title: how to make Apache proxy http requests to https
body: <p>I'm trying to configure svn mirroring with transparent proxying as described <a href="http://svnbook.red-bean.com/en/1.5/svn.serverconfig.httpd.html#svn.serverconfig.httpd.extra.writethruproxy" rel="nofollow">here</a>, but getting hard times with https.<br>
  Current setup is:<br></p>
  
  <ul>
  <li>master server is available publicly and is protected by https.<br></li>
  <li>slave server is sitting behind a nginx reverse proxy, and serves via http, but nginx is protecting all the external traffic with https. <br></li>
  </ul>
  
  <p>so I managed to setup svnsync to work over this weird setup, but struggling with writethruproxy:<br>
  mod_proxy_http does not like https on the other end and says this:</p>
  
  <pre><code>[debug] proxy_util.c(1525): [client ccc.ccc.ccc.ccc] proxy: *: found reverse proxy worker for https://xxx.xxx.xxx.xxx:yyyy/svn/my_repo/!svn/me
  [debug] mod_proxy.c(1020): Running scheme https handler (attempt 0)
  [debug] mod_proxy_http.c(1954): proxy: HTTPS: declining URL https://xxx.xxx.xxx.xxx:yyyy/svn/my_repo/!svn/me (mod_ssl not configured?)
  [debug] mod_proxy_ajp.c(677): proxy: AJP: declining URL https://xxx.xxx.xxx.xxx:yyyy/svn/my_repo/!svn/me
  [debug] mod_proxy_ftp.c(842): proxy: FTP: declining URL https://xxx.xxx.xxx.xxx:yyyy/svn/my_repo/!svn/me - not ftp:
  [debug] mod_proxy_connect.c(100): proxy: CONNECT: declining URL https://xxx.xxx.xxx.xxx:yyyy/svn/my_repo/!svn/me
  [warn] proxy: No protocol handler was valid for the URL /svn/brisbane/!svn/me. If you are using a DSO version of mod_proxy, make sure the proxy submodules are included in the configuration using LoadModule.
  </code></pre>
  
  <p>TLDR: is there any way I could configure mod_ssl and mod_proxy_http to forward http traffic to https? </p>
  
  <ul>
  <li>TIA</li>
  </ul>