README

import { getSandbox, proxyToSandbox, type Sandbox } from '@cloudflare/sandbox';
export { Sandbox } from '@cloudflare/sandbox';

type Env = { Sandbox: DurableObjectNamespace<Sandbox>; };

export default {
  async fetch(request: Request, env: Env): Promise<Response> {
    // CRITICAL: proxyToSandbox MUST be called first for preview URLs
    const proxyResponse = await proxyToSandbox(request, env);
    if (proxyResponse) return proxyResponse;

    const sandbox = getSandbox(env.Sandbox, 'my-sandbox');
    const result = await sandbox.exec('python3 -c "print(2 + 2)"');
    return Response.json({ output: result.stdout });
  }
};

{
  "name": "my-sandbox-worker",
  "main": "src/index.ts",
  "compatibility_date": "2025-01-01", // Use current date for new projects
  
  "containers": [{
    "class_name": "Sandbox",
    "image": "./Dockerfile",
    "instance_type": "lite",        // lite | standard | heavy
    "max_instances": 5
  }],
  
  "durable_objects": {
    "bindings": [{ "class_name": "Sandbox", "name": "Sandbox" }]
  },
  
  "migrations": [{
    "tag": "v1",
    "new_sqlite_classes": ["Sandbox"]
  }]
}

FROM docker.io/cloudflare/sandbox:latest
RUN pip3 install --no-cache-dir pandas numpy matplotlib
EXPOSE 8080 3000  # Required for wrangler dev