log4j2 Appenders SMTP : how to limit max number of mail during a parametric period?

Question

I migrate my application with log4j2 and I would like know how to limit the max number of mail during a parametric period

For example : only one mail per hour triggered regardless of the number of error catched

With Log4j1 I use a specific triggeringPolicy for that but TriggeringEventEvaluator class seem to be no longer exist

<triggeringPolicy class="com.xerox.xgs.log4j.appender.triggeringEventEvaluator.DelayedSMTPAppenderTriggerEvaluator">
    <param name="period" value="60000" />
</triggeringPolicy>

Answer 1

In Log4j2 you can use filters on your SMTPAppender: an e-mail is sent for every message that passes the appender's filter (cf. javadoc). Messages denied by the filter are added to the e-mail as context (up to bufferSize messages).

While the default filter allows only ERROR messages to pass through, you can use a BurstFilter to limit the amount of e-mails.

If you want ERROR messages to trigger e-mails and at least an hour interval between two consecutive e-mails you can use:

<SMTPAppender ...>
    <Filters>
        <!-- level="OFF": no exceptions to the rate limit -->
        <BurstFilter level="OFF" rate="2.777e-04" maxBurst="1" />
        <!-- use `ERROR` messages to trigger e-mails -->
        <ThresholdFilter />
    </Filters>
</SMTPAppender>