API Change in Elasticsearch 5.5.0
If a list of aliases is provided (instead of only one), indices must appear in all listed aliases or a 404 error will result, leading to no indices being matched. In older versions, if the index was associated with even one of the aliases in aliases, it would result in a match.
This setting is used only when using the alias filter.
The value of this setting must be a single alias name, or a list of alias names. This can be done in any of the ways YAML allows for lists or arrays. Here are a few examples.
filters: - filtertype: alias aliases: my_alias exclude: False
filters: - filtertype: alias aliases: [ my_alias, another_alias ] exclude: False
filters: - filtertype: alias aliases: - my_alias - another_alias exclude: False
There is no default value. This setting must be set by the user or an exception will be raised, and execution will halt.