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This product reached the end of support date on March 31, 2021.

Tomcat doesn't start properly after attaching AppMon Java agent

streitel
Newcomer

I wanted to try out AppMon on a very simple setup first before running it against our main application. So I installed Tomcat 8 on Ubuntu plus the tomcat sample webapps and checked that they work. I started the DynaTrace WebStart UI and set up a TomCat agent. I then registered the agent in

/usr/share/tomcat8/bin/setenv.sh

as per the Tomcat installation guide. After restarting Tomcat, the agent reports in with the DynaTrace WebStart UI, but Tomcat doesn't seem to start up correctly. I cannot open localhost:8080 in the browser anymore. natcat reports that the port is not in use. The TomCat logs show nothing suspicious. I waited several minutes but nothing changed.

After restarting without the DynaTrace agent, TomCat is connecting fine again. I repeated this twice with and without the agent and whenever the agent is attached, TomCat does not open the port.

Why is DynaTrace preventing TomCat from operating normally? How can I resolve this?


3 REPLIES 3

sebastian_kryst
DynaMight Leader
DynaMight Leader

Did you checked agent logs {DT_INSTALL_PATH}/logs? Check tomcat logs as well. There is mistake somewhere I think. Your Ubuntu is 64 bit so be sure that you are not using <DT_HOME>/agent/lib/libdtagent.so You should: <DT_HOME>/agent/lib64/libdtagent.so

Sebastian


streitel
Newcomer

Thank you for your answer. I did use lib64. As I wrote in my post, the agent also reports in on the WebStart UI that it attached itself successfully. So this should be correct.

The catalina.out contains no errors. Some warnings but these are the same regardless of whether the agent is attached or not.

The Dynatrace log files only contain [info] logs.


streitel
Newcomer

I'm sorry to say that apparently Dynatrace doesn't work with current versions of Tomcat 😞