Describe the bug

The documentation for server.hmr configuration specifies the following options: boolean | { protocol?: string, host?: string, port?: number, path?: string, timeout?: number, overlay?: boolean } It appears to lack the server?: Server option.

Is this option internal to Vite, or is it intended to be used as explained below? If intended for public use, perhaps the documentation could explain its usage.

In vite/src/node/server/ws.ts, there is a reference to the hmr.server option. When Vite runs in middlewareMode, the server object can be passed via this option (in this case, SvelteKit). This allows a secure web socket connection,which uses https:// for certificate validation, to 'piggyback' onto the specified server.

This option is useful for of self-signed certificates -- The acceptance of the certificate will allow both https// and wss:// connections to proceed.

Reproduction

No repo. Documentation only.

System Info

System:
    OS: Linux 5.8 Ubuntu 20.04.2 LTS (Focal Fossa)
    CPU: (6) x64 Intel(R) Core(TM) i5-8400 CPU @ 2.80GHz
    Memory: 24.35 GB / 31.04 GB
    Container: Yes
    Shell: 5.0.17 - /bin/bash
  Binaries:
    Node: 14.17.0 - /usr/bin/node
    Yarn: 1.22.10 - /usr/local/bin/yarn
    npm: 7.12.0 - /usr/local/bin/npm
  Browsers:
    Brave Browser: 90.1.24.85
    Chrome: 90.0.4430.212
    Firefox: 88.0.1

Used package manager: Not applicable

Logs

Not Applicable

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