4,153,406 hits in single day! Sounds like a really big number for many of us. I was surprised when I noticed this in Production ELK for the first time. I didn't expect that many hits for an application with only 5 microservices. That too for a Beta application
It is always better to get notified as soon as any major issues / exceptions occurred in the Application, instead of manually going thorugh huge logs to find probable exception messages. Apache log4j provides out of the box log Appender (called SMTPAppender) to send email alerts for the log level configured
Simple Logging Facade for Java (SLF4J) is an abstraction of different logging frameworks (eg. log4j, java.util.logging, commons logging etc.). This tutorial describes how to configure SLF4J with log4j as underlying logging framework. To use SLF4J, it is required to include 3 jars SLF4J API (slf4j-api-x.x.x.jar)