Reconnect watcher if Kubernetes sends an empty response

[JacobHenner]

In watch.py, next() is set to stop iteration if the k8s server provides an empty response (i.e. when the server timeout expires). I believe this is undesirable.

kubernetes_asyncio/kubernetes_asyncio/watch/watch.py

Lines 145 to 150 in 91b2c41

	line = line.decode('utf8')
	# Stop the iterator if K8s sends an empty response. This happens when
	# eg the supplied timeout has expired.
	if line == '':
	raise StopAsyncIteration

Instead, the logic should be similar to the logic in the previous except block, which handles asyncio.TimeoutError:

kubernetes_asyncio/kubernetes_asyncio/watch/watch.py

Lines 136 to 141 in 91b2c41

	except asyncio.TimeoutError:
	if 'timeout_seconds' not in self.func.keywords:
	self.resp.close()
	self.resp = None
	self.func.keywords['resource_version'] = self.resource_version
	continue

From the perspective of kubernetes_asyncio, it should not matter if the client or if the server has timed out; the watcher should attempt to reconnect unless the user-specified timeout (timeout_seconds) has elapsed.

I believe this is how the standard Python client handles it:

https://github.com/kubernetes-client/python-base/blob/d30f1e6fd4e2725aae04fa2f4982a4cfec7c682b/watch/watch.py#L141-L157

When iter_resp_lines(resp) returns a value which evaluates to False (e.g. the k8s api returns an empty response), iteration stops. Unless _stop has been set to True, the client will attempt to reconnect.

[tomplus]

It's been solved in the latest version v30.3.0.