npm install @cloudflare/sandbox@latest

{
  "name": "my-sandbox-worker",
  "main": "src/index.ts",
  "compatibility_flags": ["nodejs_compat"],
  "containers": [{
    "class_name": "Sandbox",
    "image": "cloudflare/sandbox:0.4.12",
    "instance_type": "lite"
  }],
  "durable_objects": {
    "bindings": [{
      "class_name": "Sandbox",
      "name": "Sandbox"
    }]
  },
  "migrations": [{
    "tag": "v1",
    "new_sqlite_classes": ["Sandbox"]
  }]
}

import { getSandbox, 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> {
    // Get sandbox instance (creates if doesn't exist)
    const sandbox = getSandbox(env.Sandbox, 'my-first-sandbox');

    // Execute Python code
    const result = await sandbox.exec('python3 -c "print(2 + 2)"');

    return Response.json({
      output: result.stdout,
      success: result.success,
      exitCode: result.exitCode
    });
  }
};

npm run deploy
curl https://your-worker.workers.dev

{
  "output": "4\n",
  "success": true,
  "exitCode": 0
}

┌─────────────────────────────────────────┐
│  Your Worker (Layer 1)                  │
│  - Handles HTTP requests                │
│  - Calls getSandbox()                   │
│  - Uses sandbox.exec(), writeFile(), etc│
└──────────────┬──────────────────────────┘
               │ RPC via Durable Object
┌──────────────▼──────────────────────────┐
│  Durable Object (Layer 2)               │
│  - Routes by sandbox ID                 │
│  - Maintains persistent identity        │
│  - Geographic stickiness                │
└──────────────┬──────────────────────────┘
               │ Container API
┌──────────────▼──────────────────────────┐
│  Ubuntu Container (Layer 3)             │
│  - Full Linux environment               │
│  - Python 3.11, Node 20, Git, etc.      │
│  - Filesystem: /workspace, /tmp, /home  │
│  - Process isolation (VM-based)         │
└─────────────────────────────────────────┘

┌─────────┐  First request  ┌────────┐  ~10 min idle  ┌──────┐
│ Not     │ ───────────────>│ Active │ ─────────────> │ Idle │
│ Created │                 │        │                │      │
└─────────┘                 └───┬────┘                └──┬───┘
                                │ ^                      │
                                │ │ New request          │
                                │ └──────────────────────┘
                                │                         │
                                ▼                         ▼
                            Files persist          ALL FILES DELETED
                            Processes run          ALL PROCESSES KILLED
                            State maintained       ALL STATE RESET

// Save to R2 before container goes idle
await sandbox.writeFile('/workspace/data.txt', content);
const fileData = await sandbox.readFile('/workspace/data.txt');
await env.R2.put('backup/data.txt', fileData);

// Restore on next request
const restored = await env.R2.get('backup/data.txt');
if (restored) {
  await sandbox.writeFile('/workspace/data.txt', await restored.text());
}

// Check if setup needed (handles cold starts)
const exists = await sandbox.readdir('/workspace/project').catch(() => null);
if (!exists) {
  await sandbox.gitCheckout(repoUrl, '/workspace/project');
  await sandbox.exec('npm install', { cwd: '/workspace/project' });
}
// Now safe to run build
await sandbox.exec('npm run build', { cwd: '/workspace/project' });

type ConversationState = {
  sandboxId: string;
  sessionId: string;
};

// First message: Create sandbox and session
const sandboxId = `user-${userId}`;
const sandbox = getSandbox(env.Sandbox, sandboxId);
const sessionId = await sandbox.createSession();

// Store in conversation state (database, KV, etc.)
await env.KV.put(`conversation:${conversationId}`, JSON.stringify({
  sandboxId,
  sessionId
}));

// Later messages: Reuse same session
const state = await env.KV.get(`conversation:${conversationId}`);
const { sandboxId, sessionId } = JSON.parse(state);
const sandbox = getSandbox(env.Sandbox, sandboxId);

// Commands run in same context
await sandbox.exec('cd /workspace/project', { session: sessionId });
await sandbox.exec('ls -la', { session: sessionId }); // Still in /workspace/project
await sandbox.exec('git status', { session: sessionId }); // Still in /workspace/project

// ❌ WRONG: Each command runs in separate session
await sandbox.exec('cd /workspace/project');
await sandbox.exec('ls'); // NOT in /workspace/project (different session)

const session1 = await sandbox.createSession();
const session2 = await sandbox.createSession();

// Run different tasks simultaneously
await Promise.all([
  sandbox.exec('python train_model.py', { session: session1 }),
  sandbox.exec('node generate_reports.js', { session: session2 })
]);

const sandbox = getSandbox(env.Sandbox, `user-${userId}`);

const sandboxId = `session-${Date.now()}-${crypto.randomUUID()}`;
const sandbox = getSandbox(env.Sandbox, sandboxId);
// Always destroy after use
await sandbox.destroy();

const sandbox = getSandbox(env.Sandbox, `build-${repoName}-${commitSha}`);

import { getSandbox } from '@cloudflare/sandbox';

const sandbox = getSandbox(env.Sandbox, 'unique-sandbox-id');
// Creates new sandbox if doesn't exist, or gets existing one

// Basic execution
const result = await sandbox.exec('python3 script.py');
console.log(result.stdout);   // Standard output
console.log(result.stderr);   // Standard error
console.log(result.exitCode); // Exit code (0 = success)
console.log(result.success);  // Boolean (exitCode === 0)

// With options
const result = await sandbox.exec('npm install', {
  cwd: '/workspace/project',        // Working directory
  timeout: 120000,                   // Timeout in ms (default: 30s)
  session: sessionId,                // Session ID
  env: { NODE_ENV: 'production' }   // Environment variables
});

// Always check exit codes!
if (!result.success) {
  throw new Error(`Command failed: ${result.stderr}`);
}

// Write file
await sandbox.writeFile('/workspace/data.txt', 'content');

// Read file
const content = await sandbox.readFile('/workspace/data.txt');

// Create directory
await sandbox.mkdir('/workspace/project', { recursive: true });

// List directory
const files = await sandbox.readdir('/workspace');
console.log(files); // ['data.txt', 'project']

// Delete file/directory
await sandbox.rm('/workspace/data.txt');
await sandbox.rm('/workspace/project', { recursive: true });

// Clone repository (optimized, faster than exec('git clone'))
await sandbox.gitCheckout(
  'https://github.com/user/repo',
  '/workspace/repo'
);

// Now use standard git commands
await sandbox.exec('git status', { cwd: '/workspace/repo' });
await sandbox.exec('git diff', { cwd: '/workspace/repo' });

// Create Python context
const ctx = await sandbox.createCodeContext({ language: 'python' });

// Execute code - last expression auto-returned
const result = await sandbox.runCode(`
import pandas as pd
df = pd.DataFrame({'a': [1, 2, 3], 'b': [4, 5, 6]})
df['a'].sum()  # This value is automatically returned
`, { context: ctx });

console.log(result.results[0].text); // "6"
console.log(result.logs); // Output from print() statements
console.log(result.error); // Any errors

// Start long-running process
const proc = await sandbox.spawn('python server.py');
console.log(proc.pid);

// Check if still running
const running = await sandbox.isProcessRunning(proc.pid);

// Kill process
await sandbox.killProcess(proc.pid);

// Destroy sandbox permanently
await sandbox.destroy();
// All files deleted, container removed, cannot be recovered

{
  "name": "my-sandbox-app",
  "main": "src/index.ts",
  "compatibility_date": "2025-10-29",
  "compatibility_flags": ["nodejs_compat"],

  "containers": [{
    "class_name": "Sandbox",
    "image": "cloudflare/sandbox:0.4.12",
    "instance_type": "lite"
  }],

  "durable_objects": {
    "bindings": [{
      "class_name": "Sandbox",
      "name": "Sandbox"
    }]
  },

  "migrations": [{
    "tag": "v1",
    "new_sqlite_classes": ["Sandbox"]
  }],

  "env": {
    "ANTHROPIC_API_KEY": {
      "description": "Optional: For AI features"
    }
  },

  "observability": {
    "enabled": true
  }
}

FROM cloudflare/sandbox:0.4.12

---

export default {
  async fetch(request: Request, env: Env) {
    const { code, language } = await request.json();

    // Create ephemeral sandbox
    const sandboxId = `exec-${Date.now()}-${crypto.randomUUID()}`;
    const sandbox = getSandbox(env.Sandbox, sandboxId);

    try {
      // Create code context
      const ctx = await sandbox.createCodeContext({ language });

      // Execute code safely
      const result = await sandbox.runCode(code, {
        context: ctx,
        timeout: 10000
      });

      return Response.json({
        result: result.results?.[0]?.text,
        logs: result.logs,
        error: result.error
      });
    } finally {
      // Always cleanup
      await sandbox.destroy();
    }
  }
};

export default {
  async fetch(request: Request, env: Env) {
    const userId = request.headers.get('X-User-ID');
    const { command, sessionId: existingSession } = await request.json();

    // User-specific sandbox (persists while active)
    const sandbox = getSandbox(env.Sandbox, `user-${userId}`);

    // Get or create session
    let sessionId = existingSession;
    if (!sessionId) {
      sessionId = await sandbox.createSession();
    }

    // Execute command in persistent context
    const result = await sandbox.exec(command, {
      session: sessionId,
      timeout: 30000
    });

    return Response.json({
      sessionId, // Return for next request
      output: result.stdout,
      error: result.stderr,
      success: result.success
    });
  }
};

async function runBuild(repoUrl: string, commit: string, env: Env) {
  const sandboxId = `build-${repoUrl.split('/').pop()}-${commit}`;
  const sandbox = getSandbox(env.Sandbox, sandboxId);

  try {
    // Clone repository
    await sandbox.gitCheckout(repoUrl, '/workspace/repo');

    // Checkout specific commit
    await sandbox.exec(`git checkout ${commit}`, {
      cwd: '/workspace/repo'
    });

    // Install dependencies
    const install = await sandbox.exec('npm install', {
      cwd: '/workspace/repo',
      timeout: 180000 // 3 minutes
    });

    if (!install.success) {
      throw new Error(`Install failed: ${install.stderr}`);
    }

    // Run build
    const build = await sandbox.exec('npm run build', {
      cwd: '/workspace/repo',
      timeout: 300000 // 5 minutes
    });

    if (!build.success) {
      throw new Error(`Build failed: ${build.stderr}`);
    }

    // Save artifacts to R2
    const dist = await sandbox.exec('tar -czf dist.tar.gz dist', {
      cwd: '/workspace/repo'
    });
    const artifact = await sandbox.readFile('/workspace/repo/dist.tar.gz');
    await env.R2.put(`builds/${commit}.tar.gz`, artifact);

    return { success: true, artifactKey: `builds/${commit}.tar.gz` };
  } finally {
    // Optional: Keep sandbox for debugging or destroy
    // await sandbox.destroy();
  }
}

async function runClaudeCodeOnRepo(
  repoUrl: string,
  task: string,
  env: Env
): Promise<{ diff: string; logs: string }> {
  const sandboxId = `claude-${Date.now()}`;
  const sandbox = getSandbox(env.Sandbox, sandboxId);

  try {
    // Clone repository
    await sandbox.gitCheckout(repoUrl, '/workspace/repo');

    // Run Claude Code CLI with secure environment injection
    // ⚠️ SECURITY: Use env option instead of shell export to prevent key exposure in logs
    const result = await sandbox.exec(
      `claude -p "${task}" --permission-mode acceptEdits`,
      {
        cwd: '/workspace/repo',
        timeout: 300000, // 5 minutes
        env: {
          ANTHROPIC_API_KEY: env.ANTHROPIC_API_KEY
        }
      }
    );

    // Get diff of changes
    const diff = await sandbox.exec('git diff', {
      cwd: '/workspace/repo'
    });

    return {
      diff: diff.stdout,
      logs: result.stdout
    };
  } finally {
    await sandbox.destroy();
  }
}

undefined

undefined

// Option 1: Multiple sandboxes per user (better latency)
const region = request.cf?.colo || 'default';
const sandbox = getSandbox(env.Sandbox, `user-${userId}-${region}`);

// Option 2: Single sandbox (simpler, higher latency for distant users)
const sandbox = getSandbox(env.Sandbox, `user-${userId}`);

async function safeSandboxExec(
  sandbox: Sandbox,
  cmd: string,
  options?: any
) {
  try {
    const result = await sandbox.exec(cmd, {
      ...options,
      timeout: options?.timeout || 30000
    });

    if (!result.success) {
      console.error(`Command failed: ${cmd}`, {
        exitCode: result.exitCode,
        stderr: result.stderr
      });

      return {
        success: false,
        error: result.stderr,
        exitCode: result.exitCode
      };
    }

    return {
      success: true,
      output: result.stdout,
      exitCode: 0
    };
  } catch (error) {
    console.error(`Sandbox error:`, error);
    return {
      success: false,
      error: error.message,
      exitCode: -1
    };
  }
}

// Input validation
function sanitizeCommand(input: string): string {
  const dangerous = ['rm -rf', '$(', '`', '&&', '||', ';', '|'];
  for (const pattern of dangerous) {
    if (input.includes(pattern)) {
      throw new Error(`Dangerous pattern detected: ${pattern}`);
    }
  }
  return input;
}

// Use code interpreter instead of direct exec for untrusted code
async function executeUntrustedCode(code: string, sandbox: Sandbox) {
  const ctx = await sandbox.createCodeContext({ language: 'python' });
  return await sandbox.runCode(code, { context: ctx, timeout: 10000 });
}