How to limit the number of files per day when using Logback SizeAndTimeBasedFNATP

Question

When using the Logback SizeAndTimeBasedFNATP triggering policy, how can the number of files per day be limited? For example, on any given day, I don't want to have more than 100MB of logs. Given that each log (in the example below) is 20MB, I would want to be able to set a max limit of 5 files per day.

The FixedWindowRollingPolicy provides a maxIndex property, but the TimeBasedRollingPolicy does not have maxIndex. Is there a recommended approach to applying a maxIndex when using the TimeBasedRollingPolicy?

<appender name="some.file" class="ch.qos.logback.core.rolling.RollingFileAppender">
<rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy">
    <fileNamePattern>logs/some_app_%d{yyyyMMdd}.log.%i</fileNamePattern>
    <timeBasedFileNamingAndTriggeringPolicy class="ch.qos.logback.core.rolling.SizeAndTimeBasedFNATP">
        <maxFileSize>20MB</maxFileSize>
    </timeBasedFileNamingAndTriggeringPolicy>
</rollingPolicy>
<encoder>
    <pattern>%level %date{yyyy-MM-dd HH:mm:ss:SSS} %msg%n</pattern>
</encoder>

Answer 1

currently this is not possible. Look at this answer Logback, set max history files per day. You cannot rollover both time and size based rolling/triggering policy.

Answer 2

It's possible to limit total size of logs with ch.qos.logback.core.rolling.SizeAndTimeBasedRollingPolicy

<rollingPolicy class="ch.qos.logback.core.rolling.SizeAndTimeBasedRollingPolicy">
    <fileNamePattern>log/log.%d{yyyy-MM-dd}.%i.log</fileNamePattern>
    <!-- each file should be at most 100MB, keep 60 days worth of history, but at most 20GB -->
    <maxFileSize>100MB</maxFileSize>
    <maxHistory>60</maxHistory>
    <totalSizeCap>20GB</totalSizeCap>
</rollingPolicy>

From logback docs