I am working in Application support for a Java based application as a support engineer.

I would like to understand tomcat debug logs so that i can resolve the issues at my end and do not have to forward it to next tier due to lack of log reading knowledge.

1 Answer 1


Lol @Atul. A lot of my sys admin at my past experience were kind of negative. I took it as a good thing. You need that type of negativity to understand common mistakes people make I guess; in my situation that's how I took it.

I understand logging in Tomcat and Apache should be similar. I will use Apache as an example since most web server use similar approach in logging.

Out of the Box Apache doesn't give you ton of options in logging or app logging. You will need to go over the logging doc page to get the syntax correct in what you're trying to log.

For example; in CustomLog you can specify what you're trying to log; at the end line when you receive the log and debug at your comfort level.

I would: 
 a) make sure what you're trying to log. 
 b) figure out if you need something from the app end or web server end to log 
    things specific 
 c) convert your needs to actual syntax; if it happens to be something 
    you can do on the web server end; you can accomplish all that in the 
    tomcat server config file.
  • Sounds like a plan. Lemme explain where i am! I get these logs from the application server through an automatic log fetching tool (In house tool which uses scripts to send the logs to email). I would like to know the starting point to use in understanding the debug snippets and eventually find the Root Cause. Hope i am explaining my self O_o
    – Atul
    Oct 16, 2014 at 14:08
  • You explained it well; if you're already getting log data you need to understand the errors in your app first. I would maybe do a tailf on the errors that's being generated by the app while its running to get a better understanding. Are you trying to understand startup errors or actions errors of the app?
    – unixmiah
    Oct 16, 2014 at 19:39
  • Hi, I am trying to capture the action errors. I need to understand why a error was pointed on the UI to the user and how i can find the root cause of it on the debug. Example: The user sees a sql error and simply logs a ticket for application not working! I need to understand why the error popped up, what went wrong? Was there a constraint violated? etc... Once i am able to capture some data i can either talk to tier 2 or myself explain the end user as to why the application resulted in an error..
    – Atul
    Oct 19, 2014 at 13:51
  • I remember when I was in a team developing an app for multiple devices we were using debug scripts that embed on the app and give out more details on the action errors such as if the error is an UI error in post or get or if its even a sql error. Some of the things didn't go to logs because it was the way it was configured. You can have these action errors email for better view to identify issues. You may need something along the line where you can use a debug feature on your app to dig deeper into the errors. It will give you more details; for example if there was an error because the input
    – unixmiah
    Oct 21, 2014 at 14:48
  • continued> string had text that was breaking the post to the db and threw an error. You can bind these errors to go into your logs. You can easily identify the error and log it to your bug tracker to be fixed.
    – unixmiah
    Oct 21, 2014 at 14:50

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