This setting is only used with the count filtertype

- filtertype: count
  count: 1
  pattern: '^(.*)-\d{6}$'
  reverse: true

This particular example will match indices following the basic rollover pattern of indexname-######, and keep the highest numbered index for each group.

For example, given indices a-000001, a-000002, a-000003 and b-000006, and b-000007, the indices will would be matched are a-000003 and b-000007. Indices that do not match the regular expression in pattern will be automatically excluded.

This is particularly useful with indices created and managed using the Rollover API, as you can select only the active indices with the above example (exclude defaults to False). Setting exclude to True with the above example will remove the active rollover indices, leaving only those which have been rolled-over.

While this is perhaps most useful for the aforementioned scenario, it can also be used with age-based indices as well.

Items will remain in the actionable list depending on the value of exclude, and reverse.

There is no default value. The value must include a capture group, defined by parenthesis, or left empty. If a value is provided, and there is no capture group, and exception will be raised and execution will halt.