feat: return 404 on default URL when function has custom routes

[eduardoboucas]

Summary

Follow-up to #5954. When a function defines custom routes, we should return 404 when trying to access the function on the /.netlify/functions default URL.

When this happens, we show a message in the console to help people understand why they're seeing a 404:

›   Warning: Function v2-js cannot be invoked on /.netlify/functions/v2-js, because the function has the following URL paths defined: /v2/:foo

Part of https://github.com/netlify/pod-dev-foundations/issues/578 and https://github.com/netlify/pod-dev-foundations/issues/585.

[github-actions]

📊 Benchmark results

Comparing with ba672f8

• Dependency count: 1,385 (no change)
• Package size: 388 MB ⬆️ 0.00% increase vs. ba672f8

[Skn0tt]

The functionality looks good. Noted two code-level things that I'd love to be refactored before merging this - fine to land in a refactoring as well, though.

[Skn0tt]

I believe this block should live in NetlifyFunction#matchUrlPath. That'd make the logic a little easier to reason about, as well.

It'd probably result in more regex matchings needed to be done, but I don't think that's a performance concern at the orders of magnitude that functions have in local dev.

[Skn0tt]

okay, scratch that - would make

cli/src/lib/functions/registry.mjs

Lines 137 to 147 in 05c44a6

	if (routes.length !== 0) {
	const paths = routes.map((route) => chalk.underline(route.pattern)).join(', ')
	warn(
	`Function ${chalk.yellow(func.name)} cannot be invoked on ${chalk.underline(
	urlPath,
	)}, because the function has the following URL paths defined: ${paths}`,
	)
	return

a lot harder to implement

[Skn0tt]

We should be refactoring this so that the regex is shared with isFunction

cli/src/utils/proxy.mjs

Lines 85 to 91 in 556d545

	/**
	* @param {boolean|number|undefined} functionsPort
	* @param {string} url
	*/
	function isFunction(functionsPort, url) {
	return functionsPort && url.match(/^\/.netlify\/(functions|builders)\/.+/)
	}

[Skn0tt]

Out-of-scope for this PR, but we should still address it before shipping this:

isFunction is used in a bunch of places to inform redirecting rules etc. We should check if that needs to take custom routes into account:

cli/src/utils/proxy.mjs

Lines 166 to 168 in 556d545

	if (isFunction(true, url)) {
	return []
	}

cli/src/utils/proxy.mjs

Lines 214 to 216 in 556d545

	if (isFunction(options.functionsPort, req.url)) {
	return proxy.web(req, res, { target: options.functionsServer })
	}

cli/src/utils/proxy.mjs

Line 345 in 556d545

if (isFunction(options.functionsPort, req.url) || functionWithCustomRoute) {