The problem you are very likely running into is that the documents returned by Drupal include generated links that all reference /
instead of /blog
. mod_rewrite
and proxypass
don't do anything to the contents of documents -- they only act upon the request (or, in the case of ProxyPassReverse, on links such as Location: headers in returned content).
To make an application that normally expects to be installed as /
operate on a different URL, you need either to :
(a) Configure the application to be aware of the proper base URL. Many applications include such a setting in order to support exactly the situation you have described.
(b) Install some sort of filtering proxy that can modify the content of returned documents. For Apache, mod_proxy_html is made to do exactly this. This is included natively in Apache 2.4 but may need to be installed separately for 2.2.