How to make BrowserSync work with an nginx proxy server?

Question

(If needed, please see my last question for some more background info.)

I'm developing an app that uses a decoupled front- and backend:

• The backend is a Rails app (served on localhost:3000) that primarily provides a REST API.
• The frontend is an AngularJS app, which I'm building with Gulp and serving locally (using BrowserSync) on localhost:3001.

To get the two ends to talk to each other, while honoring the same-origin policy, I configured nginx to act as a proxy between the two, available on localhost:3002. Here's my nginx.conf:

worker_processes 1;

events {
  worker_connections 1024;
}

http {
  include mime.types;
  default_type application/octet-stream;
  sendfile on;
  keepalive_timeout 65;

  server {
    listen 3002;
    root /;

    # Rails
    location ~ \.(json)$ {
      proxy_pass http://localhost:3000;
    }

    # AngularJS
    location / {
      proxy_pass http://localhost:3001;
    }
  }
}

Basically, any requests for .json files, I'm sending to the Rails server, and any other requests (e.g., for static assets), I'm sending to the BrowserSync server.

The BrowserSync task from my gulpfile.coffee:

gulp.task 'browser-sync', ->
  browserSync
    server:
      baseDir: './dist'
      directory: true
    port: 3001
    browser: 'google chrome'
    startPath: './index.html#/foo'

This all basically works, but with a couple of caveats that I'm trying to solve:

• When I run the gulp task, based on the configuration above, BrowserSync loads a Chrome tab at http://localhost:3001/index.html#/foo. Since I'm using the nginx proxy, though, I need the port to be 3002. Is there a way to tell BrowserSync, "run on port 3001, but start on port 3002"? I tried using an absolute path for startPath, but it only expects a relative path.
• I get a (seemingly benign) JavaScript error in the console every time BrowserSync starts: WebSocket connection to 'ws://localhost:3002/browser-sync/socket.io/?EIO=3&transport=websocket&sid=m-JFr6algNjpVre3AACY' failed: Error during WebSocket handshake: Unexpected response code: 400. Not sure what this means exactly, but my assumption is that BrowserSync is somehow confused by the nginx proxy.

How can I fix these issues to get this running seamlessly?

Thanks for any input!

Answer 1

To get more control over how opening the page is done, use opn instead of browser sync's mechanism. Something like this (in JS - sorry, my Coffee Script is a bit rusty):

browserSync({
    server: {
        // ...
    },
    open: false,
    port: 3001
}, function (err, bs) {
    // bs.options.url contains the original url, so
    // replace the port with the correct one:
    var url = bs.options.urls.local.replace(':3001', ':3002');
    require('opn')(url);
    console.log('Started browserSync on ' + url);
});

I'm unfamiliar with Nginx, but according to this page, the solution to the second problem might look something like this:

map $http_upgrade $connection_upgrade {
    default upgrade;
    '' close;
}

server {
    # ...

    # BrowserSync websocket
    location /browser-sync/socket.io/ {
        proxy_pass http://localhost:3001;
        proxy_http_version 1.1;
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection "Upgrade";
    }
}