diff --git a/tempest/services/baremetal/base.py b/tempest/services/baremetal/base.py
index 6e86466..5f6b513 100644
--- a/tempest/services/baremetal/base.py
+++ b/tempest/services/baremetal/base.py
@@ -114,7 +114,7 @@
         """
         uri = self._get_uri(resource, permanent=permanent)
 
-        resp, body = self.get(uri, self.headers)
+        resp, body = self.get(uri)
 
         return resp, self.deserialize(body)
 
@@ -127,7 +127,7 @@
 
         """
         uri = self._get_uri(resource, uuid=uuid, permanent=permanent)
-        resp, body = self.get(uri, self.headers)
+        resp, body = self.get(uri)
 
         return resp, self.deserialize(body)
 
@@ -145,7 +145,7 @@
         body = self.serialize(object_type, object_dict)
         uri = self._get_uri(resource)
 
-        resp, body = self.post(uri, headers=self.headers, body=body)
+        resp, body = self.post(uri, body=body)
 
         return resp, self.deserialize(body)
 
@@ -160,7 +160,7 @@
         """
         uri = self._get_uri(resource, uuid)
 
-        resp, body = self.delete(uri, self.headers)
+        resp, body = self.delete(uri)
         return resp, body
 
     def _patch_request(self, resource, uuid, patch_object):
@@ -176,7 +176,7 @@
         uri = self._get_uri(resource, uuid)
         patch_body = json.dumps(patch_object)
 
-        resp, body = self.patch(uri, headers=self.headers, body=patch_body)
+        resp, body = self.patch(uri, body=patch_body)
         return resp, self.deserialize(body)
 
     @handle_errors
diff --git a/tempest/services/identity/v3/json/credentials_client.py b/tempest/services/identity/v3/json/credentials_client.py
index a0fbb76..5d6632a 100644
--- a/tempest/services/identity/v3/json/credentials_client.py
+++ b/tempest/services/identity/v3/json/credentials_client.py
@@ -40,8 +40,7 @@
             "user_id": user_id
         }
         post_body = json.dumps({'credential': post_body})
-        resp, body = self.post('credentials', post_body,
-                               self.headers)
+        resp, body = self.post('credentials', post_body)
         body = json.loads(body)
         body['credential']['blob'] = json.loads(body['credential']['blob'])
         return resp, body['credential']
@@ -63,8 +62,7 @@
             "user_id": user_id
         }
         post_body = json.dumps({'credential': post_body})
-        resp, body = self.patch('credentials/%s' % credential_id, post_body,
-                                self.headers)
+        resp, body = self.patch('credentials/%s' % credential_id, post_body)
         body = json.loads(body)
         body['credential']['blob'] = json.loads(body['credential']['blob'])
         return resp, body['credential']
diff --git a/tempest/services/identity/v3/json/endpoints_client.py b/tempest/services/identity/v3/json/endpoints_client.py
index 1b78115..652c345 100644
--- a/tempest/services/identity/v3/json/endpoints_client.py
+++ b/tempest/services/identity/v3/json/endpoints_client.py
@@ -47,7 +47,7 @@
             'enabled': enabled
         }
         post_body = json.dumps({'endpoint': post_body})
-        resp, body = self.post('endpoints', post_body, self.headers)
+        resp, body = self.post('endpoints', post_body)
         body = json.loads(body)
         return resp, body['endpoint']
 
@@ -66,8 +66,7 @@
         if enabled is not None:
             post_body['enabled'] = enabled
         post_body = json.dumps({'endpoint': post_body})
-        resp, body = self.patch('endpoints/%s' % endpoint_id, post_body,
-                                self.headers)
+        resp, body = self.patch('endpoints/%s' % endpoint_id, post_body)
         body = json.loads(body)
         return resp, body['endpoint']
 
diff --git a/tempest/services/identity/v3/json/identity_client.py b/tempest/services/identity/v3/json/identity_client.py
index ab1dc94..ec3229e 100644
--- a/tempest/services/identity/v3/json/identity_client.py
+++ b/tempest/services/identity/v3/json/identity_client.py
@@ -49,8 +49,7 @@
             'password': password
         }
         post_body = json.dumps({'user': post_body})
-        resp, body = self.post('users', post_body,
-                               self.headers)
+        resp, body = self.post('users', post_body)
         body = json.loads(body)
         return resp, body['user']
 
@@ -72,14 +71,13 @@
             'description': description
         }
         post_body = json.dumps({'user': post_body})
-        resp, body = self.patch('users/%s' % user_id, post_body,
-                                self.headers)
+        resp, body = self.patch('users/%s' % user_id, post_body)
         body = json.loads(body)
         return resp, body['user']
 
     def list_user_projects(self, user_id):
         """Lists the projects on which a user has roles assigned."""
-        resp, body = self.get('users/%s/projects' % user_id, self.headers)
+        resp, body = self.get('users/%s/projects' % user_id)
         body = json.loads(body)
         return resp, body['projects']
 
@@ -112,7 +110,7 @@
             'name': name
         }
         post_body = json.dumps({'project': post_body})
-        resp, body = self.post('projects', post_body, self.headers)
+        resp, body = self.post('projects', post_body)
         body = json.loads(body)
         return resp, body['project']
 
@@ -135,8 +133,7 @@
             'domain_id': domain_id,
         }
         post_body = json.dumps({'project': post_body})
-        resp, body = self.patch('projects/%s' % project_id, post_body,
-                                self.headers)
+        resp, body = self.patch('projects/%s' % project_id, post_body)
         body = json.loads(body)
         return resp, body['project']
 
@@ -157,7 +154,7 @@
             'name': name
         }
         post_body = json.dumps({'role': post_body})
-        resp, body = self.post('roles', post_body, self.headers)
+        resp, body = self.post('roles', post_body)
         body = json.loads(body)
         return resp, body['role']
 
@@ -173,8 +170,7 @@
             'name': name
         }
         post_body = json.dumps({'role': post_body})
-        resp, body = self.patch('roles/%s' % str(role_id), post_body,
-                                self.headers)
+        resp, body = self.patch('roles/%s' % str(role_id), post_body)
         body = json.loads(body)
         return resp, body['role']
 
@@ -186,8 +182,7 @@
     def assign_user_role(self, project_id, user_id, role_id):
         """Add roles to a user on a project."""
         resp, body = self.put('projects/%s/users/%s/roles/%s' %
-                              (project_id, user_id, role_id), None,
-                              self.headers)
+                              (project_id, user_id, role_id), None)
         return resp, body
 
     def create_domain(self, name, **kwargs):
@@ -200,7 +195,7 @@
             'name': name
         }
         post_body = json.dumps({'domain': post_body})
-        resp, body = self.post('domains', post_body, self.headers)
+        resp, body = self.post('domains', post_body)
         body = json.loads(body)
         return resp, body['domain']
 
@@ -227,8 +222,7 @@
             'name': name
         }
         post_body = json.dumps({'domain': post_body})
-        resp, body = self.patch('domains/%s' % domain_id, post_body,
-                                self.headers)
+        resp, body = self.patch('domains/%s' % domain_id, post_body)
         body = json.loads(body)
         return resp, body['domain']
 
@@ -263,13 +257,13 @@
             'name': name
         }
         post_body = json.dumps({'group': post_body})
-        resp, body = self.post('groups', post_body, self.headers)
+        resp, body = self.post('groups', post_body)
         body = json.loads(body)
         return resp, body['group']
 
     def get_group(self, group_id):
         """Get group details."""
-        resp, body = self.get('groups/%s' % group_id, self.headers)
+        resp, body = self.get('groups/%s' % group_id)
         body = json.loads(body)
         return resp, body['group']
 
@@ -283,8 +277,7 @@
             'description': description
         }
         post_body = json.dumps({'group': post_body})
-        resp, body = self.patch('groups/%s' % group_id, post_body,
-                                self.headers)
+        resp, body = self.patch('groups/%s' % group_id, post_body)
         body = json.loads(body)
         return resp, body['group']
 
@@ -296,33 +289,30 @@
     def add_group_user(self, group_id, user_id):
         """Add user into group."""
         resp, body = self.put('groups/%s/users/%s' % (group_id, user_id),
-                              None, self.headers)
+                              None)
         return resp, body
 
     def list_group_users(self, group_id):
         """List users in group."""
-        resp, body = self.get('groups/%s/users' % group_id, self.headers)
+        resp, body = self.get('groups/%s/users' % group_id)
         body = json.loads(body)
         return resp, body['users']
 
     def delete_group_user(self, group_id, user_id):
         """Delete user in group."""
-        resp, body = self.delete('groups/%s/users/%s' % (group_id, user_id),
-                                 self.headers)
+        resp, body = self.delete('groups/%s/users/%s' % (group_id, user_id))
         return resp, body
 
     def assign_user_role_on_project(self, project_id, user_id, role_id):
         """Add roles to a user on a project."""
         resp, body = self.put('projects/%s/users/%s/roles/%s' %
-                              (project_id, user_id, role_id), None,
-                              self.headers)
+                              (project_id, user_id, role_id), None)
         return resp, body
 
     def assign_user_role_on_domain(self, domain_id, user_id, role_id):
         """Add roles to a user on a domain."""
         resp, body = self.put('domains/%s/users/%s/roles/%s' %
-                              (domain_id, user_id, role_id), None,
-                              self.headers)
+                              (domain_id, user_id, role_id), None)
         return resp, body
 
     def list_user_roles_on_project(self, project_id, user_id):
@@ -354,15 +344,13 @@
     def assign_group_role_on_project(self, project_id, group_id, role_id):
         """Add roles to a user on a project."""
         resp, body = self.put('projects/%s/groups/%s/roles/%s' %
-                              (project_id, group_id, role_id), None,
-                              self.headers)
+                              (project_id, group_id, role_id), None)
         return resp, body
 
     def assign_group_role_on_domain(self, domain_id, group_id, role_id):
         """Add roles to a user on a domain."""
         resp, body = self.put('domains/%s/groups/%s/roles/%s' %
-                              (domain_id, group_id, role_id), None,
-                              self.headers)
+                              (domain_id, group_id, role_id), None)
         return resp, body
 
     def list_group_roles_on_project(self, project_id, group_id):
@@ -404,7 +392,7 @@
             'expires_at': expires_at
         }
         post_body = json.dumps({'trust': post_body})
-        resp, body = self.post('OS-TRUST/trusts', post_body, self.headers)
+        resp, body = self.post('OS-TRUST/trusts', post_body)
         body = json.loads(body)
         return resp, body['trust']
 
@@ -507,11 +495,16 @@
             creds['auth']['scope'] = scope
 
         body = json.dumps(creds)
-        resp, body = self.post(self.auth_url, headers=self.headers, body=body)
+        resp, body = self.post(self.auth_url, body=body)
         return resp, body
 
     def request(self, method, url, headers=None, body=None):
         """A simple HTTP request interface."""
+        if headers is None:
+            # Always accept 'json', for xml token client too.
+            # Because XML response is not easily
+            # converted to the corresponding JSON one
+            headers = self.get_headers(accept_type="json")
         self._log_request(method, url, headers, body)
         resp, resp_body = self.http_obj.request(url, method,
                                                 headers=headers, body=body)
diff --git a/tempest/services/identity/v3/json/policy_client.py b/tempest/services/identity/v3/json/policy_client.py
index c376979..5a3f891 100644
--- a/tempest/services/identity/v3/json/policy_client.py
+++ b/tempest/services/identity/v3/json/policy_client.py
@@ -36,7 +36,7 @@
             "type": type
         }
         post_body = json.dumps({'policy': post_body})
-        resp, body = self.post('policies', post_body, self.headers)
+        resp, body = self.post('policies', post_body)
         body = json.loads(body)
         return resp, body['policy']
 
@@ -62,8 +62,7 @@
         }
         post_body = json.dumps({'policy': post_body})
         url = 'policies/%s' % policy_id
-        resp, body = self.patch(url, post_body,
-                                self.headers)
+        resp, body = self.patch(url, post_body)
         body = json.loads(body)
         return resp, body['policy']
 
diff --git a/tempest/services/identity/v3/json/service_client.py b/tempest/services/identity/v3/json/service_client.py
index 92f7629..094e567 100644
--- a/tempest/services/identity/v3/json/service_client.py
+++ b/tempest/services/identity/v3/json/service_client.py
@@ -41,8 +41,7 @@
             'name': name
         }
         patch_body = json.dumps({'service': patch_body})
-        resp, body = self.patch('services/%s' % service_id,
-                                patch_body, self.headers)
+        resp, body = self.patch('services/%s' % service_id, patch_body)
         body = json.loads(body)
         return resp, body['service']
 
diff --git a/tempest/services/identity/v3/xml/credentials_client.py b/tempest/services/identity/v3/xml/credentials_client.py
index eca86ab..f6fa678 100644
--- a/tempest/services/identity/v3/xml/credentials_client.py
+++ b/tempest/services/identity/v3/xml/credentials_client.py
@@ -61,8 +61,7 @@
         credential = Element('credential', project_id=project_id,
                              type=cred_type, user_id=user_id)
         credential.append(blob)
-        resp, body = self.post('credentials', str(Document(credential)),
-                               self.headers)
+        resp, body = self.post('credentials', str(Document(credential)))
         body = self._parse_body(etree.fromstring(body))
         body['blob'] = json.loads(body['blob'])
         return resp, body
@@ -85,27 +84,25 @@
                              type=cred_type, user_id=user_id)
         credential.append(blob)
         resp, body = self.patch('credentials/%s' % credential_id,
-                                str(Document(credential)),
-                                self.headers)
+                                str(Document(credential)))
         body = self._parse_body(etree.fromstring(body))
         body['blob'] = json.loads(body['blob'])
         return resp, body
 
     def get_credential(self, credential_id):
         """To GET Details of a credential."""
-        resp, body = self.get('credentials/%s' % credential_id, self.headers)
+        resp, body = self.get('credentials/%s' % credential_id)
         body = self._parse_body(etree.fromstring(body))
         body['blob'] = json.loads(body['blob'])
         return resp, body
 
     def list_credentials(self):
         """Lists out all the available credentials."""
-        resp, body = self.get('credentials', self.headers)
+        resp, body = self.get('credentials')
         body = self._parse_creds(etree.fromstring(body))
         return resp, body
 
     def delete_credential(self, credential_id):
         """Deletes a credential."""
-        resp, body = self.delete('credentials/%s' % credential_id,
-                                 self.headers)
+        resp, body = self.delete('credentials/%s' % credential_id)
         return resp, body
diff --git a/tempest/services/identity/v3/xml/endpoints_client.py b/tempest/services/identity/v3/xml/endpoints_client.py
index a20a9f5..2a88c15 100644
--- a/tempest/services/identity/v3/xml/endpoints_client.py
+++ b/tempest/services/identity/v3/xml/endpoints_client.py
@@ -58,7 +58,7 @@
 
     def list_endpoints(self):
         """Get the list of endpoints."""
-        resp, body = self.get("endpoints", self.headers)
+        resp, body = self.get("endpoints")
         body = self._parse_array(etree.fromstring(body))
         return resp, body
 
@@ -72,8 +72,7 @@
                                   interface=interface,
                                   url=url, region=region,
                                   enabled=enabled)
-        resp, body = self.post('endpoints', str(Document(create_endpoint)),
-                               self.headers)
+        resp, body = self.post('endpoints', str(Document(create_endpoint)))
         body = self._parse_body(etree.fromstring(body))
         return resp, body
 
@@ -94,8 +93,7 @@
             endpoint.add_attr("region", region)
         if enabled is not None:
             endpoint.add_attr("enabled", enabled)
-        resp, body = self.patch('endpoints/%s' % str(endpoint_id),
-                                str(doc), self.headers)
+        resp, body = self.patch('endpoints/%s' % str(endpoint_id), str(doc))
         body = self._parse_body(etree.fromstring(body))
         return resp, body
 
diff --git a/tempest/services/identity/v3/xml/identity_client.py b/tempest/services/identity/v3/xml/identity_client.py
index e7b85c1..6304628 100644
--- a/tempest/services/identity/v3/xml/identity_client.py
+++ b/tempest/services/identity/v3/xml/identity_client.py
@@ -98,8 +98,7 @@
                             enabled=str(en).lower(),
                             project_id=project_id,
                             domain_id=domain_id)
-        resp, body = self.post('users', str(Document(post_body)),
-                               self.headers)
+        resp, body = self.post('users', str(Document(post_body)))
         body = self._parse_body(etree.fromstring(body))
         return resp, body
 
@@ -120,32 +119,31 @@
                               description=description,
                               enabled=str(en).lower())
         resp, body = self.patch('users/%s' % user_id,
-                                str(Document(update_user)),
-                                self.headers)
+                                str(Document(update_user)))
         body = self._parse_body(etree.fromstring(body))
         return resp, body
 
     def list_user_projects(self, user_id):
         """Lists the projects on which a user has roles assigned."""
-        resp, body = self.get('users/%s/projects' % user_id, self.headers)
+        resp, body = self.get('users/%s/projects' % user_id)
         body = self._parse_projects(etree.fromstring(body))
         return resp, body
 
     def get_users(self):
         """Get the list of users."""
-        resp, body = self.get("users", self.headers)
+        resp, body = self.get("users")
         body = self._parse_array(etree.fromstring(body))
         return resp, body
 
     def get_user(self, user_id):
         """GET a user."""
-        resp, body = self.get("users/%s" % user_id, self.headers)
+        resp, body = self.get("users/%s" % user_id)
         body = self._parse_body(etree.fromstring(body))
         return resp, body
 
     def delete_user(self, user_id):
         """Deletes a User."""
-        resp, body = self.delete("users/%s" % user_id, self.headers)
+        resp, body = self.delete("users/%s" % user_id)
         return resp, body
 
     def create_project(self, name, **kwargs):
@@ -160,14 +158,13 @@
                             enabled=str(en).lower(),
                             name=name)
         resp, body = self.post('projects',
-                               str(Document(post_body)),
-                               self.headers)
+                               str(Document(post_body)))
         body = self._parse_body(etree.fromstring(body))
         return resp, body
 
     def list_projects(self):
         """Get the list of projects."""
-        resp, body = self.get("projects", self.headers)
+        resp, body = self.get("projects")
         body = self._parse_projects(etree.fromstring(body))
         return resp, body
 
@@ -185,14 +182,13 @@
                             enabled=str(en).lower(),
                             domain_id=domain_id)
         resp, body = self.patch('projects/%s' % project_id,
-                                str(Document(post_body)),
-                                self.headers)
+                                str(Document(post_body)))
         body = self._parse_body(etree.fromstring(body))
         return resp, body
 
     def get_project(self, project_id):
         """GET a Project."""
-        resp, body = self.get("projects/%s" % project_id, self.headers)
+        resp, body = self.get("projects/%s" % project_id)
         body = self._parse_body(etree.fromstring(body))
         return resp, body
 
@@ -206,15 +202,13 @@
         post_body = Element("role",
                             xmlns=XMLNS,
                             name=name)
-        resp, body = self.post('roles',
-                               str(Document(post_body)),
-                               self.headers)
+        resp, body = self.post('roles', str(Document(post_body)))
         body = self._parse_body(etree.fromstring(body))
         return resp, body
 
     def get_role(self, role_id):
         """GET a Role."""
-        resp, body = self.get('roles/%s' % str(role_id), self.headers)
+        resp, body = self.get('roles/%s' % str(role_id))
         body = self._parse_body(etree.fromstring(body))
         return resp, body
 
@@ -224,21 +218,19 @@
                             xmlns=XMLNS,
                             name=name)
         resp, body = self.patch('roles/%s' % str(role_id),
-                                str(Document(post_body)),
-                                self.headers)
+                                str(Document(post_body)))
         body = self._parse_body(etree.fromstring(body))
         return resp, body
 
     def delete_role(self, role_id):
         """Delete a role."""
-        resp, body = self.delete('roles/%s' % str(role_id),
-                                 self.headers)
+        resp, body = self.delete('roles/%s' % str(role_id))
         return resp, body
 
     def assign_user_role(self, project_id, user_id, role_id):
         """Add roles to a user on a tenant."""
         resp, body = self.put('projects/%s/users/%s/roles/%s' %
-                              (project_id, user_id, role_id), '', self.headers)
+                              (project_id, user_id, role_id), '')
         return resp, body
 
     def create_domain(self, name, **kwargs):
@@ -250,20 +242,19 @@
                             name=name,
                             description=description,
                             enabled=str(en).lower())
-        resp, body = self.post('domains', str(Document(post_body)),
-                               self.headers)
+        resp, body = self.post('domains', str(Document(post_body)))
         body = self._parse_body(etree.fromstring(body))
         return resp, body
 
     def list_domains(self):
         """Get the list of domains."""
-        resp, body = self.get("domains", self.headers)
+        resp, body = self.get("domains")
         body = self._parse_domains(etree.fromstring(body))
         return resp, body
 
     def delete_domain(self, domain_id):
         """Delete a domain."""
-        resp, body = self.delete('domains/%s' % domain_id, self.headers)
+        resp, body = self.delete('domains/%s' % domain_id)
         return resp, body
 
     def update_domain(self, domain_id, **kwargs):
@@ -278,14 +269,13 @@
                             description=description,
                             enabled=str(en).lower())
         resp, body = self.patch('domains/%s' % domain_id,
-                                str(Document(post_body)),
-                                self.headers)
+                                str(Document(post_body)))
         body = self._parse_body(etree.fromstring(body))
         return resp, body
 
     def get_domain(self, domain_id):
         """Get Domain details."""
-        resp, body = self.get('domains/%s' % domain_id, self.headers)
+        resp, body = self.get('domains/%s' % domain_id)
         body = self._parse_body(etree.fromstring(body))
         return resp, body
 
@@ -315,14 +305,13 @@
                             description=description,
                             domain_id=domain_id,
                             project_id=project_id)
-        resp, body = self.post('groups', str(Document(post_body)),
-                               self.headers)
+        resp, body = self.post('groups', str(Document(post_body)))
         body = self._parse_body(etree.fromstring(body))
         return resp, body
 
     def get_group(self, group_id):
         """Get group details."""
-        resp, body = self.get('groups/%s' % group_id, self.headers)
+        resp, body = self.get('groups/%s' % group_id)
         body = self._parse_body(etree.fromstring(body))
         return resp, body
 
@@ -336,112 +325,105 @@
                             name=name,
                             description=description)
         resp, body = self.patch('groups/%s' % group_id,
-                                str(Document(post_body)),
-                                self.headers)
+                                str(Document(post_body)))
         body = self._parse_body(etree.fromstring(body))
         return resp, body
 
     def delete_group(self, group_id):
         """Delete a group."""
-        resp, body = self.delete('groups/%s' % group_id, self.headers)
+        resp, body = self.delete('groups/%s' % group_id)
         return resp, body
 
     def add_group_user(self, group_id, user_id):
         """Add user into group."""
-        resp, body = self.put('groups/%s/users/%s' % (group_id, user_id),
-                              '', self.headers)
+        resp, body = self.put('groups/%s/users/%s' % (group_id, user_id), '')
         return resp, body
 
     def list_group_users(self, group_id):
         """List users in group."""
-        resp, body = self.get('groups/%s/users' % group_id, self.headers)
+        resp, body = self.get('groups/%s/users' % group_id)
         body = self._parse_group_users(etree.fromstring(body))
         return resp, body
 
     def delete_group_user(self, group_id, user_id):
         """Delete user in group."""
-        resp, body = self.delete('groups/%s/users/%s' % (group_id, user_id),
-                                 self.headers)
+        resp, body = self.delete('groups/%s/users/%s' % (group_id, user_id))
         return resp, body
 
     def assign_user_role_on_project(self, project_id, user_id, role_id):
         """Add roles to a user on a project."""
         resp, body = self.put('projects/%s/users/%s/roles/%s' %
-                              (project_id, user_id, role_id), '',
-                              self.headers)
+                              (project_id, user_id, role_id), '')
         return resp, body
 
     def assign_user_role_on_domain(self, domain_id, user_id, role_id):
         """Add roles to a user on a domain."""
         resp, body = self.put('domains/%s/users/%s/roles/%s' %
-                              (domain_id, user_id, role_id), '',
-                              self.headers)
+                              (domain_id, user_id, role_id), '')
         return resp, body
 
     def list_user_roles_on_project(self, project_id, user_id):
         """list roles of a user on a project."""
         resp, body = self.get('projects/%s/users/%s/roles' %
-                              (project_id, user_id), self.headers)
+                              (project_id, user_id))
         body = self._parse_roles(etree.fromstring(body))
         return resp, body
 
     def list_user_roles_on_domain(self, domain_id, user_id):
         """list roles of a user on a domain."""
         resp, body = self.get('domains/%s/users/%s/roles' %
-                              (domain_id, user_id), self.headers)
+                              (domain_id, user_id))
         body = self._parse_roles(etree.fromstring(body))
         return resp, body
 
     def revoke_role_from_user_on_project(self, project_id, user_id, role_id):
         """Delete role of a user on a project."""
         resp, body = self.delete('projects/%s/users/%s/roles/%s' %
-                                 (project_id, user_id, role_id), self.headers)
+                                 (project_id, user_id, role_id))
         return resp, body
 
     def revoke_role_from_user_on_domain(self, domain_id, user_id, role_id):
         """Delete role of a user on a domain."""
         resp, body = self.delete('domains/%s/users/%s/roles/%s' %
-                                 (domain_id, user_id, role_id), self.headers)
+                                 (domain_id, user_id, role_id))
         return resp, body
 
     def assign_group_role_on_project(self, project_id, group_id, role_id):
         """Add roles to a user on a project."""
         resp, body = self.put('projects/%s/groups/%s/roles/%s' %
-                              (project_id, group_id, role_id), '',
-                              self.headers)
+                              (project_id, group_id, role_id), '')
         return resp, body
 
     def assign_group_role_on_domain(self, domain_id, group_id, role_id):
         """Add roles to a user on a domain."""
         resp, body = self.put('domains/%s/groups/%s/roles/%s' %
-                              (domain_id, group_id, role_id), '',
-                              self.headers)
+                              (domain_id, group_id, role_id), '')
         return resp, body
 
     def list_group_roles_on_project(self, project_id, group_id):
         """list roles of a user on a project."""
         resp, body = self.get('projects/%s/groups/%s/roles' %
-                              (project_id, group_id), self.headers)
+                              (project_id, group_id))
         body = self._parse_roles(etree.fromstring(body))
         return resp, body
 
     def list_group_roles_on_domain(self, domain_id, group_id):
         """list roles of a user on a domain."""
         resp, body = self.get('domains/%s/groups/%s/roles' %
-                              (domain_id, group_id), self.headers)
+                              (domain_id, group_id))
         body = self._parse_roles(etree.fromstring(body))
         return resp, body
 
     def revoke_role_from_group_on_project(self, project_id, group_id, role_id):
         """Delete role of a user on a project."""
         resp, body = self.delete('projects/%s/groups/%s/roles/%s' %
-                                 (project_id, group_id, role_id), self.headers)
+                                 (project_id, group_id, role_id))
         return resp, body
 
     def revoke_role_from_group_on_domain(self, domain_id, group_id, role_id):
         """Delete role of a user on a domain."""
         resp, body = self.delete('domains/%s/groups/%s/roles/%s' %
-                                 (domain_id, group_id, role_id), self.headers)
+                                 (domain_id, group_id, role_id))
         return resp, body
 
 
@@ -501,15 +483,16 @@
             scope.append(project)
             auth.append(scope)
 
-        resp, body = self.post(self.auth_url, headers=self.headers,
-                               body=str(Document(auth)))
+        resp, body = self.post(self.auth_url, body=str(Document(auth)))
         return resp, body
 
     def request(self, method, url, headers=None, body=None):
         """A simple HTTP request interface."""
-        # Send XML, accept JSON. XML response is not easily
-        # converted to the corresponding JSON one
-        headers['Accept'] = 'application/json'
+        if headers is None:
+            # Always accept 'json', for xml token client too.
+            # Because XML response is not easily
+            # converted to the corresponding JSON one
+            headers = self.get_headers(accept_type="json")
         self._log_request(method, url, headers, body)
         resp, resp_body = self.http_obj.request(url, method,
                                                 headers=headers, body=body)
diff --git a/tempest/services/identity/v3/xml/policy_client.py b/tempest/services/identity/v3/xml/policy_client.py
index 429c6a4..a7e63a7 100644
--- a/tempest/services/identity/v3/xml/policy_client.py
+++ b/tempest/services/identity/v3/xml/policy_client.py
@@ -59,21 +59,20 @@
     def create_policy(self, blob, type):
         """Creates a Policy."""
         create_policy = Element("policy", xmlns=XMLNS, blob=blob, type=type)
-        resp, body = self.post('policies', str(Document(create_policy)),
-                               self.headers)
+        resp, body = self.post('policies', str(Document(create_policy)))
         body = self._parse_body(etree.fromstring(body))
         return resp, body
 
     def list_policies(self):
         """Lists the policies."""
-        resp, body = self.get('policies', self.headers)
+        resp, body = self.get('policies')
         body = self._parse_array(etree.fromstring(body))
         return resp, body
 
     def get_policy(self, policy_id):
         """Lists out the given policy."""
         url = 'policies/%s' % policy_id
-        resp, body = self.get(url, self.headers)
+        resp, body = self.get(url)
         body = self._parse_body(etree.fromstring(body))
         return resp, body
 
@@ -83,8 +82,7 @@
         type = kwargs.get('type')
         update_policy = Element("policy", xmlns=XMLNS, type=type)
         url = 'policies/%s' % policy_id
-        resp, body = self.patch(url, str(Document(update_policy)),
-                                self.headers)
+        resp, body = self.patch(url, str(Document(update_policy)))
         body = self._parse_body(etree.fromstring(body))
         return resp, body
 
diff --git a/tempest/services/identity/v3/xml/service_client.py b/tempest/services/identity/v3/xml/service_client.py
index df9b234..f43ed2c 100644
--- a/tempest/services/identity/v3/xml/service_client.py
+++ b/tempest/services/identity/v3/xml/service_client.py
@@ -57,14 +57,13 @@
                                  description=description,
                                  type=type)
         resp, body = self.patch('services/%s' % service_id,
-                                str(Document(update_service)),
-                                self.headers)
+                                str(Document(update_service)))
         body = self._parse_body(etree.fromstring(body))
         return resp, body
 
     def get_service(self, service_id):
         """Get Service."""
         url = 'services/%s' % service_id
-        resp, body = self.get(url, self.headers)
+        resp, body = self.get(url)
         body = self._parse_body(etree.fromstring(body))
         return resp, body
diff --git a/tempest/services/identity/xml/identity_client.py b/tempest/services/identity/xml/identity_client.py
index 81846da..50403fb 100644
--- a/tempest/services/identity/xml/identity_client.py
+++ b/tempest/services/identity/xml/identity_client.py
@@ -97,7 +97,7 @@
         """Enables or disables a user."""
         enable_user = xml.Element("user", enabled=str(enabled).lower())
         resp, body = self.put('users/%s/enabled' % user_id,
-                              str(xml.Document(enable_user)), self.headers)
+                              str(xml.Document(enable_user)))
         return resp, self._parse_resp(body)
 
     def create_service(self, name, service_type, **kwargs):
diff --git a/tempest/services/image/v1/json/image_client.py b/tempest/services/image/v1/json/image_client.py
index bc9db38..62c7d2f 100644
--- a/tempest/services/image/v1/json/image_client.py
+++ b/tempest/services/image/v1/json/image_client.py
@@ -241,7 +241,7 @@
         body = None
         if can_share:
             body = json.dumps({'member': {'can_share': True}})
-        resp, __ = self.put(url, body, self.headers)
+        resp, __ = self.put(url, body)
         return resp
 
     def delete_member(self, member_id, image_id):
@@ -252,7 +252,7 @@
     def replace_membership_list(self, image_id, member_list):
         url = 'v1/images/%s/members' % image_id
         body = json.dumps({'membership': member_list})
-        resp, data = self.put(url, body, self.headers)
+        resp, data = self.put(url, body)
         data = json.loads(data)
         return resp, data
 
diff --git a/tempest/services/image/v2/json/image_client.py b/tempest/services/image/v2/json/image_client.py
index b825519..58819d0 100644
--- a/tempest/services/image/v2/json/image_client.py
+++ b/tempest/services/image/v2/json/image_client.py
@@ -86,7 +86,7 @@
         data = json.dumps(params)
         self._validate_schema(data)
 
-        resp, body = self.post('v2/images', data, self.headers)
+        resp, body = self.post('v2/images', data)
         body = json.loads(body)
         return resp, body
 
@@ -132,7 +132,7 @@
 
     def add_image_tag(self, image_id, tag):
         url = 'v2/images/%s/tags/%s' % (image_id, tag)
-        resp, body = self.put(url, body=None, headers=self.headers)
+        resp, body = self.put(url, body=None)
         return resp, body
 
     def delete_image_tag(self, image_id, tag):
@@ -150,7 +150,7 @@
     def add_member(self, image_id, member_id):
         url = 'v2/images/%s/members' % image_id
         data = json.dumps({'member': member_id})
-        resp, body = self.post(url, data, self.headers)
+        resp, body = self.post(url, data)
         body = json.loads(body)
         self.expected_success(200, resp)
         return resp, body
@@ -159,7 +159,7 @@
         """Valid status are: ``pending``, ``accepted``,  ``rejected``."""
         url = 'v2/images/%s/members/%s' % (image_id, member_id)
         data = json.dumps({'status': status})
-        resp, body = self.put(url, data, self.headers)
+        resp, body = self.put(url, data)
         body = json.loads(body)
         self.expected_success(200, resp)
         return resp, body
diff --git a/tempest/services/object_storage/object_client.py b/tempest/services/object_storage/object_client.py
index 79c5719..09e484e 100644
--- a/tempest/services/object_storage/object_client.py
+++ b/tempest/services/object_storage/object_client.py
@@ -32,7 +32,7 @@
     def create_object(self, container, object_name, data, params=None):
         """Create storage object."""
 
-        headers = dict(self.headers)
+        headers = self.get_headers()
         if not data:
             headers['content-length'] = '0'
         url = "%s/%s" % (str(container), str(object_name))
@@ -131,7 +131,7 @@
     def create_object_segments(self, container, object_name, segment, data):
         """Creates object segments."""
         url = "{0}/{1}/{2}".format(container, object_name, segment)
-        resp, body = self.put(url, data, self.headers)
+        resp, body = self.put(url, data)
         return resp, body
 
 
diff --git a/tempest/services/orchestration/json/orchestration_client.py b/tempest/services/orchestration/json/orchestration_client.py
index b70b2e8..113003c 100644
--- a/tempest/services/orchestration/json/orchestration_client.py
+++ b/tempest/services/orchestration/json/orchestration_client.py
@@ -90,7 +90,7 @@
 
         # Password must be provided on stack create so that heat
         # can perform future operations on behalf of the user
-        headers = dict(self.headers)
+        headers = self.get_headers()
         headers['X-Auth-Key'] = self.password
         headers['X-Auth-User'] = self.user
         return headers, body
@@ -106,14 +106,14 @@
         """Suspend a stack."""
         url = 'stacks/%s/actions' % stack_identifier
         body = {'suspend': None}
-        resp, body = self.post(url, json.dumps(body), self.headers)
+        resp, body = self.post(url, json.dumps(body))
         return resp, body
 
     def resume_stack(self, stack_identifier):
         """Resume a stack."""
         url = 'stacks/%s/actions' % stack_identifier
         body = {'resume': None}
-        resp, body = self.post(url, json.dumps(body), self.headers)
+        resp, body = self.post(url, json.dumps(body))
         return resp, body
 
     def list_resources(self, stack_identifier):
@@ -232,7 +232,7 @@
     def _validate_template(self, post_body):
         """Returns the validation request result."""
         post_body = json.dumps(post_body)
-        resp, body = self.post('validate', post_body, self.headers)
+        resp, body = self.post('validate', post_body)
         body = json.loads(body)
         return resp, body
 
diff --git a/tempest/services/telemetry/telemetry_client_base.py b/tempest/services/telemetry/telemetry_client_base.py
index a35a1ab..610f07b 100644
--- a/tempest/services/telemetry/telemetry_client_base.py
+++ b/tempest/services/telemetry/telemetry_client_base.py
@@ -38,7 +38,6 @@
     def __init__(self, auth_provider):
         self.rest_client = self.get_rest_client(auth_provider)
         self.rest_client.service = CONF.telemetry.catalog_type
-        self.headers = self.rest_client.headers
         self.version = '2'
         self.uri_prefix = "v%s" % self.version
 
@@ -69,15 +68,15 @@
 
     def post(self, uri, body):
         body = self.serialize(body)
-        resp, body = self.rest_client.post(uri, body, self.headers)
+        resp, body = self.rest_client.post(uri, body)
         body = self.deserialize(body)
         return resp, body
 
     def put(self, uri, body):
-        return self.rest_client.put(uri, body, self.headers)
+        return self.rest_client.put(uri, body)
 
     def get(self, uri):
-        resp, body = self.rest_client.get(uri, self.headers)
+        resp, body = self.rest_client.get(uri)
         body = self.deserialize(body)
         return resp, body
 
diff --git a/tempest/services/volume/json/admin/volume_types_client.py b/tempest/services/volume/json/admin/volume_types_client.py
index 653532e..0d50524 100644
--- a/tempest/services/volume/json/admin/volume_types_client.py
+++ b/tempest/services/volume/json/admin/volume_types_client.py
@@ -64,7 +64,7 @@
         }
 
         post_body = json.dumps({'volume_type': post_body})
-        resp, body = self.post('types', post_body, self.headers)
+        resp, body = self.post('types', post_body)
         body = json.loads(body)
         return resp, body['volume_type']
 
@@ -98,7 +98,7 @@
         """
         url = "types/%s/extra_specs" % str(vol_type_id)
         post_body = json.dumps({'extra_specs': extra_spec})
-        resp, body = self.post(url, post_body, self.headers)
+        resp, body = self.post(url, post_body)
         body = json.loads(body)
         return resp, body['extra_specs']
 
@@ -119,6 +119,6 @@
         url = "types/%s/extra_specs/%s" % (str(vol_type_id),
                                            str(extra_spec_name))
         put_body = json.dumps(extra_spec)
-        resp, body = self.put(url, put_body, self.headers)
+        resp, body = self.put(url, put_body)
         body = json.loads(body)
         return resp, body
diff --git a/tempest/services/volume/json/snapshots_client.py b/tempest/services/volume/json/snapshots_client.py
index 0a79469..ba33c49 100644
--- a/tempest/services/volume/json/snapshots_client.py
+++ b/tempest/services/volume/json/snapshots_client.py
@@ -72,15 +72,14 @@
         post_body = {'volume_id': volume_id}
         post_body.update(kwargs)
         post_body = json.dumps({'snapshot': post_body})
-        resp, body = self.post('snapshots', post_body, self.headers)
+        resp, body = self.post('snapshots', post_body)
         body = json.loads(body)
         return resp, body['snapshot']
 
     def update_snapshot(self, snapshot_id, **kwargs):
         """Updates a snapshot."""
         put_body = json.dumps({'snapshot': kwargs})
-        resp, body = self.put('snapshots/%s' % snapshot_id, put_body,
-                              self.headers)
+        resp, body = self.put('snapshots/%s' % snapshot_id, put_body)
         body = json.loads(body)
         return resp, body['snapshot']
 
@@ -135,8 +134,7 @@
     def reset_snapshot_status(self, snapshot_id, status):
         """Reset the specified snapshot's status."""
         post_body = json.dumps({'os-reset_status': {"status": status}})
-        resp, body = self.post('snapshots/%s/action' % snapshot_id, post_body,
-                               self.headers)
+        resp, body = self.post('snapshots/%s/action' % snapshot_id, post_body)
         return resp, body
 
     def update_snapshot_status(self, snapshot_id, status, progress):
@@ -147,21 +145,21 @@
         }
         post_body = json.dumps({'os-update_snapshot_status': post_body})
         url = 'snapshots/%s/action' % str(snapshot_id)
-        resp, body = self.post(url, post_body, self.headers)
+        resp, body = self.post(url, post_body)
         return resp, body
 
     def create_snapshot_metadata(self, snapshot_id, metadata):
         """Create metadata for the snapshot."""
         put_body = json.dumps({'metadata': metadata})
         url = "snapshots/%s/metadata" % str(snapshot_id)
-        resp, body = self.post(url, put_body, self.headers)
+        resp, body = self.post(url, put_body)
         body = json.loads(body)
         return resp, body['metadata']
 
     def get_snapshot_metadata(self, snapshot_id):
         """Get metadata of the snapshot."""
         url = "snapshots/%s/metadata" % str(snapshot_id)
-        resp, body = self.get(url, self.headers)
+        resp, body = self.get(url)
         body = json.loads(body)
         return resp, body['metadata']
 
@@ -169,7 +167,7 @@
         """Update metadata for the snapshot."""
         put_body = json.dumps({'metadata': metadata})
         url = "snapshots/%s/metadata" % str(snapshot_id)
-        resp, body = self.put(url, put_body, self.headers)
+        resp, body = self.put(url, put_body)
         body = json.loads(body)
         return resp, body['metadata']
 
@@ -177,19 +175,18 @@
         """Update metadata item for the snapshot."""
         put_body = json.dumps({'meta': meta_item})
         url = "snapshots/%s/metadata/%s" % (str(snapshot_id), str(id))
-        resp, body = self.put(url, put_body, self.headers)
+        resp, body = self.put(url, put_body)
         body = json.loads(body)
         return resp, body['meta']
 
     def delete_snapshot_metadata_item(self, snapshot_id, id):
         """Delete metadata item for the snapshot."""
         url = "snapshots/%s/metadata/%s" % (str(snapshot_id), str(id))
-        resp, body = self.delete(url, self.headers)
+        resp, body = self.delete(url)
         return resp, body
 
     def force_delete_snapshot(self, snapshot_id):
         """Force Delete Snapshot."""
         post_body = json.dumps({'os-force_delete': {}})
-        resp, body = self.post('snapshots/%s/action' % snapshot_id, post_body,
-                               self.headers)
+        resp, body = self.post('snapshots/%s/action' % snapshot_id, post_body)
         return resp, body
diff --git a/tempest/services/volume/json/volumes_client.py b/tempest/services/volume/json/volumes_client.py
index 0524212..2183c56 100644
--- a/tempest/services/volume/json/volumes_client.py
+++ b/tempest/services/volume/json/volumes_client.py
@@ -81,15 +81,14 @@
         post_body = {'size': size}
         post_body.update(kwargs)
         post_body = json.dumps({'volume': post_body})
-        resp, body = self.post('volumes', post_body, self.headers)
+        resp, body = self.post('volumes', post_body)
         body = json.loads(body)
         return resp, body['volume']
 
     def update_volume(self, volume_id, **kwargs):
         """Updates the Specified Volume."""
         put_body = json.dumps({'volume': kwargs})
-        resp, body = self.put('volumes/%s' % volume_id, put_body,
-                              self.headers)
+        resp, body = self.put('volumes/%s' % volume_id, put_body)
         body = json.loads(body)
         return resp, body['volume']
 
@@ -105,7 +104,7 @@
         }
         post_body = json.dumps({'os-volume_upload_image': post_body})
         url = 'volumes/%s/action' % (volume_id)
-        resp, body = self.post(url, post_body, self.headers)
+        resp, body = self.post(url, post_body)
         body = json.loads(body)
         return resp, body['os-volume_upload_image']
 
@@ -117,7 +116,7 @@
         }
         post_body = json.dumps({'os-attach': post_body})
         url = 'volumes/%s/action' % (volume_id)
-        resp, body = self.post(url, post_body, self.headers)
+        resp, body = self.post(url, post_body)
         return resp, body
 
     def detach_volume(self, volume_id):
@@ -125,7 +124,7 @@
         post_body = {}
         post_body = json.dumps({'os-detach': post_body})
         url = 'volumes/%s/action' % (volume_id)
-        resp, body = self.post(url, post_body, self.headers)
+        resp, body = self.post(url, post_body)
         return resp, body
 
     def reserve_volume(self, volume_id):
@@ -133,7 +132,7 @@
         post_body = {}
         post_body = json.dumps({'os-reserve': post_body})
         url = 'volumes/%s/action' % (volume_id)
-        resp, body = self.post(url, post_body, self.headers)
+        resp, body = self.post(url, post_body)
         return resp, body
 
     def unreserve_volume(self, volume_id):
@@ -141,7 +140,7 @@
         post_body = {}
         post_body = json.dumps({'os-unreserve': post_body})
         url = 'volumes/%s/action' % (volume_id)
-        resp, body = self.post(url, post_body, self.headers)
+        resp, body = self.post(url, post_body)
         return resp, body
 
     def wait_for_volume_status(self, volume_id, status):
@@ -178,28 +177,25 @@
         }
         post_body = json.dumps({'os-extend': post_body})
         url = 'volumes/%s/action' % (volume_id)
-        resp, body = self.post(url, post_body, self.headers)
+        resp, body = self.post(url, post_body)
         return resp, body
 
     def reset_volume_status(self, volume_id, status):
         """Reset the Specified Volume's Status."""
         post_body = json.dumps({'os-reset_status': {"status": status}})
-        resp, body = self.post('volumes/%s/action' % volume_id, post_body,
-                               self.headers)
+        resp, body = self.post('volumes/%s/action' % volume_id, post_body)
         return resp, body
 
     def volume_begin_detaching(self, volume_id):
         """Volume Begin Detaching."""
         post_body = json.dumps({'os-begin_detaching': {}})
-        resp, body = self.post('volumes/%s/action' % volume_id, post_body,
-                               self.headers)
+        resp, body = self.post('volumes/%s/action' % volume_id, post_body)
         return resp, body
 
     def volume_roll_detaching(self, volume_id):
         """Volume Roll Detaching."""
         post_body = json.dumps({'os-roll_detaching': {}})
-        resp, body = self.post('volumes/%s/action' % volume_id, post_body,
-                               self.headers)
+        resp, body = self.post('volumes/%s/action' % volume_id, post_body)
         return resp, body
 
     def create_volume_transfer(self, vol_id, display_name=None):
@@ -210,16 +206,14 @@
         if display_name:
             post_body['name'] = display_name
         post_body = json.dumps({'transfer': post_body})
-        resp, body = self.post('os-volume-transfer',
-                               post_body,
-                               self.headers)
+        resp, body = self.post('os-volume-transfer', post_body)
         body = json.loads(body)
         return resp, body['transfer']
 
     def get_volume_transfer(self, transfer_id):
         """Returns the details of a volume transfer."""
         url = "os-volume-transfer/%s" % str(transfer_id)
-        resp, body = self.get(url, self.headers)
+        resp, body = self.get(url)
         body = json.loads(body)
         return resp, body['transfer']
 
@@ -243,7 +237,7 @@
         }
         url = 'os-volume-transfer/%s/accept' % transfer_id
         post_body = json.dumps({'accept': post_body})
-        resp, body = self.post(url, post_body, self.headers)
+        resp, body = self.post(url, post_body)
         body = json.loads(body)
         return resp, body['transfer']
 
@@ -254,28 +248,27 @@
         }
         post_body = json.dumps({'os-update_readonly_flag': post_body})
         url = 'volumes/%s/action' % (volume_id)
-        resp, body = self.post(url, post_body, self.headers)
+        resp, body = self.post(url, post_body)
         return resp, body
 
     def force_delete_volume(self, volume_id):
         """Force Delete Volume."""
         post_body = json.dumps({'os-force_delete': {}})
-        resp, body = self.post('volumes/%s/action' % volume_id, post_body,
-                               self.headers)
+        resp, body = self.post('volumes/%s/action' % volume_id, post_body)
         return resp, body
 
     def create_volume_metadata(self, volume_id, metadata):
         """Create metadata for the volume."""
         put_body = json.dumps({'metadata': metadata})
         url = "volumes/%s/metadata" % str(volume_id)
-        resp, body = self.post(url, put_body, self.headers)
+        resp, body = self.post(url, put_body)
         body = json.loads(body)
         return resp, body['metadata']
 
     def get_volume_metadata(self, volume_id):
         """Get metadata of the volume."""
         url = "volumes/%s/metadata" % str(volume_id)
-        resp, body = self.get(url, self.headers)
+        resp, body = self.get(url)
         body = json.loads(body)
         return resp, body['metadata']
 
@@ -283,7 +276,7 @@
         """Update metadata for the volume."""
         put_body = json.dumps({'metadata': metadata})
         url = "volumes/%s/metadata" % str(volume_id)
-        resp, body = self.put(url, put_body, self.headers)
+        resp, body = self.put(url, put_body)
         body = json.loads(body)
         return resp, body['metadata']
 
@@ -291,12 +284,12 @@
         """Update metadata item for the volume."""
         put_body = json.dumps({'meta': meta_item})
         url = "volumes/%s/metadata/%s" % (str(volume_id), str(id))
-        resp, body = self.put(url, put_body, self.headers)
+        resp, body = self.put(url, put_body)
         body = json.loads(body)
         return resp, body['meta']
 
     def delete_volume_metadata_item(self, volume_id, id):
         """Delete metadata item for the volume."""
         url = "volumes/%s/metadata/%s" % (str(volume_id), str(id))
-        resp, body = self.delete(url, self.headers)
+        resp, body = self.delete(url)
         return resp, body
diff --git a/tempest/services/volume/v2/json/volumes_client.py b/tempest/services/volume/v2/json/volumes_client.py
index 0524212..2183c56 100644
--- a/tempest/services/volume/v2/json/volumes_client.py
+++ b/tempest/services/volume/v2/json/volumes_client.py
@@ -81,15 +81,14 @@
         post_body = {'size': size}
         post_body.update(kwargs)
         post_body = json.dumps({'volume': post_body})
-        resp, body = self.post('volumes', post_body, self.headers)
+        resp, body = self.post('volumes', post_body)
         body = json.loads(body)
         return resp, body['volume']
 
     def update_volume(self, volume_id, **kwargs):
         """Updates the Specified Volume."""
         put_body = json.dumps({'volume': kwargs})
-        resp, body = self.put('volumes/%s' % volume_id, put_body,
-                              self.headers)
+        resp, body = self.put('volumes/%s' % volume_id, put_body)
         body = json.loads(body)
         return resp, body['volume']
 
@@ -105,7 +104,7 @@
         }
         post_body = json.dumps({'os-volume_upload_image': post_body})
         url = 'volumes/%s/action' % (volume_id)
-        resp, body = self.post(url, post_body, self.headers)
+        resp, body = self.post(url, post_body)
         body = json.loads(body)
         return resp, body['os-volume_upload_image']
 
@@ -117,7 +116,7 @@
         }
         post_body = json.dumps({'os-attach': post_body})
         url = 'volumes/%s/action' % (volume_id)
-        resp, body = self.post(url, post_body, self.headers)
+        resp, body = self.post(url, post_body)
         return resp, body
 
     def detach_volume(self, volume_id):
@@ -125,7 +124,7 @@
         post_body = {}
         post_body = json.dumps({'os-detach': post_body})
         url = 'volumes/%s/action' % (volume_id)
-        resp, body = self.post(url, post_body, self.headers)
+        resp, body = self.post(url, post_body)
         return resp, body
 
     def reserve_volume(self, volume_id):
@@ -133,7 +132,7 @@
         post_body = {}
         post_body = json.dumps({'os-reserve': post_body})
         url = 'volumes/%s/action' % (volume_id)
-        resp, body = self.post(url, post_body, self.headers)
+        resp, body = self.post(url, post_body)
         return resp, body
 
     def unreserve_volume(self, volume_id):
@@ -141,7 +140,7 @@
         post_body = {}
         post_body = json.dumps({'os-unreserve': post_body})
         url = 'volumes/%s/action' % (volume_id)
-        resp, body = self.post(url, post_body, self.headers)
+        resp, body = self.post(url, post_body)
         return resp, body
 
     def wait_for_volume_status(self, volume_id, status):
@@ -178,28 +177,25 @@
         }
         post_body = json.dumps({'os-extend': post_body})
         url = 'volumes/%s/action' % (volume_id)
-        resp, body = self.post(url, post_body, self.headers)
+        resp, body = self.post(url, post_body)
         return resp, body
 
     def reset_volume_status(self, volume_id, status):
         """Reset the Specified Volume's Status."""
         post_body = json.dumps({'os-reset_status': {"status": status}})
-        resp, body = self.post('volumes/%s/action' % volume_id, post_body,
-                               self.headers)
+        resp, body = self.post('volumes/%s/action' % volume_id, post_body)
         return resp, body
 
     def volume_begin_detaching(self, volume_id):
         """Volume Begin Detaching."""
         post_body = json.dumps({'os-begin_detaching': {}})
-        resp, body = self.post('volumes/%s/action' % volume_id, post_body,
-                               self.headers)
+        resp, body = self.post('volumes/%s/action' % volume_id, post_body)
         return resp, body
 
     def volume_roll_detaching(self, volume_id):
         """Volume Roll Detaching."""
         post_body = json.dumps({'os-roll_detaching': {}})
-        resp, body = self.post('volumes/%s/action' % volume_id, post_body,
-                               self.headers)
+        resp, body = self.post('volumes/%s/action' % volume_id, post_body)
         return resp, body
 
     def create_volume_transfer(self, vol_id, display_name=None):
@@ -210,16 +206,14 @@
         if display_name:
             post_body['name'] = display_name
         post_body = json.dumps({'transfer': post_body})
-        resp, body = self.post('os-volume-transfer',
-                               post_body,
-                               self.headers)
+        resp, body = self.post('os-volume-transfer', post_body)
         body = json.loads(body)
         return resp, body['transfer']
 
     def get_volume_transfer(self, transfer_id):
         """Returns the details of a volume transfer."""
         url = "os-volume-transfer/%s" % str(transfer_id)
-        resp, body = self.get(url, self.headers)
+        resp, body = self.get(url)
         body = json.loads(body)
         return resp, body['transfer']
 
@@ -243,7 +237,7 @@
         }
         url = 'os-volume-transfer/%s/accept' % transfer_id
         post_body = json.dumps({'accept': post_body})
-        resp, body = self.post(url, post_body, self.headers)
+        resp, body = self.post(url, post_body)
         body = json.loads(body)
         return resp, body['transfer']
 
@@ -254,28 +248,27 @@
         }
         post_body = json.dumps({'os-update_readonly_flag': post_body})
         url = 'volumes/%s/action' % (volume_id)
-        resp, body = self.post(url, post_body, self.headers)
+        resp, body = self.post(url, post_body)
         return resp, body
 
     def force_delete_volume(self, volume_id):
         """Force Delete Volume."""
         post_body = json.dumps({'os-force_delete': {}})
-        resp, body = self.post('volumes/%s/action' % volume_id, post_body,
-                               self.headers)
+        resp, body = self.post('volumes/%s/action' % volume_id, post_body)
         return resp, body
 
     def create_volume_metadata(self, volume_id, metadata):
         """Create metadata for the volume."""
         put_body = json.dumps({'metadata': metadata})
         url = "volumes/%s/metadata" % str(volume_id)
-        resp, body = self.post(url, put_body, self.headers)
+        resp, body = self.post(url, put_body)
         body = json.loads(body)
         return resp, body['metadata']
 
     def get_volume_metadata(self, volume_id):
         """Get metadata of the volume."""
         url = "volumes/%s/metadata" % str(volume_id)
-        resp, body = self.get(url, self.headers)
+        resp, body = self.get(url)
         body = json.loads(body)
         return resp, body['metadata']
 
@@ -283,7 +276,7 @@
         """Update metadata for the volume."""
         put_body = json.dumps({'metadata': metadata})
         url = "volumes/%s/metadata" % str(volume_id)
-        resp, body = self.put(url, put_body, self.headers)
+        resp, body = self.put(url, put_body)
         body = json.loads(body)
         return resp, body['metadata']
 
@@ -291,12 +284,12 @@
         """Update metadata item for the volume."""
         put_body = json.dumps({'meta': meta_item})
         url = "volumes/%s/metadata/%s" % (str(volume_id), str(id))
-        resp, body = self.put(url, put_body, self.headers)
+        resp, body = self.put(url, put_body)
         body = json.loads(body)
         return resp, body['meta']
 
     def delete_volume_metadata_item(self, volume_id, id):
         """Delete metadata item for the volume."""
         url = "volumes/%s/metadata/%s" % (str(volume_id), str(id))
-        resp, body = self.delete(url, self.headers)
+        resp, body = self.delete(url)
         return resp, body
diff --git a/tempest/services/volume/v2/xml/volumes_client.py b/tempest/services/volume/v2/xml/volumes_client.py
index deb56fd..2b500ae 100644
--- a/tempest/services/volume/v2/xml/volumes_client.py
+++ b/tempest/services/volume/v2/xml/volumes_client.py
@@ -87,7 +87,7 @@
         if params:
             url += '?%s' % urllib.urlencode(params)
 
-        resp, body = self.get(url, self.headers)
+        resp, body = self.get(url)
         body = etree.fromstring(body)
         volumes = []
         if body is not None:
@@ -103,7 +103,7 @@
         if params:
             url += '?%s' % urllib.urlencode(params)
 
-        resp, body = self.get(url, self.headers)
+        resp, body = self.get(url)
         body = etree.fromstring(body)
         volumes = []
         if body is not None:
@@ -115,7 +115,7 @@
     def get_volume(self, volume_id):
         """Returns the details of a single volume."""
         url = "volumes/%s" % str(volume_id)
-        resp, body = self.get(url, self.headers)
+        resp, body = self.get(url)
         body = self._parse_volume(etree.fromstring(body))
         body = self._check_if_bootable(body)
         return resp, body
@@ -151,8 +151,7 @@
         for key, value in attr_to_add.items():
             volume.add_attr(key, value)
 
-        resp, body = self.post('volumes', str(Document(volume)),
-                               self.headers)
+        resp, body = self.post('volumes', str(Document(volume)))
         body = xml_to_json(etree.fromstring(body))
         return resp, body
 
@@ -161,8 +160,7 @@
         put_body = Element("volume", xmlns=XMLNS_11, **kwargs)
 
         resp, body = self.put('volumes/%s' % volume_id,
-                              str(Document(put_body)),
-                              self.headers)
+                              str(Document(put_body)))
         body = xml_to_json(etree.fromstring(body))
         return resp, body
 
@@ -204,7 +202,7 @@
                             mountpoint=mountpoint
                             )
         url = 'volumes/%s/action' % str(volume_id)
-        resp, body = self.post(url, str(Document(post_body)), self.headers)
+        resp, body = self.post(url, str(Document(post_body)))
         if body:
             body = xml_to_json(etree.fromstring(body))
         return resp, body
@@ -213,7 +211,7 @@
         """Detaches a volume from an instance."""
         post_body = Element("os-detach")
         url = 'volumes/%s/action' % str(volume_id)
-        resp, body = self.post(url, str(Document(post_body)), self.headers)
+        resp, body = self.post(url, str(Document(post_body)))
         if body:
             body = xml_to_json(etree.fromstring(body))
         return resp, body
@@ -224,7 +222,7 @@
                             image_name=image_name,
                             disk_format=disk_format)
         url = 'volumes/%s/action' % str(volume_id)
-        resp, body = self.post(url, str(Document(post_body)), self.headers)
+        resp, body = self.post(url, str(Document(post_body)))
         volume = xml_to_json(etree.fromstring(body))
         return resp, volume
 
@@ -233,7 +231,7 @@
         post_body = Element("os-extend",
                             new_size=extend_size)
         url = 'volumes/%s/action' % str(volume_id)
-        resp, body = self.post(url, str(Document(post_body)), self.headers)
+        resp, body = self.post(url, str(Document(post_body)))
         if body:
             body = xml_to_json(etree.fromstring(body))
         return resp, body
@@ -244,7 +242,7 @@
                             status=status
                             )
         url = 'volumes/%s/action' % str(volume_id)
-        resp, body = self.post(url, str(Document(post_body)), self.headers)
+        resp, body = self.post(url, str(Document(post_body)))
         if body:
             body = xml_to_json(etree.fromstring(body))
         return resp, body
@@ -253,7 +251,7 @@
         """Volume Begin Detaching."""
         post_body = Element("os-begin_detaching")
         url = 'volumes/%s/action' % str(volume_id)
-        resp, body = self.post(url, str(Document(post_body)), self.headers)
+        resp, body = self.post(url, str(Document(post_body)))
         if body:
             body = xml_to_json(etree.fromstring(body))
         return resp, body
@@ -262,7 +260,7 @@
         """Volume Roll Detaching."""
         post_body = Element("os-roll_detaching")
         url = 'volumes/%s/action' % str(volume_id)
-        resp, body = self.post(url, str(Document(post_body)), self.headers)
+        resp, body = self.post(url, str(Document(post_body)))
         if body:
             body = xml_to_json(etree.fromstring(body))
         return resp, body
@@ -271,7 +269,7 @@
         """Reserves a volume."""
         post_body = Element("os-reserve")
         url = 'volumes/%s/action' % str(volume_id)
-        resp, body = self.post(url, str(Document(post_body)), self.headers)
+        resp, body = self.post(url, str(Document(post_body)))
         if body:
             body = xml_to_json(etree.fromstring(body))
         return resp, body
@@ -280,7 +278,7 @@
         """Restore a reserved volume ."""
         post_body = Element("os-unreserve")
         url = 'volumes/%s/action' % str(volume_id)
-        resp, body = self.post(url, str(Document(post_body)), self.headers)
+        resp, body = self.post(url, str(Document(post_body)))
         if body:
             body = xml_to_json(etree.fromstring(body))
         return resp, body
@@ -292,15 +290,14 @@
         if display_name:
             post_body.add_attr('name', display_name)
         resp, body = self.post('os-volume-transfer',
-                               str(Document(post_body)),
-                               self.headers)
+                               str(Document(post_body)))
         volume = xml_to_json(etree.fromstring(body))
         return resp, volume
 
     def get_volume_transfer(self, transfer_id):
         """Returns the details of a volume transfer."""
         url = "os-volume-transfer/%s" % str(transfer_id)
-        resp, body = self.get(url, self.headers)
+        resp, body = self.get(url)
         volume = xml_to_json(etree.fromstring(body))
         return resp, volume
 
@@ -310,7 +307,7 @@
         if params:
             url += '?%s' % urllib.urlencode(params)
 
-        resp, body = self.get(url, self.headers)
+        resp, body = self.get(url)
         body = etree.fromstring(body)
         volumes = []
         if body is not None:
@@ -334,7 +331,7 @@
         """Accept a volume transfer."""
         post_body = Element("accept", auth_key=transfer_auth_key)
         url = 'os-volume-transfer/%s/accept' % transfer_id
-        resp, body = self.post(url, str(Document(post_body)), self.headers)
+        resp, body = self.post(url, str(Document(post_body)))
         volume = xml_to_json(etree.fromstring(body))
         return resp, volume
 
@@ -343,7 +340,7 @@
         post_body = Element("os-update_readonly_flag",
                             readonly=readonly)
         url = 'volumes/%s/action' % str(volume_id)
-        resp, body = self.post(url, str(Document(post_body)), self.headers)
+        resp, body = self.post(url, str(Document(post_body)))
         if body:
             body = xml_to_json(etree.fromstring(body))
         return resp, body
@@ -352,7 +349,7 @@
         """Force Delete Volume."""
         post_body = Element("os-force_delete")
         url = 'volumes/%s/action' % str(volume_id)
-        resp, body = self.post(url, str(Document(post_body)), self.headers)
+        resp, body = self.post(url, str(Document(post_body)))
         if body:
             body = xml_to_json(etree.fromstring(body))
         return resp, body
@@ -376,15 +373,14 @@
         """Create metadata for the volume."""
         post_body = self._metadata_body(metadata)
         resp, body = self.post('volumes/%s/metadata' % volume_id,
-                               str(Document(post_body)),
-                               self.headers)
+                               str(Document(post_body)))
         body = self._parse_key_value(etree.fromstring(body))
         return resp, body
 
     def get_volume_metadata(self, volume_id):
         """Get metadata of the volume."""
         url = "volumes/%s/metadata" % str(volume_id)
-        resp, body = self.get(url, self.headers)
+        resp, body = self.get(url)
         body = self._parse_key_value(etree.fromstring(body))
         return resp, body
 
@@ -392,7 +388,7 @@
         """Update metadata for the volume."""
         put_body = self._metadata_body(metadata)
         url = "volumes/%s/metadata" % str(volume_id)
-        resp, body = self.put(url, str(Document(put_body)), self.headers)
+        resp, body = self.put(url, str(Document(put_body)))
         body = self._parse_key_value(etree.fromstring(body))
         return resp, body
 
@@ -402,7 +398,7 @@
             put_body = Element('meta', key=k)
             put_body.append(Text(v))
         url = "volumes/%s/metadata/%s" % (str(volume_id), str(id))
-        resp, body = self.put(url, str(Document(put_body)), self.headers)
+        resp, body = self.put(url, str(Document(put_body)))
         body = xml_to_json(etree.fromstring(body))
         return resp, body
 
diff --git a/tempest/services/volume/xml/admin/volume_hosts_client.py b/tempest/services/volume/xml/admin/volume_hosts_client.py
index 7278fd9..59652fa 100644
--- a/tempest/services/volume/xml/admin/volume_hosts_client.py
+++ b/tempest/services/volume/xml/admin/volume_hosts_client.py
@@ -67,6 +67,6 @@
         if params:
             url += '?%s' % urllib.urlencode(params)
 
-        resp, body = self.get(url, self.headers)
+        resp, body = self.get(url)
         body = self._parse_array(etree.fromstring(body))
         return resp, body
diff --git a/tempest/services/volume/xml/admin/volume_types_client.py b/tempest/services/volume/xml/admin/volume_types_client.py
index 29ba431..802d27a 100644
--- a/tempest/services/volume/xml/admin/volume_types_client.py
+++ b/tempest/services/volume/xml/admin/volume_types_client.py
@@ -72,7 +72,7 @@
         if params:
             url += '?%s' % urllib.urlencode(params)
 
-        resp, body = self.get(url, self.headers)
+        resp, body = self.get(url)
         body = etree.fromstring(body)
         volume_types = []
         if body is not None:
@@ -83,7 +83,7 @@
     def get_volume_type(self, type_id):
         """Returns the details of a single volume_type."""
         url = "types/%s" % str(type_id)
-        resp, body = self.get(url, self.headers)
+        resp, body = self.get(url)
         body = etree.fromstring(body)
         return resp, self._parse_volume_type(body)
 
@@ -108,8 +108,7 @@
                 spec.append(Text(value))
                 _extra_specs.append(spec)
 
-        resp, body = self.post('types', str(Document(vol_type)),
-                               self.headers)
+        resp, body = self.post('types', str(Document(vol_type)))
         body = xml_to_json(etree.fromstring(body))
         return resp, body
 
@@ -124,7 +123,7 @@
         if params:
             url += '?%s' % urllib.urlencode(params)
 
-        resp, body = self.get(url, self.headers)
+        resp, body = self.get(url)
         body = etree.fromstring(body)
         extra_specs = []
         if body is not None:
@@ -136,7 +135,7 @@
         """Returns the details of a single volume_type extra spec."""
         url = "types/%s/extra_specs/%s" % (str(vol_type_id),
                                            str(extra_spec_name))
-        resp, body = self.get(url, self.headers)
+        resp, body = self.get(url)
         body = etree.fromstring(body)
         return resp, self._parse_volume_type_extra_specs(body)
 
@@ -160,8 +159,7 @@
         else:
             extra_specs = None
 
-        resp, body = self.post(url, str(Document(extra_specs)),
-                               self.headers)
+        resp, body = self.post(url, str(Document(extra_specs)))
         body = xml_to_json(etree.fromstring(body))
         return resp, body
 
@@ -190,8 +188,7 @@
                 spec.append(Text(value))
                 extra_specs.append(spec)
 
-        resp, body = self.put(url, str(Document(extra_specs)),
-                              self.headers)
+        resp, body = self.put(url, str(Document(extra_specs)))
         body = xml_to_json(etree.fromstring(body))
         return resp, body
 
diff --git a/tempest/services/volume/xml/extensions_client.py b/tempest/services/volume/xml/extensions_client.py
index 21e1d04..03743a6 100644
--- a/tempest/services/volume/xml/extensions_client.py
+++ b/tempest/services/volume/xml/extensions_client.py
@@ -36,6 +36,6 @@
 
     def list_extensions(self):
         url = 'extensions'
-        resp, body = self.get(url, self.headers)
+        resp, body = self.get(url)
         body = self._parse_array(etree.fromstring(body))
         return resp, body
diff --git a/tempest/services/volume/xml/snapshots_client.py b/tempest/services/volume/xml/snapshots_client.py
index 4f066a6..9abe042 100644
--- a/tempest/services/volume/xml/snapshots_client.py
+++ b/tempest/services/volume/xml/snapshots_client.py
@@ -47,7 +47,7 @@
         if params:
             url += '?%s' % urllib.urlencode(params)
 
-        resp, body = self.get(url, self.headers)
+        resp, body = self.get(url)
         body = etree.fromstring(body)
         snapshots = []
         for snap in body:
@@ -61,7 +61,7 @@
         if params:
             url += '?%s' % urllib.urlencode(params)
 
-        resp, body = self.get(url, self.headers)
+        resp, body = self.get(url)
         body = etree.fromstring(body)
         snapshots = []
         for snap in body:
@@ -71,7 +71,7 @@
     def get_snapshot(self, snapshot_id):
         """Returns the details of a single snapshot."""
         url = "snapshots/%s" % str(snapshot_id)
-        resp, body = self.get(url, self.headers)
+        resp, body = self.get(url)
         body = etree.fromstring(body)
         return resp, xml_to_json(body)
 
@@ -86,8 +86,7 @@
         snapshot = Element("snapshot", xmlns=XMLNS_11, volume_id=volume_id)
         for key, value in kwargs.items():
             snapshot.add_attr(key, value)
-        resp, body = self.post('snapshots', str(Document(snapshot)),
-                               self.headers)
+        resp, body = self.post('snapshots', str(Document(snapshot)))
         body = xml_to_json(etree.fromstring(body))
         return resp, body
 
@@ -96,8 +95,7 @@
         put_body = Element("snapshot", xmlns=XMLNS_11, **kwargs)
 
         resp, body = self.put('snapshots/%s' % snapshot_id,
-                              str(Document(put_body)),
-                              self.headers)
+                              str(Document(put_body)))
         body = xml_to_json(etree.fromstring(body))
         return resp, body
 
@@ -155,7 +153,7 @@
                             status=status
                             )
         url = 'snapshots/%s/action' % str(snapshot_id)
-        resp, body = self.post(url, str(Document(post_body)), self.headers)
+        resp, body = self.post(url, str(Document(post_body)))
         if body:
             body = xml_to_json(etree.fromstring(body))
         return resp, body
@@ -167,7 +165,7 @@
                             progress=progress
                             )
         url = 'snapshots/%s/action' % str(snapshot_id)
-        resp, body = self.post(url, str(Document(post_body)), self.headers)
+        resp, body = self.post(url, str(Document(post_body)))
         if body:
             body = xml_to_json(etree.fromstring(body))
         return resp, body
@@ -191,15 +189,14 @@
         """Create metadata for the snapshot."""
         post_body = self._metadata_body(metadata)
         resp, body = self.post('snapshots/%s/metadata' % snapshot_id,
-                               str(Document(post_body)),
-                               self.headers)
+                               str(Document(post_body)))
         body = self._parse_key_value(etree.fromstring(body))
         return resp, body
 
     def get_snapshot_metadata(self, snapshot_id):
         """Get metadata of the snapshot."""
         url = "snapshots/%s/metadata" % str(snapshot_id)
-        resp, body = self.get(url, self.headers)
+        resp, body = self.get(url)
         body = self._parse_key_value(etree.fromstring(body))
         return resp, body
 
@@ -207,7 +204,7 @@
         """Update metadata for the snapshot."""
         put_body = self._metadata_body(metadata)
         url = "snapshots/%s/metadata" % str(snapshot_id)
-        resp, body = self.put(url, str(Document(put_body)), self.headers)
+        resp, body = self.put(url, str(Document(put_body)))
         body = self._parse_key_value(etree.fromstring(body))
         return resp, body
 
@@ -217,7 +214,7 @@
             put_body = Element('meta', key=k)
             put_body.append(Text(v))
         url = "snapshots/%s/metadata/%s" % (str(snapshot_id), str(id))
-        resp, body = self.put(url, str(Document(put_body)), self.headers)
+        resp, body = self.put(url, str(Document(put_body)))
         body = xml_to_json(etree.fromstring(body))
         return resp, body
 
@@ -230,7 +227,7 @@
         """Force Delete Snapshot."""
         post_body = Element("os-force_delete")
         url = 'snapshots/%s/action' % str(snapshot_id)
-        resp, body = self.post(url, str(Document(post_body)), self.headers)
+        resp, body = self.post(url, str(Document(post_body)))
         if body:
             body = xml_to_json(etree.fromstring(body))
         return resp, body
diff --git a/tempest/services/volume/xml/volumes_client.py b/tempest/services/volume/xml/volumes_client.py
index deb56fd..2b500ae 100644
--- a/tempest/services/volume/xml/volumes_client.py
+++ b/tempest/services/volume/xml/volumes_client.py
@@ -87,7 +87,7 @@
         if params:
             url += '?%s' % urllib.urlencode(params)
 
-        resp, body = self.get(url, self.headers)
+        resp, body = self.get(url)
         body = etree.fromstring(body)
         volumes = []
         if body is not None:
@@ -103,7 +103,7 @@
         if params:
             url += '?%s' % urllib.urlencode(params)
 
-        resp, body = self.get(url, self.headers)
+        resp, body = self.get(url)
         body = etree.fromstring(body)
         volumes = []
         if body is not None:
@@ -115,7 +115,7 @@
     def get_volume(self, volume_id):
         """Returns the details of a single volume."""
         url = "volumes/%s" % str(volume_id)
-        resp, body = self.get(url, self.headers)
+        resp, body = self.get(url)
         body = self._parse_volume(etree.fromstring(body))
         body = self._check_if_bootable(body)
         return resp, body
@@ -151,8 +151,7 @@
         for key, value in attr_to_add.items():
             volume.add_attr(key, value)
 
-        resp, body = self.post('volumes', str(Document(volume)),
-                               self.headers)
+        resp, body = self.post('volumes', str(Document(volume)))
         body = xml_to_json(etree.fromstring(body))
         return resp, body
 
@@ -161,8 +160,7 @@
         put_body = Element("volume", xmlns=XMLNS_11, **kwargs)
 
         resp, body = self.put('volumes/%s' % volume_id,
-                              str(Document(put_body)),
-                              self.headers)
+                              str(Document(put_body)))
         body = xml_to_json(etree.fromstring(body))
         return resp, body
 
@@ -204,7 +202,7 @@
                             mountpoint=mountpoint
                             )
         url = 'volumes/%s/action' % str(volume_id)
-        resp, body = self.post(url, str(Document(post_body)), self.headers)
+        resp, body = self.post(url, str(Document(post_body)))
         if body:
             body = xml_to_json(etree.fromstring(body))
         return resp, body
@@ -213,7 +211,7 @@
         """Detaches a volume from an instance."""
         post_body = Element("os-detach")
         url = 'volumes/%s/action' % str(volume_id)
-        resp, body = self.post(url, str(Document(post_body)), self.headers)
+        resp, body = self.post(url, str(Document(post_body)))
         if body:
             body = xml_to_json(etree.fromstring(body))
         return resp, body
@@ -224,7 +222,7 @@
                             image_name=image_name,
                             disk_format=disk_format)
         url = 'volumes/%s/action' % str(volume_id)
-        resp, body = self.post(url, str(Document(post_body)), self.headers)
+        resp, body = self.post(url, str(Document(post_body)))
         volume = xml_to_json(etree.fromstring(body))
         return resp, volume
 
@@ -233,7 +231,7 @@
         post_body = Element("os-extend",
                             new_size=extend_size)
         url = 'volumes/%s/action' % str(volume_id)
-        resp, body = self.post(url, str(Document(post_body)), self.headers)
+        resp, body = self.post(url, str(Document(post_body)))
         if body:
             body = xml_to_json(etree.fromstring(body))
         return resp, body
@@ -244,7 +242,7 @@
                             status=status
                             )
         url = 'volumes/%s/action' % str(volume_id)
-        resp, body = self.post(url, str(Document(post_body)), self.headers)
+        resp, body = self.post(url, str(Document(post_body)))
         if body:
             body = xml_to_json(etree.fromstring(body))
         return resp, body
@@ -253,7 +251,7 @@
         """Volume Begin Detaching."""
         post_body = Element("os-begin_detaching")
         url = 'volumes/%s/action' % str(volume_id)
-        resp, body = self.post(url, str(Document(post_body)), self.headers)
+        resp, body = self.post(url, str(Document(post_body)))
         if body:
             body = xml_to_json(etree.fromstring(body))
         return resp, body
@@ -262,7 +260,7 @@
         """Volume Roll Detaching."""
         post_body = Element("os-roll_detaching")
         url = 'volumes/%s/action' % str(volume_id)
-        resp, body = self.post(url, str(Document(post_body)), self.headers)
+        resp, body = self.post(url, str(Document(post_body)))
         if body:
             body = xml_to_json(etree.fromstring(body))
         return resp, body
@@ -271,7 +269,7 @@
         """Reserves a volume."""
         post_body = Element("os-reserve")
         url = 'volumes/%s/action' % str(volume_id)
-        resp, body = self.post(url, str(Document(post_body)), self.headers)
+        resp, body = self.post(url, str(Document(post_body)))
         if body:
             body = xml_to_json(etree.fromstring(body))
         return resp, body
@@ -280,7 +278,7 @@
         """Restore a reserved volume ."""
         post_body = Element("os-unreserve")
         url = 'volumes/%s/action' % str(volume_id)
-        resp, body = self.post(url, str(Document(post_body)), self.headers)
+        resp, body = self.post(url, str(Document(post_body)))
         if body:
             body = xml_to_json(etree.fromstring(body))
         return resp, body
@@ -292,15 +290,14 @@
         if display_name:
             post_body.add_attr('name', display_name)
         resp, body = self.post('os-volume-transfer',
-                               str(Document(post_body)),
-                               self.headers)
+                               str(Document(post_body)))
         volume = xml_to_json(etree.fromstring(body))
         return resp, volume
 
     def get_volume_transfer(self, transfer_id):
         """Returns the details of a volume transfer."""
         url = "os-volume-transfer/%s" % str(transfer_id)
-        resp, body = self.get(url, self.headers)
+        resp, body = self.get(url)
         volume = xml_to_json(etree.fromstring(body))
         return resp, volume
 
@@ -310,7 +307,7 @@
         if params:
             url += '?%s' % urllib.urlencode(params)
 
-        resp, body = self.get(url, self.headers)
+        resp, body = self.get(url)
         body = etree.fromstring(body)
         volumes = []
         if body is not None:
@@ -334,7 +331,7 @@
         """Accept a volume transfer."""
         post_body = Element("accept", auth_key=transfer_auth_key)
         url = 'os-volume-transfer/%s/accept' % transfer_id
-        resp, body = self.post(url, str(Document(post_body)), self.headers)
+        resp, body = self.post(url, str(Document(post_body)))
         volume = xml_to_json(etree.fromstring(body))
         return resp, volume
 
@@ -343,7 +340,7 @@
         post_body = Element("os-update_readonly_flag",
                             readonly=readonly)
         url = 'volumes/%s/action' % str(volume_id)
-        resp, body = self.post(url, str(Document(post_body)), self.headers)
+        resp, body = self.post(url, str(Document(post_body)))
         if body:
             body = xml_to_json(etree.fromstring(body))
         return resp, body
@@ -352,7 +349,7 @@
         """Force Delete Volume."""
         post_body = Element("os-force_delete")
         url = 'volumes/%s/action' % str(volume_id)
-        resp, body = self.post(url, str(Document(post_body)), self.headers)
+        resp, body = self.post(url, str(Document(post_body)))
         if body:
             body = xml_to_json(etree.fromstring(body))
         return resp, body
@@ -376,15 +373,14 @@
         """Create metadata for the volume."""
         post_body = self._metadata_body(metadata)
         resp, body = self.post('volumes/%s/metadata' % volume_id,
-                               str(Document(post_body)),
-                               self.headers)
+                               str(Document(post_body)))
         body = self._parse_key_value(etree.fromstring(body))
         return resp, body
 
     def get_volume_metadata(self, volume_id):
         """Get metadata of the volume."""
         url = "volumes/%s/metadata" % str(volume_id)
-        resp, body = self.get(url, self.headers)
+        resp, body = self.get(url)
         body = self._parse_key_value(etree.fromstring(body))
         return resp, body
 
@@ -392,7 +388,7 @@
         """Update metadata for the volume."""
         put_body = self._metadata_body(metadata)
         url = "volumes/%s/metadata" % str(volume_id)
-        resp, body = self.put(url, str(Document(put_body)), self.headers)
+        resp, body = self.put(url, str(Document(put_body)))
         body = self._parse_key_value(etree.fromstring(body))
         return resp, body
 
@@ -402,7 +398,7 @@
             put_body = Element('meta', key=k)
             put_body.append(Text(v))
         url = "volumes/%s/metadata/%s" % (str(volume_id), str(id))
-        resp, body = self.put(url, str(Document(put_body)), self.headers)
+        resp, body = self.put(url, str(Document(put_body)))
         body = xml_to_json(etree.fromstring(body))
         return resp, body