vite's localhost is now incompatible with node's

[mrkishi]

Describe the bug

As of v17, node respects the order of IP addresses returned by the system resolver.

This means localhost might resolve to 127.0.0.1 in a system and ::1 in another. As vite defaults to 127.0.0.1 and even translates localhost to it since #2977, it means starting up a vite server without a configured host (or with --host localhost) and doing net.connect(port) or net.connect(port, 'localhost') can fail.

I believe this could be fixed by defaulting to 'localhost' instead of the ipv4 here, but I'm unsure if that has negative complications:

vite/packages/vite/src/node/utils.ts

Lines 587 to 594 in 33f9671

	if (
	optionsHost === undefined ||
	optionsHost === false ||
	optionsHost === 'localhost'
	) {
	// Use a secure default
	host = '127.0.0.1'
	} else if (optionsHost === true) {

Why was localhost considered insecure? A system might even have reasons to have it resolved to a different, local interface—however unconventional that might be.

If there are no objections, I can open a PR with that change.

Reproduction

I'm not sure how to create a reproduction; I'd have to patch node's dns resolution.

System Info

n/a

Used Package Manager

pnpm

Logs

No response

Validations

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• The provided reproduction is a minimal reproducible example of the bug.

[haoqunjiang]

Also discussed at #5241 (comment)

Using localhost looks good to me.
The only inconvenience is that it's a minor breakage (127.0.0.1 is documented as the default value ).
But considering:

1. It fixes an inconsistency between the command line output and the documentation
2. v3.0 is only months away (soon after Node.js v12 reaches EOL).

I think the change is acceptable.

[mrkishi]

What about a two-step change? We could not override --host localhost to 127.0.0.1 as a first step, since that's not described in the docs and arguably unexpected behavior, and only change the default for v3.

With the override in place, the only alternative is to explicitly specify either --host 127.0.0.1 or --host ::1. While that works on a single system, it breaks down on shared configuration.