Deno Runtime

Basic Usage

import { serve } from "@hornjs/fest";
import { DenoRuntimeAdapter } from "@hornjs/fest/deno";

serve({
  adapter: new DenoRuntimeAdapter(),
  routes: {
    "/": () => new Response("Hello from Deno"),
  },
  fetch: () => new Response("Not Found", { status: 404 }),
});

Constructor Options

new DenoRuntimeAdapter(options) accepts DenoServerOptions, which is an alias for Deno.ServeOptions.

At setup time, fest also merges in generic listener settings such as hostname, port, reusePort, TLS certificate fields, and the server-level error handler.

Commonly Used Options

• signal: close the server when the signal aborts
• onError: customize how uncaught request errors become responses
• onListen: observe the final listening address

The final listener options also include TCP fields handled by Deno.serve(), such as hostname, port, and reusePort.

Official References

• Deno ServeOptions: https://docs.deno.com/api/deno/~/Deno.ServeOptions
• Deno serve() API: https://docs.deno.com/api/deno/~/Deno.serve
• Deno TCP serve options: https://docs.deno.com/api/deno/~/Deno.ServeTcpOptions

What the Adapter Does

DenoRuntimeAdapter converts generic ServerOptions into Deno.serve() options and waits for Deno's onListen callback before resolving the final server URL.

It is responsible for:

• resolving hostname and port
• passing reusePort
• mapping error to onError
• forwarding TLS certificate options
• exposing the resolved public URL through server.url

Deno-Specific Options

Pass native Deno.ServeOptions to the adapter constructor:

import { DenoRuntimeAdapter } from "@hornjs/fest/deno";

const adapter = new DenoRuntimeAdapter({
  signal: AbortSignal.timeout(30_000),
});

These values are merged with the generic server options during setup().

TLS

TLS works the same way as in other node-like adapters: cert and key may be provided as PEM content or as file paths.

serve({
  adapter: new DenoRuntimeAdapter(),
  protocol: "https",
  tls: {
    cert: "./certs/dev-cert.pem",
    key: "./certs/dev-key.pem",
  },
  routes: {
    "/": () => new Response("secure"),
  },
  fetch: () => new Response("Not Found", { status: 404 }),
});

Listening Semantics

Unlike Node and Bun, Deno.serve() reports the bound address asynchronously through onListen. The adapter caches that information and derives server.url from it.

CLI Usage

You can run the package through Deno with npm compatibility:

deno run -A npm:@hornjs/fest

The current CLI --import flow is only for Node.js and Bun, so JSX / TSX entry preloads should not rely on that flag under Deno.