Add flag to enable keep the watch action working all the time

Fixes issue: https://github.com/kubernetes-incubator/client-python/issues/124

watch/watch.py

@@ -83,12 +83,14 @@ class Watch(object):
             js['object'] = self._api_client.deserialize(obj, return_type)
         return js
 
-    def stream(self, func, *args, **kwargs):
+    def stream(self, func, keep=False, *args, **kwargs):
         """Watch an API resource and stream the result back via a generator.
 
         :param func: The API function pointer. Any parameter to the function
                      can be passed after this parameter.
 
+        :param keep: Flag to keep the watch work all the time.
+
         :return: Event object with these keys:
                    'type': The type of event such as "ADDED", "DELETED", etc.
                    'raw_object': a dict representing the watched object.
@@ -113,12 +115,17 @@ class Watch(object):
         return_type = self.get_return_type(func)
         kwargs['watch'] = True
         kwargs['_preload_content'] = False
-        resp = func(*args, **kwargs)
-        try:
-            for line in iter_resp_lines(resp):
-                yield self.unmarshal_event(line, return_type)
-                if self._stop:
-                    break
-        finally:
-            resp.close()
-            resp.release_conn()
+
+        while True:
+            resp = func(*args, **kwargs)
+            try:
+                for line in iter_resp_lines(resp):
+                    yield self.unmarshal_event(line, return_type)
+                    if self._stop:
+                        break
+            finally:
+                resp.close()
+                resp.release_conn()
+
+            if not keep or self._stop:
+                break

watch/watch_test.py

@@ -85,6 +85,36 @@ class WatchTests(unittest.TestCase):
             fake_resp.close.assert_called_once()
             fake_resp.release_conn.assert_called_once()
 
+    def test_watch_stream_keep(self):
+        w = Watch(float)
+
+        fake_resp = Mock()
+        fake_resp.close = Mock()
+        fake_resp.release_conn = Mock()
+        fake_resp.read_chunked = Mock(
+            return_value=['{"type": "ADDED", "object": 1}\n'])
+
+        fake_api = Mock()
+        fake_api.get_namespaces = Mock(return_value=fake_resp)
+        fake_api.get_namespaces.__doc__ = ':return: V1NamespaceList'
+
+        count = 0
+        for e in w.stream(fake_api.get_namespaces):
+            count = count + 1
+
+        self.assertEqual(count, 1)
+
+        for e in w.stream(fake_api.get_namespaces, True):
+            count = count + 1
+            if count == 2:
+                w.stop()
+
+        self.assertEqual(count, 2)
+        self.assertEqual(fake_api.get_namespaces.call_count, 2)
+        self.assertEqual(fake_resp.read_chunked.call_count, 2)
+        self.assertEqual(fake_resp.close.call_count, 2)
+        self.assertEqual(fake_resp.release_conn.call_count, 2)
+
     def test_unmarshal_with_float_object(self):
         w = Watch()
         event = w.unmarshal_event('{"type": "ADDED", "object": 1}', 'float')