Interactive browser terminals in Sandboxes

The Sandbox SDK now supports PTY (pseudo-terminal) passthrough, enabling browser-based terminal UIs to connect to sandbox shells via WebSocket.

sandbox.terminal(request)

The new terminal() method proxies a WebSocket upgrade to the container's PTY endpoint, with output buffering for replay on reconnect.

// Worker: proxy WebSocket to container terminal return sandbox.terminal(request, { cols: 80, rows: 24 });

// Worker: proxy WebSocket to container terminal return sandbox.terminal(request, { cols: 80, rows: 24 });

Multiple terminals per sandbox

Each session can have its own terminal with an isolated working directory and environment, so users can run separate shells side-by-side in the same container.

// Multiple isolated terminals in the same sandbox const dev = await sandbox.getSession("dev"); return dev.terminal(request);

// Multiple isolated terminals in the same sandbox const dev = await sandbox.getSession("dev"); return dev.terminal(request);

xterm.js addon

The new @cloudflare/sandbox/xterm export provides a SandboxAddon for xterm.js with automatic reconnection (exponential backoff + jitter), buffered output replay, and resize forwarding.

import { SandboxAddon } from "@cloudflare/sandbox/xterm"; const addon = new SandboxAddon({ getWebSocketUrl: ({ sandboxId, origin }) => `${origin}/ws/terminal?id=${sandboxId}`, onStateChange: (state, error) => updateUI(state), }); terminal.loadAddon(addon); addon.connect({ sandboxId: "my-sandbox" });

import { SandboxAddon } from "@cloudflare/sandbox/xterm"; const addon = new SandboxAddon({ getWebSocketUrl: ({ sandboxId, origin }) => `${origin}/ws/terminal?id=${sandboxId}`, onStateChange: (state, error) => updateUI(state), }); terminal.loadAddon(addon); addon.connect({ sandboxId: "my-sandbox" });

Upgrade

To update to the latest version:

npm i @cloudflare/sandbox@latest