Currently we have the following config for syslog tdagent(fluentd) config and would like to create another field for priority:Error for my log. How can I do this?

Log:

Nov 11 00:18:57 Build01v nagios: SERVICE ALERT: mmj21;Dropwizard MMJ Thread Pool;UNKNOWN;SOFT;1;**Error**: unable to access dropwizard metrics at localhost using port 8001

Current config:

<source>
  @type tail
    path           /var/log/messages
    pos_file       /var/log/td-agent/var_log_messages.pos
    read_from_head true
    tag            /var/log/messages
    <parse>
      @type regexp
        expression  ^(?<time>[^ ]* [^ ]* [^ ]*) (?<host>[^ ]*) (?<process>[^ ]*): (?<message>.*)$
        time_format %b %d %H:%M:%S
        time_key    time
    </parse>
</source>

Output:

https://fluentular.herokuapp.com/parse?regexp=%5E%28%3F%3Ctime%3E%5B%5E+%5D*+%5B%5E+%5D*+%5B%5E+%5D*%29+%28%3F%3Chost%3E%5B%5E+%5D*%29+%28%3F%3Cprocess%3E%5B%5E+%5D*%29%3A+%28%3F%3Cmessage%3E.*%29%24&input=Nov+11+00%3A18%3A57+Build01v+nagios%3A+SERVICE+ALERT%3A+mmj21%3BDropwizard+MMJ+Thread+Pool%3BUNKNOWN%3BSOFT%3B1%3B**Error%3A**+unable+to+access+dropwizard+metrics+at+localhost+using+port+8001&time_format=%25b+%25d+%25H%3A%25M%3A%25S

Records

Key     Value
host    Build01v
process nagios
message SERVICE ALERT: mmj21;Dropwizard MMJ Thread Pool;UNKNOWN;SOFT;1;**Error:** unable to access dropwizard metrics at localhost using port 8001