Sandbox Sdk

Sandbox SDK is a community skill for building applications with sandboxed execution environments, covering code isolation, runtime security, resource limits, inter-process communication, and secure code execution patterns.

What Is This?

Overview

Sandbox SDK provides patterns for creating isolated execution environments in applications. It covers code isolation using containers, virtual machines, or process sandboxes that prevent untrusted code from accessing the host system, runtime security with filesystem, network, and system call restrictions that limit what sandboxed code can do, resource limits for CPU time, memory allocation, and disk usage that prevent resource exhaustion, inter-process communication channels for exchanging data between the host and sandbox safely, and execution lifecycle management for starting, monitoring, and terminating sandbox instances. The skill enables developers to build platforms that safely execute user-submitted or third-party code.

Who Should Use This

This skill serves developers building code execution platforms like online judges or playgrounds, teams creating plugin systems that run third-party extensions safely, and engineers implementing AI agent tool execution with security boundaries.

Why Use It?

Problems It Solves

Executing untrusted code without isolation risks host system compromise. Resource-intensive code can exhaust server capacity without proper limits. Communication between host and sandboxed processes needs safe serialization to prevent injection. Managing sandbox lifecycle including creation, health monitoring, and cleanup requires robust orchestration.

Core Highlights

Container-based isolation creates ephemeral environments for each execution. Resource governor enforces CPU, memory, and time limits per sandbox. Secure IPC channel passes structured data between host and sandbox. Lifecycle manager handles creation, monitoring, and teardown of sandbox instances.

How to Use It?

Basic Usage

import { spawn } from
  'child_process';

interface SandboxResult {
  stdout: string;
  stderr: string;
  exitCode: number;
  timedOut: boolean;
}

async function executeCode(
  code: string,
  language: string,
  timeoutMs = 5000
): Promise<SandboxResult> {
  const cmd = language === 'python'
    ? ['python3', '-c', code]
    : ['node', '-e', code];

  return new Promise(
    (resolve) => {
      let stdout = '';
      let stderr = '';
      let timedOut = false;

      const proc = spawn(
        cmd[0], cmd.slice(1), {
          timeout: timeoutMs,
          stdio: 'pipe',
          env: {},
        });

      proc.stdout?.on(
        'data', (d) => {
          stdout += d; });
      proc.stderr?.on(
        'data', (d) => {
          stderr += d; });

      const timer = setTimeout(
        () => {
          timedOut = true;
          proc.kill('SIGKILL');
        }, timeoutMs);

      proc.on('close',
        (exitCode) => {
          clearTimeout(timer);
          resolve({
            stdout, stderr,
            exitCode:
              exitCode ?? 1,
            timedOut,
          });
        });
    });
}

Real-World Examples

// Container-based sandbox
import Docker from 'dockerode';

const docker = new Docker();

async function runInContainer(
  code: string,
  image: string,
  memoryMb = 128,
  timeoutMs = 10000
): Promise<SandboxResult> {
  const container =
    await docker
      .createContainer({
        Image: image,
        Cmd: ['python3',
          '-c', code],
        HostConfig: {
          Memory:
            memoryMb * 1024
            * 1024,
          NetworkMode: 'none',
          ReadonlyRootfs: true,
          PidsLimit: 50,
        },
        NetworkDisabled: true,
      });

  await container.start();

  const timeout =
    new Promise<'timeout'>(
      (r) => setTimeout(
        () => r('timeout'),
        timeoutMs));
  const wait = container.wait();

  const result =
    await Promise.race(
      [wait, timeout]);

  if (result === 'timeout') {
    await container.kill();
    await container.remove();
    return { stdout: '',
      stderr: 'Timed out',
      exitCode: 137,
      timedOut: true };
  }

  const logs =
    await container.logs({
      stdout: true,
      stderr: true });
  await container.remove();

  return {
    stdout: logs.toString(),
    stderr: '',
    exitCode:
      (result as any)
        .StatusCode ?? 0,
    timedOut: false,
  };
}

Advanced Tips

Pre-warm container pools for frequently used runtimes to reduce cold start latency. Use seccomp profiles to restrict system calls beyond basic container isolation. Implement output streaming through attached stdio for real-time execution feedback.

When to Use It?

Use Cases

Build an online code playground that executes user-submitted code in isolated containers. Create an AI agent framework where tool code runs in sandboxed environments. Implement a CI runner that executes build scripts in ephemeral containers with resource limits.

Related Topics

Container isolation, code execution, process sandboxing, Docker, and security boundaries.

Important Notes

Requirements

Docker or container runtime for container-based sandboxing. Host system permissions for creating containers or isolated processes. Monitoring infrastructure for tracking sandbox resource usage and health.

Usage Recommendations

Do: disable network access for sandboxes that do not require external connectivity. Set memory and CPU limits to prevent resource exhaustion from malicious code. Use read-only filesystems to prevent persistent modifications.

Don't: run untrusted code directly on the host without any isolation layer. Share volumes between sandboxes that could enable cross-sandbox data access. Trust sandbox output without sanitization before displaying to users.

Limitations

Container-based sandboxing adds startup latency for each execution instance. Resource limits may terminate legitimate long-running computations prematurely. Some system-level operations cannot be fully restricted within container isolation alone.