Bun

Entry point

// server.ts
import { bunAdapter } from 'lacis/adapters'

const createServer = bunAdapter.createHandler('./routes')

createServer({
  port: 3000,
  isDev: process.env.NODE_ENV !== 'production',
})

How the Bun adapter differs

Native fetch handler — requests are handled as standard Request/Response objects, wrapped in thin BunRequest/BunResponse classes
TransformStream for SSE — Bun’s Bun.serve() needs the Response synchronously, so initSSE() must be called before the first await in your handler
Faster JSON parsing — delegates directly to Bun’s native JSON parser

SSE constraint

export async function GET(req, res) {
  res.initSSE() // must be before any await

  const data = await fetchSomething()
  // ...
}

Config options

Option	Type	Default	Description
`port`	`number`	`3000`	Port to listen on
`isDev`	`boolean`	`false`	Enables dev mode
`defaultHeaders`	`Record<string, string>`	—	Headers added to every response
`cluster`	`object`	—	Multi-worker via `reusePort`
`cors`	`CorsConfig`	—	CORS policy
`middleware`	`object`	—	`beforeRequest`, `afterRequest`, `onError` hooks
`hooks`	`object`	—	`onNotFound`, `onShutdown` hooks

Cluster mode

Lacis spawns worker processes with Bun.spawn() and uses reusePort: true so the OS distributes connections across workers.

createServer({
  port: 3000,
  cluster: { enabled: true, workers: 4 },
})

Workers poll the primary’s PID every 2 seconds and exit cleanly if the primary is gone.

Running in production

Build:
Terminal window
```
bun run build
```
Start:
Terminal window
```
bun dist/server.js
```