Accept both coroutines and coroutine functions

Author: JacobHenner

examples/leaderelection.py

@@ -65,8 +65,10 @@ async def example_end_func():
             lease_duration=17,
             renew_deadline=15,
             retry_period=5,
-            onstarted_leading=example_start_func(),
-            onstopped_leading=example_end_func(),
+            # Coroutines are also accepted, to facilitate providing context
+            # (e.g. passing apic)
+            onstarted_leading=example_start_func,
+            onstopped_leading=example_end_func,
         )
 
         # Enter leader election

kubernetes_asyncio/leaderelection/electionconfig.py

@@ -12,23 +12,27 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from collections.abc import Coroutine  # noqa:F401
+from collections.abc import Callable, Coroutine  # noqa:F401
 
 
 class Config:
     # Validate config, exit if an error is detected
 
-    # onstarted_leading and onstopped_leading are defined as coroutines rather
-    # than callables in order to faciliate passing context. For example, this
-    # allows the ApiClient used by the leader election to be shared and reused.
+    # onstarted_leading and onstopped_leading accept either coroutines or
+    # coroutine functions. Coroutines faciliate passing context, but coroutine
+    # functions can be simpler when passing context is not required.
+    #
+    # One example of when passing context is helpful is sharing the ApiClient
+    # used by the leader election, which can then be used for subsequent
+    # Kubernetes API operations upon onstopped_leading or onstopped_leading.
     def __init__(
         self,
         lock,
         lease_duration,
         renew_deadline,
         retry_period,
-        onstarted_leading,  # type: Coroutine
-        onstopped_leading=None,  # type: Coroutine | None
+        onstarted_leading,  # type: Coroutine | Callable[[], Coroutine]
+        onstopped_leading=None,  # type: Coroutine | Callable[[], Coroutine] | None
     ):
         self.jitter_factor = 1.2
 

kubernetes_asyncio/leaderelection/leaderelection.py

@@ -14,6 +14,7 @@
 
 import asyncio
 import datetime
+import inspect
 import json
 import logging
 import sys
@@ -55,7 +56,13 @@ async def run(self):
                 "%s successfully acquired lease", self.election_config.lock.identity
             )
 
-            task = asyncio.create_task(self.election_config.onstarted_leading)
+            onstarted_leading_coroutine = (
+                self.election_config.onstarted_leading
+                if inspect.iscoroutine(self.election_config.onstarted_leading)
+                else self.election_config.onstarted_leading()
+            )
+
+            task = asyncio.create_task(onstarted_leading_coroutine)
 
             await self.renew_loop()
 
@@ -68,7 +75,11 @@ async def run(self):
             # preserved in order to continue to provide an interface similar to
             # the one provided by `kubernetes-client/python`.
             if self.election_config.onstopped_leading is not None:
-                await self.election_config.onstopped_leading
+                await (
+                    self.election_config.onstopped_leading
+                    if inspect.iscoroutine(self.election_config.onstopped_leading)
+                    else self.election_config.onstopped_leading()
+                )
 
     async def acquire(self):
         # Follower