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I want to try and use logj 2 in my web application. With log4j 1.x, we set-up different configuration files based on environment and use ServletContextListener to load the appropriate configuration using a call like

DOMConfigurator.configureAndWatch(logConfigFile, delay);

by passing the config file location.

I was planning on doing the same for log4j2 config file but according to this and this, it is not possible or advisable to use DOMConfigurator with log4j2.

So, my question is: How can I use different configuration files based on environment with log4j 2?

Remko Popma
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adbdkb
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4 Answers4

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What do you want to achieve with having multiple config files? I'll take a guess that you want to have separate log files for each web application.

One way you can achieve this is using the RoutingAppender; this can delegate log events to other appenders depending on key/values set in the ThreadContextMap. Some people use their web app name as the value to switch on.

Beta-9 (the last beta before GA) will be released soon and it will have better docs for using log4j2 with web apps (and the FAQ will have a detailed RoutingAppender example).

Does this answer your question?

Remko Popma
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  • Thank you for the response. No, here I am not trying to have separate logfiles for each web application, but a separate config file for each of the environments, so that, for example, I can have DEBUG in dev and UAT, but not in PROD or can have large file sizes in dev and uat, but not in prod. Like I mentioned in the question, what we do with version 1 is that we have, say, log4j-dev.xml, log4j-prod.xml etc. and have a servlet context listener and an env variable such that without making code changes, when I deploy the app to an env, it picks up correct config – adbdkb Sep 09 '13 at 11:35
  • I see. This may already be possible, otherwise you can request this as a new feature. Either way you probably want to raise this on the user mailing list. – Remko Popma Sep 10 '13 at 06:17
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Thanks to Remko Popma, I posted the question and got an answer from log4j user mailing list. One can use a System property or environment variable with 'log4jconfiguration' context-param to dynamically set the configuration file at runtime

adbdkb
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  • Is it possible to share the post or comment? I have a similar use case i am trying to solve – Gowtham Mar 24 '15 at 22:05
  • This (http://apache-logging.6191.n7.nabble.com/Defining-different-log4j2-xml-configurations-based-on-environment-td40639.html#a40662 is the post that I have mentioned in the reply – adbdkb Mar 27 '15 at 02:15
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If you are in a Servlet 3.x container, I would recommend going with what Log4j2 recommends by adding the log4j-web jar to the others being used and setting the Context Parameters as stated in the log4j2 usage manual for web applications.

Eric Wolf
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The mailing list link in the answer is broken. Although it is currently accessible here. For a full answer, you can use a system property in the context param like this:

<context-param>
    <param-name>log4jConfiguration</param-name>
    <param-value>file:/${sys:MYLOGDIR}/log4j2.xml</param-value>
</context-param>

This one was really hard to find as it is only mentioned in the mailing list.

user3501921
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