How to change root logging level programmatically

Question

I have the following logback.xml file:

<configuration debug="true"> 

<appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender"> 
<encoder>
  <pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n</pattern>
</encoder>
</appender>

<root level="debug">
  <appender-ref ref="STDOUT" />
</root>
</configuration>

Now, upon the occurrence of a specific event, I want to programmatically change the level of the root logger from debug to error. I can't use variable substitution, it is mandatory that I do this within the code.

How can it be done ? Thanks.

Answer 1

I assume you are using logback (from the configuration file).

From logback manual, I see

Logger rootLogger = LoggerFactory.getLogger(org.slf4j.Logger.ROOT_LOGGER_NAME);

Perhaps this can help you change the value?

Answer 2

I'm not sure, but think you get the root logger by calling LoggerFactory.getLogger(String), using Logger.ROOT_LOGGER_NAME as the logger name.

At least, that's what the logback manual says.

You should then be able to call setLevel(Level) ... according to the manual. But I think you first need to cast the Logger to cast the Logger to ch.qos.logback.classic.Logger.

Answer 3

Try this:

import org.slf4j.LoggerFactory;
import ch.qos.logback.classic.Level;
import ch.qos.logback.classic.Logger;

Logger root = (Logger)LoggerFactory.getLogger(Logger.ROOT_LOGGER_NAME);
root.setLevel(Level.INFO);

Note that you can also tell logback to periodically scan your config file like this:

<configuration scan="true" scanPeriod="30 seconds" > 
  ...
</configuration>