Useful valves to help debug Tomcat

You can configure two useful valves in server.xml. One is RequestDumperValve, which can dump request header in the log files. The other one is AccessLogValve, which help you to trace who accessed which at when.

Below is a sample configuration of there two valves.

<Engine name="Catalina" defaultHost="localhost" debug="9">

 

<!-- The request dumper valve dumps useful debugging information about

the request headers and cookies that were received, and the response

headers and cookies that were sent, for all requests received by

this instance of Tomcat.  If you care only about requests to a

particular virtual host, or a particular application, nest this

element inside the corresponding <Host> or <Context> entry instead.

 

For a similar mechanism that is portable to all Servlet 2.4

containers, check out the "RequestDumperFilter" Filter in the

example application (the source for this filter may be found in

"$CATALINA_HOME/webapps/examples/WEB-INF/classes/filters").

 

Request dumping is disabled by default.  Uncomment the following

element to enable it. -->

 

<!-- This valve is used to dump request information. Useful when troubleshooting

web application -->

<Valve className="org.apache.catalina.valves.RequestDumperValve"/>

 

<!-- This valve used to monitor all access to this engine -->

<Valve className="org.apache.catalina.valves.AccessLogValve"

directory="/root/tomcat-access-log"

pattern="common"/>

/valve>

Although the valves are configured at an engine level, they can also be configured at any level, e.g. Connector or Host.