What is the recommended way to use Vite+ with Bun as an application runtime instead of Node?

[jchitel]

I really like the toolchain provided by Vite+ and don't want to let it go, but I also really like some of the runtime features provided by Bun, and additionally there are some frameworks and libraries that only run on Bun. There is no explicit support for this in Vite+ since it is intended to run with the vp env-managed Node version. The only documented support is Bun as the package manager, which is not what I'm talking about here.

After giving it some thought, I don't really see anything preventing the use of Vite+ and Bun's runtime together. Vite+ is a development toolchain, and an app's runtime is inherently separate from that. I'm even ok with Vite+ using Node internally to run all of its contained tools (i.e. run Vite, Oxfmt, Oxlint with managed Node), I just need the application code to be able to use Bun APIs. I want to know what configuration I need to be aware of to make sure that Vite's dev server can interact with a separate Bun process for the actual app.

One potential issue here that I'm aware of is testing. vp test would use Vitest running on managed Node, but the actual app code under test expects a Bun runtime. A few ways I can think of to resolve that:

• Disable Vitest and just use bun test for this case
• Abstract the Bun-specific API calls behind an adapter and use a Node-compatible adapter for unit tests

In a perfect world, it would be really nice if Vite+ had first-class support for managing and running on Node-compatible runtimes like Bun and Deno. I recognize that there are more pressing features though.

[dfbustosus]

Your separation is the right model, with one current limitation: Vite+ manages Node as the JavaScript tool runtime and treats Bun as a separate package-manager/direct-command shim. There is no Vite+ setting that changes the built-in Vite or Vitest process into a Bun process.

For a Vite frontend plus Bun backend, make Bun explicit in project scripts:

{
  "packageManager": "bun@1.x",
  "scripts": {
    "dev:api": "bun --watch src/server.ts",
    "test:bun": "bun test"
  }
}

Run those with:

vp run dev:api
vp run test:bun

Then run vp dev separately and proxy browser API calls to the Bun server:

export default defineConfig({
  server: {
    proxy: {
      '/api': 'http://localhost:3000',
    },
  },
})

The distinction matters for tests: vp test selects Vite+'s built-in Vitest command and remains Node-hosted, whereas vp run <name> executes the named project script. Use vp run test:bun when the code under test requires Bun APIs, or keep those APIs behind an adapter if you also want a Node/Vitest suite.

If the whole framework development command must run under Bun, put that command in package.json and invoke it with vp run dev rather than vp dev. For SSR, the exact process integration remains framework-specific; Vite+ does not currently provide a Bun-backed SSR runner.

This separation is reflected in the environment documentation, built-in commands versus project scripts, and the current Node-only runtime implementation.