Rails: InvalidAuthenticityToken while using BrowserSync

[r3oath]

I seem to be getting ActionController::InvalidAuthenticityToken exceptions while using BrowserSync. I've tried setting the config line mentioned here https://github.com/rails/rails/issues/21948#issuecomment-235079906 and had no luck. I have noticed however that it seems to be set to false anyway https://github.com/rails/rails/blob/60c6b538170ce35cc8ff8382bef2f082868b4b09/actionpack/lib/action_controller/metal/request_forgery_protection.rb#L82

Granted I am new to rails so I may be setting the config value incorrectly. I'm not sure what else to try. My educated guess still leads me to believe that it may be the host differences/origin-url that's causing the issue as the rails server is running on localhost:3000 and I am viewing it via the browsersync proxy at localhost:3001. Is there a way to verify this is the issue or to determine what else is at play here? The CSRF issue simply goes away when not submitting anything via the localhost:3001 proxy.

Obviously the end result here is I'd like to continue using browsersync, and not have to disable CSRF protection while in local development.

System configuration

Rails version: 5.0.0.1
Ruby version: 2.3.1p112
BrowserSync version: 2.18.2

[r3oath]

Seems I've managed to find a solution. Requires manually setting the X-Forwarded-Host host from the broswersync init config.

sync.init({
    proxy: {
      target: "localhost:3000",
      proxyReq: [
        function(proxyReq) {
            proxyReq.setHeader('X-Forwarded-Host', 'localhost:3001');
        }
      ],
    },
  })