Sandbox Configuration

Sandbox settings are owned by the LangBot main process; Box Runtime performs the actual execution. For most deployments, you only need to choose a backend, set the workspace directory, and pick a security profile.

All box.* settings on this page live in data/config.yaml. See System Environment Settings for the file’s location and how it’s loaded.

Recommended Configuration

box:
  enabled: true
  backend: 'local'        # auto-pick from Docker / Nsjail
  local:
    profile: 'default'
    host_root: './data/box'
    skills_root: 'skills'

enabled: master switch. When false, all Box-dependent features are disabled (sandbox tools, skill add/edit, stdio MCP hosting).
backend: see “Backend Selection” below.
local.profile: security profile — controls network, mounts, and resource limits.
local.host_root: host workspace directory, mapped to /workspace inside the sandbox.
local.skills_root: skill package directory; relative paths resolve under host_root (defaults to host_root/skills).

Skills are loaded only from the Box-managed skill store. When Box Runtime or the backend is unavailable, the skill list is empty and create/edit/register_skill are disabled — there’s no fallback to data/skills/.

Backend Selection

The sandbox can run on local containers or in the cloud. box.backend picks which:

`backend`	Where it runs	Behavior
`local` (default)	Local containers	Auto-pick from Docker / Nsjail (Docker preferred)
`docker`	Local containers	Force Docker; requires the Docker daemon
`nsjail`	Local containers	Force Nsjail (Linux only); no custom image support
`e2b`	Cloud	Use E2B cloud sandbox; requires API key

local is shorthand for “auto-pick”, not a fourth backend sitting next to docker/nsjail. The local backends (local/docker/nsjail) share the box.local.* config section; the cloud backend uses box.e2b.*.

backend is a hard selection. Setting docker and finding Docker unavailable does not fall back to Nsjail or E2B — only local auto-fans-out.BOX__BACKEND environment variable overrides box.backend (highest priority).

Security Profiles

box.local.profile controls network, mounts, and resource limits for local backends:

Profile	Network	Mounts	Resources	When to use
`default`	Off	Read-write	Default limits	Default choice
`offline_readonly`	Off	Read-only	Stricter	Reading untrusted files
`network_basic`	Basic network	Read-write	Default limits	API access or dependency install
`network_extended`	Full network	Read-write	Relaxed	Development, debugging, complex tasks

Prefer least privilege: skip the network unless you need it (default / offline_readonly); only add necessary directories to allowed_mount_roots.

Local Backend Configuration (box.local.*)

The local backends (local / docker / nsjail) share these settings:

Setting	Default	Notes
`local.profile`	`default`	See “Security Profiles” above
`local.image`	empty	Docker-only custom image; empty = use profile default
`local.host_root`	`./data/box`	Host workspace base, mapped to `/workspace` inside the sandbox
`local.default_workspace`	empty	Default workspace name; empty = `<host_root>/default`
`local.skills_root`	`skills`	Skill package directory; relative paths resolve under `host_root`
`local.allowed_mount_roots`	`[host_root]`	Allowlist of host directories the Agent can mount
`local.workspace_quota_mb`	`null`	Workspace disk quota (MB); `null` = use profile default

Cloud Backend Configuration (box.e2b.*)

Configure after setting backend: 'e2b':

Setting	Default	Notes
`e2b.api_key`	empty	E2B API key; can also be set via `E2B_API_KEY`
`e2b.api_url`	empty	Self-hosted E2B endpoint; can also be set via `E2B_API_URL`
`e2b.template`	empty	Default E2B template ID

E2B doesn’t need Docker or Nsjail on the host — every execution goes through the remote sandbox.

Docker Compose Deployment

In Docker Compose, sandbox settings live on the langbot service. LangBot forwards them to langbot_box via INIT RPC at startup.

services:
  langbot_box:
    image: rockchin/langbot:latest
    container_name: langbot_box
    profiles: ["box", "all"]
    volumes:
      - ${LANGBOT_BOX_ROOT:-${PWD}/data/box}:${LANGBOT_BOX_ROOT:-${PWD}/data/box}
      - /var/run/docker.sock:/var/run/docker.sock
    command: ["uv", "run", "--no-sync", "-m", "langbot_plugin.cli.__init__", "box"]

  langbot:
    image: rockchin/langbot:latest
    volumes:
      - ./data:/app/data
    environment:
      - BOX__LOCAL__HOST_ROOT=${LANGBOT_BOX_ROOT:-${PWD}/data/box}
      - BOX__LOCAL__SKILLS_ROOT=skills
      - BOX__LOCAL__ALLOWED_MOUNT_ROOTS=${LANGBOT_BOX_ROOT:-${PWD}/data/box}

langbot_box needs the Docker daemon. Only mount docker.sock in trusted environments, and keep the Box root path identical on the host and inside the langbot_box container.

To point LangBot at an externally-managed Box Runtime (e.g. a remote host), use box.runtime.endpoint:

box:
  runtime:
    endpoint: 'ws://192.168.1.10:5410'

Environment Variables

Environment variable	Maps to
`BOX__ENABLED`	`box.enabled`
`BOX__BACKEND`	`box.backend`
`BOX__LOCAL__PROFILE`	`box.local.profile`
`BOX__LOCAL__IMAGE`	`box.local.image`
`BOX__LOCAL__HOST_ROOT`	`box.local.host_root`
`BOX__LOCAL__DEFAULT_WORKSPACE`	`box.local.default_workspace`
`BOX__LOCAL__SKILLS_ROOT`	`box.local.skills_root`
`BOX__LOCAL__ALLOWED_MOUNT_ROOTS`	`box.local.allowed_mount_roots`, comma-separated
`BOX__LOCAL__WORKSPACE_QUOTA_MB`	`box.local.workspace_quota_mb`
`BOX__E2B__API_KEY`	`box.e2b.api_key`
`BOX__E2B__API_URL`	`box.e2b.api_url`
`BOX__E2B__TEMPLATE`	`box.e2b.template`

Don’t set BOX__* or LANGBOT_BOX_* on the langbot_box service — Box Runtime doesn’t read them directly. Its configuration arrives over INIT RPC from LangBot.

​Recommended Configuration

​Backend Selection

​Security Profiles

​Local Backend Configuration (box.local.*)

​Cloud Backend Configuration (box.e2b.*)

​Docker Compose Deployment

​Environment Variables

Recommended Configuration

Backend Selection

Security Profiles

Local Backend Configuration (box.local.*)

Cloud Backend Configuration (box.e2b.*)

Docker Compose Deployment

Environment Variables