jetty-documentation/src/main/asciidoc/administration/logging/example-java-util-logging.adoc - jetty - Git at Google

 //  ========================================================================
 //  Copyright (c) 1995-2017 Mort Bay Consulting Pty. Ltd.
 //  ========================================================================
 //  All rights reserved. This program and the accompanying materials
 //  are made available under the terms of the Eclipse Public License v1.0
 //  and Apache License v2.0 which accompanies this distribution.
 //
 //      The Eclipse Public License is available at
 //      http://www.eclipse.org/legal/epl-v10.html
 //
 //      The Apache License v2.0 is available at
 //      http://www.opensource.org/licenses/apache2.0.php
 //
 //  You may elect to redistribute this code under either of these licenses.
 //  ========================================================================

 [[example-logging-java-util-logging]]
 === 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 http://slf4j.org/manual.html[Slf4j] and the http://slf4j.org/manual.html#swapping[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`.

 [source, screen, subs="{sub-order}"]
 ....
 [mybase]$ mkdir modules
 [mybase]$ cd modules

 [modules]$ curl -O https://raw.githubusercontent.com/jetty-project/logging-modules/master/java.util.logging-slf4j/logging.mod
   % 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: http://central.maven.org/maven2/org/slf4j/slf4j-jdk14/1.6.6/slf4j-jdk14-1.6.6.jar to lib/logging/slf4j-jdk14-1.6.6.jar
 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: https://raw.githubusercontent.com/jetty-project/logging-modules/master/java.util.logging-slf4j/jetty-logging.xml to etc/jetty-logging.xml
 DOWNLOAD: https://raw.githubusercontent.com/jetty-project/logging-modules/master/java.util.logging-slf4j/logging.properties to resources/logging.properties
 DOWNLOAD: https://raw.githubusercontent.com/jetty-project/logging-modules/master/java.util.logging-slf4j/jetty-logging.properties to resources/jetty-logging.properties
 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.

 .  `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.
 ..  The `--module=logging` command is added to the `${jetty.base}/start.ini` configuration.
 ..  Required `${jetty.base}` directories are created: `${jetty.base}/logs` and `${jetty.base}/resources`.
 ..  Required libraries are downloaded (if not present already): slf4j-api, and slf4j-jdk14.
 * The libraries are put in the `${jetty.base}/lib/logging/` directory.
 ..  Required configuration files are downloaded (if not present already): `jetty-logging.properties`, and `logging.properties`.
 * The configuration files are put in the `${jetty.base}/resources/` directory.
 ..  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/logging.properties`.

 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/logging.properties` file.

 ____
 [NOTE]
 `java.util.logging` is configured via the `${jetty.base}/resources/logging.properties` 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 http://docs.oracle.com/javase/7/docs/api/java/util/logging/LogManager.html[documentation from Oracle].
 ____
	// ========================================================================
	// Copyright (c) 1995-2017 Mort Bay Consulting Pty. Ltd.
	// ========================================================================
	// All rights reserved. This program and the accompanying materials
	// are made available under the terms of the Eclipse Public License v1.0
	// and Apache License v2.0 which accompanies this distribution.
	//
	// The Eclipse Public License is available at
	// http://www.eclipse.org/legal/epl-v10.html
	//
	// The Apache License v2.0 is available at
	// http://www.opensource.org/licenses/apache2.0.php
	//
	// You may elect to redistribute this code under either of these licenses.
	// ========================================================================

	[[example-logging-java-util-logging]]
	=== 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 http://slf4j.org/manual.html[Slf4j] and the http://slf4j.org/manual.html#swapping[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`.

	[source, screen, subs="{sub-order}"]
	....
	[mybase]$ mkdir modules
	[mybase]$ cd modules

	[modules]$ curl -O https://raw.githubusercontent.com/jetty-project/logging-modules/master/java.util.logging-slf4j/logging.mod
	% 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: http://central.maven.org/maven2/org/slf4j/slf4j-jdk14/1.6.6/slf4j-jdk14-1.6.6.jar to lib/logging/slf4j-jdk14-1.6.6.jar
	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: https://raw.githubusercontent.com/jetty-project/logging-modules/master/java.util.logging-slf4j/jetty-logging.xml to etc/jetty-logging.xml
	DOWNLOAD: https://raw.githubusercontent.com/jetty-project/logging-modules/master/java.util.logging-slf4j/logging.properties to resources/logging.properties
	DOWNLOAD: https://raw.githubusercontent.com/jetty-project/logging-modules/master/java.util.logging-slf4j/jetty-logging.properties to resources/jetty-logging.properties
	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.

	. `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.
	.. The `--module=logging` command is added to the `${jetty.base}/start.ini` configuration.
	.. Required `${jetty.base}` directories are created: `${jetty.base}/logs` and `${jetty.base}/resources`.
	.. Required libraries are downloaded (if not present already): slf4j-api, and slf4j-jdk14.
	* The libraries are put in the `${jetty.base}/lib/logging/` directory.
	.. Required configuration files are downloaded (if not present already): `jetty-logging.properties`, and `logging.properties`.
	* The configuration files are put in the `${jetty.base}/resources/` directory.
	.. 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/logging.properties`.

	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/logging.properties` file.

	____
	[NOTE]
	`java.util.logging` is configured via the `${jetty.base}/resources/logging.properties` 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 http://docs.oracle.com/javase/7/docs/api/java/util/logging/LogManager.html[documentation from Oracle].
	____