use ip route structured data to retrieve default interface

Author: Bjoern Anters

utils/src/main/java/com/cloud/utils/net/NetUtils.java

@@ -306,7 +306,7 @@ public static String getDefaultEthDevice() {
             final String defDev = Script.runSimpleBashScript("/sbin/route -n get default 2> /dev/null | grep interface | awk '{print $2}'");
             return defDev;
         }
-        return Script.runSimpleBashScript("ip route show default 0.0.0.0/0 | head -1 | awk '{print $5}'");
+        return Script.runSimpleBashScript("ip -j a | jq -r '.[] | .addr_info | map(select(.local == "'"$(ip -j r s default | jq -r '.[0] | .prefsrc')"'")) | .[].label'");
     }
 
     public static String getLocalIPString() {