CODEWITHSUNDEEP
javaspringtomcatlog4jlog4j2
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membersound

Reputation: 86925

How to lookup property parameter in web app for log4j2?

I want to configure log4j2 to lookup the logging path dynamically from web startup (tomcat).

From the docs (http://logging.apache.org/log4j/2.x/manual/lookups.html) there is a web: lookup with different parameter possibilities.

At first I'm trying the provided example:

<Appenders>
   <File name="ApplicationLog" fileName="${web:rootDir}/app.log"/>
</Appenders>

Result: ERROR Unable to create file ${web:rootDir}/app.log java.io.IOException

I also tried the other buildin properties like servletContextName and contextPath with the same error message.

So I'm probably still missing something important. But what?

Upvotes: 1

Views: 3006

Answers (2)

JeroenHoek
JeroenHoek

Reputation: 1479

Add log4j-web JAR

Your usual log4j-core JAR file on its own is not enough.

There is an additional component called log4j-web.

For automatic replacement of the ${web:...} placeholders in your logging configuration, you need the additional log4j-web JAR file. If you don't have this log4j-web JAR file, then Log4j2 itself will still work, but it will not replace these placeholders with anything. So for example ${web:rootDir} will just end up as the literal text ${web:rootDir}.

Perhaps you are missing that dependency in your project?

Log4j-web on Maven Central

Upvotes: 4

Pierpaolo Cira
Pierpaolo Cira

Reputation: 1477

Is ${web:rootDir} a value? The placeholder is not replaced by its real value.

In the page you can red:

Information on how to use Lookups in configuration files can be found in the Property Substitution: http://logging.apache.org/log4j/2.x/manual/configuration.html#PropertySubstitution

Upvotes: 0

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