Graceful shutdown for Node HTTP servers

                  import http from 'node:http';

export function setupGracefulShutdown(server: http.Server, opts?: { timeoutMs?: number }) {
  const timeoutMs = opts?.timeoutMs ?? 10_000;
  const sockets = new Set<import('node:net').Socket>();
  let isShuttingDown = false;

  server.on('connection', (socket) => {
    sockets.add(socket);
    socket.on('close', () => sockets.delete(socket));
  });

  const shutdown = (signal: string) => {
    if (isShuttingDown) return;
    isShuttingDown = true;

    // Stop accepting new connections.
    server.close(() => {
      // eslint-disable-next-line no-console
      console.log(`[shutdown] closed server (${signal})`);
    });

    // Force-close lingering sockets.
    setTimeout(() => {
      for (const s of sockets) s.destroy();
    }, timeoutMs).unref();
  };

  process.on('SIGTERM', () => shutdown('SIGTERM'));
  process.on('SIGINT', () => shutdown('SIGINT'));

  return {
    get isShuttingDown() {
      return isShuttingDown;
    }
  };
}