[HUDI-3827] Promote the inetAddress picking strategy for NetworkUtils#getHostname (#5260)

hudi-common/src/main/java/org/apache/hudi/common/util/NetworkUtils.java

@@ -22,11 +22,14 @@ import org.apache.hudi.exception.HoodieException;
 
 import java.io.IOException;
 import java.net.DatagramSocket;
+import java.net.Inet4Address;
 import java.net.InetAddress;
-import java.net.InterfaceAddress;
 import java.net.NetworkInterface;
 import java.net.SocketException;
-import java.util.Enumeration;
+import java.net.UnknownHostException;
+import java.util.Collections;
+import java.util.List;
+import java.util.stream.Collectors;
 
 /**
  * A utility class for network.
@@ -34,28 +37,51 @@ import java.util.Enumeration;
 public class NetworkUtils {
 
   public static synchronized String getHostname() {
-    try {
+    InetAddress localAddress;
-      Enumeration<NetworkInterface> networkInterfaceEnumeration = NetworkInterface.getNetworkInterfaces();
-      while (networkInterfaceEnumeration.hasMoreElements()) {
-        for (InterfaceAddress interfaceAddress : networkInterfaceEnumeration.nextElement().getInterfaceAddresses()) {
-          InetAddress address = interfaceAddress.getAddress();
-          if (!address.isLinkLocalAddress() && !address.isLoopbackAddress() && !address.isAnyLocalAddress()) {
-            return address.getHostAddress();
-          }
-        }
-      }
-    } catch (SocketException e) {
-      throw new HoodieException("Unable to find server port", e);
-    }
-
-    // fallback
     try (DatagramSocket s = new DatagramSocket()) {
       // see https://stackoverflow.com/questions/9481865/getting-the-ip-address-of-the-current-machine-using-java
       // for details.
       s.connect(InetAddress.getByName("8.8.8.8"), 10002);
-      return s.getLocalAddress().getHostAddress();
+      localAddress = s.getLocalAddress();
+      if (validAddress(localAddress)) {
+        return localAddress.getHostAddress();
+      }
     } catch (IOException e) {
       throw new HoodieException("Unable to find server port", e);
     }
+
+    // fallback
+    try {
+      List<NetworkInterface> activeNetworkIFs = Collections.list(NetworkInterface.getNetworkInterfaces());
+      // On unix-like system, getNetworkInterfaces returns ifs in reverse order
+      // compared to ifconfig output order,
+      // pick ip address following system output order.
+      Collections.reverse(activeNetworkIFs);
+      for (NetworkInterface ni : activeNetworkIFs) {
+        List<InetAddress> addresses = Collections.list(ni.getInetAddresses()).stream()
+            .filter(NetworkUtils::validAddress)
+            .collect(Collectors.toList());
+        if (addresses.size() > 0) {
+          // IPv4 has higher priority
+          InetAddress address = addresses.stream()
+              .filter(addr -> addr instanceof Inet4Address).findAny()
+              .orElse(addresses.get(0));
+          try {
+            // Inet6Address.toHostName may add interface at the end if it knows about it
+            return InetAddress.getByAddress(address.getAddress()).getHostAddress();
+          } catch (UnknownHostException e) {
+            throw new HoodieException("Unable to fetch raw IP address for: " + address);
+          }
+        }
+      }
+
+      return localAddress.getHostAddress();
+    } catch (SocketException e) {
+      throw new HoodieException("Unable to find server port", e);
+    }
+  }
+
+  private static boolean validAddress(InetAddress address) {
+    return !(address.isLinkLocalAddress() || address.isLoopbackAddress() || address.isAnyLocalAddress());
   }
 }