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Example on GitHub

Full working example with a sandboxed Hono dev server.
Let users run their own dev servers inside a sandboxed isolate. Secure Exec can host long-lived Node servers from untrusted code, not just one-shot scripts. The host starts the user’s server inside the isolate, verifies it’s ready, proxies requests to it, and tears it down when done.

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Run a user’s Hono server

Start a user-provided Hono server inside the isolate, wait for its health endpoint, fetch a response from the host, then terminate.
Hono Dev Server
import { createServer } from "node:net";
import {
  NodeRuntime,
  allowAllNetwork,
  createNodeDriver,
  createNodeRuntimeDriverFactory,
} from "secure-exec";

const host = "127.0.0.1";
const port = await findOpenPort();
const logs: string[] = [];

const runtime = new NodeRuntime({
  systemDriver: createNodeDriver({
    useDefaultNetwork: true,
    permissions: { ...allowAllNetwork },
  }),
  runtimeDriverFactory: createNodeRuntimeDriverFactory(),
  memoryLimit: 128,
  cpuTimeLimitMs: 60_000,
});

const execPromise = runtime.exec(`
  import { Hono } from "hono";
  import { serve } from "@hono/node-server";

  const app = new Hono();
  app.get("/", (c) => c.text("hello from sandboxed hono"));
  app.get("/health", (c) => c.json({ ok: true }));

  serve({
    fetch: app.fetch,
    port: ${port},
    hostname: "${host}",
  });

  console.log("server:listening:${port}");
  await new Promise(() => {});
`, {
  filePath: "/app/server.mjs",
  onStdio: (event) => logs.push(`[${event.channel}] ${event.message}`),
});

try {
  await waitForServer(runtime, `http://${host}:${port}/health`);

  const response = await runtime.network.fetch(`http://${host}:${port}/`, {
    method: "GET",
  });

  console.log(response.status); // 200
  console.log(response.body); // "hello from sandboxed hono"
} finally {
  await runtime.terminate();
  await execPromise.catch(() => undefined);
}

async function findOpenPort(): Promise<number> {
  return new Promise((resolve, reject) => {
    const server = createServer();

    server.once("error", reject);
    server.listen(0, host, () => {
      const address = server.address();
      if (!address || typeof address !== "object") {
        reject(new Error("Failed to allocate a port"));
        server.close();
        return;
      }

      const allocatedPort = address.port;
      server.close((error) => {
        if (error) {
          reject(error);
          return;
        }
        resolve(allocatedPort);
      });
    });
  });
}

async function waitForServer(runtime: NodeRuntime, url: string): Promise<void> {
  for (let attempt = 0; attempt < 50; attempt += 1) {
    try {
      const response = await runtime.network.fetch(url, { method: "GET" });
      if (response.status === 200) {
        return;
      }
    } catch {
      // Retry until the server is ready.
    }

    await new Promise((resolve) => setTimeout(resolve, 100));
  }

  throw new Error(`Timed out waiting for ${url}`);
}
Your platform stays in control of the lifecycle while the user’s code runs isolated:
  • The isolate owns the user’s server process and application code
  • The host verifies readiness through the network adapter
  • The host proxies traffic to the sandboxed server
  • The host terminates the runtime when the session ends
This is useful for platforms that let users write and preview server-side code (live coding environments, serverless playgrounds, educational tools) without giving them access to the host machine. For a simpler request-only model without a bound TCP port, Hono also works with direct app.fetch(...) handlers. See Quickstart.