According to current ElasticSearch documentation of TTL:
"In case you do not specify a time unit like d (days), m (minutes), h (hours), ms (milliseconds) or w (weeks), milliseconds is used as default unit.
If no default is set and no _ttl value is given then the document has an infinite _ttl and will not expire."
Current flume ElasticSearchSink index TTL configuration:
agent.sinks.myESsink.ttl = <some integer value> and defaults to 5 days.
It will be good to have a qualifier like "d" / "s" / "m" / "w" / "h" to mimic the TTL configuration in ElasticSearch mapping.
When user specifies agent.sinks.myESsink.ttl = "3w" index TTL should be set to 3 weeks while agent.sinks.myESsink.ttl = 3 will set the TTL to 3 days.