Apache subfolder as Reverse Proxy not handling RewriteRule

Question

I have a proxy setup on an Apache 2.4 (Server A) as follows

SSLProxyEngine On
ProxyRequests Off
ProxyPreserveHost On
ProxyHTMLInterp On
ProxyHTMLExtended On
SSLProxyVerify none
SSLProxyCheckPeerCN off
SSLProxyCheckPeerName off
SSLProxyCheckPeerExpire off
<Location /proxy>
    ProxyPass https://example.com
    ProxyPassReverse https://example.com
    SetOutputFilter proxy-html
    ProxyHTMLURLMap https://example.com
</Location>

Server B (example.com in this example) has a rewrite rule:

RewriteRule ^/?$ /subdir [L]

When I browse to https://servera.com/proxy the url changes to https://servera.com/subdir which throws a 404 error. If I change the url to https://servera.com/proxy/subdir everything works.

My question is how can I setup Server A's proxy to preserve the /proxy in the url?

Answer 1

Try adding / like in the ProxyPass examples.

<Location /proxy/>
    ProxyPass https://example.com/
    ProxyPassReverse https://example.com/
    SetOutputFilter proxy-html
    ProxyHTMLURLMap https://example.com/
</Location>

It might help in this case where the site behind the proxy redirects to an absolute path on the same hostname.