Filter Not Working (Version 2.3.1)

New to Logstash, was trying to filer certain messages which have matching either of INFO, ERROR, WARNING and having time stamp in certain format only. I don't want any other message by having bellow filter.

filter { date { match => [ "timestamp" , "dd/MMM/yyyy:HH:mm:ss Z" ] } grok { match => [ "message" , "INFO" ] } grok { match => [ "message" , "ERROR" ] } grok { match => [ "message" , "WARNING" ] } }
But i see messages like below were as well getting filtered.
qqqqqqqqqqqqqqqqqqqqqqqqq or aaaaaaaaaaaaaaaaaaaaaaa

Something missing in the filter?


So you don't want messages with INFO/ERROR?WARNING, and with that date format to be processed?

I want messages which contain INFO or ERROR or WARNING or having timestamp to be filtered to output. Rest all messages should be stopped for writing to output stream.

Any issue with the configuration

grok is useful to transform an unstructured message to a document.
It's not done to remove some messages.

If you want to do that :

if [message] !~ "INFO|WARNING|ERROR" {