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Version: 9.3.14.v20161028
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Example: Logging with Java’s java.util.logging via Slf4j

It is possible to have the Jetty Server logging configured so that java.util.logging controls the output of logging events produced by Jetty.

This example demonstrates how to configuring Jetty for logging to java.util.logging via Slf4j and the Slf4j binding layer for java.util.logging. If you want to use the built-in native JavaUtilLog implementation, see #example-logging-java-util-logging-native .

A convenient replacement logging module has been created to bootstrap your ${jetty.base} directory for logging with java.util.logging.

[mybase]$ mkdir modules
[mybase]$ cd modules

[modules]$ curl -O
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100   826  100   826    0     0   2468      0 --:--:-- --:--:-- --:--:--  2473
[modules]$ cd ..

[mybase]$ java -jar /opt/jetty-dist/start.jar --add-to-start=logging
INFO: logging         initialised in ${jetty.base}/start.ini (appended)
MKDIR: ${jetty.base}/logs
DOWNLOAD: to lib/logging/slf4j-jdk14-1.6.6.jar
DOWNLOAD: to lib/logging/slf4j-api-1.6.6.jar
DOWNLOAD: to etc/jetty-logging.xml
DOWNLOAD: to resources/
DOWNLOAD: to resources/
INFO: resources       initialised transitively
INFO: resources       enabled in     ${jetty.base}/start.ini

[mybase]$ java -jar /opt/jetty-dist/start.jar

The replacement logging.mod performs a number of tasks.

  1. mybase is a ${jetty.base} directory
  2. The jetty-distribution is unpacked (and untouched) into /opt/jetty-dist/ `and becomes the `${jetty.home} directory for this demonstration.
  3. The curl command downloads the replacement logging.mod and puts it into the ${jetty.base}/modules/ directory for use by mybase only.
  4. The start.jar --add-to-start=logging command performs a number of steps to make the logging module available to the ${jetty.base} configuration.

    1. The --module=logging command is added to the ${jetty.base}/start.ini configuration.
    2. Required ${jetty.base} directories are created: ${jetty.base}/logs and ${jetty.base}/resources.
    3. Required libraries are downloaded (if not present already): slf4j-api, and slf4j-jdk14.

      • The libraries are put in the ${jetty.base}/lib/logging/ directory.
    4. Required configuration files are downloaded (if not present already):, and

      • The configuration files are put in the ${jetty.base}/resources/ directory.
    5. Required java.util.logging initialization commands are downloaded (if not present already): jetty-logging.xml.

      • The xml file is put in the ${jetty.base}/etc/ directory.

At this point the Jetty mybase is configured so that the Jetty server itself will log using java.util.logging, using the java.util.logging configuration found in mybase/resources/

The server classpath can be verified by using the start.jar --list-config command.

In essence, Jetty is now configured to emit its own logging events to slf4j, and slf4j itself is using the static log binder found in slf4j-jdk14.jar, making all Jetty + Slf4j + java.util.logging events emitted by the Jetty server go to java.util.logging for routing (to console, file, etc…​).

If there any custom java.util.logging handlers to be used, put the implementation jar in the ${jetty.base}/lib/logging/ directory and reference them in the ${jetty.base}/resources/ file.


java.util.logging is configured via the ${jetty.base}/resources/ file during a valid startup of Jetty.

This means that if there is any startup errors that occur before java.util.logging is configured, they will likely be lost and/or not routed through your configuration.

Other logging frameworks are more reliable in that they always initialize and configure on first use, unlike java.util.logging.

  • While it is possible to configure java.util.logging sooner, even at JVM startup, the example demonstrated here does not show this technique. For more information consult the official java.util.logging.LogManager javadoc documentation from Oracle.

See an error or something missing? Contribute to this documentation at Github!(Generated: 2016-10-28)