Logging configuration#

Default configuration#

Logging configuration is based on the following components :

SLF4J API for every logging invocation (Logger and MDC)
Log4j2 (from X.X.X) for logging backend
Log4j2 CompositeConfiguration for logging configuration

How dependencies are managed#

Logging subsystem is provided by these dependencies :

igloo-component-core-logging : import slf4j API and slf4j bindings for JCL (commons-logging) and JUL (java.util.logging)
- JUL binding implies to call SLF4JBridgeHandler.install(). This is done in Igloo project using SLF4JLoggingListener servlet listener. This listener is added in basic-application-webapp web.xml.
  
  Logger org.iglooproject.slf4j.jul.bridge.SLF4JLoggingListener, level INFO, can be used to check if the binding is done.
- JCL binding is automatic
igloo-component-core-logging-log4j1 : dependency to use log4j 1.2 (deprecated) backend
igloo-component-core-logging-log4j2 : dependency to use log4j2 backend

How log4j configuration can be customized#

Log4j 1.2 and Log4j2 uses similar behavior. log4j2 must be transformed to log4j when Log4j 1.2 is used.

At early startup stage :

log4j 1.2 uses log4j.properties file (default configuration)
log4j2 uses log4j2.properties as configured by log4j2.component.properties in igloo-component-spring-bootstrap-config module

During Spring early initialization :

Log4j2 configuration is customized by loading custom files
It is managed by AbstractExtendedApplicationContextInitializer class and uses log4j2.configurationLocations property.
This property is set (default) in configuration-bootstrap-default.properties, configuration-bootstrap.properties (in your project).
A custom bootstrap properties path can be specified : Custom bootstrap files
Switch between log4j 1.2 and log4j2 is done base on SLF4J selected backend.
It is adviced to ensure you include only 1 implementation and 1 SLF4J binding in your classpath to ensure proper backend is used. So check your application dependencies.

With default configuration (take a look at configuration-bootstrap-default.properties), you can use :

log4j2-user-USERNAME.properties to manage your personal configuration
log4j2-env-development.properties to manage configuration dedicated to development
log4j2-env-deployment.properties to manage configuration for all deployment targets (qualification, preproduction, production)
log4j2-env-{qualification,preproduction,production}.properties to manage configuration for earch target
You can use igloo.log4j2 property to specify a path to an extra configuration. It is commonly used to provides a local on-disk extra configuration. Default path for this value is classpath:/log4j2-extra.properties.

Last configuration has the highest precedence. Configuration are loaded with this order :

General igloo config (log4j2-igloo.properties)
Project configuration (log4j2.properties)
Environment configuration
User configuration
Extra configuration

Logger igloo@config allows to see loaded files.

INFO  - igloo@config - Log4j configurations (ordered): classpath:/log4j2-igloo.properties, classpath:/log4j2.properties, classpath:/log4j2-env-development.properties, classpath:/log4j2-user-lalmeras.properties

Other customizations#

org.iglooproject.wicket.servlet.filter.Log4jUrlFilter, a servlet filter, installed in basic-application-webapp web.xml set current page URL using MDC API.

It allows to include URL in logging messages by using %X{ow-url} in the configured pattern.

How to keep log4j 1.2#

To keep log4j 1.2, you need to add this new dependency to your application-core/pom.xml:

<!-- Logging backend -->
<dependency>
   <groupId>org.iglooproject.dependencies</groupId>
   <artifactId>igloo-dependency-core-logging-log4j1</artifactId>
   <version>${igloo.version}</version>
   <type>pom</type>
</dependency>

Check that your core, init and webapp dependencies only include log4j 1.2.

How to migrate a log4j 1.2 configuration#

To migrate to log4j2, you need to add this new dependency to your application-core/pom.xml:

<!-- Logging backend -->
<dependency>
   <groupId>org.iglooproject.dependencies</groupId>
   <artifactId>igloo-dependency-core-logging-log4j2</artifactId>
   <version>${igloo.version}</version>
   <type>pom</type>
</dependency>

Check that your core, init and webapp dependencies only include log4j2.

If you use a custom configuration-bootstrap.properties, you need to create the multiple log4j2.configurationLocations entries. You can use igloo basic-application-core configuration-bootstrap.properties as a model.

You need to check if deployment uses custom bootstrap files (ask your deployment guy) to update it. You also need to update any local log4j configuration file.

Then log4j-*.properties must be renamed log4j2-*.properties, and configuration rewritten to use log4j2 syntax.

Here are examples:

Main configuration#

#
# log4j 1.2
#
log4j.appender.Stdout=org.apache.log4j.ConsoleAppender
log4j.appender.Stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.Stdout.layout.ConversionPattern=[%d{ISO8601}][%X{PID}] %-5p - %-26.26c{1} - %X{ow-url} - %m\n

log4j.rootLogger=WARN, Stdout

#
# log4j2
#
status=error
dest=err
name=PropertiesConfig

appender.console.type=Console
appender.console.name=STDOUT
appender.console.layout.type=PatternLayout
appender.console.layout.pattern=[%d{ISO8601}] %-5p - %-26.26c{1} - %X{ow-url} - %m\n

rootLogger.level=warn
rootLogger.appenderRef.stdout.ref=STDOUT

Logger configuration#

#
# log4j 1.2
#
log4j.logger.package.Class=DEBUG

#
# log4j2
#
# NAME is an arbitrary string used to link name and level together
logger.NAME.name=package.Class
logger.NAME.level=DEBUG

Advanced logger configuration#

#
# log4j 1.2
#
# synchro is an appender
log4j.logger.package.Class=INFO, synchro
log4j.additivity.package.Class=false

#
# log4j2
#
# NAME is an arbitrary string used to link name and level together
# EITHER is an arbitrary string used to link append configurations together
# REFNAME is an arbitrary string used to link logger and appender together
# [...]
appender.EITHER.name=synchro
# [...]
logger.NAME.name=package.Class
logger.NAME.level=DEBUG
logger.NAME.additivity=false
logger.NAME.appenderRef.REFNAME.ref=SYNCHRO
logger.NAME.SYNCHRO.ref=synchro
# if multiple append must be specified
#logger.NAME.appenderRef.REFNAME.ref=SYNCHRO
#logger.NAME.appenderRef.REFNAMEStdout.ref=STDOUT
#logger.NAME.SYNCHRO.ref=synchro
#logger.NAME.STDOUT.ref=STDOUT

Alternate appender configuration#

#
# log4j 1.2
#
log4j.appender.SYNCHRO=org.apache.log4j.FileAppender
log4j.appender.SYNCHRO.File=${catalina.base}/logs/synchro.log
log4j.appender.SYNCHRO.layout=org.apache.log4j.PatternLayout
log4j.appender.SYNCHRO.layout.ConversionPattern=[%d{ISO8601}] %-5p - %-26.26c{1} - %X{ow-url} - %m\n

#
# log4j2
#
# sys: prefix is used to use system properties
# env: prefix may be used for environment variables
appender.synchro.type=File
appender.synchro.name=SYNCHRO
appender.synchro.fileName=${sys:catalina.base}/logs/synchro.log
appender.synchro.layout.type=PatternLayout
appender.synchro.layout.pattern=[%d{ISO8601}] %-5p - %-26.26c{1} - %X{ow-url} - %m\n

Multiple rootLogger appender configuration#

 #
 # log4j 1.2
 #
 log4j.rootLogger=WARN, Stdout, FILE

 log4j.appender.FILE=org.apache.log4j.FileAppender
 log4j.appender.FILE.File=${catalina.base}/logs/synchro.log
 log4j.appender.FILE.layout=org.apache.log4j.PatternLayout
 log4j.appender.FILE.layout.ConversionPattern=[%d{ISO8601}] %-5p - %-26.26c{1} - %X{ow-url} - %m\n

 #
 # log4j2
 #
 # NAME is an arbitrary string used to link name
 # EITHER is an arbitrary string used to link append configurations together
 rootLogger.appenderRef.EITHER.ref=File
 rootLogger.appenderRef.stdout.ref=STDOUT

 appender.NAME.type=File
 appender.NAME.name=FILE
 appender.NAME.fileName=${sys:catalina.base}/logs/synchro.log
 appender.NAME.layout.type=PatternLayout
 appender.NAME.layout.pattern=[%d{ISO8601}] %-5p - %-26.26c{1} - %X{ow-url} - %m\n

Logging configuration

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