Drop some line when match in logstash

Elastic Stack Logstash
1

At the moment i have this filter working to drop some lines

## var_log_messages filter
filter {
        if [type] == "var_log_messages" {
                grok {
                                        patterns_dir => ["/etc/logstash/patterns/"]
                        match => { "message" => "%{SYSLOGTIMESTAMP:var_log_messages_timestamp} %{SYSLOGHOST:var_log_messages_hostname} %{DATA:syslog_program}(?:\[%{POSINT:var_log_secure_pid}\])?: %{GREEDYDATA:message}" }
                        overwrite => [ "message"]
                }
                        ##ignore unknown spam line
                        if ([message] =~ "(Got|Sent) message type[=](method\_return|method\_call|signal) (sender)\=(n\/a|\:1\.0|org\.freedesktop\.[a-zA-Z0-9]+|[0-9\:\.]+) destination[=](n\/a|\:1\.0|org\.freedesktop\.[a-zA-Z0-9]+) object\=\/org\/freedesktop\/[a-zA-Z0-9\/\_]+ interface\=org\.freedesktop\.[a-zA-Z0-9]+"){
                            drop{}
                        }
                        else if ([message] =~ "GSSAPI client step ([0-9]{1,2})"){
                            drop{}
                        }
                        else if ([message] =~ "nss\_getpwnam\: name \'root\@test\.cloud\' does not map into domain \'test\.nl"){
                            drop{}
                        }
                }
}

But i want to make an universal way to drop unwanted log lines with grok patterns.
i've made a custom pattern to wich matches a part of an unwanted message.

it would be nice to add some line like:
else if ([message] =~ "[%{IPA_TIMESTAMP}] attrlist_replace - attr_replace (nsslapd-referral, ldap://%{HOSTNAME:host}"){
}

but grok isnt useable in a logstash conditional.

How could i check multiple matches with grok and drop the unwanted?

2

You can use the fact that the grok filter tags events that didn't match any of the expressions with _grokparsefailure (or some other tag if you like) and then you can drop events with that tag.