XenAPI: add support for conntrack with XenServer

With XenServer as hypervisor, the commands neutron-ovs-agent in
compute node run are actually executed in Dom0. But current Dom0
plugin doesn't allow conntrack command, this patch is to add such
support.
Also, the exitcode the commands returned in Dom0 will pass through
Dom0 to neutron to make sure the plugin is only aimed executing
commands, it doesn't deal with business scenario.

Closes-Bug: #1603400

Change-Id: I304788240bcd590ec211bca052fe64594a4e6eca

bin/neutron-rootwrap-xen-dom0

@@ -29,7 +29,6 @@ from oslo_serialization import jsonutils as json
 import os
 import select
 import sys
-import traceback
 
 import XenAPI
 
@@ -45,7 +44,7 @@ def parse_args():
     exec_name = sys.argv.pop(0)
     # argv[0] required; path to conf file
     if len(sys.argv) < 2:
-        print("%s: No command specified" % exec_name)
+        sys.stderr.write("%s: No command specified" % exec_name)
         sys.exit(RC_NOCOMMAND)
 
     config_file = sys.argv.pop(0)
@@ -59,7 +58,7 @@ def _xenapi_section_name(config):
     if len(sections) == 1:
         return sections[0]
 
-    print("Multiple [xenapi] sections or no [xenapi] section found!")
+    sys.stderr.write("Multiple [xenapi] sections or no [xenapi] section found!")
     sys.exit(RC_BADCONFIG)
 
 
@@ -74,13 +73,14 @@ def load_configuration(exec_name, config_file):
         username = config.get(section, "xenapi_connection_username")
         password = config.get(section, "xenapi_connection_password")
     except ConfigParser.Error:
-        print("%s: Incorrect configuration file: %s" % (exec_name, config_file))
+        sys.stderr.write("%s: Incorrect configuration file: %s" %
+                         (exec_name, config_file))
         sys.exit(RC_BADCONFIG)
     if not url or not password:
         msg = ("%s: Must specify xenapi_connection_url, "
                "xenapi_connection_username (optionally), and "
                "xenapi_connection_password in %s") % (exec_name, config_file)
-        print(msg)
+        sys.stderr.write(msg)
         sys.exit(RC_BADCONFIG)
     return dict(
         filters_path=filters_path,
@@ -105,7 +105,7 @@ def filter_command(exec_name, filters_path, user_args, exec_dirs):
     filter_match = wrapper.match_filter(
         filters, user_args, exec_dirs=exec_dirs)
     if not filter_match:
-        print("Unauthorized command: %s" % ' '.join(user_args))
+        sys.stderr.write("Unauthorized command: %s" % ' '.join(user_args))
         sys.exit(RC_UNAUTHORIZED)
 
 
@@ -118,11 +118,17 @@ def run_command(url, username, password, user_args, cmd_input):
             result = session.xenapi.host.call_plugin(
                 host, 'netwrap', 'run_command',
                 {'cmd': json.dumps(user_args), 'cmd_input': json.dumps(cmd_input)})
-            return json.loads(result)
+            result_dict = json.loads(result)
+            returncode = result_dict.get('returncode')
+            captured_stdout = result_dict.get('out')
+            captured_stderr = result_dict.get('err')
+            sys.stdout.write(captured_stdout)
+            sys.stderr.write(captured_stderr)
+            sys.exit(returncode)
         finally:
             session.xenapi.session.logout()
     except Exception as e:
-        traceback.print_exc()
+        sys.stderr.write("Failed to execute command in Dom0, %s" % e)
         sys.exit(RC_XENAPI_ERROR)
 
 
@@ -142,4 +148,4 @@ def main():
 
 
 if __name__ == '__main__':
-    print(main())
+    main()

neutron/plugins/ml2/drivers/openvswitch/agent/xenapi/etc/xapi.d/plugins/netwrap

@@ -44,6 +44,7 @@ ALLOWED_CMDS = [
     'ovs-ofctl',
     'ovs-vsctl',
     'ovsdb-client',
+    'conntrack',
     ]
 
 
@@ -61,10 +62,7 @@ def _run_command(cmd, cmd_input):
     proc = subprocess.Popen(cmd, shell=False, stdin=pipe, stdout=pipe,
                             stderr=pipe, close_fds=True)
     (out, err) = proc.communicate(cmd_input)
-
-    if proc.returncode != 0:
-        raise PluginError(err)
-    return out
+    return proc.returncode, out, err
 
 
 def run_command(session, args):
@@ -72,7 +70,16 @@ def run_command(session, args):
     if cmd and cmd[0] not in ALLOWED_CMDS:
         msg = _("Dom0 execution of '%s' is not permitted") % cmd[0]
         raise PluginError(msg)
-    result = _run_command(cmd, json.loads(args.get('cmd_input', 'null')))
+    returncode, out, err = _run_command(
+                                cmd, json.loads(args.get('cmd_input', 'null')))
+    if not err:
+        err = ""
+    if not out:
+        out = ""
+    # This runs in Dom0, will return to neutron-ovs-agent in compute node
+    result = {'returncode': returncode,
+              'out': out,
+              'err': err}
     return json.dumps(result)