Better sorting of flavors in the "Launch Instance" view

By default, returns the available flavors, sorted by RAM usage
(ascending).  Override these behaviours with a CREATE_INSTANCE_FLAVOR_SORT
dict in local_settings.py.

DocImpact: a new django setting, CREATE_INSTANCE_FLAVOR_SORT.

Change-Id: I9f466ff306739369a85f7176da27932958fc8867
Fixes: Bug 1196690

openstack_dashboard/dashboards/project/instances/workflows/create_instance.py

@@ -21,6 +21,7 @@
 import json
 import logging
 
+from django.conf import settings
 from django.utils.text import normalize_newlines
 from django.utils.translation import ugettext_lazy as _
 from django.views.decorators.debug import sensitive_variables
@@ -264,15 +265,23 @@ class SetInstanceDetailsAction(workflows.Action):
         return choices
 
     def populate_flavor_choices(self, request, context):
+        """By default, returns the available flavors, sorted by RAM
+        usage (ascending).
+        Override these behaviours with a CREATE_INSTANCE_FLAVOR_SORT dict
+        in local_settings.py."""
         try:
             flavors = api.nova.flavor_list(request)
+            flavor_sort = getattr(settings, 'CREATE_INSTANCE_FLAVOR_SORT', {})
+            rev = flavor_sort.get('reverse', False)
+            key = flavor_sort.get('key', lambda flavor: flavor.ram)
+
             flavor_list = [(flavor.id, "%s" % flavor.name)
-                           for flavor in flavors]
+                           for flavor in sorted(flavors, key=key, reverse=rev)]
         except:
             flavor_list = []
             exceptions.handle(request,
                               _('Unable to retrieve instance flavors.'))
-        return sorted(flavor_list)
+        return flavor_list
 
     def populate_availability_zone_choices(self, request, context):
         try:

openstack_dashboard/local/local_settings.py.example

@@ -184,6 +184,16 @@ API_RESULT_PAGE_SIZE = 20
 # of your entire OpenStack installation, and hopefully be in UTC.
 TIME_ZONE = "UTC"
 
+# When launching an instance, the menu of available flavors is
+# sorted by RAM usage, ascending.  Provide a callback method here
+# (and/or a flag for reverse sort) for the sorted() method if you'd
+# like a different behaviour.  For more info, see
+# http://docs.python.org/2/library/functions.html#sorted
+# CREATE_INSTANCE_FLAVOR_SORT = {
+#     'key': my_awesome_callback_method,
+#     'reverse': False,
+# }
+
 LOGGING = {
     'version': 1,
     # When set to True this will disable all logging except