Tomcat – Virtual Hosts with Tomcat + Mod JK

mod-jktomcatvirtualhost

I have set up Apache and Tomcat on my system and I want to combine both using Mod_JK.
I have created a mod_jk worker (ajp13_worker) and added a virtual host to my Apache config:

<VirtualHost *:80>
    ServerName      tomcat.mydomain.com
    DocumentRoot    /usr/local/tomcat/webapps/      

        # Tomcat
    JkMount /* ajp13_worker
    JkMount /*.jsp ajp13_worker
    JkMount /*.jspx ajp13_worker
</VirtualHost>

and it works fine, I end up on the default Tomcat page. The Manager applications are working fine too.

Next, I have my application, which sits in the PATH-TO-TOMCAT/webapps/myapp folder. It should be reachable under myapp.mydomain.com, so I added a second vhost, this time with "DocumentRoot /usr/local/tomcat/webapps/myapp". But it did not work: I always landed on the default Tomact page and not in the root of my app.
So I used ModRewite, to rewite the request to the context of my app. The Apache vhost looks like this:

<VirtualHost *:80>
        ServerName      myapp.mydomain.com
        DocumentRoot    /usr/local/tomcat/webapps/myapp/

        RewriteEngine On
        RewriteCond     %{REQUEST_URI}   !^/myapp/.*
        RewriteRule ^/(.*)$ /myapp/$1 [PT]

        # Tomcat
        JkMount /* ajp13_worker
        JkMount /*.jsp ajp13_worker
        JkMount /*.jspx ajp13_worker
</VirtualHost>

That vhost works, the requests are rewritten and my app is reachable under myapp.mydomain.com
But now, my Tomcat creates for every single request a new session and the session count explodes when a few users access the page.

I tried several tutorials, but most of them did not address this issue. I think I am missing something. Could someone explain to me how virtual hosts are correctly set up in the combination Apache/Tomcat/Mod-JK?

Thanks a lot,

Claude

Best Answer

Ok, I found it. In the Tomcat sever.xml, you can specify the context path for each host:

<Host name="app.mydomain.com" appBase="webapps" unpackWARs="true" autoDeploy="true">
<Context path="" docBase="PATH-TO-TOMCAT/webapps/app"/>
</Host>

My mistake was, that I always tried to modify the appBase parameter and did not know about the Context element!

Related Solutions

Tomcat – Adobe Coldfusion Railo OpenBD Apache Tomcat Multiple Sites

You generally want your Tomcat Host's appbase="webapps" (default) and have the Context's docBase point to your Web root (docBase="/Users/[my username]/Websites/example.mydev/wwwroot/"). Your Web root will contain a WEB-INF for whichever WAR you're using (ColdFusion/OpenBD/Railo). It sounds like you're using a symlink or something for the WEB-INF dir?

In any case, you can't run requests against 3 different WARs in the same Web root (at least not without some fancy connector stuff--you could let a JRun instance/connector run while having WEB-INF of Railo or OpenBD in the Web root to then use 2 different Apache vhosts to handle... but this all sounds messy:). So, since you can't run them at the same time with this setup, I'm not sure why you're using separate host names?

It's also worth noting that you'll likely need to restart the Tomcat service each time you replace (re-map symlink) the WEB-INF folder.

Finally, if you do have the same Web root (docBase) for all three Tomcat Host entries, I'd imagine this will most certainly cause problems -- this could be the root of your errors, but not sure. Since you want the same Web root for each host, you might as well use an Alias (or just one host), something like this:

<Host name="local.mydev" appBase="webapps">
<Alias>local.mydev.railo</Alias>
<Alias>local.mydev.openbd</Alias>
<Context path="" docBase="/Users/[my username]/Websites/example.mydev/wwwroot" />
</Host>

Apache virtualhost permission denied with several different DocumentRoots tried. How to try next

Okay, so I fixed this about 5 mins later by putting this

<Directory "/usr/local/apache2/htdocs/Binarytales">
    Options Indexes FollowSymLinks  
    AllowOverride All
    Order allow,deny
    Allow from all
</Directory>

inside my virtualhost declaration. so in the end it read as thus:

NameVirtualHost *:80

<VirtualHost *:80>
    DocumentRoot /usr/local/apache2/htdocs
    ServerName localhost
</VirtualHost>

<VirtualHost *:80>
    DocumentRoot /usr/local/apache2/htdocs/Binarytales
    ServerName binarytales.local

    <Directory "/usr/local/apache2/htdocs/Binarytales">
        Options Indexes FollowSymLinks
        AllowOverride All
        Order allow,deny
        Allow from all
    </Directory>
</VirtualHost>

I think the magic juice here is Options ... FollowSymLinks but it anyone has a good explanation as to why this works then please let me know, or if there is a better/alternative solutions.

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