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Migrating from Log4j 1 to Log4j 2

The logging framework in NexJ CRM has been upgraded from Log4j version 1 to Log4j version 2 in the 21.12.1.0 release. The syntax for configuring logging has changed, and the table below has been provided to assist with your transition. It is important to review each row item and apply the corresponding changes after upgrading.

Task

Log4j 1 syntax

Log4j 2 syntax

Setting the system property for the configuration file

Uses the following syntax:

log4j.configuration


Instead, use the following syntax:

log4j.configurationFile


Setting the root logger

Uses the following syntax:

log4j.rootLogger=INFO


Instead, use the following syntax:

log4j.rootLogger.level=INFO


Property substitution

Not applicable

If you have a system property called log.location, it can be used within the configuration.

For example, you can use the following syntax: 

log4j.appender.rolling.fileName=${sys:log.location}


Automatic reconfiguration

When file reconfiguration was on or off in Log4j 1, it uses the following syntax:

log4j.configuration.watched=true 

 

File reconfiguration in Log4j 2 is applied using the monitorInterval attribute, which is stored in seconds. The file is examined the next time a log event is evaluated and the monitorInterval period has elapsed.

For example, you can set the interval to 60 seconds using the following syntax:

log4j.monitorInterval=60


Setting a logger

Uses the following syntax:

log4j.logger.nexj.core.rpc=INFO

Also, supports the following syntax:

log4j.logger.nexj.core.container=WARN



log4j.logger.nexj.core.rpc.Auditor=DEBUG


Instead, use the following syntax:

log4j.logger.<unique name>.name = <fully qualified class name>
log4j.logger.<unique name>.level = <level>

For example, use:

log4j.logger.nexj-core-rpc.name=nexj.core.rpc
log4j.logger.nexj-core-rpc.level=INFO


nexj-core-rpc is considered a single token for Log4j 2. The unique name used here is only an example. The developer configuring the logger may choose unique names as appropriate for their purpose.

Additional examples are provided below:

log4j.logger.nexj-core-container.name=nexj.core.container
log4j.logger.nexj-core-container.level=WARN



log4j.logger.nexj‑core‑rpc‑tomcat‑Auditor.name=nexj.core.rpc.Auditor
log4j.logger.nexj-core-rpc-tomcat-Auditor.level=DEBUG


Setting an appender

Uses the following syntax to add an appender to the root logger:

log4j.rootLogger=INFO, console

Uses the following syntax to define an appender:

log4j.appender.console=org.apache.log4j.ConsoleAppender
log4j.appender.console.layout=org.apache.log4j.PatternLayout
log4j.appender.console.layout.ConversionPattern=%d[%t]%‑5p%c‑%m%n


To add an appender to the root logger, use the following syntax:

Log4j.rootLogger.appenderRef.stdout.ref=STDOUT

To define an appender, use the following syntax:

log4j.appender.console.type=Console
log4j.appender.console.name=STDOUT
log4j.appender.console.layout.type=PatternLayout
log4j.appender.console.layout.pattern=%d[%t]%‑5p%c‑%m%n


Setting a rolling file appender

Uses the following syntax to add an appender to the root logger (console appender is also added):


log4j.rootLogger=INFO,console,R

Uses the following syntax to define the type:

log4j.appender.R=org.apache.log4j.RollingFileAppender

Uses the following syntax to set the pattern:

log4j.appender.R.layout=org.apache.log4j.PatternLayout
log4j.appender.R.layout.ConversionPattern=%d[%t]% 5p%c %m%n

Uses the following syntax to set the maximum file size for the log: 

log4j.appender.R.MaxFileSize=256MB

Uses the following syntax to set the file location:

log4j.appender.R.File=e:\console.log

Uses the following syntax to set the maximum number of rollover files: 

log4j.appender.R.MaxBackupIndex=5

Supports the following additional options:

log4j.appender.R.immediateFlush=true
log4j.appender.R.Append=false


To add an appender to the root logger, use the following syntax:

log4j.rootLogger.appenderRef.rolling.ref=RollingFile

 To define a type (and also set the name), use the following syntax:

log4j.appender.rolling.type=RollingFile
log4j.appender.rolling.name=RollingFile

To set a pattern, use the following syntax:

log4j.appender.rolling.layout.type=PatternLayout
log4j.appender.rolling.layout.pattern=%d[%t]%‑5p%c‑%m%n

To set a max file size for the log, use the following syntax:

If you are adding one or more policies, the first line must be added.


log4j.appender.rolling.policies.type=Policies
log4j.appender.rolling.policies.size.type=SizeBasedTriggeringPolicy
log4j.appender.rolling.policies.size.size=256MB

 To set a file location, use the following syntax:

filePattern is a new attribute, and it defines the look of the rollover file name.


log4j.appender.rolling.fileName=e:\console.log
log4j.appender.rolling.filePattern=e:\%d.%i.log.gz

To set the max number of rollover files, use the following syntax:

log4j.appender.rolling.strategy.type=DefaultRolloverStrategy
log4j.appender.rolling.strategy.max=5

Supports the following additional options:

log4j.appender.rolling.immediateFlush=true
log4j.appender.rolling.append=false

The following code shows an example:

log4j.rootLogger.appenderRef.rolling.ref=RollingFile
log4j.appender.rolling.type=RollingFile
log4j.appender.rolling.name=RollingFile
log4j.appender.rolling.fileName=${sys:log.location}
log4j.appender.rolling.filePattern=${sys:log.location}-%i.log.gz
log4j.appender.rolling.layout.type=PatternLayout
log4j.appender.rolling.layout.pattern="%d %-5p [%c] (%t:%x) %m%n"
log4j.appender.rolling.policies.type=Policies
log4j.appender.rolling.policies.size.type=SizeBasedTriggeringPolicy
log4j.appender.rolling.policies.size.size=256MB
log4j.appender.rolling.filter.threshold.type=ThresholdFilter
log4j.appender.rolling.filter.threshold.level=ALL



The examples listed above include the “log4j.” prefix, which is used when you are setting system properties through VM arguments. When you are configuring properties using a properties file, you will need to omit this prefix to conform to the standard Log4j 2 syntax.

Additional references

For additional Log4j 2 information, see:

Troubleshooting

The common error shown below is caused by Log4j 2 attempting to parse a Log4j 1 property (for example, log4j.logger.nexj.core.rpc=INFO). Log4j 2 expects a token “name” after nexj and is unable to find it.

Exception in thread "Thread-0" java.lang.ExceptionInInitializerError
...
Caused by: nexj.core.util.UncheckedException: err.logger.initFailed
...
Caused by: org.apache.logging.log4j.core.config.ConfigurationException: No name attribute provided for Logger nexj

Logging configuration issues can be evaluated in more detail through the logs by setting the log4j.debug=true property in the application environment file.