Apache mod-proxy ProxyErrorOverride for specific URL patterns - apache

Question

I am using Apache 2.2 with mod-proxy and I have configured it with several ProxyPass statements to proxy from remote URL to local URL. I need to have custom error documents returned from Apache for these proxied URLs so I set "ProxyErrorOverride On" in my mod-proxy configuration along with some ErrorDocument directives (with local URL path) to return custom error pages for a few HTTP status codes of interest. However, when a status code is returned for which I have NOT created an ErrorDocument directive for, Apache replaces the response body with a default error page instead of leaving the original response body intact. This won't work with the application. So I really have 2 questions:
1) Is it possible to configure Apache to leave the original response body intact for a particular status code if I don't have an ErrorDocument override defined for it?
2) Is it possible to have the ProxyErrorOverride directive only apply to some of the URLs in my ProxyPass statements?

Answer 1

As arober11 pointed out in the comment above:
Afraid the answer is: No and No. If the directive could be limited to
a location, directory, or set of URL's, then there would be something
in the "Context" section, of the man page:
httpd.apache.org/docs/2.2/mod/mod_proxy.html#proxyerroroverride
on the other hand: you can always add it to mod_proxy.c yourself.

Answer 2

For question 2:
Definitely doable. Using internal redirects to either new host or port this is possible. Brief outline using hosts (add noErrorOverrideUrl,doErrorOverrideUrl in DNS or /etc/hosts of apache-machine):
NameVirtualHost *:80
<VirtualHost *:80>
RewriteEngine On
RewriteRule ^(/noErrorOverrideUrl/.*) http://noErrorOverrideUrl$1 [L,P]
RewriteRule ^(/doErrorOverrideUrl/.*) http://doErrorOverrideUrl$1 [L,P]
</VirtualHost>
<VirtualHost *:80>
ServerName noErrorOverrideUrl
ProxyErrorOverride Off
ProxyPass ...
...
</VirtualHost>
<VirtualHost *:80>
ServerName doErrorOverrideUrl
ProxyErrorOverride On
ProxyPass ...
...
</VirtualHost>
Brief outline using ports:
Listen 80
Listen 81
Listen 82
<VirtualHost *:80>
RewriteEngine On
RewriteRule ^(/noErrorOverrideUrl/.*) http://server:81$1 [L,P]
RewriteRule ^(/doErrorOverrideUrl/.*) http://server:82$1 [L,P]
</VirtualHost>
<VirtualHost *:81>
ProxyErrorOverride Off
ProxyPass ...
...
</VirtualHost>
<VirtualHost *:82>
ProxyErrorOverride On
ProxyPass ...
...
</VirtualHost>

Answer 3

You can upgrade apache and use the If sentence avaible on 2.4+
<VirtualHost *:80>
...
<If "%{REQUEST_URI} =~ m#^\/QA(.*)$#">
ProxyErrorOverride Off
</If>
..
</VirtualHost>
Documentation