Adding Appender dynamically in logback

Question

I have a logger instance coming from slf4j. This logger already logs to console. I want to add an additional appender to it which will log to a file separately for each thread. So I want to use the SiftingAppender

I created the following utils class to add an appender to the logger instance.

package com.worksap.company.hue.com.bizcore.outputengine.devtools;

import org.slf4j.LoggerFactory;

import ch.qos.logback.classic.Logger;
import ch.qos.logback.classic.LoggerContext;
import ch.qos.logback.classic.encoder.PatternLayoutEncoder;
import ch.qos.logback.classic.sift.MDCBasedDiscriminator;
import ch.qos.logback.classic.sift.SiftingAppender;
import ch.qos.logback.classic.spi.ILoggingEvent;
import ch.qos.logback.core.Appender;
import ch.qos.logback.core.Context;
import ch.qos.logback.core.joran.spi.JoranException;
import ch.qos.logback.core.rolling.RollingFileAppender;
import ch.qos.logback.core.rolling.SizeAndTimeBasedFNATP;
import ch.qos.logback.core.rolling.TimeBasedRollingPolicy;
import ch.qos.logback.core.sift.AppenderFactory;

public class Utils {

    public static Logger putNewAppender(String file, org.slf4j.Logger log) {

        LoggerContext lc = (LoggerContext)LoggerFactory.getILoggerFactory();
        Logger logger = lc.getLogger(log.getName());
        SiftingAppender sa = new SiftingAppender();
        sa.setName("SIFT");
        sa.setContext(lc);

        MDCBasedDiscriminator discriminator = new MDCBasedDiscriminator();
        discriminator.setKey("logFileName");
        discriminator.setDefaultValue("head0");
        discriminator.start();

        sa.setDiscriminator(discriminator);

        sa.setAppenderFactory(new AppenderFactory<ILoggingEvent>() {

            @Override
            public Appender<ILoggingEvent> buildAppender(Context context, String discriminatingValue)
                    throws JoranException {
                RollingFileAppender<ILoggingEvent> appender = new RollingFileAppender<>();
                appender.setName("ROLLINGFILE-" + discriminatingValue);
                appender.setContext(context);
                appender.setFile(discriminatingValue + ".log");

                TimeBasedRollingPolicy<ILoggingEvent> policy = new TimeBasedRollingPolicy<>();
                policy.setContext(context);
                policy.setMaxHistory(5);
                policy.setFileNamePattern(discriminatingValue + "-%d{yyyy-MM-dd-HH-mm}-%i.log.gz");
                policy.setParent(appender);
                policy.start();

                SizeAndTimeBasedFNATP<ILoggingEvent> innerpolicy = new SizeAndTimeBasedFNATP<>();
                innerpolicy.setContext(context);
                innerpolicy.setMaxFileSize("512KB");
                innerpolicy.setTimeBasedRollingPolicy(policy);
                innerpolicy.start();

                policy.setTimeBasedFileNamingAndTriggeringPolicy(innerpolicy);
                policy.start();

                appender.setRollingPolicy(policy);

                PatternLayoutEncoder pl = new PatternLayoutEncoder();
                pl.setContext(context);
                pl.setPattern("%d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n");
                pl.start();
                appender.setEncoder(pl);

                appender.start();
                return appender;
            }
        });

        sa.start();
        logger.addAppender(sa);
        logger.setAdditive(false);

        return logger;

    }
}

I am trying to test the log here:

@Slf4j
public class IfxOutputJobToolTest {

    @Test
    public void outputTest() throws Exception {

        Logger logger2 = Utils.putNewAppender("C:\\Users\\works\\Downloads\\somename", log);
        MDC.put("logFileName", "somename");
        logger2.info("something is getting logged");
        logger2.error("somerghing");
        logger2.warn("somrgklsajg");
        logger2.debug("ser");
        MDC.remove("logFileName");

        LoggerContext context = (LoggerContext)LoggerFactory.getILoggerFactory();
        for (ch.qos.logback.classic.Logger logger3 : context.getLoggerList()) {
            for (Iterator<Appender<ILoggingEvent>> index = logger3.iteratorForAppenders(); index.hasNext();) {
                Appender<ILoggingEvent> appender = index.next();
                System.out.println(appender);
            }
        }
    }
}

The output on the console is the following:

ch.qos.logback.classic.sift.SiftingAppender[SIFT]
ch.qos.logback.core.ConsoleAppender[CONSOLE]
ch.qos.logback.core.ConsoleAppender[CONSOLE]
ch.qos.logback.core.ConsoleAppender[CONSOLE_SPRING]

But, none of the logger information is actually printed on the console or in a file. It prints correctly on the console if I don't add the siftingAppender . How can I add the SiftingAppender programatically?

I am not allowed to change the logback.xml

After enabling logging in logback, I get the following:

16:40:08,943 |-INFO in c.q.l.core.rolling.TimeBasedRollingPolicy - Will use gz compression
16:40:08,946 |-INFO in c.q.l.core.rolling.TimeBasedRollingPolicy - Will use the pattern somename-%d{yyyy-MM-dd-HH-mm}-%i.log for the active file
16:40:08,956 |-INFO in c.q.l.core.rolling.DefaultTimeBasedFileNamingAndTriggeringPolicy - The date pattern is 'yyyy-MM-dd-HH-mm' from file name pattern 'somename-%d{yyyy-MM-dd-HH-mm}-%i.log.gz'.
16:40:08,956 |-INFO in c.q.l.core.rolling.DefaultTimeBasedFileNamingAndTriggeringPolicy - Roll-over every minute.
16:40:08,957 |-INFO in c.q.l.core.rolling.DefaultTimeBasedFileNamingAndTriggeringPolicy - Setting initial period to Tue Jun 06 16:35:47 JST 2017
16:40:08,962 |-INFO in ch.qos.logback.core.rolling.SizeAndTimeBasedFNATP@77a4bac - The date pattern is 'yyyy-MM-dd-HH-mm' from file name pattern 'somename-%d{yyyy-MM-dd-HH-mm}-%i.log.gz'.
16:40:08,962 |-INFO in ch.qos.logback.core.rolling.SizeAndTimeBasedFNATP@77a4bac - Roll-over every minute.
16:40:08,962 |-INFO in ch.qos.logback.core.rolling.SizeAndTimeBasedFNATP@77a4bac - Setting initial period to Tue Jun 06 16:35:47 JST 2017
16:40:08,964 |-INFO in c.q.l.core.rolling.TimeBasedRollingPolicy - Will use gz compression
16:40:08,964 |-INFO in c.q.l.core.rolling.TimeBasedRollingPolicy - Will use the pattern somename-%d{yyyy-MM-dd-HH-mm}-%i.log for the active file
16:40:08,965 |-INFO in ch.qos.logback.core.rolling.SizeAndTimeBasedFNATP@77a4bac - The date pattern is 'yyyy-MM-dd-HH-mm' from file name pattern 'somename-%d{yyyy-MM-dd-HH-mm}-%i.log.gz'.
16:40:08,966 |-INFO in ch.qos.logback.core.rolling.SizeAndTimeBasedFNATP@77a4bac - Roll-over every minute.
16:40:08,966 |-INFO in ch.qos.logback.core.rolling.SizeAndTimeBasedFNATP@77a4bac - Setting initial period to Tue Jun 06 16:35:47 JST 2017
16:40:08,969 |-INFO in ch.qos.logback.core.rolling.RollingFileAppender[ROLLINGFILE-somename] - Active log file name: somename.log
16:40:08,969 |-INFO in ch.qos.logback.core.rolling.RollingFileAppender[ROLLINGFILE-somename] - File property is set to [somename.log]
16:40:08,975 |-INFO in c.q.l.co.rolling.helper.RenameUtil - Renaming file [somename.log] to [somename.log91512733365898.tmp]
16:40:08,979 |-INFO in ch.qos.logback.core.rolling.helper.SizeAndTimeBasedArchiveRemover@96be1ae - first clean up after appender initialization
16:40:08,979 |-INFO in ch.qos.logback.core.rolling.helper.SizeAndTimeBasedArchiveRemover@96be1ae - periodsElapsed = 336
16:40:08,979 |-INFO in ch.qos.logback.core.rolling.helper.Compressor - GZ compressing [somename.log91512733365898.tmp] as [somename-2017-06-06-16-35-0.log.gz]

Edit

Logs get printed on the console after removing this line logger.setAdditive(false); . However, I can't see the file getting created.

Answer 1

It seems like there is some issue with the way you are building appender in appender factory. Not sure, what is the exact issue, but i tried below code and it worked. `

sa.setAppenderFactory(new AppenderFactory() {

                 public Appender<ILoggingEvent> buildAppender(Context context, String discriminatingValue)
                         throws JoranException {
                     PatternLayoutEncoder ple = new PatternLayoutEncoder();

                    ple.setPattern("%date [%thread] [%file:%line] %msg%n");
                    ple.setContext(context);
                    ple.start();


                    RollingFileAppender<ILoggingEvent> logFileAppender = new RollingFileAppender();
                            logFileAppender.setContext(context);
                            logFileAppender.setName("File-"+discriminatingValue);
                            logFileAppender.setEncoder(ple);
                            logFileAppender.setFile(filename+"-"+discriminatingValue+".txt");

                            SizeAndTimeBasedRollingPolicy<ILoggingEvent> logFilePolicy = new SizeAndTimeBasedRollingPolicy();
                            logFilePolicy.setContext(context);
                            logFilePolicy.setParent(logFileAppender);
                            logFilePolicy.setFileNamePattern(filename+"-"+discriminatingValue+"-%d{yyyy-MM-dd}.%i.txt");
                            logFilePolicy.setMaxHistory(5);
                            logFilePolicy.setMaxFileSize(FileSize.valueOf("512kb"));
                            logFilePolicy.setTotalSizeCap(FileSize.valueOf("1gb"));
                            logFilePolicy.start();

                            logFileAppender.setRollingPolicy(logFilePolicy);
                            logFileAppender.start();

                          logFileAppender.start();
                     return logFileAppender;
                 }
             });

`