Additional config options for hot reloader web socket connection

[jaslakson]

We run Next on a sub-set of urls and the root url is not included in this group. Additionally, we run nginx over https as a proxy server for all urls, in all environments (local, staging, production, etc). The existing WebSocket configuration options are not sufficient for our needs.

Proposed changes:

• conditionally set WebSocket protocol based on location.protocol (wss or ws)
• add the following configuration options for onDemandEntries
  • websocketProxyPort: allows us to configure nginx to listen on one port and proxy pass to websocketProxyPort
  • websocketProxyPath: since the root of our site is not served by Next, we need a path to use in order to establish the socket connection

Tests:

I might need a little help here - looking at the existing ondemand tests, I wasn't sure where or how to test these options or if testing these options is completely necessary.

Thanks for all of your hard work on Next.js. My WebSocket experience is limited so I am open to feedback or pointers on how to do this differently.

I tried the steps outlined in your contributing guide but ran into errors when trying to test this in my local repository.

[timneutkens]

Should this instead just be taking assetPrefix into account instead?

[jaslakson]

I don't think so - at least in my case what I'm trying to accomplish here is set a unique path which corresponds to a location block in my nginx config. This allows the sw request to successfully establish itself.

Here's a snippet from my conf files so you can see what I am working with:

I am listening on 7001 and forwarding to 7002, which I have set as my websocketPort locally.

location /hmr {
  proxy_http_version 1.1;
  proxy_set_header Upgrade $http_upgrade;
  proxy_set_header Connection "upgrade";
  proxy_pass http://espresso_hot_server;
}
...elsewhere
upstream espresso_hot_server {
  server 127.0.0.1:7002;
}

[timneutkens]

/home/circleci/repo/packages/next/server/hot-reloader.js:170:6: Extra semicolon.

Looks like linting didn't run.

[jaslakson]

Just updated, removing the extra ; and confirmed linters run successfully locally.

[timneutkens]

Could you add these new options to the readme too? After that + the changes I proposed I can merge the PR 👍