Search

16.2. Logging per Application

download PDF

Overview

Using Mapped Diagnostic Context (MDC) logging, you create a separate log file for each of your applications. The basic idea of MDC logging is that you associate each logging message with a particular context (for example, by associating it with a set of key-value pairs). Later on, when it comes to writing the log stream, you can use the context data to sort or filter the logging messages in various ways.
Note
MDC logging is supported only by log4j and slf4j.

Application key

To use MDC logging, you must define a unique MDC key for each of your applications. The MDC key is a string that is associated with one application or logging context. At runtime, you can then use the application key to sort logging messages and write them into separate files for each application key.

Enabling per application logging

To enable per application logging:
  1. In each of your applications, edit the Java source code to define a unique application key.
    If you are using slf4j, add the following static method call to your application:
    org.slf4j.MDC.put("app.name","MyFooApp");
    If you are using log4j, add the following static method call to your application:
    org.apache.log4j.MDC.put("app.name","MyFooApp");
  2. Edit the etc/org.ops4j.pax.logging PID to customize the sift appender.
    1. Set log4j.appender.sift.key to app.name.
    2. Set log4j.appender.sift.appender.file to =${karaf.data}/log/$\\{app.name\\}.log.
  3. Edit the etc/org.ops4j.pax.logging PID to add the sift appender to the root logger.
    JBossFuse:karaf@root> config:edit org.ops4j.pax.logging
    JBossFuse:karaf@root> config:propset log4j.rootLogger "INFO, out, sift, osgi:VmLogAppender"
    JBossFuse:karaf@root> config:update
Red Hat logoGithubRedditYoutubeTwitter

Learn

Try, buy, & sell

Communities

About Red Hat Documentation

We help Red Hat users innovate and achieve their goals with our products and services with content they can trust.

Making open source more inclusive

Red Hat is committed to replacing problematic language in our code, documentation, and web properties. For more details, see the Red Hat Blog.

About Red Hat

We deliver hardened solutions that make it easier for enterprises to work across platforms and environments, from the core datacenter to the network edge.

© 2024 Red Hat, Inc.