Add list_availability_zone_names method

Nodepool would like to do smart things with scheduling across AZs. In
order for it to that, it needs a list of them, which we can provide.

Change-Id: I9a3b97ccb797ea7a66a832b03da2bd4afd659097

releasenotes/notes/list-az-names-a38c277d1192471b.yaml

@@ -0,0 +1,3 @@
+---
+features:
+  - Added list_availability_zone_names API call.

shade/openstackcloud.py

@@ -1733,6 +1733,29 @@ class OpenStackCloud(_normalize.Normalizer):
             return self._normalize_volume_types(
                 self.manager.submit_task(_tasks.VolumeTypeList()))
 
+    @_utils.cache_on_arguments()
+    def list_availability_zone_names(self, unavailable=False):
+        """List names of availability zones.
+
+        :param bool unavailable: Whether or not to include unavailable zones
+                                 in the output. Defaults to False.
+
+        :returns: A list of availability zone names, or an empty list if the
+                  list could not be fetched.
+        """
+        try:
+            zones = self._compute_client.get('/os-availability-zone')
+        except OpenStackCloudHTTPError:
+            self.log.debug(
+                "Availability zone list could not be fetched",
+                exc_info=True)
+            return []
+        ret = []
+        for zone in zones:
+            if zone['zoneState']['available'] or unavailable:
+                ret.append(zone['zoneName'])
+        return ret
+
     @_utils.cache_on_arguments()
     def list_flavors(self, get_extra=True):
         """List all available flavors.

shade/tests/functional/test_compute.py

@@ -148,6 +148,10 @@ class TestCompute(base.BaseFunctionalTestCase):
             if len(log) > 0:
                 break
 
+    def test_list_availability_zone_names(self):
+        self.assertEqual(
+            ['nova'], self.user_cloud.list_availability_zone_names())
+
     def test_get_server_console_bad_server(self):
         self.assertRaises(
             exc.OpenStackCloudException,

shade/tests/unit/test_availability_zones.py

@@ -0,0 +1,79 @@
+# Copyright (c) 2017 Red Hat, Inc.
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License. You may obtain
+# a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+
+
+from shade.tests.unit import base
+from shade.tests import fakes
+
+
+_fake_zone_list = {
+    "availabilityZoneInfo": [
+        {
+            "hosts": None,
+            "zoneName": "az1",
+            "zoneState": {
+                "available": True
+            }
+        },
+        {
+            "hosts": None,
+            "zoneName": "nova",
+            "zoneState": {
+                "available": False
+            }
+        }
+    ]
+}
+
+
+class TestAvailabilityZoneNames(base.RequestsMockTestCase):
+
+    def test_list_availability_zone_names(self):
+        self.register_uris([
+            dict(method='GET',
+                 uri='{endpoint}/os-availability-zone'.format(
+                     endpoint=fakes.COMPUTE_ENDPOINT),
+                 json=_fake_zone_list),
+        ])
+
+        self.assertEqual(
+            ['az1'], self.cloud.list_availability_zone_names())
+
+        self.assert_calls()
+
+    def test_unauthorized_availability_zone_names(self):
+        self.register_uris([
+            dict(method='GET',
+                 uri='{endpoint}/os-availability-zone'.format(
+                     endpoint=fakes.COMPUTE_ENDPOINT),
+                 status_code=403),
+        ])
+
+        self.assertEqual(
+            [], self.cloud.list_availability_zone_names())
+
+        self.assert_calls()
+
+    def test_list_all_availability_zone_names(self):
+        self.register_uris([
+            dict(method='GET',
+                 uri='{endpoint}/os-availability-zone'.format(
+                     endpoint=fakes.COMPUTE_ENDPOINT),
+                 json=_fake_zone_list),
+        ])
+
+        self.assertEqual(
+            ['az1', 'nova'],
+            self.cloud.list_availability_zone_names(unavailable=True))
+
+        self.assert_calls()