json. add_error_key: false not honored

[ycombinator]

• Version: master / 8.0.0
• Operating System: Mac OS X
• Discuss Forum URL: https://discuss.elastic.co/t/error-key-populated-even-when-explicitly-disabled/172602
• Steps to Reproduce:
  1. Setup filebeat.yml like so:

     filebeat.inputs:
     - type: stdin
     
       enabled: true
       json.add_error_key: false
       json.overwrite_keys: true
       json.keys_under_root: true
     
     output.console:
       enabled: true

  2. Run Filebeat:

     ./filebeat -e

  3. Give it the following input on STDIN:

     { "type": 12345 }
     

Filebeat expectedly fails with this error:

ERROR   jsontransform/jsonhelper.go:76  JSON: Won't overwrite type because value is not string

However, in the event that is generated (see example below), the error field is set to an object, despite json.add_error_key being set to false in the configuration.

{"@timestamp":"2019-03-18T21:03:42.045Z","@metadata":{"beat":"filebeat","type":"_doc","version":"8.0.0"},"log":{"offset":0,"file":{"path":""}},"error":{"message":"type not overwritten (not string)","type":"json"},"input":{"type":"stdin"},"agent":{"type":"filebeat","ephemeral_id":"7e40fe2c-8d09-430e-b661-aa9773ae6c87","hostname":"Shaunaks-MBP-2","id":"51a8bb52-16b0-4129-a33b-9fba504fe6e8","version":"8.0.0"},"ecs":{"version":"1.0.0-beta2"},"host":{"name":"Shaunaks-MBP-2"}}