[syslog-ng] elasticsearch and ILM

I have been using the elasticsearch_http driver to push stuff into ES for well over a year. Now I am trying to use the Index Lifecycle Management (ILM) to manage these indexes and finding it very confusing. There seem to be holes in the ES docs and help on their forum is a bit erratic. The most confusing thing is the “rollover index alias” and I have yet to find a coherent explanation of exactly what it does and how to set it. Most of the documentation seems to assume you are using filebeat, logstash or datastreams. So far as I can see you syslog-ng can not write to datastreams as you need to use “create” rather than “index”. If anyone has a working set up that they are happy to share it would be wonderful. Russell