Server

const server = Bun.serve({
  // `routes` requires Bun v1.2.3+
  routes: {
    // Static routes
    "/api/status": new Response("OK"),

    // Dynamic routes
    "/users/:id": req => {
      return new Response(`Hello User ${req.params.id}!`);
    },

    // Per-HTTP method handlers
    "/api/posts": {
      GET: () => new Response("List posts"),
      POST: async req => {
        const body = await req.json();
        return Response.json({ created: true, ...body });
      },
    },

    // Wildcard route for all routes that start with "/api/" and aren't otherwise matched
    "/api/*": Response.json({ message: "Not found" }, { status: 404 }),

    // Redirect from /blog/hello to /blog/hello/world
    "/blog/hello": Response.redirect("/blog/hello/world"),

    // Serve a file by lazily loading it into memory
    "/favicon.ico": Bun.file("./favicon.ico"),
  },

  // (optional) fallback for unmatched routes:
  // Required if Bun's version < 1.2.3
  fetch(req) {
    return new Response("Not Found", { status: 404 });
  },
});

console.log(`Server running at ${server.url}`);

PORT=4002 bun server.ts

NODE_PORT=4002 bun server.ts

import type { Serve } from "bun";

export default {
  fetch(req) {
    return new Response("Bun!");
  },
} satisfies Serve.Options<undefined>;

Bun.serve({
  fetch(req: Request) {
    return new Response("Bun!");
  },
  port: 3000,
});

interface Server extends Disposable {
  /**
   * Stop the server from accepting new connections.
   * @param closeActiveConnections If true, immediately terminates all connections
   * @returns Promise that resolves when the server has stopped
   */
  stop(closeActiveConnections?: boolean): Promise<void>;

  /**
   * Update handlers without restarting the server.
   * Only fetch and error handlers can be updated.
   */
  reload(options: Serve): void;

  /**
   * Make a request to the running server.
   * Useful for testing or internal routing.
   */
  fetch(request: Request | string): Response | Promise<Response>;

  /**
   * Upgrade an HTTP request to a WebSocket connection.
   * @returns true if upgrade successful, false if failed
   */
  upgrade<T = undefined>(
    request: Request,
    options?: {
      headers?: Bun.HeadersInit;
      data?: T;
    },
  ): boolean;

  /**
   * Publish a message to all WebSocket clients subscribed to a topic.
   * @returns Bytes sent, 0 if dropped, -1 if backpressure applied
   */
  publish(
    topic: string,
    data: string | ArrayBufferView | ArrayBuffer | SharedArrayBuffer,
    compress?: boolean,
  ): ServerWebSocketSendStatus;

  /**
   * Get count of WebSocket clients subscribed to a topic.
   */
  subscriberCount(topic: string): number;

  /**
   * Get client IP address and port.
   * @returns null for closed requests or Unix sockets
   */
  requestIP(request: Request): SocketAddress | null;

  /**
   * Set custom idle timeout for a request.
   * @param seconds Timeout in seconds, 0 to disable
   */
  timeout(request: Request, seconds: number): void;

  /**
   * Keep process alive while server is running.
   */
  ref(): void;

  /**
   * Allow process to exit if server is only thing running.
   */
  unref(): void;

  /** Number of in-flight HTTP requests */
  readonly pendingRequests: number;

  /** Number of active WebSocket connections */
  readonly pendingWebSockets: number;

  /** Server URL including protocol, hostname and port */
  readonly url: URL;

  /** Port server is listening on */
  readonly port: number;

  /** Hostname server is bound to */
  readonly hostname: string;

  /** Whether server is in development mode */
  readonly development: boolean;

  /** Server instance identifier */
  readonly id: string;
}

interface WebSocketHandler<T = undefined> {
  /** Maximum WebSocket message size in bytes */
  maxPayloadLength?: number;

  /** Bytes of queued messages before applying backpressure */
  backpressureLimit?: number;

  /** Whether to close connection when backpressure limit hit */
  closeOnBackpressureLimit?: boolean;

  /** Called when backpressure is relieved */
  drain?(ws: ServerWebSocket<T>): void | Promise<void>;

  /** Seconds before idle timeout */
  idleTimeout?: number;

  /** Enable per-message deflate compression */
  perMessageDeflate?:
    | boolean
    | {
        compress?: WebSocketCompressor | boolean;
        decompress?: WebSocketCompressor | boolean;
      };

  /** Send ping frames to keep connection alive */
  sendPings?: boolean;

  /** Whether server receives its own published messages */
  publishToSelf?: boolean;

  /** Called when connection opened */
  open?(ws: ServerWebSocket<T>): void | Promise<void>;

  /** Called when message received */
  message(ws: ServerWebSocket<T>, message: string | Buffer): void | Promise<void>;

  /** Called when connection closed */
  close?(ws: ServerWebSocket<T>, code: number, reason: string): void | Promise<void>;

  /** Called when ping frame received */
  ping?(ws: ServerWebSocket<T>, data: Buffer): void | Promise<void>;

  /** Called when pong frame received */
  pong?(ws: ServerWebSocket<T>, data: Buffer): void | Promise<void>;
}

interface TLSOptions {
  /** Certificate authority chain */
  ca?: string | Buffer | BunFile | Array<string | Buffer | BunFile>;

  /** Server certificate */
  cert?: string | Buffer | BunFile | Array<string | Buffer | BunFile>;

  /** Path to DH parameters file */
  dhParamsFile?: string;

  /** Private key */
  key?: string | Buffer | BunFile | Array<string | Buffer | BunFile>;

  /** Reduce TLS memory usage */
  lowMemoryMode?: boolean;

  /** Private key passphrase */
  passphrase?: string;

  /** OpenSSL options flags */
  secureOptions?: number;

  /** Server name for SNI */
  serverName?: string;
}