| name | sandbox-next |
| description | Use when building or changing Cloudflare Sandbox apps on @cloudflare/sandbox@next (Sandbox SDK 1.0 preview)—code execution, AI runners, interpreters, CI-like jobs, terminals, files, mounts, tunnels, preview URLs, lifecycle, or errors. Not for the default stable package (use sandbox-stable) or for porting stable to @next (use sandbox-migrate-to-next). |
Sandbox SDK — @next (1.0 preview)
Isolated Linux environments on Cloudflare Containers, driven from Workers.
Prefer preview docs and installed @next types over memory. APIs change; this skill is a gate, a contract, and a retrieval map—not a full manual.
We recommend new projects on this line. Apps still on the default package use sandbox-stable. Port only when asked, via sandbox-migrate-to-next.
1. Gate — confirm the package line
Before writing code, inspect the app:
| Check | Must match |
|---|
| npm dependency | @cloudflare/sandbox@next (or another preview tag) |
| Container image | Same line (e.g. cloudflare/sandbox:next, next-python) |
| If you find… | Action |
|---|
Default @cloudflare/sandbox (no @next) | Stop. Load sandbox-stable. Do not apply this skill’s APIs. |
User wants to port stable → @next | Stop. Load sandbox-migrate-to-next. |
| Self-deployed bridge only | Bridge is not on the 1.0 preview line yet. Keep bridge on stable package + image. Bridge (stable) |
Never mix an @next Worker package with a stable container image (or the reverse).
Skills install: Agent setup · cloudflare/skills
2. Contract — non-negotiables
sandbox.exec(argv) takes an argv list and resolves when the process starts. It returns a handle, not a finished command result.- Collect results with handle methods:
output(), logs(), waitForExit(), waitForPort(), waitForLog(), kill(signal?).
- No implicit shell. Shell syntax needs an explicit shell, e.g.
["/bin/bash", "-lc", script].
- Each launch is independent. A
cd / export in one exec is not visible to the next. Pass cwd and env per launch, or one shell script.
- Process handles have no stdin. Interactive use → terminals (
createTerminal + connect).
- Local wait
timeout / AbortSignal cancel the wait only. They do not kill the process. Use kill or exec’s remote timeout.
getProcess / listProcesses / getTerminal / listTerminals do not start a container; they return null / [] when none is up.- Process and terminal IDs belong to the current container, not forever to a sandbox ID. For work that must survive replace, store the full job (argv, cwd, env, app state)—not only an id.
- Non-secret config only in
setEnvVars / launch env. Live credentials stay in the Worker; use outbound handlers when the sandbox calls external APIs.
- Do not invent removed stable APIs (
gitCheckout on core, string-exec completion, session execution, sandbox.terminal(request)).
- Do not use one retry loop for every error (see Errors docs).
Minimal shape:
import { getSandbox, proxyToSandbox, Sandbox } from "@cloudflare/sandbox";
export { Sandbox };
const sandbox = getSandbox(env.Sandbox, "user-123");
const process = await sandbox.exec(["python3", "-c", "print(2 + 2)"]);
const result = await process.output({ encoding: "utf8" });
Optional non-exhaustive cheatsheet (process/terminal/interpreter only): references/api-quick-ref.md
Examples index (next branch): references/examples.md
3. Retrieve — open the doc for the task
Fetch the page before implementing. Installed @next types win over guesses.
| You need to… | Open |
|---|
| Orient / choose preview | 1.0 preview overview |
| First Worker, wrangler, Dockerfile | Get started |
exec, handles, readiness, durability | Process execution |
| Process API signatures | Processes API |
| Sandbox ID vs container vs sleep/destroy | Lifecycle |
cwd / env / setEnvVars | Environment |
| Interactive PTY / browser terminal | Terminals · Terminals API |
| Python/JS code interpreter | Interpreter · Interpreter API |
| Extensions model | Extensions |
| Error classes and recovery | Errors · Errors API |
| Common failures | Troubleshooting |
| API hub | API reference |
Files, mounts, backups, ports, tunnels, proxyToSandbox | Main docs for shared surfaces (ignore stable-only session/transport/sandbox.terminal): Files · Storage / mounts · Ports · · · · · |
4. Before you ship
- Lockfile and Dockerfile on the same
@next line
- Typecheck against installed
@next types
- No live secrets in sandbox env
- Production preview hostnames need wildcard DNS on a custom domain when using those URL patterns
