how2nginx ur socket.io (posted 14 Jun 2013)

(or, in my case, engine.io, but it’s pretty much the same.)

Recently, I decided to install nginx on my webserver. I used to be running a custom proxy based on node-http-proxy, but then I realized that all my servers were doing static hosting with ecstatic and I figured it made way more sense to use something actually designed to handle static fileserving. Wherein nginx came into play.

Honestly, nginx is pretty awesome. The configs are Actually Sane unlike Apache, and it’s totally SO fast. Not that I really know what I’m talking about here, but… I dig it.

But then, I had an internal dashboard I wanted to run that uses engine.io.

Back in the day, nginx didn’t support websockets. Heck, very few of the reverse proxying solutions at the time supported them. You may recall that this is part of the reason nodejitsu wrote node-http-proxy in the first place. But nowadays, nginx fully supports websockets. Which is badass. You can read a little bit about how to set up basic websocket support here.

Problem is, that doesn’t quite work for socket.io. My understanding is that this is because the polling transport has slightly different requirements than websockets when it comes to proxying. I Googled for some time about this, but unfortunately all the gists on github are about how to hack together the ol’ ‘tcp proxying’ workaround.

Luckily, Guillermo is straight awesome, and LearnBoost is using nginx + websockets in production, so he was able to help me out.

Here’s (more or less) the config I came up with, which totally works:

server {
  server_name this-uses-websockets.jesusabdullah.net;
  access_log /var/log/nginx/this-uses-websockets.jesusabdullah.net.log main;
 
  location / {
 
    proxy_set_header Upgrade $http_upgrade;
    proxy_set_header Connection "upgrade";
    proxy_set_header Host $host;
    proxy_http_version 1.1;
 
    proxy_pass http://localhost:1338;
  }
}

Here are the salient features, as I understand it:

• proxy_pass is the server you want to proxy to. This is pretty standard.
• proxy_http_version needs to be set to 1.1 for websockets to work. 1.0 won’t cut the mustard.
• The Upgrade and Connection headers are used to initiate websocket upgrades, so these are crucial.
• Finally: The Host header was what was missing from the nginx example, and is what breaks engine.io if not set.

HERE USED TO BE A LINK TO A DEMO BUT I TOOK IT DOWN

Enjoy, I hope this was helpful, and remember: Guillermo Rauch rocks.

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