Configuring Apache HHTPD with Tomcat can be confusing the first time. It's best to try to break it down into sections.
First, get your application running under Tomcat via TC's HTTP service (e.g., the port 8080 URLs).
FYI, the error you're getting indicates a DB configuration problem. You may need to double check your jforum-custom.conf file settings.
OK, once it's running, you need to verify that your Tomcat config is set up correctly for AJP connections. The server.xml config file should have a "Connector" element with a protocol="AJP/1.3" defined on it.
If needed, restart Tomcat to make sure changes are being used.
Next, in the HTTPD config, you need to make sure that the jk_module mod is loaded via a "LoadModule jk_module modules/modjk.so" statement. (And that the mod library is available.
Then you need to add the Jk* statements (you're look fine), into the HTTPD config file(s). Note that if you have virtual servers defined, you may need to do this inside the virtual server definitions.
That should get you started. If you want a fancier setup, there is a Tomcat "Listener" class org.apache.jk.config.ApacheConfig that can be used to automatically create a set of Jk* HTTPD statements when TC starts. This will have all web applications included in it and can be "Included" into your HTTPD.conf file. [originally posted on jforum.net by monroe]