I need to address an urgent issue with our application’s logging configuration. We are trying to implement data masking using Log4j2’s custom pattern converter %mask in the log4j2.xml file. However, we are encountering a problem where the masking is not applied when deploying the application to the production server. If we remove %mask from log4j2.xml, the deployment is successful, but the masking is not applied.

To provide some context, we have added the @ConverterKeys({“mask”}) annotation to the %mask custom pattern converter, as recommended in the Log4j2 documentation. This setup works perfectly fine in our local development environment, but when we deploy the application to the production server, the data masking feature fails to function as expected.

We have thoroughly reviewed the implementation of the %mask custom pattern converter and ensured that it is correctly implemented and compatible with the version of Log4j2 being used. Additionally, we have checked for any dependency conflicts and ensured that all necessary dependencies are included in the application’s classpath during deployment.

Java class:

@Plugin(name = "MaskedPatternConverter", category = "Converter")
@ConverterKeys({"mask","masked"})
public class MaskedPatternConverter extends LogEventPatternConverter {
    public void format(LogEvent event, StringBuilder outputmsg) {
        String message = event.getMessage().getFormattedMessage();
        // Implement your masking logic here
        String maskedMessage = maskSensitiveData(message);
        
        if (message.toLowerCase().contains("email") ||
            message.toLowerCase().contains("adharcard") ||
            message.toLowerCase().contains("creditcard")) {
            String mask = maskEmailandAdhar(message);
            outputmsg.append(mask);
        } else {
            outputmsg.append(maskedMessage);
        }
    }
}

log4j2.xml:

<Appenders>
    <Routing name="AppzillonServerLogFile">
        <Routes pattern="$${ctx:AppId}/$${ctx:UserId}/">
            <Route>
                <RollingFile name="MainLogFile" fileName="${loghome}/${ctx:AppId}/${ctx:UserId}/MainLogFile.log"
                             filePattern="${loghome}/${ctx:AppId}/${ctx:UserId}/%d{dd-MM-yyyy}-MainLogFile-%i.log.zip">
                    <PatternLayout>
                        <Pattern>%d %p %-40c{1.} [$${ctx:reqRef}] [$${ctx:UserId}] %mask{email}{pass}{aadhaar}%n
                        </Pattern>
                    </PatternLayout>
                </RollingFile>
            </Route>
        </Routes>
    </Routing>
</Appenders>