Make it easier to use the eventlet backdoor locally

In order to determine what to do about this module it
is quite useful to provide for a way to run it as its own
main program (and interact with it from another telnet
session).

This adds a simple `main` function and uses it.

This can then be used like:

$ python oslo_service/eventlet_backdoor.py --backdoor_port 8000

Then from another terminal:

$ telnet localhost 8000

Change-Id: I8c2b93dfad328929e1a106c5883903fe0bfb188a

oslo_service/eventlet_backdoor.py

@@ -93,7 +93,7 @@ def _listen(host, start_port, end_port, listen_func):
             try_port += 1
 
 
-def initialize_if_enabled(conf):
+def _initialize_if_enabled(conf):
     conf.register_opts(_options.eventlet_backdoor_opts)
     backdoor_locals = {
         'exit': _dont_use_this,      # So we don't exit the entire process
@@ -127,6 +127,40 @@ def initialize_if_enabled(conf):
         _LI('Eventlet backdoor listening on %(port)s for process %(pid)d'),
         {'port': port, 'pid': os.getpid()}
     )
-    eventlet.spawn_n(eventlet.backdoor.backdoor_server, sock,
-                     locals=backdoor_locals)
-    return port
+    thread = eventlet.spawn(eventlet.backdoor.backdoor_server, sock,
+                            locals=backdoor_locals)
+    return (port, thread)
+
+
+def initialize_if_enabled(conf):
+    port_thread = _initialize_if_enabled(conf)
+    if not port_thread:
+        return None
+    else:
+        port, _thread = port_thread
+        return port
+
+
+def _main():
+    import eventlet
+    eventlet.monkey_patch(all=True)
+
+    from oslo_config import cfg
+
+    logging.basicConfig(level=logging.DEBUG)
+
+    conf = cfg.ConfigOpts()
+    conf.register_cli_opts(_options.eventlet_backdoor_opts)
+    conf(sys.argv[1:])
+
+    port_thread = _initialize_if_enabled(conf)
+    if not port_thread:
+        raise RuntimeError("Did not create backdoor at requested port")
+    else:
+        _port, thread = port_thread
+        thread.wait()
+
+
+if __name__ == '__main__':
+    # simple CLI for testing
+    _main()

oslo_service/tests/test_eventlet_backdoor.py

@@ -36,7 +36,7 @@ class BackdoorPortTest(base.ServiceBaseTestCase):
     def common_backdoor_port_setup(self):
         self.sock = self.mox.CreateMockAnything()
         self.mox.StubOutWithMock(eventlet, 'listen')
-        self.mox.StubOutWithMock(eventlet, 'spawn_n')
+        self.mox.StubOutWithMock(eventlet, 'spawn')
 
     def test_backdoor_port_inuse(self):
         self.config(backdoor_port=2345)
@@ -52,8 +52,8 @@ class BackdoorPortTest(base.ServiceBaseTestCase):
         self.common_backdoor_port_setup()
         eventlet.listen(('localhost', 8800)).AndReturn(self.sock)
         self.sock.getsockname().AndReturn(('127.0.0.1', 8800))
-        eventlet.spawn_n(eventlet.backdoor.backdoor_server, self.sock,
-                         locals=moxstubout.mox.IsA(dict))
+        eventlet.spawn(eventlet.backdoor.backdoor_server, self.sock,
+                       locals=moxstubout.mox.IsA(dict))
         self.mox.ReplayAll()
         port = eventlet_backdoor.initialize_if_enabled(self.conf)
         self.assertEqual(port, 8800)

oslo_service/tests/test_service.py

@@ -287,12 +287,12 @@ class LauncherTest(base.ServiceBaseTestCase):
 
         sock = self.mox.CreateMockAnything()
         self.mox.StubOutWithMock(eventlet, 'listen')
-        self.mox.StubOutWithMock(eventlet, 'spawn_n')
+        self.mox.StubOutWithMock(eventlet, 'spawn')
 
         eventlet.listen(('localhost', 1234)).AndReturn(sock)
         sock.getsockname().AndReturn(('127.0.0.1', 1234))
-        eventlet.spawn_n(eventlet.backdoor.backdoor_server, sock,
-                         locals=mox.IsA(dict))
+        eventlet.spawn(eventlet.backdoor.backdoor_server, sock,
+                       locals=mox.IsA(dict))
 
         self.mox.ReplayAll()
 
@@ -315,14 +315,14 @@ class LauncherTest(base.ServiceBaseTestCase):
 
         sock = self.mox.CreateMockAnything()
         self.mox.StubOutWithMock(eventlet, 'listen')
-        self.mox.StubOutWithMock(eventlet, 'spawn_n')
+        self.mox.StubOutWithMock(eventlet, 'spawn')
 
         eventlet.listen(('localhost', 8800)).AndRaise(
             socket.error(errno.EADDRINUSE, ''))
         eventlet.listen(('localhost', 8801)).AndReturn(sock)
         sock.getsockname().AndReturn(('127.0.0.1', 8801))
-        eventlet.spawn_n(eventlet.backdoor.backdoor_server, sock,
-                         locals=mox.IsA(dict))
+        eventlet.spawn(eventlet.backdoor.backdoor_server, sock,
+                       locals=mox.IsA(dict))
 
         self.mox.ReplayAll()