Apache Commons Logging

Apache Commons Logging (JCL) is one of the oldest Java logging API available. Released for the first time in 2002, it immediately saw a widespread adoption in the Java community.

While newer APIs, like SLF4J and our own Log4j API, appeared over time, even in 2023 it is hard to find an application stack that does not depend on JCL. According to Sonatype, Apache Commons Logging is used in over 1 million artifacts, while the second place is taken by SLF4J with almost 40 thousand artifacts.

Version 1.3.0

After more than 9 years since its previous release (version 1.2 released in July 2014), Apache Commons Logging released a new 1.3.0 version today (cf. announcement). Among the most prominent changes, the new version:

• forwards logging to the Log4j API out-of-the-box (if present),
• also supports forwarding to SLF4J,
• adds support for the Java Platform Module System (JPMS) with the module name org.apache.commons.logging.

Upgrade instructions (Log4j Core/Logback)

The upgrade path for users of the Log4j Core and Logback logging backends is easy. The first step is upgrading commons-logging. In Maven this can be done using dependency management.

<dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>commons-logging</groupId>
            <artifactId>commons-logging</artifactId>
            <version>1.3.0</version>
        </dependency>
    </dependencies>
</dependencyManagement>

The second step consists in removing obsolete dependencies. Since version 1.2 only supported old generation logging backends out-of-the-box (Log4j 1.x, Avalon and Lumberjack), the Java community developed many LogFactory implementations and complete Apache Commons Logging replacements:

• org.slf4j:jcl-over-slf4j (replacement),
• org.springframework:spring-jcl (replacement),
• our own org.apache.logging.log4j:log4j-jcl (LogFactory implementation).

These artifacts can be safely removed from your dependency stack. For JPMS users this operation is even required.

To do so Maven users can use exclusions:

<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-jcl</artifactId>
    <exclusions>
        <exclusion>
            <groupId>org.springframework</groupId>
            <artifactId>spring-jcl</artifactId>
        </exclusion>
    </exclusions>
</dependency>

and to prevent regressions, add those dependencies to a bannedDependencies Maven Enforcer rule.

Upgrade instructions (Log4j 1.x/Reload4j users)

For users that use Log4j 1.x or Reload4j as logging backend the upgrade is more complicated: version 1.3.0 disabled the Log4j 1.x backend by default.

Log4j 1.x/Reload4j users are:

• encouraged to migrate to Log4j 2.x Core (cf. migration guide) or Logback,
• if that is not possible (or if a transitional period is required) they need to add a commons-logging.properties file to their applications containing:

org.apache.commons.logging.Log = org.apache.commons.logging.impl.Log4JLogger

JPMS users

The org.apache.commons.logging JPMS module has an optional dependency on the Log4j API. In order for the JVM to automatically add the org.apache.logging.log4j module to your application’s runtime, you need to add:

requires org.apache.logging.log4j;

to your application’s module descriptor.