NginX和Rails：子域名不起作用

Question

我尝试将NginX设置为使用子域名已经有2天了。

这是我对NginX的“.conf”：

upstream mydomain_staging {
        server unix:tmp/unicorn.mydomain_staging.sock fail_timeout=0;
}

server {
        listen   80; ## listen for ipv4; this line is default and implied
        #listen   [::]:80 default ipv6only=on; ## listen for ipv6

        root /home/mtaville/mtaville_staging/current/public;

        # Make site accessible from http://localhost/
        server_name staging.mydomain.fr admin.staging.mydomain.fr;

        location ^~ /assets/ {
                gzip_static on;
                expires max;
                add_header Cache-Control public;
        }

        location /doc/ {
                alias /usr/share/doc/;
                autoindex on;
                allow 127.0.0.1;
                deny all;
        }

        location / {
                try_files $uri $uri/index.html $uri.html @mydomain_staging;
        }

        location @mydomain_staging {
                proxy_read_timeout 300; # https://github.com/gitlabhq/gitlabhq/issues/694
                proxy_connect_timeout 300; # https://github.com/gitlabhq/gitlabhq/issues/694
                proxy_redirect     off;

                proxy_set_header   X-Forwarded-Proto $scheme;
                proxy_set_header   Host              $http_host;
                proxy_set_header   X-Real-IP         $remote_addr;
                proxy_set_header   X-Forwarded-For   $remote_addr;

                proxy_pass http://mydomain_staging;
        }

}

当我尝试访问staging.mydomain.fr时，它可以正常工作！但是当我尝试访问admin.staging.mydomain.fr时，前端显示而不是后端;

这是我的routes.rb：

MyApp::Application.routes.draw do

  constraints(subdomain: /admin/) do
    match '/', to: 'dashboard#show', as: :admin_root
    resources :posts, controller: "admin/posts"
  end

  root to: "pages#home"

end

我不知道为什么它不起作用！有人帮帮我吗？

非常感谢！