Add flag to skip looking at custom resource class

When you are in transition, post pike upgrade, you may have only some
nodes with a custom Resource class, and no flavors with matching custom
resource classes. In this case you will want to skip checking the custom
resource classes.

To skip you set the following environment variable:
OS_CAPACITY_IGNORE_CUSTOM_RC

Author: JohnGarbutt

os_capacity/utils.py

@@ -14,13 +14,16 @@
 
 import collections
 from datetime import datetime
+import os
 
 from os_capacity.data import flavors
 from os_capacity.data import metrics
 from os_capacity.data import resource_provider
 from os_capacity.data import server as server_data
 from os_capacity.data import users
 
+IGNORE_CUSTOM_RC = 'OS_CAPACITY_IGNORE_CUSTOM_RC' in os.environ
+
 
 def get_flavors(app):
     app.LOG.debug("Getting flavors")
@@ -54,10 +57,11 @@ def group_providers_by_type_with_capacity(app):
     grouped_flavors = collections.defaultdict(list)
     for flavor in all_flavors:
         custom_rc = None
-        for extra_spec in flavor.extra_specs:
-            if extra_spec.startswith('resources:CUSTOM'):
-                custom_rc = extra_spec.replace('resources:', '')
-                break  # Assuming a good Ironic setup here
+        if not IGNORE_CUSTOM_RC:
+            for extra_spec in flavor.extra_specs:
+                if extra_spec.startswith('resources:CUSTOM'):
+                    custom_rc = extra_spec.replace('resources:', '')
+                    break  # Assuming a good Ironic setup here
 
         key = (flavor.vcpus, flavor.ram_mb, flavor.disk_gb, custom_rc)
         grouped_flavors[key] += [flavor.name]
@@ -83,7 +87,8 @@ def group_providers_by_type_with_capacity(app):
             if "DISK" in inventory.resource_class:
                 disk_gb += inventory.total
             if inventory.resource_class.startswith('CUSTOM_'):
-                custom_rc = inventory.resource_class  # Ironic specific
+                if not IGNORE_CUSTOM_RC:
+                    custom_rc = inventory.resource_class  # Ironic specific
         key = (vcpus, ram_mb, disk_gb, custom_rc)
 
         inventory_counts[key] += 1