Use zaza.model.run_on_unit for ca checks

Existing code uses the python libjuju unit.run in order to execute
a wait check for ca readiness across the units. The behavior of libjuju
changed between 2.x and 3.x and causes this functionality to break. This
is abstracted and handled in the zaza library, so use that code instead
as it properly handles the differences.

Signed-off-by: Billy Olsen <billy.olsen@canonical.com>

unit_tests/utilities/test_zaza_utilities_openstack.py

@@ -1700,6 +1700,7 @@ class TestAsyncOpenstackUtils(ut_utils.AioTestCase):
                     'Stderr': stderr,
                     'Stdout': stdout}}
             return action
+
         results = {
             '/tmp/missing.cert': _get_action_output(
                 '',
@@ -1707,12 +1708,16 @@ class TestAsyncOpenstackUtils(ut_utils.AioTestCase):
                 'cat: /tmp/missing.cert: No such file or directory'),
             '/tmp/good.cert': _get_action_output('CERTIFICATE', '0')}
 
-        async def _run(command, timeout=None):
-            return results[command.split()[-1]]
+        self.patch_object(openstack_utils.zaza.model, "async_run_on_unit")
+
+        async def _run_on_unit(unit_name, command, model_name=None,
+                               timeout=None):
+            return results[command.split()[-1]].data.get('results')
+
+        self.async_run_on_unit.side_effect = _run_on_unit
+
         self.unit1 = mock.MagicMock()
         self.unit2 = mock.MagicMock()
-        self.unit2.run.side_effect = _run
-        self.unit1.run.side_effect = _run
         self.units = [self.unit1, self.unit2]
         _units = mock.MagicMock()
         _units.units = self.units

zaza/openstack/utilities/openstack.py

@@ -237,8 +237,12 @@ async def async_block_until_ca_exists(application_name, ca_cert,
         for ca_file in ca_files:
             for unit in units:
                 try:
-                    output = await unit.run('cat {}'.format(ca_file))
-                    contents = output.data.get('results').get('Stdout', '')
+                    output = await zaza.model.async_run_on_unit(
+                        unit.name,
+                        'cat {}'.format(ca_file),
+                        model_name=model_name
+                    )
+                    contents = output.get('Stdout', '')
                     if ca_cert not in contents:
                         break
                 # libjuju throws a generic error for connection failure. So we