nginx and trailing slash with proxy pass

Question

I am using the following configuration for nginx 1.4.1:

server {
    listen       8000;
    server_name  correct.name.gr;

    location /test/register {
        proxy_set_header X-Forwarded-Host $host;
        proxy_set_header X-Forwarded-Server $host;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_pass http://127.0.0.1;
    }
}

What I want to do is when the users vist http://correct.name.gr:8000/test/register/ they should be proxied to the apache which runs on port 80.

When I visit http://correct.name.gr:8000/test/register/ I get correct results (index.php). When I visit http://correct.name.gr:8000/test/register/asd I get correct results (404 from apache). When I visit http://correct.name.gr:8000/test/asd I get correct results (404 from nginx). When I visit http://correct.name.gr:8000/test/register123 I get correct results (404 from apache).

The problem is when I visit http://correct.name.gr:8000/test/register. I get a 301 response and I am redirected to http://localhost/test/register/ (notice the trailing slash and of course the 'localhost')!!!

I haven't done any other configurations to nginx to put trailing slashes or something similar. Do you know what is the problem ? I want http://correct.name.gr:8000/test/register to work correctly by proxying to apache (or if not possible at least to issue a 404 error and not a redirect to the localhost of the user).

Update 1: I tried http://correct.name.gr:8000/test/register from a different computer than the one with which I had the bad behavior yesterday.. Well, it worked: I just got a 301 response that pointed me to the correct http://correct.name.gr:8000/test/register/! How is it possible to work from one computer but not from the other (I'm using the same browser-Chrome in both computers)? I will try again tomorrow to test from a third one to see the behavior.

Thank you !

Answer 1

My guess is that your upstream server (either apache or your script) triggered a redirect to the absolute url http://localhost/test/register/. Because you use http://127.0.0.1 in your proxy_pass directive, nginx doesn't find a match of the domain name and returns the Location header as is.

I think the right solution is to NOT use absolute redirect if the redirect is to an internal url. This is always a good practice.

However, without changing upstream server, there are two quick solutions.

you can use

proxy_pass http://localhost;

This will tell nginx the domain name of upstream is localhost. Then nginx will know to replace http://localhost by http://correct.name.gr:8000 when it finds that part in the Location header from upstream.

Another one is to add a proxy_redirect line to force nginx to rewrite any location header with http://localhost/ in it.

 proxy_pass http://127.0.0.1;
 proxy_redirect http://localhost/ /;

I prefer to the first solution because it's simpler. There is no DNS lookup overhead of using proxy_pass http://localhost; because nginx does the lookup in advance when it starts the web server.

reference: http://nginx.org/en/docs/http/ngx_http_proxy_module.html#proxy_redirect