HDDS-342. Add example byteman script to print out hadoop rpc traffic.

Contributed by Elek, Marton.

dev-support/byteman/README.md

@@ -0,0 +1,31 @@
+<!--
+  Licensed to the Apache Software Foundation (ASF) under one or more
+  contributor license agreements.  See the NOTICE file distributed with
+  this work for additional information regarding copyright ownership.
+  The ASF licenses this file to You under the Apache License, Version 2.0
+  (the "License"); you may not use this file except in compliance with
+  the License.  You may obtain a copy of the License at
+
+      http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+-->
+
+This folder contains example byteman scripts (http://byteman.jboss.org/) to help 
+Hadoop debuging.
+
+As the startup script of the hadoop-runner docker image supports byteman 
+instrumentation it's enough to set the URL of a script to a specific environment
+variable to activate it with the docker runs:
+
+
+```
+BYTEMAN_SCRIPT_URL=https://raw.githubusercontent.com/apache/hadoop/trunk/dev-support/byteman/hadooprpc.btm
+```
+
+For more info see HADOOP-15656 and HDDS-342
+

dev-support/byteman/hadooprpc.btm

@@ -0,0 +1,44 @@
+# Licensed to the Apache Software Foundation (ASF) under one or more
+# contributor license agreements.  See the NOTICE file distributed with
+# this work for additional information regarding copyright ownership.
+# The ASF licenses this file to You under the Apache License, Version 2.0
+# (the "License"); you may not use this file except in compliance with
+# the License.  You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+#
+# This script instruments hadoop rpc layer to print out all the request/response messages to the standard output.
+#
+
+RULE Hadoop RPC request
+INTERFACE ^com.google.protobuf.BlockingService
+METHOD callBlockingMethod
+IF true
+DO traceln("--> RPC message request: " + $3.getClass().getSimpleName() + " from " + linked(Thread.currentThread(), "source")); 
+   traceln($3.toString())
+ENDRULE
+
+
+RULE Hadoop RPC response
+INTERFACE ^com.google.protobuf.BlockingService
+METHOD callBlockingMethod
+AT EXIT
+IF true
+DO traceln("--> RPC message response: " + $3.getClass().getSimpleName() + " to " + unlink(Thread.currentThread(), "source")); 
+   traceln($!.toString())
+ENDRULE
+
+
+RULE Hadoop RPC source IP
+CLASS org.apache.hadoop.ipc.Server$RpcCall
+METHOD run
+IF true
+DO link(Thread.currentThread(), "source", $0.connection.toString())
+ENDRULE

hadoop-dist/src/main/compose/ozone/docker-config

@@ -29,3 +29,5 @@ LOG4J.PROPERTIES_log4j.rootLogger=INFO, stdout
 LOG4J.PROPERTIES_log4j.appender.stdout=org.apache.log4j.ConsoleAppender
 LOG4J.PROPERTIES_log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
 LOG4J.PROPERTIES_log4j.appender.stdout.layout.ConversionPattern=%d{yyyy-MM-dd HH:mm:ss} %-5p %c{1}:%L - %m%n
+#Enable this variable to print out all hadoop rpc traffic to the stdout. See http://byteman.jboss.org/ to define your own instrumentation.
+#BYTEMAN_SCRIPT_URL=https://raw.githubusercontent.com/apache/hadoop/trunk/dev-support/byteman/hadooprpc.btm