This setting is only used by the alias action.

This setting must be either True or False.

The default value for this setting is False.

action: alias
description: "Add/Remove selected indices to or from the specified alias"
  name: alias_name
  warn_if_no_indices: False
  - filtertype: ...
  - filtertype: ...

This setting specifies whether or not the alias action should continue with a warning or return immediately in the event that the filters in the add or remove section result in an empty index list.

Improper use of this setting can yield undesirable results

Ideal use case: For example, you want to add the most recent seven days of time-series indices into a lastweek alias, and remove indices older than seven days from this same alias. If you do not not yet have any indices older than seven days, this will result in an empty index list condition which will prevent the entire alias action from completing successfully. If warn_if_no_indices were set to True, however, it would avert that potential outcome.

Potentially undesirable outcome: A non-beneficial case would be where if warn_if_no_indices is set to True, and a misconfiguration results in indices not being found, and therefore not being disassociated from the alias. As a result, an alias that should only query one week now references multiple weeks of data. If warn_if_no_indices were set to False, this scenario would have been averted because the empty list condition would have resulted in an error.