The title says it all really. The settings I’m interested in are the following:
indices.lifecycle.rollover.only_if_has_documents
(Dynamic, Boolean) Whether ILM will only roll over non-empty indices. If enabled, ILM will only roll over indices as long as they contain at least one document. Defaults to true.
index.lifecycle.origination_date
(Dynamic, long) If specified, this is the timestamp used to calculate the index age for its phase transitions. Use this setting if you create a new index that contains old data and want to use the original creation date to calculate the index age. Specified as a Unix epoch value in milliseconds.
index.lifecycle.parse_origination_date
(Dynamic, Boolean) Set to true to parse the origination date from the index name. This origination date is used to calculate the index age for its phase transitions. The index name must match the pattern ^.*-{date_format}-\d+, where the date_format is yyyy.MM.dd and the trailing digits are optional. An index that was rolled over would normally match the full format, for example logs-2016.10.31-000002). If the index name doesn’t match the pattern, index creation fails.
Documentation copied from: Index lifecycle management settings in Elasticsearch | Elasticsearch Guide [8.13] | Elastic