Apache As A Front End To ZServer
Created by .
Last modified on 2003/08/01.
Problem
In my situation, Apache is currently used to serve all our content. Each Apache
server typically supports a few virtual hosts. I'd like to use ZServer
to serve some content to take advantage of Zope's features. However, some
of our content, eg. third-party documentation, generated JavaDoc, is not
really suitable to be added into the ZODB. In addition, we are likely to
continue to use Apache as we have found it to be very good.
Hence, I needed a way of configuring Apache and Zope to permit me to
use Apache as a front end to manage virtual hosts, serve some content
and redirect the remaining URLs to ZServer.
Solution
The How-Tos listed below were very useful in getting me started.
I encountered problems as I tried each one, which pushed me into trying the others.
In the end, the problems turned out to be browser related (I think), so
I suspect the other solutions work just as well as mine. However, having to
try out several solutions helped me reach a very neat solution (in my opinion).
ZServer Configuration
I used the standard startup script for Zope. This means a ZServer running
on port 8080 of my host. I created a Folder called
XYZ in the
root folder to represent the (virtual) host
xyz.mydomain.com.
SiteAccess Configuration
I added a
SiteRoot object into the
XYZ folder.
It was configured with a blank title, a base equal to
http://xyz.mydomain.com and a path equal to
/.
Apache Configuration
My solution uses Apache's re-write rules, which means Apache must be built
with
mod_rewrite. The key re-write rule uses the proxy option,
which means Apache must also be built with
mod_proxy.
Below are relevant commands from Apache's
httpd.conf file.
NameVirtualHost 123.456.78.9
<VirtualHost 123.456.78.9>
ServerName xyz.mydomain.com
DocumentRoot /path/to/htdocs
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteLog "/path/to/apache/logs/rewrite_log"
RewriteLogLevel 0
RewriteRule ^/local/ - [L]
RewriteRule ^/(.*) http://xyz.mydomain.com:8080/XYZ/$1 [P]
<IfModule>
<VirtualHost>
The Apache rewrite rules work as follows.
The
RewriteEngine
command turns the rewrite engine on.
The
RewriteLog
command specifies where to log rewrite actions.
The
RewriteLogLevel
determine how much is logged. A level of 0 is useful for production. Levels
from 1-9 give you useful debugging output.
The
RewriteRule
commands specify what Apache does with incoming requests to
xyz.mydomain.com.
The rules are processed from first to last, hence order is important.
The first rule specifies that all requests beginning with
/local/
are served by Apache. (This is achieved by the
- implying no
action, and the
[L] implying that rule processing is to stop.
The second rule, specifies that all remaining requests are forwarded to
http://xyz.mydomain.com:8080/XYZ/ using Apache's proxy
module (the
[P]).
Tricks and Traps
I found the order of things important in my solution. You should configure
ZServer, install SiteAccess, start ZServer, create any Folders, add SiteRoot
objects and then configure and start Apache.
I found that if I reconfigured Apache and tried to manage the new virtual host
before I added the SiteRoot object, I was asked to login twice. The first
login appeared to be to
xyz.mydomain.com.
The second appeared to be to
xyz.mydomain.com:8080.
Once the SiteRoot object was added this problem went away.
The other problem I encountered was a kind of infinite loop. If I started
with a vanilla Apache configuration, configured the Zope side of things
(which required logging in) and then reconfigured Apache I got into trouble.
When I tried to manage the virtual host again within Zope the browser kept trying, over
and over, to go to the site. A check of the Apache server log revealed
repeated 401 errors. 401 is Authorisation Failure, suggesting the browser
thought it had access permission but ZServer did not. The only way around this
was to restart the browser. The broswer in question is Netscape 4.73 under NT.
Environment
The above solution has been verified using the following software.
However, I don't believe I used any version specific features.
Relevant How-Tos
Using Apache with ZServer (NOT Zope.cgi)
Serving ZOPE and other content from Apache
ZOPE/Apache Virtual Host
For a full list, search for
Apache
using the main
zope.org search facility.
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