fix(nsc): remove error for lookupFWMarkByService

lookupFWMarkByService() was previous returning an error when no fwmark
was found in the tracking map for a given service. However, this isn't
really an error condition and shouldn't be treated as such. When it was
treated as an error condition users got a lot of confusing errors in the
logs.

pkg/controllers/proxy/service_endpoints_sync.go

@@ -367,10 +367,8 @@ func (nsc *NetworkServicesController) setupExternalIPServices(serviceInfoMap ser
 				externalIPServiceID = generateIPPortID(externalIP, svc.protocol, strconv.Itoa(svc.port))
 
 				// ensure there is NO iptables mangle table rule to FW mark the packet
-				fwMark, err := nsc.lookupFWMarkByService(externalIP, svc.protocol, strconv.Itoa(svc.port))
+				fwMark := nsc.lookupFWMarkByService(externalIP, svc.protocol, strconv.Itoa(svc.port))
 				switch {
-				case err != nil:
-					klog.Errorf("failed to find FW mark for the service: %v", err)
 				case fwMark == 0:
 					klog.V(2).Infof("no FW mark found for service, nothing to cleanup")
 				case fwMark != 0:

pkg/controllers/proxy/utils.go

@@ -211,14 +211,14 @@ func (nsc *NetworkServicesController) generateUniqueFWMark(ip, protocol, port st
 
 // lookupFWMarkByService finds the related FW mark from the internal fwMarkMap kept by the NetworkServiceController
 // given the related ip, protocol, and port. If it isn't able to find a matching FW mark, then it returns an error.
-func (nsc *NetworkServicesController) lookupFWMarkByService(ip, protocol, port string) (uint32, error) {
+func (nsc *NetworkServicesController) lookupFWMarkByService(ip, protocol, port string) uint32 {
 	needle := fmt.Sprintf("%s-%s-%s", ip, protocol, port)
 	for fwMark, serviceKey := range nsc.fwMarkMap {
 		if needle == serviceKey {
-			return fwMark, nil
+			return fwMark
 		}
 	}
-	return 0, fmt.Errorf("no key matching %s:%s:%s was found in fwMarkMap", protocol, ip, port)
+	return 0
 }
 
 // lookupServiceByFWMark Lookup service ip, protocol, port by given FW Mark value (reverse of lookupFWMarkByService)

pkg/controllers/proxy/utils_test.go

@@ -87,21 +87,17 @@ func TestNetworkServicesController_lookupFWMarkByService(t *testing.T) {
 	t.Run("ensure existing FW mark is found in lookup", func(t *testing.T) {
 		nsc := getMoqNSC()
 		fwMark1, err1 := nsc.generateUniqueFWMark("10.255.0.1", "TCP", "80")
-		fwMark2, err2 := nsc.lookupFWMarkByService("10.255.0.1", "TCP", "80")
+		fwMark2 := nsc.lookupFWMarkByService("10.255.0.1", "TCP", "80")
 
 		assert.NoError(t, err1, "there shouldn't have been an error calling generateUniqueFWMark")
-		assert.NoError(t, err2, "there shouldn't have been an error calling lookupFWMarkByService")
 
 		assert.Equal(t, fwMark1, fwMark2,
 			"given the same inputs, lookupFWMarkByService should be able to find the previously generated FW mark")
 	})
 	t.Run("ensure error is returned when a service doesn't exist in FW mark map", func(t *testing.T) {
 		nsc := getMoqNSC()
-		fwMark, err := nsc.lookupFWMarkByService("10.255.0.1", "TCP", "80")
+		fwMark := nsc.lookupFWMarkByService("10.255.0.1", "TCP", "80")
 
-		assert.EqualErrorf(t, err,
-			fmt.Sprintf("no key matching %s:%s:%s was found in fwMarkMap", "TCP", "10.255.0.1", "80"),
-			"expected to get an error when service had not yet been added to fwMarkMap")
 		assert.Equal(t, uint32(0), fwMark, "expected FW mark to be 0 on error condition")
 	})
 }