Example: Logging with Logback

Example: Logging with Logback
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It is possible to have the Jetty Server logging configured so that Logback controls the output of logging events produced by Jetty. This is accomplished by configuring Jetty for logging to Logback, which uses Slf4j and the Logback Implementation for Slf4j.

A convenient replacement logging module has been created to bootstrap the ${jetty.base} directory for logging with logback.

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

[modules]$ curl -O https://raw.githubusercontent.com/jetty-project/logging-modules/master/logback/logging.mod
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100   742  100   742    0     0   2196      0 --:--:-- --:--:-- --:--:--  2201
[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/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/logback/logback.xml to resources/logback.xml
DOWNLOAD: https://raw.githubusercontent.com/jetty-project/logging-modules/master/logback/jetty-logging.properties to resources/jetty-logging.properties

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

The replacement logging.mod performs a number of tasks.

mybase is a ${jetty.base} directory.
The jetty-distribution is unpacked (and untouched) into /opt/jetty-dist/ `and becomes the `${jetty.home} directory for this demonstration.
The 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.
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) to the ${jetty.base}/lib/logging/ directory: slf4j-api, logback-core, and logback-classic.
4. Required configuration files are downloaded (if not present already) to the ${jetty.base}/lib/resources/ directory.: jetty-logging.properties, and logback.xml.

At this point the Jetty mybase is configured so that the Jetty server itself will log using Logback, using the Logback configuration found in mybase/resources/logback.xml

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 logback-classic.jar, making all Jetty + Slf4j + Logback events emitted by the Jetty server go to Logback for routing (to console, file, syslog, etc…).

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