Improve the ipAddrAdd performance

This commit replaces the `Exec()` call with `netlink.RouteReplace()`. When calling `ipAddrAdd` in a loop (e.g., inside `setupClusterIPServices`), this gives a significant performance boost.

pkg/controllers/proxy/network_services_controller.go

@@ -29,6 +29,7 @@ import (
 	"github.com/vishvananda/netlink"
 	"github.com/vishvananda/netns"
 	"golang.org/x/net/context"
+	"golang.org/x/sys/unix"
 	api "k8s.io/api/core/v1"
 	"k8s.io/client-go/kubernetes"
 	"k8s.io/client-go/tools/cache"
@@ -140,12 +141,17 @@ func (ln *linuxNetworking) ipAddrAdd(iface netlink.Link, ip string, addRoute boo
 		return nil
 	}
 
-	// TODO: netlink.RouteReplace which is replacement for below command is not working as expected. Call succeeds but
-	// route is not replaced. For now do it with command.
-	out, err := exec.Command("ip", "route", "replace", "local", ip, "dev", KubeDummyIf, "table", "local", "proto", "kernel", "scope", "host", "src",
-		NodeIP.String(), "table", "local").CombinedOutput()
+	err = netlink.RouteReplace(&netlink.Route{
+		Dst:       &net.IPNet{IP: net.ParseIP(ip), Mask: net.IPv4Mask(255, 255, 255, 255)},
+		LinkIndex: iface.Attrs().Index,
+		Table:     unix.RT_TABLE_LOCAL,
+		Protocol:  unix.RTPROT_KERNEL,
+		Scope:     unix.RT_SCOPE_HOST,
+		Type:      unix.RTN_LOCAL,
+		Src:       NodeIP,
+	})
 	if err != nil {
-		glog.Errorf("Failed to replace route to service VIP %s configured on %s. Error: %v, Output: %s", ip, KubeDummyIf, err, out)
+		glog.Errorf("Failed to replace route to service VIP %s configured on %s. Error: %v", ip, KubeDummyIf, err)
 	}
 	return nil
 }