quota: Use neutron default quota (read-only) API

Neutron provides an API to retrieve default quotas since newton.
Unfortunately there is no corresponding neutron API extension
is not defined, so there is no way to detect it via API.
The API exists since newton, so this commit just switches to
the default quota API.

Closes-Bug: #1337473
blueprint make-quotas-great-again
Change-Id: Ia826b67f4cec7d95335c62ef98c3040feaa06117

openstack_dashboard/api/neutron.py

@@ -1454,6 +1454,13 @@ def tenant_quota_detail_get(request, tenant_id=None):
     return response['quota']
 
 
+@profiler.trace
+def default_quota_get(request, tenant_id=None):
+    tenant_id = tenant_id or request.user.tenant_id
+    response = neutronclient(request).show_quota_default(tenant_id)
+    return base.QuotaSet(response['quota'])
+
+
 @profiler.trace
 def agent_list(request, **params):
     agents = neutronclient(request).list_agents(**params)

openstack_dashboard/usage/quotas.py

@@ -183,11 +183,9 @@ def get_default_quota_data(request, disabled_quotas=None, tenant_id=None):
             exceptions.handle(request, msg)
 
     if NEUTRON_QUOTA_FIELDS - disabled_quotas:
-        # TODO(jpichon): There is no API to access the Neutron default quotas
-        # (LP#1204956). For now, use the values from the current project.
         try:
-            quotasets.append(neutron.tenant_quota_get(request,
-                                                      tenant_id=tenant_id))
+            quotasets.append(neutron.default_quota_get(request,
+                                                       tenant_id=tenant_id))
         except Exception:
             disabled_quotas.update(NEUTRON_QUOTA_FIELDS)
             msg = _('Unable to retrieve Neutron quota information.')

releasenotes/notes/neutron-default-quotas-ddd237af2935fde3.yaml

@@ -0,0 +1,9 @@
+---
+fixes:
+  - |
+    [:bug:`1337473`] The default quotas of neutron resource for a new project
+    are no longer got from the quotas of the current project.
+    Neutron did not provide a way to retrieve the default quotas and horizon
+    used the quotas of the current project as the default quotas for a new
+    project as a workaround. Neutron implemented an API to retrieve default
+    quotas since newton and horizon now consumes it.