Opendistro ES is using mustache template for accessing
ctx keys in the trigger action. We have some use cases where we have to compare (but the mustache is a logicless templating script so cannot compare) the value of some keys and then write the actions accordingly.
P.S: We wanted to use a generic monitor extraction (for all hosts) using term aggregation over the host and write different trigger condition and action based on hosts. And there are exclusive slack channels for each host to trigger alerts.