Removing Tomcat context from URLs for a virtual host (mod_jk, mod_rewrite)

Question

I have a single Tomcat instance containing a number of webapps, each accessible via it's /Context. Tomcat is behind httpd (actually Debian Apache2), configured with virtual hosts to serve each app/Context. Tomcat connectivity is with mod_jk.

This works fine when I don't care about removing the context from urls: when the root of a virtual domain is requested, the requested is redirected to domain.com/Context.

However for one app I do want to remove the context. I believe this can be done by using mod_rewrite, and passing the re-written url to mod_jk for passing on to the correct Tomcat context. So my Debian Apache2 sites-available file looks like this:

NameVirtualHost *

<VirtualHost *>
    ServerName domain.be

    DocumentRoot /home/webapp/app/static/domain/

    RewriteEngine on
    RewriteRule ^/(.*)$ /Context/$1 [L,PT]
    RewriteLog "/var/log/apache2/domain-rewrite.log"
    RewriteLogLevel 4

    JkLogFile     /var/log/apache2/domain-mod_jk.log
    JkLogLevel    debug
    JkLogStampFormat "[%a %b %d %H:%M:%S %Y] "
    JkMount /Context w1
    JKMount /Context* w1
    JkOptions +ForwardURICompat

    ErrorLog /var/log/apache2/domain_error.log
    CustomLog /var/log/apache2/domain_access.log combined
    LogLevel warn

</VirtualHost>

According to the docs, the [PT] flag and +ForwardURICompat options should result in the rewritten URL being passed to jk_mod. However that doesn't seem to be happening.

The URL is being re-written, but it seems as if mod_jk is ignoring it: A request for domain.be/Context for example gets rewritten as /Context/Context - but is still handed to mod_jk as /Context.

Any ideas? Incidentally, I cannot use mod_proxy at the moment.

Thanks

Answer 1

@Josh, I think this solution won't work if tomcat performs any redirects. This is the typical case for example in an application demanding a login. When the user is not authenticated the app will redirect to something like /login however tomcat will append the current context like in /context/login so at the end the context does show in the URL.

As you mentioned in your other question/response using just mod-jk plus tomcat virtual hosts is an option but there you will need to deploy your applications as ROOT.war which might not be that straightforward. There is a workaround so your application can be just dropped into tomcat webapps folder but as I described here the server will deploy the app at least twice.

It would be great if RewriteRule[P] plus JkOptions +ForwardURICompat could work but it doesn't. BTW I have tested this and I know mod_proxy does work as I proxied my site to cnn.com and I got their page under my site URL. Below are the logs BTW for the requests where you can see a proxy is being used:

127.0.0.1 - - [15/Dec/2011:12:56:34 --0500] [localhost/sid#1008ef278][rid#1009980a8/initial] (2) forcing proxy-throughput with http://localhost/nestorurquiza-app/
127.0.0.1 - - [15/Dec/2011:12:56:34 --0500] [localhost/sid#1008ef278][rid#1009980a8/initial] (1) go-ahead with proxy request proxy:http://localhost/nestorurquiza-app/ [OK]
127.0.0.1 - - [15/Dec/2011:12:56:49 --0500] [localhost/sid#1008ef278][rid#1009aaca8/initial] (2) forcing proxy-throughput with http://localhost/nestorurquiza-app/login
127.0.0.1 - - [15/Dec/2011:12:56:49 --0500] [localhost/sid#1008ef278][rid#1009aaca8/initial] (1) go-ahead with proxy request proxy:http://localhost/nestorurquiza-app/login [OK]
127.0.0.1 - - [15/Dec/2011:12:57:15 --0500] [localhost/sid#1008ef278][rid#1009980a8/initial] (2) forcing proxy-throughput with http://localhost/nestorurquiza-app/j_spring_security_check
127.0.0.1 - - [15/Dec/2011:12:57:15 --0500] [localhost/sid#1008ef278][rid#1009980a8/initial] (1) go-ahead with proxy request proxy:http://localhost/nestorurquiza-app/j_spring_security_check [OK]
127.0.0.1 - - [15/Dec/2011:13:08:41 --0500] [localhost/sid#1008ef278][rid#1009980a8/initial] (2) forcing proxy-throughput with http://localhost/nestorurquiza-app/
127.0.0.1 - - [15/Dec/2011:13:08:41 --0500] [localhost/sid#1008ef278][rid#1009980a8/initial] (1) go-ahead with proxy request proxy:http://localhost/nestorurquiza-app/ [OK]

Answer 2

I'll leave my original answer up but it is wrong. The proper way to do this would be with a Tomcat VirtualHost:

http://tomcat.apache.org/tomcat-6.0-doc/virtual-hosting-howto.html

The official walk-through in the link above is exactly what I've used several times now. I won't attempt to boil it down here.

The concept is the same as an Apache Vhost. Create a virtual host (eg. for something.yourtdomain.com) and deploy your webapp to the ROOT application (/) for that vhost and you're all set. This way, if you already have a ROOT webapp, you can have another at a different domain and the prior will remain unaffected.

As Nestor mentioned, an Apache rewrite rule will not handle things like tag libs and frameworks that automatically create links/form actions/etc for you based on the context root. In this case they will create the correct context root (/).