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Docker Sandboxes runs code in isolated cloud sandboxes hosted by Docker. Phoenix uses it as a hosted backend for both Python and TypeScript code evaluators. Python runs on the python:3.13-slim image and TypeScript on node:24-slim.
Docker marks the Sandboxes API as experimental. Its interfaces and behavior may change.

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Requirements

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Configure

  1. Create a personal access token with the sandbox:use permission in your Docker account settings.
  2. Add your Docker ID as DOCKER_ID and the token as DOCKER_PAT from Settings → Sandboxes, or set them as environment variables on the Phoenix server.
  3. In Sandbox Configurations, click New Sandbox, pick Docker Sandboxes, and choose Python or TypeScript.

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Behavior

  • Internet access: Deny blocks all outbound traffic. Phoenix creates a network policy named phoenix-deny-all-egress on your Docker account the first time it’s needed, and it applies only to the sandboxes Phoenix attaches it to. Allow adds no policy, so your Docker account’s default network policy applies.
  • Dependencies install with pip or npm when the sandbox is created, and need internet access.
  • Environment variables are passed to each run, not set on the sandbox when it’s created.
  • Phoenix deletes each sandbox when it’s done with it. Every sandbox also expires after 10 minutes.
See Sandbox Backends for self-hosting setup.