[GitHub] [zeppelin] felixcheung commented on a change in pull request #3364: [ZEPPELIN-4155] Unable get available HostAddress in multi-NIC environment

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felixcheung commented on a change in pull request #3364: [ZEPPELIN-4155] Unable get available HostAddress in multi-NIC environment
URL: https://github.com/apache/zeppelin/pull/3364#discussion_r284328179
 
 

 ##########
 File path: zeppelin-interpreter/src/main/java/org/apache/zeppelin/interpreter/remote/RemoteInterpreterUtils.java
 ##########
 @@ -93,22 +97,53 @@ public static TServerSocket createTServerSocket(String portRange)
     throw new IOException("No available port in the portRange: " + portRange);
   }
 
+  // 1) Multiple NetworkCard will be configured on some servers
+  // 2) In the docker container environment, A container will also generate multiple virtual NetworkCard
   public static String findAvailableHostAddress() throws UnknownHostException, SocketException {
-    InetAddress address = InetAddress.getLocalHost();
-    if (address.isLoopbackAddress()) {
-      for (NetworkInterface networkInterface : Collections
-          .list(NetworkInterface.getNetworkInterfaces())) {
-        if (!networkInterface.isLoopback()) {
-          for (InterfaceAddress interfaceAddress : networkInterface.getInterfaceAddresses()) {
-            InetAddress a = interfaceAddress.getAddress();
-            if (a instanceof Inet4Address) {
-              return a.getHostAddress();
-            }
+    List<NetworkInterface> netlist = new ArrayList<NetworkInterface>();
+
+    // Get all the network cards in the current environment
+    Enumeration<?> netInterfaces = NetworkInterface.getNetworkInterfaces();
+    while (netInterfaces.hasMoreElements()) {
+      NetworkInterface networkInterface = (NetworkInterface)netInterfaces.nextElement();
+      LOGGER.info("networkInterface = " + networkInterface.toString());
+      if (networkInterface.isLoopback()) {
+        // Filter lo network card
+        continue;
+      }
+      // When all the network cards are obtained by the above method,
+      // The order obtained is the reverse of the order of the NICs
+      // seen in the server with the ifconfig command.
+      // Therefore, when you want to traverse from the first NIC,
+      // Need to reverse the elements in Enumeration<?>
+      netlist.add(0, networkInterface);
+    }
+
+    for (NetworkInterface list:netlist) {
+      Enumeration<?> enumInetAddress = list.getInetAddresses();
+
+      while (enumInetAddress.hasMoreElements()) {
+        InetAddress ip = (InetAddress) enumInetAddress.nextElement();
+        LOGGER.info("ip = " + ip.toString());
+        if (!ip.isLoopbackAddress()) {
+          if (ip.getHostAddress().equalsIgnoreCase("127.0.0.1")){
 
 Review comment:
   isn't `isLoopbackAddress` enough?

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