ryu.contrib: Be explicit about sys.path modification

Avoid the automatic modification of sys.path because it hurts
ryu-as-a-library use cases.
An example is the recent versions of neutron OVS-agent,
which optionally imports OVS python bindings, and ends up to
use a wrong copy in ryu.contrib.ovs.

Signed-off-by: YAMAMOTO Takashi <yamamoto@valinux.co.jp>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>

ryu/app/wsgi.py

@@ -23,12 +23,16 @@ from ryu import cfg
 from ryu.lib import hub
 from routes import Mapper
 from routes.util import URLGenerator
+
+import ryu.contrib
+ryu.contrib.update_module_path()
 from tinyrpc.server import RPCServer
 from tinyrpc.dispatch import RPCDispatcher
 from tinyrpc.dispatch import public as rpc_public
 from tinyrpc.protocols.jsonrpc import JSONRPCProtocol
 from tinyrpc.transports import ServerTransport, ClientTransport
 from tinyrpc.client import RPCClient
+ryu.contrib.restore_module_path()
 
 CONF = cfg.CONF
 CONF.register_cli_opts([

ryu/cmd/manager.py

@@ -27,6 +27,7 @@ hub.patch(thread=False)
 # NOTE: this modifies sys.path and thus affects the following imports.
 # eg. oslo.config.cfg.
 import ryu.contrib
+ryu.contrib.update_module_path()
 
 from ryu import cfg
 import logging

ryu/cmd/of_config_cli.py

@@ -24,6 +24,7 @@
 #     (Cmd) raw_get sw1
 
 import ryu.contrib
+ryu.contrib.update_module_path()
 
 from ryu import cfg
 

ryu/cmd/rpc_cli.py

@@ -30,6 +30,7 @@
 #     (Cmd)
 
 import ryu.contrib
+ryu.contrib.update_module_path()
 
 from ryu import cfg
 

ryu/cmd/ryu_base.py

@@ -15,6 +15,7 @@
 # limitations under the License.
 
 import ryu.contrib
+ryu.contrib.update_module_path()
 
 from ryu import cfg
 from ryu import utils

ryu/contrib/__init__.py

@@ -1,11 +1,23 @@
-# Adjust module loading path for third party libraries
-import os
 import sys
 
-for path in __path__:
-    if path in sys.path:
-        sys.path.remove(path)
-    path = os.path.abspath(path)
-    if path in sys.path:
-        sys.path.remove(path)
-    sys.path.insert(0, path)  # prioritize our own copy than system's
+_orig_sys_path = None
+
+def update_module_path():
+    # Adjust module loading path for third party libraries
+    import os
+    global _orig_sys_path
+
+    _orig_sys_path = sys.path[:]
+    for path in __path__:
+        if path in sys.path:
+            sys.path.remove(path)
+        path = os.path.abspath(path)
+        if path in sys.path:
+            sys.path.remove(path)
+        sys.path.insert(0, path)  # prioritize our own copy than system's
+
+def restore_module_path():
+    global _orig_sys_path
+
+    sys.path = _orig_sys_path
+    _orig_sys_path = None

ryu/lib/of_config/__init__.py

@@ -22,7 +22,9 @@ import glob
 import os.path
 import sys
 
-import ryu.contrib  # we require ncclient
+# we require ncclient
+import ryu.contrib
+ryu.contrib.update_module_path()
 
 SCHEMA_DIR = os.path.dirname(__file__)