Configuration

new BunAdapter({
  trustProxy: true,
  bodyLimit: '1mb',
  serve: {
    idleTimeout: 120,
    maxRequestBodySize: 128 * 1024 * 1024,
    shutdownTimeout: 10_000,
    reusePort: true,
  },
});

Adapter options

Option	Default	What it does
trustProxy	false	Use X-Forwarded-For, X-Forwarded-Proto and X-Forwarded-Host for req.ip, req.protocol and req.hostname. Turn on behind a load balancer.
bodyLimit	'100kb'	Size limit for the built-in JSON and urlencoded parsers, matching Express. Bodies over the limit get a 413.
serve		Options forwarded to Bun.serve(), below.

serve options

Option	Default	What it does
idleTimeout	120	Seconds a connection may sit idle before Bun closes it. Max 255, 0 disables. Bun’s own default is 10, which is too short for slow handlers.
maxRequestBodySize	128 MiB	Hard cap enforced by Bun before the adapter sees the body.
shutdownTimeout	10000	Milliseconds app.close() waits for in-flight requests before dropping them.
reusePort	false	Let several processes bind the same port (cluster mode).
tls		TLS options. Set automatically from Nest’s httpsOptions.
development		Bun’s development mode (verbose errors).

Nest application options

These NestFactory.create() options are honored:

• httpsOptions maps key, cert, ca and passphrase to Bun’s TLS config.
• rawBody: true exposes the unparsed body as req.rawBody (a Buffer).
• bodyParser: false skips the default parsers.
• forceCloseConnections: true drops in-flight requests on app.close() instead of draining.
• return503OnClosing: true answers 503 with Connection: close while shutting down.
• cors and app.enableCors() use the cors package with the same options as Express.

Listening

await app.listen(3000);                 // all interfaces
await app.listen(3000, '127.0.0.1');    // one interface
await app.listen(0);                    // random free port; read it with app.getUrl()
await app.listen('/tmp/api.sock');      // unix socket

app.getHttpServer() returns a BunHttpServer: an EventEmitter with listen, close, address() and a bun property holding the live Bun.serve() instance.