Ok, but that isn't quite what I was asking for. Let's say I wanted to create an index that is named by the year, week of year, and day of week (ok, stupid example). If I assume that the default 'YYYY.MM.dd' specification comes from the same Joda DateTimeFormat as the logstash date filter plugin, my ugly index name in the elasticsearch output would be:
index => "logstash-%{+YYYY.ww.ee}"
So, is the format specification the Joda DateTimeFormat, or something completely different?
Are there other options? With the %{} format, can I access other logstash terms, like the type, or, I don't know, the host name, etc.?
Sorry if this isn't clear 