feat(linux_networking.go): add more logging info

Adds more logging information (in the form of warnings) when we come
across common errors that are not big enough to stop processing, but
will still confuse users when the error gets bubbled up to NSC.

pkg/controllers/proxy/linux_networking.go

@@ -79,20 +79,30 @@ func (ln *linuxNetworking) ipAddrDel(iface netlink.Link, ip string, nodeIP strin
 
 	naddr := &netlink.Addr{IPNet: &net.IPNet{IP: parsedIP, Mask: netMask}, Scope: syscall.RT_SCOPE_LINK}
 	err := netlink.AddrDel(iface, naddr)
-	if err != nil && err.Error() != IfaceHasNoAddr {
-		klog.Errorf("Failed to verify is external ip %s is assocated with dummy interface %s due to %s",
-			ip, KubeDummyIf, err.Error())
-		return err
+	if err != nil {
+		if err.Error() != IfaceHasNoAddr {
+			klog.Errorf("Failed to verify is external ip %s is assocated with dummy interface %s due to %s",
+				ip, KubeDummyIf, err.Error())
+			return err
+		} else {
+			klog.Warningf("got an IfaceHasNoAddr error while trying to delete address from netlink: %v (this is not "+
+				"normally bad enough to stop processing)", err)
+		}
 	}
 
 	// Delete VIP addition to "local" rt table also, fail silently if not found (DSR special case)
 	// #nosec G204
 	ipRouteCmdArgs = append(ipRouteCmdArgs, "route", "delete", "local", ip, "dev", KubeDummyIf,
 		"table", "local", "proto", "kernel", "scope", "host", "src", nodeIP, "table", "local")
 	out, err := exec.Command("ip", ipRouteCmdArgs...).CombinedOutput()
-	if err != nil && !strings.Contains(string(out), "No such process") {
-		klog.Errorf("Failed to delete route to service VIP %s configured on %s. Error: %v, Output: %s",
-			ip, KubeDummyIf, err, out)
+	if err != nil {
+		if !strings.Contains(string(out), "No such process") {
+			klog.Errorf("Failed to delete route to service VIP %s configured on %s. Error: %v, Output: %s",
+				ip, KubeDummyIf, err, out)
+		} else {
+			klog.Warningf("got a No such process error while trying to remove route: %v (this is not normally bad "+
+				"enough to stop processing)", err)
+		}
 	}
 
 	return err