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How to run a Hopx sandbox

How to run a Hopx sandbox

David Tice

Head of Product

how-to sandboxes hopx

You can clone this repo and update your credentials to run locally.

Hopx is a cloud platform providing secure, isolated Linux micro-VM sandboxes. It enables AI coding agents and developers to safely execute untrusted code, run tests, and build applications with millisecond startup times. Let’s walk through the process of getting a basic application running inside a Hopx sandbox.

Why use Hopx as your sandbox provider?

  • Hopx provides secure, isolated Linux micro-VM sandboxes with millisecond startup times.
  • They are purpose-built for AI coding agents that need to safely execute untrusted code.
  • Hopx offers robust security boundaries ideal for running and testing AI-generated code at scale.

Let’s see how we can easily run a basic Vite app inside of a Hopx sandbox.

Let’s start by creating a new Next.js project

Run this command in your terminal:

npx create-next-app@latest hopx-basic

You can use all of the defaults when prompted.

Create an .env file

Once it has been created, be sure to create an .env file to add your necessary credentials to.

HOPX_API_KEY=your_hopx_api_key

Install ComputeSDK and the HopX provider

ComputeSDK ships as a small core package plus one package per provider, so you only install what you use.

npm install computesdk @computesdk/hopx

Create or log in to your Hopx account

Create a Hopx account or log in here.
Once you have created an account, you’ll need to get your Hopx API key.
Go to your dashboard and create an API key.

Save your API key in your .env file to the HOPX_API_KEY variable.

HOPX_API_KEY=your_hopx_api_key

Now we’ll move on to creating the actual sandbox logic

We need to create the API route to create the sandbox

Import the hopx factory from @computesdk/hopx and pass it your API key. compute.sandbox.create() provisions a sandbox on Hopx.

// app/api/sandbox/route.ts
import { NextResponse } from 'next/server';
import { hopx } from '@computesdk/hopx';

const compute = hopx({
  apiKey: process.env.HOPX_API_KEY,
});

export async function POST() {

  const sandbox = await compute.sandbox.create();

  return NextResponse.json({
    sandboxId: sandbox.sandboxId,
  });
}

Next, we’ll edit the page.tsx file

We’ll keep it simple and just add one button to run our sandbox test with.
Paste this code into Page.tsx

// app/page.tsx
'use client';

export default function Home() {
  const createSandbox = async () => {
    const res = await fetch('/api/sandbox', { method: 'POST' });
    const data = await res.json();
    console.log(data);
  };

  return (
    <div className="flex min-h-screen flex-col items-center justify-center p-24">
      <h1 className="mb-8 text-4xl font-bold">ComputeSDK Sandbox Test</h1>
      <button
        className="rounded bg-blue-500 px-4 py-2 font-bold text-white hover:bg-blue-700"
        type="button"
        onClick={createSandbox}
      >
        Create Hopx sandbox
      </button>
    </div>
  );
}

Now, our first test

Click the button on the main page.

screenshot of next.js app button

Then check your Hopx dashboard.
You should see a new sandbox created!

Success!

You’ve successfully created your first Hopx sandbox

If you want to use another sandbox provider like E2B or Daytona, swap the import and factory call — install @computesdk/e2b and use import { e2b } from '@computesdk/e2b' instead, with that provider’s own credentials. The rest of your code (runCommand, filesystem, getUrl) stays the same — that’s the point of the universal Sandbox interface.

Making changes within the sandbox

Now, let’s take the next step and run a primitive Vite app inside of our sandbox as an example of what we are able to do within the sandbox itself.

Update /api/sandbox/route.ts

Add the following to your route.ts file directly below this in your code:

const sandbox = await compute.sandbox.create();

Create a basic Vite app inside our sandbox subfolder

// Scaffold Vite React app
await sandbox.runCommand('npm create vite@5 app -- --template react');

Use the writeFile method

Customize the vite.config.js so we can access the local dev server.

// Custom vite.config.js to allow access to sandbox at port 5173
  const viteConfig = `import { defineConfig } from 'vite'
  import react from '@vitejs/plugin-react'

  export default defineConfig({
    plugins: [react()],
    server: {
      host: '0.0.0.0',
      port: 5173,
      strictPort: true,
      hmr: false,
      allowedHosts: ['.hopx.ai', 'localhost', '127.0.0.1'],
    },
  })
  `;
  await sandbox.filesystem.writeFile('app/vite.config.js', viteConfig);

Run npm install using the runCommand method

cwd is an optional per-call override — if you don’t pass one, commands run in whatever HopX’s own sandbox default working directory is. We pass cwd: 'app' here simply because that’s the subfolder we just scaffolded the Vite project into.

  // Install dependencies
  await sandbox.runCommand('npm install', {
    cwd: 'app',
  })

Start local dev server in the background with runCommand

  // Start dev server
  sandbox.runCommand('npm run dev', {
    cwd: 'app',
  });

Use the getUrl method to get a preview URL

  // Get preview URL
  const url = await sandbox.getUrl({ port: 5173 });
  console.log('previewUrl:', url)

HopX resolves this through its own preview URL API — check your terminal’s console output for the exact domain it returns; it’s HopX’s own domain, not a shared ComputeSDK one.

Return the preview url along with the sandboxId

  return NextResponse.json({
    sandboxId: sandbox.sandboxId,
    url,
  });

Finished route.ts file

Your /app/api/sandbox/route.ts file should look like this now:

import { NextResponse } from 'next/server';
import { hopx } from '@computesdk/hopx';

const compute = hopx({
  apiKey: process.env.HOPX_API_KEY,
});

export async function POST() {

  const sandbox = await compute.sandbox.create();

  // Create basic Vite React app
  await sandbox.runCommand('npm create vite@5 app -- --template react');

  // Custom vite.config.js to allow access to sandbox at port 5173
  const viteConfig = `import { defineConfig } from 'vite'
  import react from '@vitejs/plugin-react'

  export default defineConfig({
    plugins: [react()],
    server: {
      host: '0.0.0.0',
      port: 5173,
      strictPort: true,
      hmr: false,
      allowedHosts: ['.hopx.ai', 'localhost', '127.0.0.1'],
    },
  })
  `;
  await sandbox.filesystem.writeFile('app/vite.config.js', viteConfig);

  // Install dependencies
  await sandbox.runCommand('npm install', {
    cwd: 'app',
  })

  // Start dev server
  sandbox.runCommand('npm run dev', {
    cwd: 'app',
  });

  // Get preview URL
  const url = await sandbox.getUrl({ port: 5173 });
  console.log('previewUrl:', url)

  return NextResponse.json({
    sandboxId: sandbox.sandboxId,
    url,
  });
}

Testing Vite app inside sandbox

Now, after you click the “Create Hopx Sandbox” button on your localhost homepage you should:

  1. See a new sandbox created in your Hopx dashboard.
  2. See a preview URL logged to your terminal — HopX’s own domain.
  3. Finally, if you visit that URL you should see the boilerplate Vite React app running in your Hopx sandbox!
screenshot of Vite app running in Hopx sandbox via ComputeSDK

Congrats! You’ve successfully created your first sandbox application

You have done the following:

  • created a Hopx sandbox with ComputeSDK
  • used our runCommand, writeFile, and getUrl methods (these work with any provider)
  • ran a Vite app inside the sandbox
  • accessed the app running within the sandbox through its preview URL

ComputeSDK makes it easy to standardize this process across providers.
So now that you’ve written this code in Hopx, you can easily adjust this code to run in any sandbox provider.

Happy Sandboxing!

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