Devbox Skill

Devboxes are OpenClaw sandbox containers running a custom image with VSCode Web, noVNC, Chromium (CDP), and up to 5 app ports routed via Traefik or Cloudflare Tunnels.

OpenClaw manages the full container lifecycle. The main agent assigns each devbox a sequential ID by maintaining a local counter file, then passes DEVBOX_ID to the subagent task. The devbox agent runs devbox-init as its first action, which builds URL env vars, writes env files, and sets up routing.

File Locations

Resolve paths relative to this SKILL.md's parent directory.

Key files:

• references/setup-script-guide.md — conventions for project setup scripts (.openclaw/setup.sh)

Architecture

• Agent id: devbox (configured in openclaw.json)
• Sandbox mode: all / scope: session — one container per session
• Image: ghcr.io/adshrc/openclaw-devbox:latest (pulled from GHCR)
• Network: traefik (for Traefik routing) or default Docker network (for Cloudflare Tunnel routing)
• Browser: sandbox.browser.enabled: true, CDP on port 9222

ID Assignment

The main agent manages the devbox counter:

1. Reads and increments /home/node/.openclaw/.devbox-counter before spawning
2. Includes the DEVBOX_ID in the task, instructing the devbox agent to run devbox-init {id} as its very first action

Two-Phase Startup

Phase 1 — Entrypoint (runs automatically at container start):

• Starts core services: Xvfb, Chromium (CDP), VNC, VSCode Web
• Does NOT require DEVBOX_ID — services are available immediately

Phase 2 — devbox-init \x3Cid> (run by the sub-agent/devbox agent):

1. Builds APP_URL_1..5, VSCODE_URL, NOVNC_URL from tags + domain + ID
2. Writes /etc/devbox.env and /etc/profile.d/devbox.sh (available in all shells)
3. Routes based on ROUTING_MODE:
   • traefik (default): Writes Traefik config to /traefik/devbox-{id}.yml
   • cloudflared: Generates cloudflared ingress config, registers DNS CNAME records via CF API, starts cloudflared tunnel run

The devbox-init script is installed at /usr/local/bin/devbox-init in the Docker image.

Bind Mounts (configured in openclaw.json)

Important: Due to OpenClaw Security measures, all user capabilites are dropped by default. So even root (in the devbox) has no write access to bind mounts, and can only read from them. The only solution currently is chmod 777 on the host path that is mapped to /home/node/.openclaw/traefik.

Known Paths

These paths are always the same inside the OpenClaw container:

• OpenClaw data: /home/node/.openclaw
• Traefik dynamic config: /home/node/.openclaw/traefik (must be mounted into the OpenClaw container; only if using Traefik routing)

Onboarding Flow

Important: After this skill is installed, the next step MUST be this onboarding flow. The user CANNOT use the devboxes skill until the onboarding flow is completed and the infrastructure is set up.

Important: This runs on the MAIN agent, NOT in a sandbox. The main agent has access to exec, gateway, and the file system.

When the user asks to set up the devbox skill, do the following:

Step 1: Verify Docker Access

Verify that you have access to the Docker socket and Docker binary:

which docker
docker version

If not, abort here and tell the user they need to run the OpenClaw container with:

-v /usr/bin/docker:/usr/bin/docker:ro
-v /var/run/docker.sock:/var/run/docker.sock

and that they need to set chmod 666 /var/run/docker.sock manually on the host, so that the OpenClaw container can work with it.

The OpenClaw container needs to be restarted then. After that, they can ask to set up the devbox skill again.

Step 2: Gather configuration info

Ask the user for:

• Routing mode: Traefik or Cloudflare Tunnel?
• Domain: with wildcard A-Record pointing to the server (e.g. *.example.com)
• GitHub token (optional): for cloning private repos inside devboxes

If Cloudflare Tunnel is chosen, also ask for:

• Cloudflare API token: must have permissions for the zone (DNS edit + Tunnel edit)

Step 3: Validate the Host Mapping Path (ONLY if using Traefik routing, skip otherwise!)

Find out what the host path/mapping is for /home/node/.openclaw inside the container:

# Returns the host path that is mapped to /home/node/.openclaw inside the container
docker inspect --format='{{range .Mounts}}{{if eq .Destination "/home/node/.openclaw"}}{{.Source}}{{end}}{{end}}' $(hostname)

Store the value as HOST_OPENCLAW_PATH. If HOST_OPENCLAW_PATH is a "system directory", OpenClaw will not be able to spawn a devbox.

System directories are: /etc, /private/etc, /proc, /sys, /dev, /root, /boot, /run, /var/run, /private/var/run, /var/run/docker.sock, /private/var/run/docker.sock and /run/docker.sock.

If the HOST_OPENCLAW_PATH is such a "system directory", abort here and tell the user they need to change their OpenClaw container setup to use a host path for OpenClaw data that is not a system directory. For example, they can create a directory like /home/openclaw or /opt/openclaw on the host.

Step 4: Verify Routing prerequisites

If routing mode is Traefik:

Check that /home/node/.openclaw/traefik is mounted:

ls /home/node/.openclaw/traefik

If /home/node/.openclaw/traefik doesn't exist, abort here and tell the user they need to add e.g. -v path_to_traefik:/home/node/.openclaw/traefik to their OpenClaw container and restart it. Remind the user that they cannot use system directories for the host path (OpenClaw Sandboxes restriction). After that, a container restart is needed, and then they can ask to set up the devbox skill again.

If routing mode is Cloudflare Tunnel:

Validate the CF API token and domain:

# 1. Get zone ID for the domain (extract root domain from the provided domain)
curl -s -X GET "https://api.cloudflare.com/client/v4/zones?name=${ROOT_DOMAIN}" \
  -H "Authorization: Bearer ${CF_API_TOKEN}" | jq .

# 2. Get account ID from the zone response
# account_id = .result[0].account.id
# zone_id = .result[0].id

Then create the tunnel:

# 4. Create a named tunnel
curl -s -X POST "https://api.cloudflare.com/client/v4/accounts/${CF_ACCOUNT_ID}/cfd_tunnel" \
  -H "Authorization: Bearer ${CF_API_TOKEN}" \
  -H "Content-Type: application/json" \
  -d '{"name": "devboxes@'"$(hostname)"'", "config_src": "local", "tunnel_secret": "'$(openssl rand -base64 32)'"}' | jq .

# Extract tunnel_id and tunnel_token from the response
# tunnel_id = .result.id
# tunnel_token = .result.token

Store the values: CF_API_TOKEN, CF_ZONE_ID, CF_ACCOUNT_ID, CF_TUNNEL_ID, CF_TUNNEL_TOKEN.

Step 5: Create counter file

echo "0" > /home/node/.openclaw/.devbox-counter

Important: The counter file is managed by the main agent only. The counter CANNOT be reset, or decremented, only increment is allowed!

Step 6: Configure OpenClaw

First, check the current agents config:

node /app/openclaw.mjs config get agents

Then, decide what needs to be adjusted based on the existing config:

Main Agent

If there is an agent with default: true, note its index and add subagents.allowAgents to it:

node /app/openclaw.mjs config set agents.list[{index}].subagents.allowAgents '["devbox"]' --json

then (if needed), set sandbox mode to off (since the main agent doesn't need a sandbox):

node /app/openclaw.mjs config set agents.list[{index}].sandbox.mode "off"

else, if there's no agent with default: true, create one at the next index with the necessary structure:

node /app/openclaw.mjs config set agents.list[{index}] '{
  "id": "main",
  "default": true,
  "subagents": {
    "allowAgents": [
        "devbox"
    ]
  },
  "sandbox": {
    "mode": "off"
  }
}' --json

Devbox Agent

1. Pull the Docker image so that it's available when OpenClaw tries to spawn it:

docker pull ghcr.io/adshrc/openclaw-devbox:latest

2. Add the devbox agent at the next index in agents.list. Adjust the sandbox and docker config as needed (replace placeholders in curly brackets):

node /app/openclaw.mjs config set agents.list[{index}] '{
    "id": "devbox",
    "name": "Devbox Agent",
    "sandbox": {
      "mode": "all",
      "workspaceAccess": "none",
      "scope": "session",
      "docker": {
        "image": "ghcr.io/adshrc/openclaw-devbox:latest",
        "readOnlyRoot": false,
        "network": "traefik", # Only needed for Traefik routing mode, exclude otherwise
        "env": {
          "ENABLE_VNC": "true",
          "ENABLE_VSCODE": "true",
          "DEVBOX_DOMAIN": "{domain}",
          "APP_TAG_1": "app1",
          "APP_TAG_2": "app2",
          "APP_TAG_3": "app3",
          "APP_TAG_4": "app4",
          "APP_TAG_5": "app5",
          "GITHUB_TOKEN": "{github_token}",
          "ROUTING_MODE": "{traefik|cloudflared}",
          # Cloudflare Tunnel variables (only needed if using cloudflared routing, exclude otherwise)
          "CF_TUNNEL_TOKEN": "{cf_tunnel_token}",
          "CF_API_TOKEN": "{cf_api_token}",
          "CF_ZONE_ID": "{cf_zone_id}",
          "CF_TUNNEL_ID": "{cf_tunnel_id}",
        },
        "binds": [
          "{host_openclaw_path}/traefik:/traefik:rw" # Only needed for Traefik routing mode, exclude otherwise
        ]
      },
      "browser": {
        "enabled": true,
        "cdpPort": 9222
      },
      "prune": {
        "idleHours": 0,
        "maxAgeDays": 0
      }
    }
  }
]' --json

3. Allow Agents to communicate with each other so that subsequent tasks can be sent to the devbox agent:

node /app/openclaw.mjs config set tools.agentToAgent.enabled true
node /app/openclaw.mjs config set tools.sessions.visibility "all"

After this is done, restart the gateway to apply the changes. If this is not working (e.g. command is disabled), ask the user to restart the OpenClaw container manually.

Workflow: Spawn a Devbox

Step 1: Assign ID (main agent)

Read and increment the counter file:

DEVBOX_ID=$(( $(cat /home/node/.openclaw/.devbox-counter) + 1 ))
echo "$DEVBOX_ID" > /home/node/.openclaw/.devbox-counter

Step 2: Spawn subagent (main agent)

Use devbox-\x3Cid> as the label and include the DEVBOX_ID in the task:

sessions_spawn(
    agentId="devbox",
    label=f"devbox-{DEVBOX_ID}",
    task=f"Your task description. Your DEVBOX_ID is {DEVBOX_ID} — run `devbox-init {DEVBOX_ID}` as your very first action before doing anything else. This sets up routing and writes env vars. After that, env vars (APP_URL_*, VSCODE_URL, etc.) are in your shell via `source /etc/profile.d/devbox.sh`. GitHub token is in $GITHUB_TOKEN. ALWAYS use /workspace as the working directory! When cloning, the structure must be /workspace/\x3Crepo>."
)

Step 3: Report URLs to user (main agent)

The main agent already knows the assigned ID from Step 1. Report:

• VSCode: https://vscode-{DEVBOX_ID}.{domain}
• noVNC: https://novnc-{DEVBOX_ID}.{domain}/vnc.html
• App URLs: https://{tag}-{DEVBOX_ID}.{domain}

Cleanup

OpenClaw manages container lifecycle — containers are removed when sessions end. Traefik route configs left behind are harmless.

Environment Variables

Static (set in openclaw.json sandbox.docker.env)

Dynamic (built by devbox-init, available in all shells after running it)

Ports

Browser

The devbox agent has browser access via Chromium CDP (port 9222). The subagent can use the browser tool to navigate, screenshot, and interact with apps running inside the container (use http://localhost:{port}).

Project Setup Scripts

Projects can include .openclaw/setup.sh that runs inside the devbox. It has access to all env vars (APP_URL_*, APP_PORT_*, DEVBOX_ID, etc.) via /etc/profile.d/devbox.sh.

See references/setup-script-guide.md for conventions.