# How to use NGINX as a reverse-proxy server for a Node.js application using socket.io

#### Friday, May 01 2020

Despite the long name of the article, I have a feeling this may apply to more people than I might think. If you have a Node.js application which needs socket.io connections that you want to pass throgh nginx’s `reverse_proxy` directive then this is the article for you!

You must seperate the socket.io sockets and the static resources.

- The socket connections can be routed through the default `$host/socket.io` if you want to ease modifications to the source code.
- The connections to your main npm Node.js application can be routed through the relevant directory.

Here is the relevant part of my `projects.tait.tech.conf` file:

    location /socket.io {
      proxy_pass http://localhost:8080/socket.io/;
      proxy_set_header Upgrade $http_upgrade;
      proxy_set_header Connection "upgrade";
      proxy_http_version 1.1;
      proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
      proxy_set_header Host $host;
    }

    location /ttrpg {
      proxy_pass http://localhost:8080/;
      proxy_set_header Host $host;
      proxy_set_header X-Real-IP $remote_addr;
      proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    }

### Explaination:

For this application, I needed the `/ttrpg` directory to connect to my main Node.js instance. This was going to be the root of a ttrpg project. It was to have static files served form my Node.js application.

I also needed `/socket.io` to conenct to my running `npm` instance. When I tried to route all the traffic through the `/trrpg` location directive I had no luck whatsoever; `$host/ttrpg/socket.io/*` calls always failed with a 404.

Having two seperate blocks forwarding in different ways seems to fix this. I am not knowledgable enough to understand how.

For now, the project is alive!!!

Happy hacking!

P.S. I forgot to mention I also symbolically linked the `socket.io.js` file (that node is supposed to serve automatically) to the static client dir. For some reson the node instance would not serve this file without that.

    $ pwd
    /home/user/ttrpg.co/client
    $ ln -s ../server/node_modules/socket.io-client/dist/socket.io.js .

Happy hacking 2.0!