Serve a web framework
Deno Sandbox provide a sandboxed environment for evaluating JavaScript code. This is useful for evaluating code that is not trusted or for testing code that is not safe to run in the main runtime.
With Deno Sandbox you can create a package.json, install dependencies, run a
web framework (Express), and expose it publicly over HTTP.
This example shows how to create a minimal Express app inside the sandbox, runs
it on port 3000, and exposes it publicly using sandbox.exposeHttp().
import { Sandbox } from "@deno/sandbox";
await using sandbox = await Sandbox.create();
// 1) Write package.json and server.js in the sandbox
const PACKAGE_JSON = {
name: "sandbox-express-demo",
private: true,
type: "module",
dependencies: { express: "^4.19.2" },
};
await sandbox.fs.writeTextFile(
"package.json",
JSON.stringify(PACKAGE_JSON, null, 2),
);
await sandbox.fs.writeTextFile(
"server.js",
`import express from 'express';
const app = express();
app.get('/', (req, res) => res.send('Hello from Express in @deno/sandbox!'));
app.get('/time', (req, res) => res.json({ now: new Date().toISOString() }));
app.listen(3000, () => console.log('listening on :3000'));
`,
);
// 2) Install dependencies
await sandbox.sh`deno install`;
// 3) Start the server
const server = await sandbox.deno.run({ entrypoint: "server.js" });
// 4) Publish to the internet
const publicUrl = await sandbox.exposeHttp({ port: 3000 });
console.log("Public URL:", publicUrl); // e.g. https://<random>.sandbox.deno.net
// Fetch from your local machine to verify
const resp = await fetch(`${publicUrl}/time`);
console.log(await resp.json());
// Keep the process alive as long as you need; when done, closing the sandbox
// will tear it down.
For more information, see the Deno Sandbox documentation.