nginx.conf

server {
    listen 80;

    # Proxy settings
    # resolver 127.0.0.11;
    proxy_redirect off;
    proxy_set_header Host $host;
    proxy_set_header X-Real_IP $remote_addr;
    proxy_set_header X-Forwarded_For $proxy_add_x_forwarded_for;

    # This nonsense is to force runtime (instead of boot-time) resolution of DNS
    # so that Docker containers can be swapped, while being functionally
    # equivalent to the following block:
    #
    #     location /api/ {
    #         proxy_pass http://server/;
    #     }
    #
    # It rewrites the path, stripping the prefix of the location block, so that
    # Rails doesn't have to be completely aware that it's nested under /api/.
    location /api/ {
        proxy_pass http://server/api/;
        # set $upstream "http://server/";
        # proxy_pass $upstream$1$is_args$args;
    }
    location / {
        proxy_pass http://client/;
        # set $upstream "http://client/";
        # proxy_pass $upstream$1$is_args$args;
    }
}