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This page describes how to configure Jetty for capturing multiple logging frameworks logging events into a single logging implementation handled by Slf4j.
A single logging solution can be configured for the variety of logging libraries available in common use when using Slf4j. With careful setup, all of the following logging APIs can be supported at the same time, with a single configuration file to control the output of events produced.
Logging APIs that Slf4j supports:
java.util.logging)To accomplish this configuration a single underlying logging framework should first be chosen. This decision guides the rest of the choices about jar files to place on the server classpath.
Caution
There MUST NOT be multiple underlying logging frameworks on the classpath. If there are, the Slf4j framework fails to load.
Note
Some third party libraries provide their own implementations of common logging APIs; be careful not to accidentally include an underlying logging framework. For example, if you are using SpringSource you likely have a
com.springsource.org.apache.log4j.jaralong with alog4j.jar, which have the same classes in them. In this example, use thecom.springsource.org.apache.log4j.jarversion and exclude thelog4j.jar, as the SpringSource version includes extra metadata suitable for using SpringSource.
Table 20.1. Slf4j Logging Grid
| Logging API | Slf4j Binding Jar | Slf4j Adapter Jar | Underlying Logging Framework |
|---|---|---|---|
Logback API | n/a | logback-classic.jar | logback-core.jar |
Log4j | slf4j-log4j12.jar | log4j.jar | |
JDK 1.4 Logging | slf4j-jdk14.jar | (Core Java Classlib) | |
Commons Logging | slf4j-jcl.jar | commons-logging.jar |
The following sections use Logback as the underlying Logging framework.
This requires using logback-classic.jar and logback-core.jar, and excluding any other Slf4j adapter JAR or underlying logging framework.
It also requires including the other Slf4j binding JARs in the classpath, along with some special initialization for java.util.logging.
A convenient replacement logging module has been created to bootstrap the ${jetty.base} directory for capturing all Jetty server logging from multiple logging frameworks into a single logging output file managed by logback.
[mybase]$ mkdir modules
[mybase]$ cd modules
[modules]$ curl -O https://raw.githubusercontent.com/jetty-project/logging-modules/master/capture-all/logging.mod
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
100 1293 100 1293 0 0 3693 0 --:--:-- --:--:-- --:--:-- 3694
[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: http://central.maven.org/maven2/org/slf4j/slf4j-api/1.6.6/slf4j-api-1.6.6.jar to lib/logging/slf4j-api-1.6.6.jar
DOWNLOAD: http://central.maven.org/maven2/org/slf4j/log4j-over-slf4j/1.6.6/log4j-over-slf4j-1.6.6.jar to lib/logging/log4j-over-slf4j-1.6.6.jar
DOWNLOAD: http://central.maven.org/maven2/org/slf4j/jul-to-slf4j/1.6.6/jul-to-slf4j-1.6.6.jar to lib/logging/jul-to-slf4j-1.6.6.jar
DOWNLOAD: http://central.maven.org/maven2/org/slf4j/jcl-over-slf4j/1.6.6/jcl-over-slf4j-1.6.6.jar to lib/logging/jcl-over-slf4j-1.6.6.jar
DOWNLOAD: http://central.maven.org/maven2/ch/qos/logback/logback-core/1.0.7/logback-core-1.0.7.jar to lib/logging/logback-core-1.0.7.jar
DOWNLOAD: http://central.maven.org/maven2/ch/qos/logback/logback-classic/1.0.7/logback-classic-1.0.7.jar to lib/logging/logback-classic-1.0.7.jar
DOWNLOAD: https://raw.githubusercontent.com/jetty-project/logging-modules/master/capture-all/logback.xml to resources/logback.xml
DOWNLOAD: https://raw.githubusercontent.com/jetty-project/logging-modules/master/capture-all/jetty-logging.properties to resources/jetty-logging.properties
DOWNLOAD: https://raw.githubusercontent.com/jetty-project/logging-modules/master/capture-all/jetty-logging.xml to etc/jetty-logging.xml
INFO: resources initialised transitively
INFO: resources enabled in ${jetty.base}/start.ini
[mybase]$ java -jar /opt/jetty-dist/start.jarThe replacement logging.mod performs a number of tasks.
mybase is a ${jetty.base} directory./opt/jetty-dist/ `and becomes the `${jetty.home} directory for this demonstration.curl command downloads the replacement logging.mod and puts it into the ${jetty.base}/modules/ directory for use by mybase only.The start.jar --add-to-start=logging command performs a number of steps to make the logging module available to the ${jetty.base} configuration.
--module=logging command is added to the ${jetty.base}/start.ini configuration.${jetty.base} directories are created: ${jetty.base}/logs and ${jetty.base}/resources.Required libraries are downloaded (if not present already) to the the ${jetty.base}/lib/logging/ directory:
slf4j-api.jar - API jar for Slf4j (used by most of the rest of the jars)log4j-over-slf4j.jar - Slf4j jar that captures all log4j emitted logging eventsjul-to-slf4j.jar - Slf4j jar that captures all java.util.logging eventsjcl-over-slf4j.jar - Slf4j jar that captures all commons-logging eventslogback-classic.jar - the Slf4j adapter jar that routes all of the captured logging events to logback itself.logback-core.jar - the logback implementation jar, that handles all of the filtering and output of the logging events.${jetty.base}/resources/ directory: jetty-logging.properties, and logback.xmljava.util.logging initialization commands are downloaded (if not present already) to the ${jetty.base}/etc/ directory: jetty-logging.xmlAt this point the Jetty mybase is configured so that the jetty server itself will log using slf4j, and all other logging events from other Jetty server components (such as database drivers, security layers, jsp, mail, and other 3rd party server components) are routed to logback for filtering and output.
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 various slf4j bridge jars are acting on behalf of log4j, java.util.logging, and commons-logging, routing all of the logging events to logback (a Slf4j adapter) for routing (to console, file, etc…).