Adding Swift backend Region support

This adds support to configure the region_name for the
Swift backend.

We need to override the object_storage_url, as the
swiftclient does not respect the region_name when
using sessions.

Change-Id: I13d9b1b6d75f2566622881286d80fba71dbc8af5
Closes-Bug: #1771647

zaqar/storage/swift/driver.py

@@ -104,6 +104,7 @@ class _ClientWrapper(object):
 
     def __init__(self, conf):
         self.conf = conf
+        self.endpoint = None
         self.parsed_url = urllib.parse.urlparse(conf.uri)
         self.session = None
 
@@ -118,10 +119,19 @@ class _ClientWrapper(object):
             project_domain_name=self.conf.project_domain_name,
             auth_url=self.conf.auth_url)
         self.session = keystone_session.Session(auth=auth)
+        self.endpoint = self.session.get_endpoint(
+            service_type='object-store',
+            interface=self.conf.interface,
+            region_name=self.conf.region_name
+        )
 
     def __getattr__(self, attr):
         if self.session is None:
             self._init_auth()
+        os_options = {
+            'object_storage_url': self.endpoint
+        }
         client = swiftclient.Connection(session=self.session,
-                                        insecure=self.conf.insecure)
+                                        insecure=self.conf.insecure,
+                                        os_options=os_options)
         return getattr(client, attr)

zaqar/storage/swift/options.py

@@ -26,6 +26,9 @@ MESSAGE_SWIFT_OPTIONS = (
     cfg.StrOpt("project_domain_name", help="Domain name containing project"),
     cfg.StrOpt("user_domain_id", default="default", help="User's domain id"),
     cfg.StrOpt("user_domain_name", help="User's domain name"),
+    cfg.StrOpt("region_name", help="Region name"),
+    cfg.StrOpt("interface", default="publicURL",
+               help="The default interface for endpoint URL discovery."),
 )