Move to kubernetes python client 9.0.0

This version [0] makes the adal package optional [1], which also
removes its dependency on the cryptography package.

It also fixes a thread pool issue [2] allowing us to remove the
workaround we had in place.

[0]: https://github.com/kubernetes-client/python/blob/master/CHANGELOG.md#v900
[1]: kubernetes-client/python-base#108
[2]: kubernetes-client/gen#91

Change-Id: I55aa8b97483b118fbde7e11df817ad8330da9bf1

Author: seaneagan

armada/handlers/k8s.py

@@ -17,9 +17,7 @@
 from kubernetes import client
 from kubernetes import config
 from kubernetes import watch
-from kubernetes.client import api_client
 from kubernetes.client.rest import ApiException
-from unittest.mock import Mock
 from oslo_config import cfg
 from oslo_log import log as logging
 
@@ -29,12 +27,6 @@
 CONF = cfg.CONF
 LOG = logging.getLogger(__name__)
 
-# TODO: Remove after this bug is fixed and we have uplifted to a fixed version:
-#       https://github.com/kubernetes-client/python/issues/411
-# Avoid creating thread pools in kubernetes api_client.
-_dummy_pool = Mock()
-api_client.ThreadPool = lambda *args, **kwargs: _dummy_pool
-
 
 class K8s(object):
     '''

requirements.txt

@@ -4,7 +4,7 @@ grpcio==1.16.0
 jsonschema>=2.6.0
 keystoneauth1==2.21.0
 keystonemiddleware==4.9.1
-kubernetes>=6.0.0
+kubernetes>=9.0.0
 Paste>=2.0.3
 PasteDeploy>=1.5.2
 protobuf>=3.4.0