Bug 1316952 introduces a new "SNS Notifier" service on hgssh. It is essentially the same as the "Pulse Notifier" service but it posts messages to Amazon SNS instead of Pulse. There is now a check_snsnotifier_lag nagios check configured on hgssh. It should be activated in Nagios monitoring. The settings, docs, etc should essentially be copies of whatever we have for check_pulsenotifier_lag.
Added nagios check and docs - https://mana.mozilla.org/wiki/display/NAGIOS/hg+sns+notifier+lag