SINGLE BUN SERVER: Server entry point for Bun runtime.

server.ts

/**
 * SINGLE BUN SERVER
 * Server entry point for Bun runtime.
 * © 2025 Gustavo Gondim
 * MIT License
 *
 * Sets up a simple HTTP server that listens for requests to a single route
 * and method (configurable via environment variables) and delegates request
 * handling to a shared handler function.
 *
 * This server file is intended to be minimal. Complex routing or middleware
 * can be added by integrating with a more full-featured framework if needed,
 * using the fetch function as middleware.
 *
 * Additional parameter/endpoint validation related to the operation
 * should be performed in the handler to keep this server file simple and
 * focused on server setup.
 *
 * Defaults:
 * - Port: 3000 (configurable via PORT env var)
 * - Pathname: / (configurable via SERVER_HTTP_PATHNAME env var)
 * - Method: POST (configurable via SERVER_HTTP_METHOD env var)
 */

// REPLACE with your actual handler import
import { yourHandlerFunction } from "./path/to/yourHandlerFile";

// Minimal Bun detection: this project targets the Bun runtime.
// If Bun is not present or does not expose `serve`, fail early.
type BunLike = { serve?: (opts: unknown) => void };
const bun = (globalThis as unknown as { Bun?: BunLike }).Bun;

if (!bun || typeof bun.serve !== "function") {
	throw new Error("This server must run on Bun.");
}

const port = parseInt(process.env.PORT || "3000", 10);
const PATHNAME = process.env.SERVER_HTTP_PATHNAME || "/";
const METHOD = process.env.SERVER_HTTP_METHOD || "POST";

bun.serve({
	port,
	// Simple router wrapper: validate method/path here so the handler
	// remains agnostic and can be reused as middleware by other frameworks.
	fetch: async (req: Request) => {
		try {
			const url = new URL(req.url);
			if (req.method !== METHOD || url.pathname !== PATHNAME) {
				return new Response("Not found", { status: 404 });
			}
			return await handleFetch(req);
		} catch (err: unknown) {
			const msg = err instanceof Error ? err.message : String(err);
			return new Response(msg, { status: 500 });
		}
	},
});

console.log(`Server listening on http://0.0.0.0:${port}`);