Writing to the Correct Log
Let's start with the basics first. In order to write into the log files correctly, we should make use of the LogUtil (Source code: https://github.com/jogetworkflow/jw-community/blob/6.0-SNAPSHOT/wflow-commons/src/main/java/org/joget/commons/util/LogUtil.java) utility class.
We should not use the following to print out log in writing our own plugins.
System.out.println("Execution is successful");
This is because this line of message would appear in catalina.out but not in the default Joget's log file, joget.log.
Instead, we should make use of these methods provided by LogUtil. Check out the sample codes used by Email Tool (Source code: https://github.com/jogetworkflow/jw-community/blob/6.0-SNAPSHOT/wflow-core/src/main/java/org/joget/apps/app/lib/EmailTool.java#L227)
LogUtil.info(EmailTool.class.getName(), "EmailTool: Sending email from=" + email.getFromAddress().toString() + ", to=" + to + "cc=" + cc + ", bcc=" + bcc + ", subject=" + email.getSubject()); LogUtil.info(EmailTool.class.getName(), "EmailTool: Sending email completed for subject=" + email.getSubject()); LogUtil.error(EmailTool.class.getName(), ex, "");
Separate Logs of Different Origin/Plugins into Different Log Files
You may have already noticed that by default, we have log file named as email.log as Email Tool and related plugins are writing into this specific file. We may also consider this approach in breaking down the number of lines being written into a single log file for better troubleshooting.
Navigate to the "[JogetFolder]\apache-tomcat-8.5.23\webapps\jw\WEB-INF\classes\log4j.properties" configuration file and check out the use of R2 tag to see how EmailTool, UserNotificationAuditTrail, and ExportFormEmailTool are writing into email.log file.
log4j.logger.org.joget.apps.app.lib.EmailTool=DEBUG, R2
log4j.logger.org.joget.apps.app.lib.UserNotificationAuditTrail=DEBUG, R2
log4j.logger.org.joget.plugin.enterprise.ExportFormEmailTool=DEBUG, R2
# A1 is set to be a ConsoleAppender.
log4j.appender.A1=org.apache.log4j.ConsoleAppender
# A1 uses PatternLayout.
log4j.appender.A1.layout=org.apache.log4j.PatternLayout
log4j.appender.A1.layout.ConversionPattern=%-5p %d{dd MMM yyyy HH:mm:ss} %c %x - %m%n
# R is set to be DailyRollingFileAppender
log4j.appender.R=org.apache.log4j.DailyRollingFileAppender
log4j.appender.R.File=${catalina.home}/logs/joget.log
log4j.appender.R.DatePattern='.'yyyyMMdd
log4j.appender.R.layout=org.apache.log4j.PatternLayout
log4j.appender.R.layout.ConversionPattern=%-5p %d{dd MMM yyyy HH:mm:ss} %c %x - %m%n
# R2 is set to be DailyRollingFileAppender
log4j.appender.R2=org.apache.log4j.DailyRollingFileAppender
log4j.appender.R2.File=${catalina.home}/logs/email.log
log4j.appender.R2.DatePattern='.'yyyyMMdd
log4j.appender.R2.layout=org.apache.log4j.EnhancedPatternLayout
log4j.appender.R2.layout.ConversionPattern=%-5p %d{dd MMM yyyy HH:mm:ss} %-50c - %m%throwable{0}%n
Identifying App Origin in Log Files
In the section above, we talked about using LogUtil to write into the log file. When we have too many apps running in the same copy of Joget, sometimes it is hard to tell where certain line of messages come from which apps.
Large catalina.out File
We can consider to LogRotate the log files. Please see the following links:-
- https://dzone.com/articles/how-rotate-tomcat-catalinaout
- https://www.thegeekstuff.com/2010/07/logrotate-examples
As for joget.log, we are already using Log4J for rotation as seen in the log4j.properties file snippet above.