How do I programmatically tell Logback 1.4.x to Reload Configuration

Question

How do I programmatically tell Logback 1.4.x to Reload Configuration?

I found an answer to reload logback 1.2.x configuration but it doesn't work with logback 1.4.x (nor 1.3.x) as it gives a compilation error:

The method findURLOfDefaultConfigurationFile(boolean) is undefined for the type ContextInitializer

Answer 1

In Logback 1.4.x, the method findURLOfDefaultConfigurationFile(boolean) is indeed not available. Instead, Logback 1.4.x introduced a new way to programmatically reload its configuration using the LoggerContext class. To programmatically trigger a configuration reload, you can use the following approach:

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import ch.qos.logback.classic.LoggerContext;
import ch.qos.logback.classic.joran.JoranConfigurator;
import ch.qos.logback.core.joran.spi.JoranException;

public class LogbackConfigReload {
    private static final Logger logger = LoggerFactory.getLogger(LogbackConfigReload.class);

    public static void main(String[] args) {
        LoggerContext loggerContext = (LoggerContext) LoggerFactory.getILoggerFactory();

        try {
            JoranConfigurator configurator = new JoranConfigurator();
            configurator.setContext(loggerContext);
            loggerContext.reset();

            // Reload the configuration from the default configuration file
            configurator.doConfigure("logback.xml"); // <<< REPLACE THE FILENAME

            logger.info("Configuration reloaded successfully");
        } 
        catch (JoranException e) {
            logger.error("Failed to reload config", e);
        }
    }
}

In this code:

1. I obtain the LoggerContext using LoggerFactory.getILoggerFactory().
2. I create a JoranConfigurator and set it to work with the LoggerContext.
3. I call loggerContext.reset() to reset the context, which clears the previous configuration.
4. I use configurator.doConfigure("logback.xml") to reload the configuration from the specified file (replace "logback.xml" with the path to your Logback configuration file).

Finally, I log a message to indicate that the configuration was reloaded.

Answer 2

Thanks to Michael for pointing out ci.autoConfig(), it does seem to work...

import ch.qos.logback.classic.LoggerContext;
import ch.qos.logback.classic.util.ContextInitializer;
import org.slf4j.LoggerFactory; // I'm using slf4j + logback

[..]

    public void resetLogger() {
        LoggerContext loggerContext = (LoggerContext) LoggerFactory.getILoggerFactory();
        loggerContext.reset();

        ContextInitializer ci = new ContextInitializer(loggerContext);
        ci.autoConfig();
    }