add some tags for the cluster nodes to telegraf

Former-commit-id: 7d31c398

roles/telegraf/templates/telegraf.conf.j2

@@ -11,6 +11,9 @@
 
 # Global tags can be specified here in key="value" format.
 [tags]
+  hostgroup = {{ hostgroup | default('undefined') }}
+  cluster = {{ clustername | default('undefined') }}
+  computenodeclass = {{ computenodeclass | default('undefined') }}
   # dc = "us-east-1" # will tag all metrics with dc=us-east-1
   # rack = "1a"