Sandbox SDK — @next (1.0 preview)

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:

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).