How to programmatically serve a tanstack start application bundled with nitro on bun.js

[eyueldk]

Question. How can I programmatically run a nitro app on bun.js?

I reviewed both tanstack start's and nitro's documentation and I couldn't figure out how to programmatically serve the output. I have a cli that can "serve" a tanstack start app. The closest documentation I've come across is using nitro's node deployment model via this documentation

But I'm not sure if this is the recommended approach for a Bun runtime as well. There's a separate documentation for bun here but it doesn't show how to programmatically run it - it invokes bun instead of running it programmatically in code.

Any help is much appreciated.

[everton-dgn]

The output at .output/server/index.mjs from the bun preset is self-contained: it calls Bun.serve() the moment it gets imported. "Programmatic" here is just a dynamic import with the env vars set beforehand.

// cli/serve.ts
import { parseArgs } from "util"

const { values } = parseArgs({
  args: Bun.argv,
  options: {
    port: { type: "string", default: "3000" },
    host: { type: "string", default: "0.0.0.0" },
  },
  strict: false,
  allowPositionals: true,
})

process.env.PORT = values.port
process.env.HOST = values.host

await import("./.output/server/index.mjs")
console.log(`serving on http://${values.host}:${values.port}`)

Run it: bun cli/serve.ts --port 8080.

Env vars Nitro reads: PORT, HOST, NITRO_PORT, NITRO_HOST. Set them before the dynamic import so the bundled server picks them up. There's no separate programmatic API; the import itself is the entry point, same as running bun .output/server/index.mjs directly.