Append Processoredit

The append processor appends one or more values to an existing array if the target field already exists and it is an array. Converts a scaler to an array and appends one or more values to it if the field exists and it is a scaler. Here the values can either be one or more static values or one or more values from the fields listed under fields key.

The field in which you want to append the data.
(Optional) List of fields from which you want to copy data from. If the value is of a concrete type it will be appended directly to the target. However, if the value is an array, all the elements of the array are pushed individually to the target field.
(Optional) List of static values you want to append to target field.
(Optional) If set to true, all the "" and nil are omitted from being appended to the target field.
(Optional) If set to true and an error occurs, the changes are reverted and the original is returned. If set to false, processing continues if an error occurs. Default is true.
(Optional) If set to false, the processor does not append values already present in the field. The default is true, which will append duplicate values in the array.
(Optional) Indicates whether to ignore events that lack the source field. The default is false, which will fail processing of an event if a field is missing.

note: If you want to use fields parameter with fields under message, make sure you use decode_json_fields first with target: "".

For example, this configuration:

  - decode_json_fields:
      fields: message
      target: ""
  - append:
      target_field: target-field
        - concrete.field
        - static-value
        - ""
      ignore_missing: true
      fail_on_error: true
      ignore_empty_values: true

Copies the values of concrete.field, response fields and the static values to target-field:

  "concrete": {
    "field": "val0"
  "array": {
      "one": [ "val1", "val2" ]
  "target-field": [