Deploy Bun

Falak runs Bun apps the same way as Node apps: built once on the builder, started as a supervised process on each server, and proxied by Caddy. Bun itself is installed on a server the first time a Bun site targets it.

Prerequisites

• A server of type app, web or worker.
• A package.json with a start script, and a Bun lockfile (bun.lock or bun.lockb) or "packageManager": "bun@…".
• Your app listens on process.env.PORT.

src/index.ts (Hono)

import { Hono } from 'hono';

const app = new Hono();
app.get('/', (c) => c.text('Hello from Bun on Falak'));

export default {
  port: Number(process.env.PORT ?? 3000),
  hostname: process.env.HOST ?? '127.0.0.1',
  fetch: app.fetch,
};

package.json

{
  "scripts": { "start": "bun run src/index.ts" },
  "dependencies": { "hono": "^4" }
}

Deploy

1. + Create → Git repository, pick the repository.
2. Choose the Generic Node preset and set the runtime to Bun. Falak also picks Bun when it detects bun.lock.
3. Pick servers and a domain, then Deploy.

If a server is not ready for Bun yet, the deployment shows Waiting for servers while the agent installs Bun, then continues on its own.

How it runs

Aspect	Value
Bun version	1.4.2 (FALAK_BUN_VERSION), from Bun’s official release binaries (SHA-256 verified)
Build	bun install --frozen-lockfile, bun run build if defined, then bun install --production
Web process	bun run start in the current release
Environment	Site variables + PORT, HOST=127.0.0.1, NODE_ENV=production (unless set)
Entry point without a start script	The builder’s detection looks for index.ts, src/index.ts, server.ts, then JavaScript entry files, but the web process still runs bun run start, so define start.

TypeScript runs directly; no build step is required.

APM

Bun.serve is not auto-instrumented. Wrap your handler with withFalakRequest from @falak/apm-node. See APM for Node, Bun and Deno.

Air-gapped servers

Set FALAK_BUN_MIRROR on the control plane to download Bun from your own mirror. See Configuration.

Next steps

DenoDeploy Deno apps.

ProcessesBackground workers and cron for Bun apps.