Add support for worker configuration

config.yaml

@@ -181,3 +181,10 @@ options:
       order for this charm to function correctly, the privacy extension must be
       disabled and a non-temporary address must be configured/available on
       your network interface.
+  worker-multiplier:
+    type: int
+    default: 2
+    description: |
+      The CPU core multiplier to use when configuring worker processes for
+      Cinder.  By default, the number of workers for each daemon is set to
+      twice the number of CPU cores a service unit has.

hooks/charmhelpers/contrib/openstack/context.py

@@ -903,3 +903,22 @@ class BindHostContext(OSContextGenerator):
             return {
                 'bind_host': '0.0.0.0'
             }
+
+
+class WorkerConfigContext(OSContextGenerator):
+
+    @property
+    def num_cpus(self):
+        try:
+            from psutil import NUM_CPUS
+        except ImportError:
+            apt_install('python-psutil', fatal=True)
+            from psutil import NUM_CPUS
+        return NUM_CPUS
+
+    def __call__(self):
+        multiplier = config('worker-multiplier') or 1
+        ctxt = {
+            "workers": self.num_cpus * multiplier
+        }
+        return ctxt

hooks/cinder_utils.py

@@ -131,7 +131,8 @@ CONFIG_FILES = OrderedDict([
                           cinder_contexts.StorageBackendContext(),
                           cinder_contexts.LoggingConfigContext(),
                           context.IdentityServiceContext(),
-                          context.BindHostContext()],
+                          context.BindHostContext(),
+                          context.WorkerConfigContext()],
         'services': ['cinder-api', 'cinder-volume',
                      'cinder-scheduler', 'haproxy']
     }),

templates/icehouse/cinder.conf

@@ -16,6 +16,7 @@ auth_strategy = keystone
 state_path = /var/lib/cinder
 lock_path = /var/lock/cinder
 volumes_dir = /var/lib/cinder/volumes
+osapi_volume_workers = {{ workers }}
 
 {% include "parts/rabbitmq" %}