filters: expect: add 'result_key' property

Signed-off-by: Takahiro Yamashita <[email protected]>

Author: nokute78

pipeline/filters/expect.md

@@ -23,7 +23,8 @@ The plugin supports the following configuration parameters:
 | key\_val\_is\_null | check that the value of the key is NULL. |
 | key\_val\_is\_not\_null | check that the value of the key is NOT NULL. |
 | key\_val\_eq | check that the value of the key equals the given value in the configuration. |
-| action | action to take when a rule does not match. The available options are  `warn` or `exit`. On `warn`, a warning message is sent to the logging layer when a mismatch of the rules above is found; using `exit` makes Fluent Bit abort with status code `255` |
+| action | action to take when a rule does not match. The available options are  `warn` , `exit` or "result_key". On `warn`, a warning message is sent to the logging layer when a mismatch of the rules above is found; using `exit` makes Fluent Bit abort with status code `255`; `result_key` is to add a matching result to each record. |
+| result\_key | specify a key name of matching result. This key is to be used only when 'action' is 'result_key'.|
 
 ## Getting Started