Monorepo support for config imports

[swandir]

Clear and concise description of the problem

Vite currently supports monorepo-based setups for application code.

Now, in a monorepo, I want to implement a vite-plugin package in TypeScript that I plan to make use of in other monorepo packages without additional build step.

Right now Vite crashed when trying to load vite.config.ts that imports my plugin.

That happens because all bare imports are externalized during config bundling here:

vite/packages/vite/src/node/config.ts

Lines 776 to 780 in 70536b4

	build.onResolve({ filter: /.*/ }, (args) => {
	const id = args.path
	if (id[0] !== '.' && !path.isAbsolute(id)) {
	return {
	external: true

Suggested solution

Vite could check if a package being imported in the config is a local package before externalizing it.

Alternative

UPD: Build step can be avoided on the local vite-plugin package by using an intermediary index.js module that wires up esbuild-register or tsm and then re-exports the actual entry point written in TS.

Additional context

[bluwy]

This sounds like it would open a can of worms, especially if the linked dependency contains transitive dependencies too. Node can't resolve those normally as we would have bundled the linked dependency, unless we bundle everything in the linked dependency, including it's transitive dependencies. Though now, there are two issues: (1) The Vite config would have to bundle a lot every time, (2) Transitive dependencies could be duplicated, causing weird runtime errors. With the reasons, I think it's simpler to have a build step for the linked dependency instead.

[swandir]

Makes sense.

And build step can be avoided on the local vite-plugin package by using an intermediary index.js module that wires up esbuild-register or tsm and then re-exports the actual entry point in TS.

[bluwy]

Actually I just noticed that we have a duplicate #5370 too proposing the same thing, so perhaps it's something doable within Vite, but let's keep that issue open up as it has more discussion about the feature.