Ability to set lock_path

PROD-34037

Change-Id: Iff1fde5e8cc9d4405ea03e8e5556568bedb89c50
diff --git a/metadata/service/server/single/common.yml b/metadata/service/server/single/common.yml
index bb60d05..6e04509 100644
--- a/metadata/service/server/single/common.yml
+++ b/metadata/service/server/single/common.yml
@@ -17,6 +17,8 @@
       bind:
         host: ${_param:single_address}
         port: 8777
+      concurrency:
+        lock_path: '/var/lib/ceilometer/tmp'
       identity:
         engine: keystone
         host: ${_param:single_address}