Rolling policy in logback.xml - roll file after x number of hours - spring-boot

Question

<rollingPolicy
class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy">
<!-- rollover hourly -->
<fileNamePattern>${DEV_HOME}/archived/server.%d{yyyy-MM-dd_HH}.log
</fileNamePattern>
</rollingPolicy>
I m using this method now for hourly rollover but need to change this at 8hr rollover {i.e., we have 24 hr then 3 files will be created of 8hr log value each}.
Is there any solution to it?

Answer 1

By default, logback does not provide a rolling policy implementation for such functionality. You can create your own rolling policy trigger for this by extending DefaultTimeBasedFileNamingAndTriggeringPolicy and overriding the computeNextCheck method to perform the next roll after a specified multiple of the rolling time period it inferred from the file name pattern.
Custom Rolling Trigger Policy Class:
import ch.qos.logback.core.joran.spi.NoAutoStart;
import ch.qos.logback.core.rolling.DefaultTimeBasedFileNamingAndTriggeringPolicy;
#NoAutoStart // #NoAutoStart prevents null pointer exception by stopping Joran from launching the start method before initialization
public class ArbitraryTimeRollingTriggerPolicy<E> extends DefaultTimeBasedFileNamingAndTriggeringPolicy<E> {
// Setters and getters are required to set times inside logback configuration xml file
private int times;
public int getTimes() {
return times;
}
public void setTimes(int times) {
this.times = times;
}
#Override
protected void computeNextCheck() {
nextCheck = rc.getEndOfNextNthPeriod(dateInCurrentPeriod, times).getTime();
}
}
The rolling policy to use inside your appender in logback config:
<rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy">
<fileNamePattern>${DEV_HOME}/archived/server.%d{yyyy-MM-dd_HH}.log</fileNamePattern>
<!-- Custom Rolling Trigger Policy -->
<timeBasedFileNamingAndTriggeringPolicy class="<YOUR-PACKAGE>.ArbitraryTimeRollingTriggerPolicy">
<!-- Number of hours, after which you want to rotate the file -->
<times>8</times>
</timeBasedFileNamingAndTriggeringPolicy>
</rollingPolicy>