Nginx with dockerized NodeJS

Question

I have a NodeJS app that is dockerized and I have an NGINX docker container that load balances between the NodeJS processes in the docker containers. I am able to curl both NodeJs servers successfully, but NGINX can't find the upstream servers.

Here is the nginx conf:

upstream app {
    least_conn;              # Use Least Connections strategy
    server 127.0.0.1:3000;   # NodeJS Server 1
    server 127.0.0.1:3001;   # NodeJS Server 2
}
server {
    listen 80;
    server_name example.com;

    access_log /var/log/nginx/example.com-access.log;
    error_log  /var/log/nginx/example.com-error.log error;

    # Browser and robot always look for these
    # Turn off logging for them
    location = /favicon.ico { log_not_found off; access_log off; }
    location = /robots.txt  { log_not_found off; access_log off; }

    # Handle static files so they are not proxied to NodeJS
    # You may want to also hand these requests to other upstream
    # servers, as you can define more than one!
    location ~* (images/|img/|javascript/|js/|css/|stylesheets/|flash/|media/|static/|robots.txt|humans.txt|favicon.ico) {
      root /usr/share/nginx/html;
    }

    # pass the request to the node.js server
    # with some correct headers for proxy-awareness
    location / {
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header Host $http_host;
        proxy_set_header X-NginX-Proxy true;

        proxy_pass http://app/;
        proxy_redirect off;

        # Handle Web Socket connections
        proxy_http_version 1.1;
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection "upgrade";
    }

    # Proxy requests to the mobile api to the mobile api servers (old version of Android App uses m.goodrx.com URLs)
    location /mobile-api {
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header Host $http_host;
        proxy_set_header X-NginX-Proxy true;

        proxy_pass http://www.goodrx.com/mobile-api;
        proxy_redirect off;

        # Handle Web Socket connections
        proxy_http_version 1.1;
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection "upgrade";
    }
}

I then start the node containers binding ports 3000 and 3001 and the nginx container binding port 80. When curling 127.0.0.1:80 I get a Bad Request, but curling 127.0.0.1:3000 and 127.0.0.1:3001 works. Any ideas what could be going wrong with NGINX proxying?

Answer 1

127.0.0.1, or localhost points to the nginx container. You can check my answer here but basically you need to run the nginx container with --add-host docker:<IP ADDRESS>, then change your nginx config:

upstream app {
    least_conn;              # Use Least Connections strategy
    server docker:3000;   # NodeJS Server 1
    server docker:3001;   # NodeJS Server 2
}