remote: use more explicit event loop handling

Calling asyncio.get_event_loop() with no current event loop is deprecated
since Python 3.10 and will be an error in some future Python release
[1].

Whenever we don't expect to run with an event loop, create one
explicitly. In coroutine and callbacks from asynchronous code, use the
more explicit asyncio.get_running_loop() to get the loop.

Note that this does not work in
labgrid.resources.ethernetport.EthernetPortManager: This code is usually
not called in coroutines and callbacks from asynchronous code, so
asyncio.get_running_loop() does not work there. So stick to
asyncio.get_event_loop() there and just expect to be called with a
running event loop (which is the non-deprecated use case for this
function).
Users that do not have an event loop running will see a justified
DeprecationWarning with Python >= 3.12 and an error in some future Python
version.

[1] https://docs.python.org/3/library/asyncio-eventloop.html#asyncio.get_event_loop

Signed-off-by: Bastian Krause <bst@pengutronix.de>

labgrid/remote/coordinator.py

@@ -194,7 +194,7 @@ def __init__(self) -> None:
         self.clients: dict[str, ClientSession] = {}
         self.load()
 
-        self.loop = asyncio.get_event_loop()
+        self.loop = asyncio.get_running_loop()
         self.poll_task = self.loop.create_task(self.poll())
 
     async def _poll_step(self):
@@ -1025,7 +1025,9 @@ def main():
 
     logging.basicConfig(level=logging.DEBUG if args.debug else logging.INFO)
 
-    loop = asyncio.get_event_loop()
+    loop = asyncio.new_event_loop()
+    asyncio.set_event_loop(loop)
+
     cleanup = []
     loop.set_debug(True)
     try:

labgrid/remote/exporter.py

@@ -778,7 +778,7 @@ def __init__(self, config) -> None:
         - Setup loop, name, authid and address
         - Join the coordinator as an exporter"""
         self.config = config
-        self.loop = asyncio.get_event_loop()
+        self.loop = asyncio.get_running_loop()
         self.name = config["name"]
         self.hostname = config["hostname"]
         self.isolated = config["isolated"]
@@ -1061,6 +1061,9 @@ def main():
     print(f"exporter hostname: {config['hostname']}")
     print(f"resource config file: {config['resources']}")
 
+    loop = asyncio.new_event_loop()
+    asyncio.set_event_loop(loop)
+
     asyncio.run(amain(config), debug=bool(args.debug))
 
     if reexec: