Configure nova_cell1.conf to use placement for reschedules

Nova now calculates alternate hosts in the scheduler and
sends those to the cell for reschedules in case a build on
a given compute node fails.

The cell conductor needs to claim resources against the
alternate hosts in Placement during a reschedule, therefore
it needs to be configured to talk to the placement service.

Part of blueprint return-alternate-hosts

Change-Id: Ie599968d9e7537e551fe6d9deb63a91b256b1e11
diff --git a/lib/placement b/lib/placement
index 1875857..1d68f8a 100644
--- a/lib/placement
+++ b/lib/placement
@@ -103,14 +103,16 @@
 }
 
 function configure_placement_nova_compute {
-    iniset $NOVA_CONF placement auth_type "password"
-    iniset $NOVA_CONF placement auth_url "$KEYSTONE_SERVICE_URI"
-    iniset $NOVA_CONF placement username placement
-    iniset $NOVA_CONF placement password "$SERVICE_PASSWORD"
-    iniset $NOVA_CONF placement user_domain_name "$SERVICE_DOMAIN_NAME"
-    iniset $NOVA_CONF placement project_name "$SERVICE_TENANT_NAME"
-    iniset $NOVA_CONF placement project_domain_name "$SERVICE_DOMAIN_NAME"
-    iniset $NOVA_CONF placement os_region_name "$REGION_NAME"
+    # Use the provided config file path or default to $NOVA_CONF.
+    local conf=${1:-$NOVA_CONF}
+    iniset $conf placement auth_type "password"
+    iniset $conf placement auth_url "$KEYSTONE_SERVICE_URI"
+    iniset $conf placement username placement
+    iniset $conf placement password "$SERVICE_PASSWORD"
+    iniset $conf placement user_domain_name "$SERVICE_DOMAIN_NAME"
+    iniset $conf placement project_name "$SERVICE_TENANT_NAME"
+    iniset $conf placement project_domain_name "$SERVICE_DOMAIN_NAME"
+    iniset $conf placement os_region_name "$REGION_NAME"
     # TODO(cdent): auth_strategy, which is common to see in these
     # blocks is not currently used here. For the time being the
     # placement api uses the auth_strategy configuration setting