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

config.yaml

@@ -211,3 +211,10 @@ 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
+      Keystone.  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/keystone_utils.py

@@ -115,7 +115,8 @@ BASE_RESOURCE_MAP = OrderedDict([
                      context.PostgresqlDBContext(),
                      context.SyslogContext(),
                      keystone_context.HAProxyContext(),
-                     context.BindHostContext()],
+                     context.BindHostContext(),
+                     context.WorkerConfigContext()],
     }),
     (HAPROXY_CONF, {
         'contexts': [context.HAProxyContext(),

templates/icehouse/keystone.conf

@@ -14,6 +14,8 @@ verbose = {{ verbose }}
 public_endpoint = {{ public_endpoint }}
 admin_endpoint = {{ admin_endpoint }}
 bind_host = {{ bind_host }}
+public_workers = {{ workers }}
+admin_workers = {{ workers }}
 
 [database]
 {% if database_host -%}