I would like to change some properties from the log4j2.xml
file depending on the my application.properties, for example define some properties and then substitute in the log4j2
those properties that are parameters.
I ran different approaches but I still did not get the right thing. I would like to have different configs depending on the environment (DEV, QA or PROD). How to accomplish this?
I'm trying to have this in my properties
#Place holders for log4j2.xml file
log.file.path=/opt/tomcat/logs
log.file.name=dummydummy
log.file.size=100 MB
log.level=DEBUG
My log4j2 below.
<?xml version="1.0" encoding="UTF-8"?>
<Configuration status="WARN" monitorInterval="30">
<Properties>
<Property name="PID">????</Property>
<property name="name">my-log</property>
</Properties>
<Appenders>
<RollingFile name="file" fileName="${log.file.path}${log.file}.log"
filePattern="${log.file.path}${log.file}-%d{yyyy-MM-dd}-%i.log.gz">
<PatternLayout
pattern="%d{yyyy-MM-dd HH:mm:ss.SSS} %5p ${sys:PID} --- [%t] %c{1}(%M:%L) : %m%n%wEx" />
<Policies>
<TimeBasedTriggeringPolicy /><!-- Rotated everyday -->
<SizeBasedTriggeringPolicy size="${log.file.size}" /> <!-- Or every 100 MB -->
</Policies>
</RollingFile>
<Console name="Console" target="SYSTEM_OUT" follow="true">
<PatternLayout
pattern="%clr{%d{yyyy-MM-dd HH:mm:ss.SSS}}{faint} %clr{%5p} %clr{${sys:PID}}{magenta} %clr{---}{faint} %clr{[%t]}{faint} %clr{%c{1}(%M:%L)}{cyan} %clr{:}{faint} %m%n%wEx" />
</Console>
</Appenders>
<Loggers>
<Logger name="org.hibernate.validator.internal.util.Version"
level="warn" />
<Logger name="org.apache.coyote.http11.Http11NioProtocol" level="warn" />
<Logger name="org.apache.tomcat.util.net.NioSelectorPool" level="warn" />
<Logger name="org.apache.catalina.startup.DigesterFactory" level="error" />
<Logger name="org.springframework.web" level="error" />
<Root level="${log.level}">
<AppenderRef ref="Console" />
<AppenderRef ref="file" />
</Root>
</Loggers>
</Configuration>
Best Answer
The properties lookup element allows to refer properties from an external properties file in the log4j configuration. For your example it should be something like this:
A file env.properties contains the following properties:
The properties lookup should be defined as properties of the log4j2.xml:
Now the properties may be referred in appenders with ${property_name} notation. Each property reference will be interpolated with the real value from the env.properties.
You can find another example of properties lookup here.