[logback-user] How to know the filename used by the appender of a given logger

[David Roussel]

Ulrich,

> I thought logback would know the file it uses - why not supply the name?


There could be no file (console) or a hundred files, so it's not possible to generalise.

Try something like this:

<configuration>
  <appender name="ROLLING" class="ch.qos.logback.core.rolling.RollingFileAppender">
    <file>mylog.txt</file>
    <rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy">
      <!-- rollover daily -->
      <fileNamePattern>mylog-%d{yyyy-MM-dd}.%i.txt</fileNamePattern>
      <timeBasedFileNamingAndTriggeringPolicy
            class="ch.qos.logback.core.rolling.SizeAndTimeBasedFNATP">
        <!-- or whenever the file size reaches 100MB -->
        <maxFileSize>100MB</maxFileSize>
      </timeBasedFileNamingAndTriggeringPolicy>
    </rollingPolicy>
    <encoder>
      <pattern>%msg%n</pattern>
    </encoder>
  </appender>


  <root level="DEBUG">
    <appender-ref ref="ROLLING" />
  </root>

</configuration>

This example is directly from http://logback.qos.ch/manual/appenders.html

But instead SizeAndTimeBasedFNATP, you should subclass SizeAndTimeBasedFNATP and override the getActiveFileName() method. Then capture the filename, and put it into somewhere your app can see.

There might be other ways, but I think this approach would work.

David



On 31 Jul 2013, at 13:41, Ulrich <Forums at gombers.de> wrote:

> Thank you. I don't want to set the filename or maintain the appender from my program. This is up to the operators running the application. And I don't want to add limitations beyond those given by logback itself. I thought logback would know the file it uses - why not supply the name?
> I could also (and I do it already) set the logfile by the operationg system and provide the name as an argument. In this case the I must request that only the console-appender can be used. But I don't like this approach.
> 
> Ulrich
> 
> 
> Am 31.07.2013 12:21, schrieb David Roussel:
>> I've made my app know the logger file name so that I can put a link to it in an email.
>> 
>> Buy the way I did it was to make the app choose the filename and set a system property. Then in logback.xml refer to the system property.
>> 
>> If that approach does not work, because you are using a dynamic log file name, then I suggest you try subclassing the rolling appender and getting the new filename each time one is generated, and then putting that value into a static singleton that is visible to your app.
>> 
>> David
>> 
>> On 31 Jul 2013, at 11:12, Ulrich <Forums at gombers.de> wrote:
>> 
>>> 
>>> Within my application I would like to know the filename used by it's logger. I've asked this question before but didn't get an answer. So I will give it another try.
>>> I've browsed through the Javadoc of the classes and interfaces where I thought by their name they should be able to provide this piece of information (LoggerContext and Appender to name two of them), but wasn't lucky.
>>> 
>>> Can anyone help here?
>>> Ulrich
>>> 
>>> 
>>> 
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