Do not update kubernetes endpoints when endpoint address count is less than or…

pkg/master/controller.go

@@ -296,9 +296,14 @@ func (c *Controller) ReconcileEndpoints(serviceName string, ip net.IP, endpointP
 	return c.EndpointRegistry.UpdateEndpoints(ctx, e)
 }
 
-// Determine if the endpoint is in the format ReconcileEndpoints expect (one subset,
-// correct ports, N IP addresses); and if the specified IP address is present and
-// the correct number of ip addresses are found.
+// Determine if the endpoint is in the format ReconcileEndpoints expects.
+//
+// Return values:
+// * formatCorrect is true if exactly one subset is found.
+// * ipCorrect is true when current master's IP is found and the number
+//     of addresses is less than or equal to the master count.
+// * portsCorrect is true when endpoint ports exactly match provided ports.
+//     portsCorrect is only evaluated when reconcilePorts is set to true.
 func checkEndpointSubsetFormat(e *api.Endpoints, ip string, ports []api.EndpointPort, count int, reconcilePorts bool) (formatCorrect bool, ipCorrect bool, portsCorrect bool) {
 	if len(e.Subsets) != 1 {
 		return false, false, false
@@ -318,7 +323,7 @@ func checkEndpointSubsetFormat(e *api.Endpoints, ip string, ports []api.Endpoint
 	}
 	for _, addr := range sub.Addresses {
 		if addr.IP == ip {
-			ipCorrect = len(sub.Addresses) == count
+			ipCorrect = len(sub.Addresses) <= count
 			break
 		}
 	}

pkg/master/controller_test.go

@@ -161,6 +161,54 @@ func TestReconcileEndpoints(t *testing.T) {
 			},
 		},
 		{
+			testName:          "existing endpoints satisfy and endpoint addresses length less than master count",
+			serviceName:       "foo",
+			ip:                "4.3.2.2",
+			endpointPorts:     []api.EndpointPort{{Name: "foo", Port: 8080, Protocol: "TCP"}},
+			additionalMasters: 3,
+			endpoints: &api.EndpointsList{
+				Items: []api.Endpoints{{
+					ObjectMeta: om("foo"),
+					Subsets: []api.EndpointSubset{{
+						Addresses: []api.EndpointAddress{
+							{IP: "4.3.2.1"},
+							{IP: "4.3.2.2"},
+						},
+						Ports: []api.EndpointPort{{Name: "foo", Port: 8080, Protocol: "TCP"}},
+					}},
+				}},
+			},
+			expectUpdate: nil,
+		},
+		{
+			testName:          "existing endpoints current IP missing and address length less than master count",
+			serviceName:       "foo",
+			ip:                "4.3.2.2",
+			endpointPorts:     []api.EndpointPort{{Name: "foo", Port: 8080, Protocol: "TCP"}},
+			additionalMasters: 3,
+			endpoints: &api.EndpointsList{
+				Items: []api.Endpoints{{
+					ObjectMeta: om("foo"),
+					Subsets: []api.EndpointSubset{{
+						Addresses: []api.EndpointAddress{
+							{IP: "4.3.2.1"},
+						},
+						Ports: []api.EndpointPort{{Name: "foo", Port: 8080, Protocol: "TCP"}},
+					}},
+				}},
+			},
+			expectUpdate: &api.Endpoints{
+				ObjectMeta: om("foo"),
+				Subsets: []api.EndpointSubset{{
+					Addresses: []api.EndpointAddress{
+						{IP: "4.3.2.1"},
+						{IP: "4.3.2.2"},
+					},
+					Ports: []api.EndpointPort{{Name: "foo", Port: 8080, Protocol: "TCP"}},
+				}},
+			},
+		},
+		{
 			testName:      "existing endpoints wrong name",
 			serviceName:   "foo",
 			ip:            "1.2.3.4",