Zookeeper backend SSL support

Bump kazoo version to 2.6.0 that supports SSL.

Allow to configure ssl config options via conf
* keyfile
* keyfile_password
* certfile
* use_ssl
* verify_certs

https://kazoo.readthedocs.io/en/latest/api/client.html#kazoo.client.KazooClient

This should be done in conformance with Redis
jobboard backend, that already allows SSL settings.

Change-Id: Ic2670c3c4caa93f69bc2d541c3701df2b6037d2e

lower-constraints.txt

@@ -22,7 +22,7 @@ imagesize==0.7.1
 iso8601==0.1.11
 Jinja2==2.10
 jsonschema==2.6.0
-kazoo==2.2
+kazoo==2.6.0
 keystoneauth1==3.4.0
 kombu==4.0.0
 linecache2==1.0.0

releasenotes/notes/zookeeper-ssl-support-b9abf24a39096b62.yaml

@@ -0,0 +1,6 @@
+---
+features:
+  - |
+    SSL support for zookeeper backend (kazoo client). Now the following options
+    can be passed to zookeeper config: *keyfile*, *keyfile_password*,
+    *certfile*, *use_ssl*, *verify_certs*.

setup.cfg

@@ -57,7 +57,7 @@ taskflow.engines =
 # NOTE(dhellmann): The entries in this section of the file need to be
 # kept consistent with the entries in test-requirements.txt.
 zookeeper =
-  kazoo>=2.2 # Apache-2.0
+  kazoo>=2.6.0 # Apache-2.0
   zake>=0.1.6 # Apache-2.0
 redis =
   redis>=2.10.0 # MIT

taskflow/utils/kazoo_utils.py

@@ -175,6 +175,13 @@ def make_client(conf):
     - ``handler``: a kazoo handler object that can be used to provide the
       client with alternate async strategies (the default is `thread`_
       based, but `gevent`_, or `eventlet`_ ones can be provided as needed)
+    - ``keyfile`` : SSL keyfile to use for authentication
+    - ``keyfile_password``: SSL keyfile password
+    -  ``certfile``: SSL certfile to use for authentication
+    - ``ca``: SSL CA file to use for authentication
+    - ``use_ssl``: argument to control whether SSL is used or not
+    - ``verify_certs``: when using SSL, argument to bypass
+        certs verification
 
     .. _client: https://kazoo.readthedocs.io/en/latest/api/client.html
     .. _kazoo: https://kazoo.readthedocs.io/
@@ -191,6 +198,12 @@ def make_client(conf):
         'read_only': bool(conf.get('read_only')),
         'randomize_hosts': bool(conf.get('randomize_hosts')),
         'logger': LOG,
+        'keyfile': conf.get('keyfile', None),
+        'keyfile_password': conf.get('keyfile_password', None),
+        'certfile': conf.get('certfile', None),
+        'use_ssl': conf.get('use_ssl', False),
+        'verify_certs': conf.get('verify_certs', True),
+
     }
     # See: https://kazoo.readthedocs.io/en/latest/api/retry.html
     if 'command_retry' in conf:

test-requirements.txt

@@ -3,7 +3,7 @@
 # entries need to be kept consistent.
 
 # zookeeper
-kazoo>=2.2 # Apache-2.0
+kazoo>=2.6.0 # Apache-2.0
 zake>=0.1.6 # Apache-2.0
 
 # redis