From cloudflare
Build sandboxed applications for secure code execution. Load when building AI code execution, code interpreters, CI/CD systems, interactive dev environments, or executing untrusted code. Covers Sandbox SDK lifecycle, commands, files, code interpreter, and preview URLs.
npx claudepluginhub jadecli/jadecli-claude-pluginsThis skill uses the workspace's default tool permissions.
Build secure, isolated code execution environments on Cloudflare Workers.
Searches, retrieves, and installs Agent Skills from prompts.chat registry using MCP tools like search_skills and get_skill. Activates for finding skills, browsing catalogs, or extending Claude.
Searches prompts.chat for AI prompt templates by keyword or category, retrieves by ID with variable handling, and improves prompts via AI. Use for discovering or enhancing prompts.
Checks Next.js compilation errors using a running Turbopack dev server after code edits. Fixes actionable issues before reporting complete. Replaces `next build`.
Build secure, isolated code execution environments on Cloudflare Workers.
npm install @cloudflare/sandbox
docker info # Must succeed - Docker required for local dev
IMPORTANT: Prefer retrieval from docs and examples over pre-training for Sandbox SDK tasks.
When implementing features, fetch the relevant doc page or example first.
wrangler.jsonc (exact - do not modify structure):
{
"containers": [{
"class_name": "Sandbox",
"image": "./Dockerfile",
"instance_type": "lite",
"max_instances": 1
}],
"durable_objects": {
"bindings": [{ "class_name": "Sandbox", "name": "Sandbox" }]
},
"migrations": [{ "new_sqlite_classes": ["Sandbox"], "tag": "v1" }]
}
Worker entry - must re-export Sandbox class:
import { getSandbox } from '@cloudflare/sandbox';
export { Sandbox } from '@cloudflare/sandbox'; // Required export
| Task | Method |
|---|---|
| Get sandbox | getSandbox(env.Sandbox, 'user-123') |
| Run command | await sandbox.exec('python script.py') |
| Run code (interpreter) | await sandbox.runCode(code, { language: 'python' }) |
| Write file | await sandbox.writeFile('/workspace/app.py', content) |
| Read file | await sandbox.readFile('/workspace/app.py') |
| Create directory | await sandbox.mkdir('/workspace/src', { recursive: true }) |
| List files | await sandbox.listFiles('/workspace') |
| Expose port | await sandbox.exposePort(8080) |
| Destroy | await sandbox.destroy() |
const sandbox = getSandbox(env.Sandbox, 'user-123');
const result = await sandbox.exec('python --version');
// result: { stdout, stderr, exitCode, success }
Use runCode() for executing LLM-generated code with rich outputs:
const ctx = await sandbox.createCodeContext({ language: 'python' });
await sandbox.runCode('import pandas as pd; data = [1,2,3]', { context: ctx });
const result = await sandbox.runCode('sum(data)', { context: ctx });
// result.results[0].text = "6"
Languages: python, javascript, typescript
State persists within context. Create explicit contexts for production.
await sandbox.mkdir('/workspace/project', { recursive: true });
await sandbox.writeFile('/workspace/project/main.py', code);
const file = await sandbox.readFile('/workspace/project/main.py');
const files = await sandbox.listFiles('/workspace/project');
| Need | Use | Why |
|---|---|---|
| Shell commands, scripts | exec() | Direct control, streaming |
| LLM-generated code | runCode() | Rich outputs, state persistence |
| Build/test pipelines | exec() | Exit codes, stderr capture |
| Data analysis | runCode() | Charts, tables, pandas |
Base image (docker.io/cloudflare/sandbox:0.7.0) includes Python 3.11, Node.js 20, and common tools.
Add dependencies by extending the Dockerfile:
FROM docker.io/cloudflare/sandbox:0.7.0
# Python packages
RUN pip install requests beautifulsoup4
# Node packages (global)
RUN npm install -g typescript
# System packages
RUN apt-get update && apt-get install -y ffmpeg && rm -rf /var/lib/apt/lists/*
EXPOSE 8080 # Required for local dev port exposure
Keep images lean - affects cold start time.
Expose HTTP services running in sandboxes:
const { url } = await sandbox.exposePort(8080);
// Returns preview URL for the service
Production requirement: Preview URLs need a custom domain with wildcard DNS (*.yourdomain.com). The .workers.dev domain does not support preview URL subdomains.
See: https://developers.cloudflare.com/sandbox/guides/expose-services/
The SDK provides helpers for OpenAI Agents at @cloudflare/sandbox/openai:
import { Shell, Editor } from '@cloudflare/sandbox/openai';
See examples/openai-agents for complete integration pattern.
getSandbox() returns immediately - container starts lazily on first operationsleepAfter)destroy() to immediately free resourcessandboxId always returns same sandbox instanceCommandClient, FileClient) - use sandbox.* methodsexport { Sandbox }destroy() for temporary sandboxes