addresses:  []string{"10.1.3.3"},
 					Zone:       utilpointer.StringPtr("zone-c"),
+					Conditions: discovery.EndpointConditions{Ready: utilpointer.BoolPtr(true)},
 				}, {
 					Addresses:  []string{"10.1.3.4"},
 					Zone:       utilpointer.StringPtr("zone-c"),
+					Conditions: discovery.EndpointConditions{Ready: utilpointer.BoolPtr(true)},
 				}, {
 					Addresses:  []string{"10.1.3.4"},
 					Zone:       utilpointer.StringPtr("zone-a"),
+					Conditions: discovery.EndpointConditions{Ready: utilpointer.BoolPtr(true)},
 				}},
 			}},
 			ToUpdate: []*discovery.EndpointSlice{{
 				Endpoints: []discovery.Endpoint{{
 					Addresses:  []string{"10.2.2.3"},
 					Zone:       utilpointer.StringPtr("zone-a"),
+					Conditions: discovery.EndpointConditions{Ready: utilpointer.BoolPtr(true)},
 				}, {
 					Addresses:  []string{"10.2.2.4"},
 					Zone:       utilpointer.StringPtr("zone-a"),
+					Conditions: discovery.EndpointConditions{Ready: utilpointer.BoolPtr(true)},
 				}},
 			}, {
 				Endpoints: []discovery.Endpoint{{
 					Addresses:  []string{"10.2.3.3"},
 					Zone:       utilpointer.StringPtr("zone-b"),
+					Conditions: discovery.EndpointConditions{Ready: utilpointer.BoolPtr(true)},
 				}, {
 					Addresses:  []string{"10.2.3.4"},
 					Zone:       utilpointer.StringPtr("zone-c"),
+					Conditions: discovery.EndpointConditions{Ready: utilpointer.BoolPtr(true)},
 				}, {
 					Addresses:  []string{"10.2.3.4"},
 					Zone:       utilpointer.StringPtr("zone-a"),
+					Conditions: discovery.EndpointConditions{Ready: utilpointer.BoolPtr(true)},
 				}},
 			}},
 		},
@@ -197,24 +274,29 @@ func TestAddHints(t *testing.T) {
 				Addresses:  []string{"10.1.2.3"},
 				Zone:       utilpointer.StringPtr("zone-a"),
 				Hints:      &discovery.EndpointHints{ForZones: []discovery.ForZone{{Name: "zone-b"}}},
+				Conditions: discovery.EndpointConditions{Ready: utilpointer.BoolPtr(true)},
 			}, {
 				Addresses:  []string{"10.1.2.4"},
 				Zone:       utilpointer.StringPtr("zone-b"),
 				Hints:      &discovery.EndpointHints{ForZones: []discovery.ForZone{{Name: "zone-b"}}},
+				Conditions: discovery.EndpointConditions{Ready: utilpointer.BoolPtr(true)},
 			}},
 		}, {
 			Endpoints: []discovery.Endpoint{{
 				Addresses:  []string{"10.1.3.3"},
 				Zone:       utilpointer.StringPtr("zone-c"),
 				Hints:      &discovery.EndpointHints{ForZones: []discovery.ForZone{{Name: "zone-c"}}},
+				Conditions: discovery.EndpointConditions{Ready: utilpointer.BoolPtr(true)},
 			}, {
 				Addresses:  []string{"10.1.3.4"},
 				Zone:       utilpointer.StringPtr("zone-c"),
 				Hints:      &discovery.EndpointHints{ForZones: []discovery.ForZone{{Name: "zone-c"}}},
+				Conditions: discovery.EndpointConditions{Ready: utilpointer.BoolPtr(true)},
 			}, {
 				Addresses:  []string{"10.1.3.4"},
 				Zone:       utilpointer.StringPtr("zone-a"),
 				Hints:      &discovery.EndpointHints{ForZones: []discovery.ForZone{{Name: "zone-a"}}},
+				Conditions: discovery.EndpointConditions{Ready: utilpointer.BoolPtr(true)},
 			}},
 		}},
 		expectedSlicesToUpdate: []*discovery.EndpointSlice{{
@@ -222,24 +304,29 @@ func TestAddHints(t *testing.T) {
 				Addresses:  []string{"10.2.2.3"},
 				Zone:       utilpointer.StringPtr("zone-a"),
 				Hints:      &discovery.EndpointHints{ForZones: []discovery.ForZone{{Name: "zone-a"}}},
+				Conditions: discovery.EndpointConditions{Ready: utilpointer.BoolPtr(true)},
 			}, {
 				Addresses:  []string{"10.2.2.4"},
 				Zone:       utilpointer.StringPtr("zone-a"),
 				Hints:      &discovery.EndpointHints{ForZones: []discovery.ForZone{{Name: "zone-a"}}},
+				Conditions: discovery.EndpointConditions{Ready: utilpointer.BoolPtr(true)},
 			}},
 		}, {
 			Endpoints: []discovery.Endpoint{{
 				Addresses:  []string{"10.2.3.3"},
 				Zone:       utilpointer.StringPtr("zone-b"),
 				Hints:      &discovery.EndpointHints{ForZones: []discovery.ForZone{{Name: "zone-b"}}},
+				Conditions: discovery.EndpointConditions{Ready: utilpointer.BoolPtr(true)},
 			}, {
 				Addresses:  []string{"10.2.3.4"},
 				Zone:       utilpointer.StringPtr("zone-c"),
 				Hints:      &discovery.EndpointHints{ForZones: []discovery.ForZone{{Name: "zone-c"}}},
+				Conditions: discovery.EndpointConditions{Ready: utilpointer.BoolPtr(true)},
 			}, {
 				Addresses:  []string{"10.2.3.4"},
 				Zone:       utilpointer.StringPtr("zone-a"),
 				Hints:      &discovery.EndpointHints{ForZones: []discovery.ForZone{{Name: "zone-a"}}},
+				Conditions: discovery.EndpointConditions{Ready: utilpointer.BoolPtr(true)},
 			}},
 		}},
 	}}

pkg/controller/endpointslice/topologycache/utils.go

@@ -19,9 +19,10 @@ package topologycache
 import (
 	"math"
 
-	"k8s.io/api/core/v1"
+	v1 "k8s.io/api/core/v1"
 	discovery "k8s.io/api/discovery/v1"
 	"k8s.io/klog/v2"
+	endpointsliceutil "k8s.io/kubernetes/pkg/controller/util/endpointslice"
 )
 
 // RemoveHintsFromSlices removes topology hints on EndpointSlices and returns
@@ -75,6 +76,10 @@ func redistributeHints(slices []*discovery.EndpointSlice, givingZones, receiving
 
 	for _, slice := range slices {
 		for i, endpoint := range slice.Endpoints {
+			if !endpointsliceutil.EndpointReady(endpoint) {
+				endpoint.Hints = nil
+				continue
+			}
 			if len(givingZones) == 0 || len(receivingZones) == 0 {
 				return redistributions
 			}
@@ -185,6 +190,9 @@ func getMost(zones map[string]float64) (string, float64) {
 func getHintsByZone(slice *discovery.EndpointSlice, allocatedHintsByZone EndpointZoneInfo, allocations map[string]Allocation) map[string]int {
 	hintsByZone := map[string]int{}
 	for _, endpoint := range slice.Endpoints {
+		if !endpointsliceutil.EndpointReady(endpoint) {
+			continue
+		}
 		if endpoint.Hints == nil || len(endpoint.Hints.ForZones) == 0 {
 			return nil
 		}
@@ -248,3 +256,15 @@ func NodeReady(nodeStatus v1.NodeStatus) bool {
 	}
 	return false
 }
+
+// numReadyEndpoints returns the number of Endpoints that are ready from the
+// specified list.
+func numReadyEndpoints(endpoints []discovery.Endpoint) int {
+	var total int
+	for _, ep := range endpoints {
+		if ep.Conditions.Ready != nil && *ep.Conditions.Ready {
+			total++
+		}
+	}
+	return total
+}

pkg/controller/endpointslice/topologycache/utils_test.go

@@ -43,6 +43,7 @@ func Test_redistributeHints(t *testing.T) {
 			Endpoints: []discovery.Endpoint{{
 				Zone:       utilpointer.StringPtr("zone-a"),
 				Hints:      &discovery.EndpointHints{ForZones: []discovery.ForZone{{Name: "zone-a"}}},
+				Conditions: discovery.EndpointConditions{Ready: utilpointer.BoolPtr(true)},
 			}},
 		}},
 		givingZones:             map[string]int{"zone-a": 1},
@@ -54,12 +55,15 @@ func Test_redistributeHints(t *testing.T) {
 			Endpoints: []discovery.Endpoint{{
 				Zone:       utilpointer.StringPtr("zone-a"),
 				Hints:      &discovery.EndpointHints{ForZones: []discovery.ForZone{{Name: "zone-a"}}},
+				Conditions: discovery.EndpointConditions{Ready: utilpointer.BoolPtr(true)},
 			}, {
 				Zone:       utilpointer.StringPtr("zone-a"),
 				Hints:      &discovery.EndpointHints{ForZones: []discovery.ForZone{{Name: "zone-a"}}},
+				Conditions: discovery.EndpointConditions{Ready: utilpointer.BoolPtr(true)},
 			}, {
 				Zone:       utilpointer.StringPtr("zone-a"),
 				Hints:      &discovery.EndpointHints{ForZones: []discovery.ForZone{{Name: "zone-a"}}},
+				Conditions: discovery.EndpointConditions{Ready: utilpointer.BoolPtr(true)},
 			}},
 		}},
 		givingZones:             map[string]int{"zone-a": 2},
@@ -213,6 +217,30 @@ func Test_getHintsByZone(t *testing.T) {
 			Endpoints: []discovery.Endpoint{{
 				Zone:       utilpointer.StringPtr("zone-a"),
 				Hints:      &discovery.EndpointHints{ForZones: []discovery.ForZone{{Name: "zone-a"}}},
+				Conditions: discovery.EndpointConditions{Ready: utilpointer.BoolPtr(true)},
+			}},
+		},
+		allocations: map[string]Allocation{
+			"zone-a": {Maximum: 3},
+		},
+		allocatedHintsByZone: EndpointZoneInfo{"zone-a": 1},
+		expectedHintsByZone: map[string]int{
+			"zone-a": 1,
+		},
+	}, {
+		name: "single zone hint with 1 unready endpoint and 1 unknown endpoint",
+		slice: discovery.EndpointSlice{
+			Endpoints: []discovery.Endpoint{{
+				Zone:       utilpointer.StringPtr("zone-a"),
+				Hints:      &discovery.EndpointHints{ForZones: []discovery.ForZone{{Name: "zone-a"}}},
+				Conditions: discovery.EndpointConditions{Ready: utilpointer.BoolPtr(true)},
+			}, {
+				Zone:       utilpointer.StringPtr("zone-a"),
+				Hints:      &discovery.EndpointHints{ForZones: []discovery.ForZone{{Name: "zone-a"}}},
+				Conditions: discovery.EndpointConditions{Ready: utilpointer.BoolPtr(false)},
+			}, {
+				Zone:  utilpointer.StringPtr("zone-a"),
+				Hints: &discovery.EndpointHints{ForZones: []discovery.ForZone{{Name: "zone-a"}}},
 			}},
 		},
 		allocations: map[string]Allocation{
@@ -229,14 +257,17 @@ func Test_getHintsByZone(t *testing.T) {
 				{
 					Zone:       utilpointer.StringPtr("zone-a"),
 					Hints:      &discovery.EndpointHints{ForZones: []discovery.ForZone{{Name: "zone-a"}}},
+					Conditions: discovery.EndpointConditions{Ready: utilpointer.BoolPtr(true)},
 				},
 				{
 					Zone:       utilpointer.StringPtr("zone-a"),
 					Hints:      &discovery.EndpointHints{ForZones: []discovery.ForZone{{Name: "zone-b"}}},
+					Conditions: discovery.EndpointConditions{Ready: utilpointer.BoolPtr(true)},
 				},
 				{
 					Zone:       utilpointer.StringPtr("zone-b"),
 					Hints:      &discovery.EndpointHints{ForZones: []discovery.ForZone{{Name: "zone-b"}}},
+					Conditions: discovery.EndpointConditions{Ready: utilpointer.BoolPtr(true)},
 				},
 			},
 		},
@@ -257,6 +288,7 @@ func Test_getHintsByZone(t *testing.T) {
 				{
 					Zone:       utilpointer.StringPtr("zone-a"),
 					Hints:      &discovery.EndpointHints{ForZones: []discovery.ForZone{{Name: "zone-non-existent"}}},
+					Conditions: discovery.EndpointConditions{Ready: utilpointer.BoolPtr(true)},
 				},
 			},
 		},
@@ -272,6 +304,7 @@ func Test_getHintsByZone(t *testing.T) {
 				{
 					Zone:       utilpointer.StringPtr("zone-a"),
 					Hints:      nil,
+					Conditions: discovery.EndpointConditions{Ready: utilpointer.BoolPtr(true)},
 				},
 			},
 		},
@@ -287,6 +320,7 @@ func Test_getHintsByZone(t *testing.T) {
 				{
 					Zone:       utilpointer.StringPtr("zone-a"),
 					Hints:      &discovery.EndpointHints{ForZones: []discovery.ForZone{}},
+					Conditions: discovery.EndpointConditions{Ready: utilpointer.BoolPtr(true)},
 				},
 			},
 		},
@@ -302,10 +336,12 @@ func Test_getHintsByZone(t *testing.T) {
 				{
 					Zone:       utilpointer.StringPtr("zone-a"),
 					Hints:      &discovery.EndpointHints{ForZones: []discovery.ForZone{{Name: "zone-a"}}},
+					Conditions: discovery.EndpointConditions{Ready: utilpointer.BoolPtr(true)},
 				},
 				{
 					Zone:       utilpointer.StringPtr("zone-a"),
 					Hints:      &discovery.EndpointHints{ForZones: []discovery.ForZone{{Name: "zone-a"}}},
+					Conditions: discovery.EndpointConditions{Ready: utilpointer.BoolPtr(true)},
 				},
 			},
 		},

pkg/controller/util/endpointslice/utils.go

@@ -0,0 +1,27 @@
+/*
+Copyright 2021 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package endpointslice
+
+import (
+	discovery "k8s.io/api/discovery/v1"
+)
+
+// EndpointReady returns true if an Endpoint has the Ready condition set to
+// true.
+func EndpointReady(endpoint discovery.Endpoint) bool {
+	return endpoint.Conditions.Ready != nil && *endpoint.Conditions.Ready
+}