Nginx configuration works in production but not in docker

Question

I've been working towards dockerizing our production environment, which consists of a React frontend which makes API calls to an Nginx server. The Nginx server reverse-proxies all the requests to an ASP .NET Core application. I've managed to get the backend images (.NET and database) working and communicating correctly via docker-compose, but now I'm trying to tie in Nginx and it isn't working correctly. My configuration is as follows:

user www-data;
worker_processes auto;
pid /run/nginx.pid;
include /etc/nginx/modules-enabled/*.conf;

events { worker_connections 1024; }

http {
    sendfile on;
    tcp_nopush on;
    tcp_nodelay on;
    keepalive_timeout 65;
    types_hash_max_size 2048;

    ssl_protocols TLSv1 TLSv1.1 TLSv1.2; # Dropping SSLv3, ref: POODLE
    ssl_prefer_server_ciphers on;

    include /etc/nginx/mime.types;
    default_type application/octet-stream;

    access_log /var/log/nginx/access.log;
    error_log /var/log/nginx/error.log;

    gzip on;

    # docker provides 'app' network address for api image
    upstream app_servers {
        server api:8080;
    }

    server {
        listen 80 default_server;
        listen [::]:80 default_server;
        server_name _;
        return 301 https://$host$request_uri;
    }

    server {

        # SSL configuration
        listen 443 ssl default_server;
        listen [::]:443 ssl default_server;

        ssl_certificate /etc/nginx/server.crt;
        ssl_certificate_key /etc/nginx/server.key;

        root /var/www/html;

        # Add index.php to the list if you are using PHP
        index index.html index.htm index.nginx-debian.html;

        server_name localhost;

        location /ver {
            proxy_pass   http://app_servers/api/version;
            proxy_set_header Host $host;
        }
        location / {
            if ($request_method = OPTIONS ) {
                add_header 'Access-Control-Allow-Origin' '*' always; 
                add_header Access-Control-Allow-Methods "POST, OPTIONS";
                add_header Access-Control-Allow-Headers "Accept, Cache-Control, x-csrf-token, Authorization, Content-Type";
                add_header Content-Length 0;
                add_header Content-Type text/plain;
                return 200;
            }    

            add_header 'Access-Control-Allow-Origin' '*' always;


            proxy_set_header   Host $host;
            proxy_set_header   X-Real-IP $remote_addr;
            proxy_set_header   X-Forwarded-For $proxy_add_x_forwarded_for;
            proxy_set_header   X-Forwarded-Host $server_name;

            proxy_pass         http://app_servers/graphql;
            # 
            #proxy_redirect     off;

            # First attempt to serve request as file, then
            # as directory, then fall back to displaying a 404.
            try_files $uri $uri/ =404;
        }
    }
}

The only difference between this configuration and the production server is that in production the proxy_pass is targeting 127.0.0.1 instead of app_servers, and the servername is an actual server name instead of localhost. The hostname api comes from the service definition in docker-compose.

What I'm experiencing is that I can successfully access the /ver endpoint, but any other request which should be routed to api:8080/graphql results in a 404. However, I can easily connect to the docker container exposing 8080 with GraphQL playground and make requests.

Any insight would be greatly appreciated, I'm not 100% confident this is specifically an Nginx issue but all evidence points that way.

Answer 1

It appears the solution was to remove the following lines:

try_files $uri $uri/ =404;
proxy_set_header   Host $host;