Question

I’ve got some special setup to do for my Rails app. My app is hosted behind a reverse proxy and it is for some reason rewriting the requests. The server the app runs on only has an internal IP address. The reverse proxy has the public address and redirects all incoming requests to the app server.

The problem is, while all requests come in as example.com/my/url they are being rewritten and sent to the app server as 10.0.0.2/my/url. This becomes a problem when e.g. devise comes into play by requiring authentication and redirecting to the login page. The redirect sent will include the local IP address instead of the FQDN that was originally requested.

Any idea how I can tell my Rails app to use a specific hostname in redirects? I’ve tried setting HTTP_HOST using passenger_set_cgi_param which didn’t work and also tried to manually set request.host in a before_filter.

Answer 1

I think you need to have your reverse proxy forward the crucial HTTP headers to your Rails app. It sounds like those are getting stripped out.

For nginx I have these directives in my server block:

server {
  proxy_set_header  X-Forwarded-For $proxy_add_x_forwarded_for;
  proxy_set_header X-Forwarded-Proto $scheme;
  proxy_set_header Host $http_host;
  proxy_redirect off;
  passenger_set_cgi_param HTTP_X_FORWARDED_PROTO https;
}