Correctly Clear conntrack entrty on endpoint changes when using nodeport

pkg/proxy/iptables/proxier.go

@@ -607,7 +607,13 @@ func (proxier *Proxier) deleteEndpointConnections(connectionMap []proxy.ServiceE
 	for _, epSvcPair := range connectionMap {
 		if svcInfo, ok := proxier.serviceMap[epSvcPair.ServicePortName]; ok && svcInfo.GetProtocol() == v1.ProtocolUDP {
 			endpointIP := utilproxy.IPPart(epSvcPair.Endpoint)
-			err := conntrack.ClearEntriesForNAT(proxier.exec, svcInfo.ClusterIPString(), endpointIP, v1.ProtocolUDP)
+			nodePort := svcInfo.GetNodePort()
+			var err error
+			if nodePort != 0 {
+				err = conntrack.ClearEntriesForPortNAT(proxier.exec, endpointIP, nodePort, v1.ProtocolUDP)
+			} else {
+				err = conntrack.ClearEntriesForNAT(proxier.exec, svcInfo.ClusterIPString(), endpointIP, v1.ProtocolUDP)
+			}
 			if err != nil {
 				klog.Errorf("Failed to delete %s endpoint connections, error: %v", epSvcPair.ServicePortName.String(), err)
 			}

pkg/proxy/service.go

@@ -74,6 +74,11 @@ func (info *BaseServiceInfo) GetHealthCheckNodePort() int {
 	return info.HealthCheckNodePort
 }
 
+// GetNodePort is part of the ServicePort interface.
+func (info *BaseServiceInfo) GetNodePort() int {
+	return info.NodePort
+}
+
 func (sct *ServiceChangeTracker) newBaseServiceInfo(port *v1.ServicePort, service *v1.Service) *BaseServiceInfo {
 	onlyNodeLocalEndpoints := false
 	if apiservice.RequestsOnlyLocalTraffic(service) {

pkg/proxy/types.go

@@ -54,6 +54,8 @@ type ServicePort interface {
 	GetProtocol() v1.Protocol
 	// GetHealthCheckNodePort returns service health check node port if present.  If return 0, it means not present.
 	GetHealthCheckNodePort() int
+	// GetNodePort returns a service Node port if present. If return 0, it means not present.
+	GetNodePort() int
 }
 
 // Endpoint in an interface which abstracts information about an endpoint.

pkg/util/conntrack/conntrack.go

@@ -107,3 +107,19 @@ func ClearEntriesForNAT(execer exec.Interface, origin, dest string, protocol v1.
 	}
 	return nil
 }
+
+// ClearEntriesForPortNAT uses the conntrack tool to delete the contrack entries
+// for connections specified by the {dest IP, port} pair.
+// Known issue:
+// https://github.com/kubernetes/kubernetes/issues/59368
+func ClearEntriesForPortNAT(execer exec.Interface, dest string, port int, protocol v1.Protocol) error {
+	if port <= 0 {
+		return fmt.Errorf("Wrong port number. The port number must be greater then zero")
+	}
+	parameters := parametersWithFamily(utilnet.IsIPv6String(dest), "-D", "-p", protoStr(protocol), "--dport", strconv.Itoa(port), "--dst-nat", dest)
+	err := Exec(execer, parameters...)
+	if err != nil && !strings.Contains(err.Error(), NoConnectionToDelete) {
+		return fmt.Errorf("error deleting conntrack entries for UDP port: %d, error: %v", port, err)
+	}
+	return nil
+}

pkg/util/conntrack/conntrack_test.go

@@ -234,3 +234,50 @@ func TestDeleteUDPConnections(t *testing.T) {
 		t.Errorf("Expect command executed %d times, but got %d", svcCount, fexec.CommandCalls)
 	}
 }
+
+func TestClearUDPConntrackForPortNAT(t *testing.T) {
+	fcmd := fakeexec.FakeCmd{
+		CombinedOutputScript: []fakeexec.FakeCombinedOutputAction{
+			func() ([]byte, error) { return []byte("1 flow entries have been deleted"), nil },
+			func() ([]byte, error) {
+				return []byte(""), fmt.Errorf("conntrack v1.4.2 (conntrack-tools): 0 flow entries have been deleted")
+			},
+			func() ([]byte, error) { return []byte("1 flow entries have been deleted"), nil },
+		},
+	}
+	fexec := fakeexec.FakeExec{
+		CommandScript: []fakeexec.FakeCommandAction{
+			func(cmd string, args ...string) exec.Cmd { return fakeexec.InitFakeCmd(&fcmd, cmd, args...) },
+			func(cmd string, args ...string) exec.Cmd { return fakeexec.InitFakeCmd(&fcmd, cmd, args...) },
+			func(cmd string, args ...string) exec.Cmd { return fakeexec.InitFakeCmd(&fcmd, cmd, args...) },
+		},
+		LookPathFunc: func(cmd string) (string, error) { return cmd, nil },
+	}
+	testCases := []struct {
+		name string
+		port int
+		dest string
+	}{
+		{
+			name: "IPv4 success",
+			port: 30211,
+			dest: "1.2.3.4",
+		},
+	}
+	svcCount := 0
+	for i, tc := range testCases {
+		err := ClearEntriesForPortNAT(&fexec, tc.dest, tc.port, v1.ProtocolUDP)
+		if err != nil {
+			t.Errorf("%s test case: unexpected error: %v", tc.name, err)
+		}
+		expectCommand := fmt.Sprintf("conntrack -D -p udp --dport %d --dst-nat %s", tc.port, tc.dest) + familyParamStr(utilnet.IsIPv6String(tc.dest))
+		execCommand := strings.Join(fcmd.CombinedOutputLog[i], " ")
+		if expectCommand != execCommand {
+			t.Errorf("%s test case: Expect command: %s, but executed %s", tc.name, expectCommand, execCommand)
+		}
+		svcCount++
+	}
+	if svcCount != fexec.CommandCalls {
+		t.Errorf("Expect command executed %d times, but got %d", svcCount, fexec.CommandCalls)
+	}
+}