[Exist-open] reverse proxying eXist on a hidden port: apache configuration

[Ron V. d. B. <ron...@ka...>]

Hi all,

I'm starting a new thread, since this specific problem was only sideways 
or partially mentioned in two other threads on this list: 
<http://markmail.org/message/ianhydc7hirr6s3n> and 
<http://markmail.org/thread/y7mh7flixdsjqx3c>.

Basically, the problem is that when eXist is running on a port that is 
closed by the firewall, and accessed via reverse proxy behind an Apache 
HTTP server, all goes well, except for the webstart java client. 
Following the instructions from 
<http://exist-db.org/exist/production_web_proxying.xml#d43688e330>,  I 
have set up following reverse proxy configuration in the httpd.conf file 
of an Apache server listening at <http://mydomain/>:

   ProxyRequests	off
   ProxyPass/     http://localhost:8082/
   ProxyPassReverse/     http://localhost:8082/
   ProxyPassReverseCookiePath/  /

This allows me to address e.g. <http://mydomain/exist/eXide/> 
successfully, which will be redirected to 
<http://mydomain/exist/eXide/index.html>. Yet, accessing the webstart 
client at <http://mydomain/exist/webstart/exist.jnlp> generates an 
exist.jnlp file which will try to connect to an eXist instance at 
<http://localhost:8082/exist/webstart.jnlp>, instead of 
<http://mydomain/exist/webstart.jnlp>. In short: the webstart client 
only sees the URL of the 'real' request; not the original request that 
is proxied.

Meanwhile, I have found how this can be solved: Apache's mod_proxy 
module also has a ProxyPreserveHost directive, which will pass on the 
host of the original request to the proxied host 
(<http://httpd.apache.org/docs/2.2/mod/mod_proxy.html#proxypreservehost>). 
Adding this to the httpd.conf file:

   ProxyRequests	off
   ProxyPreserveHost on
   ProxyPass/     http://localhost:8082/
   ProxyPassReverse/     http://localhost:8082/
   ProxyPassReverseCookiePath/  /

...makes everything work, including the webstart client.

So far, so good. Yet, I don't want /all/ requests to be reverse proxied, 
but rather limit the proxying to requests starting with /apps/. Hence, I 
would like to proxy requests for <http://mydomain/apps/exist/eXide/> to 
<http://localhost:8082/exist/eXide/> (i.e. while an /apps/ path is in 
the request it should be filtered out from the proxied request):

   ProxyRequests	off
   ProxyPreserveHost on
   ProxyPass/apps/     http://localhost:8082/
   ProxyPassReverse/apps/http://localhost:8082/
   ProxyPassReverseCookiePath/apps/  /

This works well, except when redirections are at play: 
<http://mydomain/apps/exist/eXide/> is rewritten to 
<http://mydomain/exist/eXide/index.htm>. Note: this does not happen when 
the ProxyPreserveHost is switched off: in that case, 
<http://mydomain/apps/exist/eXide/> is successfully redirected to 
<http://mydomain/apps/exist/eXide/index.html>. I guess the same issue is 
at play with requests for the webstart client (with ProxyPreserveHost 
switched on): while an exist.jnlp file /is /generated, it will try to 
connect to <http://mydomain/exist/webstart/>, instead of 
<http://mydomain/apps/exist/webstart/>.

I have the feeling I'm nearly there. Can anyone advice on the final fix?

Kind regards,

Ron