[jamespage,r=gnuoy] Add support for worker process configuration

config.yaml

@@ -146,3 +146,10 @@ 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
+      Glance.  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/glance_utils.py

@@ -83,7 +83,8 @@ CONFIG_FILES = OrderedDict([
                           context.IdentityServiceContext(),
                           context.SyslogContext(),
                           glance_contexts.LoggingConfigContext(),
-                          glance_contexts.GlanceIPv6Context()],
+                          glance_contexts.GlanceIPv6Context(),
+                          context.WorkerConfigContext()],
         'services': ['glance-registry']
     }),
     (GLANCE_API_CONF, {
@@ -97,6 +98,7 @@ CONFIG_FILES = OrderedDict([
                           context.SyslogContext(),
                           glance_contexts.LoggingConfigContext(),
                           glance_contexts.GlanceIPv6Context(),
+                          context.WorkerConfigContext(),
                           glance_contexts.MultiStoreContext()],
         'services': ['glance-api']
     }),

templates/icehouse/glance-api.conf

@@ -2,6 +2,7 @@
 verbose = {{ verbose }}
 use_syslog = {{ use_syslog }}
 debug = {{ debug }}
+workers = {{ workers }}
 
 {% if rbd_pool -%}
 default_store = rbd

templates/icehouse/glance-registry.conf

@@ -2,6 +2,7 @@
 verbose = {{ verbose }}
 use_syslog = {{ use_syslog }}
 debug = {{ debug }}
+workers = {{ workers }}
 
 bind_host = {{ bind_host }}
 bind_port = 9191

templates/juno/glance-api.conf

@@ -2,6 +2,7 @@
 verbose = {{ verbose }}
 use_syslog = {{ use_syslog }}
 debug = {{ debug }}
+workers = {{ workers }}
 
 known_stores = {{ known_stores }}
 {% if rbd_pool -%}