The drop_fields processor specifies which fields to drop if a certain condition is fulfilled. The condition is optional. If it’s missing, the specified fields are always dropped. The @timestamp and type fields cannot be dropped, even if they show up in the drop_fields list.

processors:
 - drop_fields:
     when:
        condition
     fields: ["field1", "field2", ...]

See the section called “Conditionsedit” for a list of supported conditions.

If you define an empty list of fields under drop_fields, then no fields are dropped.