[autotest] log rpc server name in the metadata logged to metadb

BUG=None
TEST=local test

Change-Id: Ic63b93ac5f8d19e8f00ffb2527e2ac8b9ca3878f
Reviewed-on: https://chromium-review.googlesource.com/446727
Commit-Ready: Dan Shi <dshi@google.com>
Tested-by: Dan Shi <dshi@google.com>
Reviewed-by: Kevin Cheng <kevcheng@chromium.org>
diff --git a/frontend/afe/json_rpc/serviceHandler.py b/frontend/afe/json_rpc/serviceHandler.py
index e3e52f9..577b6da 100644
--- a/frontend/afe/json_rpc/serviceHandler.py
+++ b/frontend/afe/json_rpc/serviceHandler.py
@@ -18,6 +18,7 @@
   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 """
 
+import socket
 import traceback
 
 from json import decoder
@@ -110,6 +111,7 @@
 
         metadata = request.copy()
         metadata['_type'] = 'rpc'
+        metadata['rpc_server'] = socket.gethostname()
         timer = autotest_stats.Timer('rpc', metadata=metadata)
 
         try: