Configuration

The ServerConfig object is passed as the second argument to createServer (for Node/Bun) or as part of ServerlessConfig (for Vercel/Netlify).

Top-level options

Option	Type	Default	Description
port	number	3000	Port to listen on
platform	'node' | 'bun' | 'vercel' | 'netlify' | 'cloudflare'	'node'	Target platform
isDev	boolean	NODE_ENV === 'development'	Enables dev mode (verbose errors, monitoring)
timeout	number	30000	Request timeout in milliseconds
maxBodySize	number	10485760 (10 MB)	Max request body in bytes; larger requests get 413. Applies to all adapters.
defaultHeaders	Record<string, string>	—	Headers added to every response (node, bun, cloudflare)

httpsOptions

TLS configuration for HTTPS (Node.js only).

httpsOptions: {
  cert: readFileSync('./certs/cert.pem'),
  key:  readFileSync('./certs/key.pem'),
}

cors

See the CORS page for all options.

cors: {
  origin: 'https://myapp.com',
  credentials: true,
  maxAge: 86400,
}

middleware

Global middleware applied to every request.

middleware: {
  beforeRequest: async (req, res) => { /* ... */ },
  afterRequest:  async (req, res) => { /* ... */ },
  onError:       async (req, res, ctx) => { /* ... */ },
}

Each property accepts a single handler or an array of handlers.

hooks

Server lifecycle hooks.

hooks: {
  onNotFound: async (req, res) => {
    res.status(404).json({ error: 'Not found' })
  },
  onShutdown: async () => {
    await db.end()
  },
}

Hook	When it runs
onNotFound	No route matched the request
onShutdown	SIGINT, SIGTERM, or SIGHUP received

cluster

Multi-process clustering (Node.js and Bun).

cluster: {
  enabled: false,          // default
  workers: undefined,      // defaults to os.cpus().length
}

monitoring

Development performance monitoring (Node.js only, requires isDev: true).

monitoring: {
  enabled: false,           // default
  sampleInterval: 5000,    // ms between samples
  reportInterval: 60000,   // ms between console reports
  thresholds: {
    cpu: 80,               // % — triggers alert
    memory: 512,           // MB
    responseTime: 500,     // ms
    errorRate: 5,          // %
  },
}

When enabled, a /health endpoint returns live metrics as JSON.

routes

Pre-compiled routes manifest (serverless platforms only). Generated by lacis build.

import { routes, middlewares } from './routes/_manifest.js'

// Passed to vercelAdapter or netlifyAdapter
vercelAdapter.createHandler({ routes, middlewares })

openapi

OpenAPI spec generation.

openapi: {
  path: '/openapi.json',
  info: {
    title: 'My API',
    version: '1.0.0',
    description: 'Optional description.',
  },
  servers: [
    { url: 'https://api.example.com', description: 'production' },
  ],
}

Runtime behavior by platform

A few behaviors differ by runtime, by necessity. These are stable and intentional.

Behavior	node	bun	cloudflare	vercel	netlify
Streaming (res.stream / SSE)	live	live	live	buffered	buffered
initSSE() before first await	not required	required	required	not required	not required
defaultHeaders	✓	✓	✓	—	—
req.platform	{}	{}	{ env, ctx, cf }	{}	{}
405 Allow header	✓	✓	✓	✓	✓

Node cluster mode distributes requests via the OS (round-robin SCHED_RR); Lacis does no application-level load balancing.