diff --git a/instack_undercloud/undercloud.py b/instack_undercloud/undercloud.py
index 09e58bf82..08ef4bf8d 100644
--- a/instack_undercloud/undercloud.py
+++ b/instack_undercloud/undercloud.py
@@ -232,8 +232,12 @@ _auth_opts = [
                      'If left unset, one will be automatically generated.')
                ),
     cfg.StrOpt('undercloud_ceilometer_snmpd_user',
-               help=('Ceilometer snmpd user. '
-                     'If left unset, one will be automatically generated.')
+               default='ro_snmp_user',
+               help=('Ceilometer snmpd read-only user. If this value is '
+                     'changed from the default, the new value must be passed '
+                     'in the overcloud environment as the parameter '
+                     'SnmpdReadonlyUserName. This value must be between '
+                     '1 and 32 characters long.')
                ),
     cfg.StrOpt('undercloud_ceilometer_snmpd_password',
                help=('Ceilometer snmpd password. '
diff --git a/undercloud.conf.sample b/undercloud.conf.sample
index 562bbe27b..233bcf7b6 100644
--- a/undercloud.conf.sample
+++ b/undercloud.conf.sample
@@ -141,9 +141,11 @@
 # generated. (string value)
 #undercloud_ceilometer_metering_secret = <None>
 
-# Ceilometer snmpd user. If left unset, one will be automatically
-# generated. (string value)
-#undercloud_ceilometer_snmpd_user = <None>
+# Ceilometer snmpd read-only user. If this value is changed from the
+# default, the new value must be passed in the overcloud environment
+# as the parameter SnmpdReadonlyUserName. This value must be between 1
+# and 32 characters long. (string value)
+#undercloud_ceilometer_snmpd_user = ro_snmp_user
 
 # Ceilometer snmpd password. If left unset, one will be automatically
 # generated. (string value)