HDFS-9049. Make Datanode Netty reverse proxy port to be configurable. Contributed by Vinayakumar B.

(cherry picked from commit 09efdfe9e13c9695867ce4034aa6ec970c2032f1)

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/DFSConfigKeys.java

@@ -617,6 +617,8 @@ public class DFSConfigKeys extends CommonConfigurationKeys {
   public static final String  DFS_DATANODE_HTTP_ADDRESS_KEY = "dfs.datanode.http.address";
   public static final int     DFS_DATANODE_HTTP_DEFAULT_PORT = 9864;
   public static final String  DFS_DATANODE_HTTP_ADDRESS_DEFAULT = "0.0.0.0:" + DFS_DATANODE_HTTP_DEFAULT_PORT;
+  public static final String  DFS_DATANODE_HTTP_INTERNAL_PROXY_PORT =
+      "dfs.datanode.http.internal-proxy.port";
   public static final String  DFS_DATANODE_MAX_RECEIVER_THREADS_KEY =
       HdfsClientConfigKeys.DeprecatedKeys.DFS_DATANODE_MAX_RECEIVER_THREADS_KEY;
   public static final int     DFS_DATANODE_MAX_RECEIVER_THREADS_DEFAULT = 4096;

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/web/DatanodeHttpServer.java

@@ -72,6 +72,7 @@ import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_ADMIN;
 import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_DATANODE_HTTPS_ADDRESS_DEFAULT;
 import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_DATANODE_HTTPS_ADDRESS_KEY;
 import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_DATANODE_HTTP_ADDRESS_KEY;
+import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_DATANODE_HTTP_INTERNAL_PROXY_PORT;
 
 public class DatanodeHttpServer implements Closeable {
   private final HttpServer2 infoServer;
@@ -97,12 +98,14 @@ public class DatanodeHttpServer implements Closeable {
 
     Configuration confForInfoServer = new Configuration(conf);
     confForInfoServer.setInt(HttpServer2.HTTP_MAX_THREADS_KEY, 10);
+    int proxyPort =
+        confForInfoServer.getInt(DFS_DATANODE_HTTP_INTERNAL_PROXY_PORT, 0);
     HttpServer2.Builder builder = new HttpServer2.Builder()
         .setName("datanode")
         .setConf(confForInfoServer)
         .setACL(new AccessControlList(conf.get(DFS_ADMIN, " ")))
         .hostName(getHostnameForSpnegoPrincipal(confForInfoServer))
-        .addEndpoint(URI.create("http://localhost:0"))
+        .addEndpoint(URI.create("http://localhost:" + proxyPort))
         .setFindPort(true);
 
     final boolean xFrameEnabled = conf.getBoolean(

hadoop-hdfs-project/hadoop-hdfs/src/main/resources/hdfs-default.xml

@@ -145,6 +145,15 @@
   </description>
 </property>
 
+<property>
+  <name>dfs.datanode.http.internal-proxy.port</name>
+  <value>0</value>
+  <description>
+    The datanode's internal web proxy port.
+    By default it selects a random port available in runtime.
+  </description>
+</property>
+
 <property>
   <name>dfs.datanode.handler.count</name>
   <value>10</value>