add missing docs for copy_fields and truncate_fields

libbeat/docs/processors-list.asciidoc

@@ -38,6 +38,9 @@ endif::[]
 ifndef::no_convert_processor[]
 * <<convert,`convert`>>
 endif::[]
+ifndef::no_copy_fields_processor[]
+* <<copy-fields, `copy_fields`>>
+endif::[]
 ifndef::no_decode_base64_field_processor[]
 * <<decode-base64-field,`decode_base64_field`>>
 endif::[]
@@ -86,6 +89,9 @@ endif::[]
 ifndef::no_timestamp_processor[]
 * <<processor-timestamp,`timestamp`>>
 endif::[]
+ifndef::no_truncate_fields_processor[]
+* <<truncate-fields, `truncate_fields`>>
+endif::[]
 //# end::processors-list[]
 
 //# tag::processors-include[]

libbeat/processors/actions/docs/copy_fields.asciidoc

@@ -0,0 +1,38 @@
+[[copy-fields]]
+=== Copy fields
+
+The `copy_fields` processor copies a field to another one.
+
+`fields`:: List of `from` and `to` pairs to copy from and to.
+`fail_on_error`:: (Optional) If set to true, in case of an error the changes to
+the event are reverted, and the original event is returned. If set to `false`,
+processing continues also if an error happens. Default is `true`.
+`ignore_missing`:: (Optional) Whether to ignore events which lack the source
+                   field. The default is `false`, which will fail processing of
+                   an event if a field is missing.
+
+For example, this configuration:
+
+[source,yaml]
+------------------------------------------------------------------------------
+processors:
+- copy_fields:
+  fields:
+  - from: message
+    to: event.original
+  fail_on_error: false
+  ignore_missing: true
+------------------------------------------------------------------------------
+
+Copies the original `message` field to `event.original`:
+
+[source,json]
+-------------------------------------------------------------------------------
+{
+  "message": "my-interesting-message",
+  "event": {
+      "original": "my-interesting-message"
+  }
+}
+-------------------------------------------------------------------------------
+

libbeat/processors/actions/docs/truncate_fields.asciidoc

@@ -0,0 +1,29 @@
+[[truncate-fields]]
+=== Truncate fields
+
+The `truncate_fields` truncates a field to a given size if bigger. If the size of the field is smaller than
+the limit, the field is left as is.
+
+`fields`:: List of `from` and `to` pairs to copy from and to.
+`max_bytes`:: Maximum number of bytes in a field. Mutually exclusive with `max_characters`.
+`max_characters`:: Maximum number of characters in a field. Mutually exclusive with `max_bytes`.
+`fail_on_error`:: (Optional) If set to true, in case of an error the changes to
+the event are reverted, and the original event is returned. If set to `false`,
+processing continues also if an error happens. Default is `true`.
+`ignore_missing`:: (Optional) Whether to ignore events which lack the source
+                   field. The default is `false`, which will fail processing of
+                   an event if a field is missing.
+
+For example, this configuration truncates the field named `message` to 5 characters:
+
+[source,yaml]
+------------------------------------------------------------------------------
+processors:
+- truncate_fields:
+  fields:
+  - message
+  max_characters: 5
+  fail_on_error: false
+  ignore_missing: true
+------------------------------------------------------------------------------
+