Switch examples from kubernetes to pykube-ng

The examples are used as the e2e test. With the warnings converted
to errors, they fails quite often (randomly) due to SSL sockets
not closed properly (ResourceWarnings), noticed within the executor's
threads (which are used only for the sync-handlers).

Switching to `pykube-ng` and closing the request's session explicitly
(instead of on garbage collection) seems to fix it. So as not having
the session0owning object module-scoped.

examples/02-children/example.py

@@ -1,5 +1,5 @@
 import kopf
-import kubernetes.client
+import pykube
 import yaml
 
 
@@ -28,8 +28,10 @@ def create_fn(spec, **kwargs):
     kopf.adopt(doc)
 
     # Actually create an object by requesting the Kubernetes API.
-    api = kubernetes.client.CoreV1Api()
-    pod = api.create_namespaced_pod(namespace=doc['metadata']['namespace'], body=doc)
+    api = pykube.HTTPClient(pykube.KubeConfig.from_env())
+    pod = pykube.Pod(api, doc)
+    pod.create()
+    api.session.close()
 
     # Update the parent's status.
-    return {'children': [pod.metadata.uid]}
+    return {'children': [pod.metadata['uid']]}

examples/10-builtins/example.py

@@ -5,12 +5,6 @@
 
 tasks = {}  # dict{namespace: dict{name: asyncio.Task}}
 
-try:
-    cfg = pykube.KubeConfig.from_service_account()
-except FileNotFoundError:
-    cfg = pykube.KubeConfig.from_file()
-api = pykube.HTTPClient(cfg)
-
 
 @kopf.on.resume('', 'v1', 'pods')
 @kopf.on.create('', 'v1', 'pods')
@@ -36,8 +30,10 @@ async def pod_killer(namespace, name, logger, timeout=30):
         await asyncio.sleep(timeout)
         logger.info(f"=== Pod killing happens NOW!")
 
+        api = pykube.HTTPClient(pykube.KubeConfig.from_env())
         pod = pykube.Pod.objects(api, namespace=namespace).get_by_name(name)
         pod.delete()
+        api.session.close()
 
     except asyncio.CancelledError:
         logger.info(f"=== Pod killing is cancelled!")

examples/99-all-at-once/example.py

@@ -18,12 +18,6 @@
 E2E_FAILURE_COUNTS = {}
 E2E_TRACEBACKS = True
 
-try:
-    cfg = pykube.KubeConfig.from_service_account()
-except FileNotFoundError:
-    cfg = pykube.KubeConfig.from_file()
-api = pykube.HTTPClient(cfg)
-
 
 @kopf.on.startup()
 async def startup_fn_simple(logger, **kwargs):
@@ -112,8 +106,10 @@ def create_pod(**kwargs):
     kopf.label(pod_data, {'application': 'kopf-example-10'})
 
     # Actually create an object by requesting the Kubernetes API.
+    api = pykube.HTTPClient(pykube.KubeConfig.from_env())
     pod = pykube.Pod(api, pod_data)
     pod.create()
+    api.session.close()
 
 
 @kopf.on.event('', 'v1', 'pods', labels={'application': 'kopf-example-10'})