ClearBot

This code is a Slack application (bot) written using Slack Bolt. It allows users to play mp3 clips on a Sonos speaker. It connects to Slack using Socket Mode (an outbound WebSocket — no public endpoint required) and relays commands over a native WebSocket to Sonos Proxy, which in turn communicates with node-sonos-http-api.

We affectionately refer to this as "Burn Bot."

Architecture

Both connections are established outbound — ClearBot dials Slack, and each Sonos Proxy dials ClearBot — so neither ClearBot nor the proxies need a public inbound endpoint. Messages then flow back over those sockets:

sequenceDiagram
    Note over Slack,ClearBot: ClearBot connects out to Slack (Socket Mode)
    Slack-->>ClearBot: message event (e.g. "burn")
    Note over ClearBot,Sonos Proxy: Sonos Proxy connects out to ClearBot (WebSocket, token auth)
    ClearBot-->>Sonos Proxy: { type: play_url, url: burn.mp3 }
    Sonos Proxy-->>node-sonos-http-api: GET http://localhost:5005/Office/clip/burn.mp3/20

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Requirements

• Bun

Running Locally

Because ClearBot uses Socket Mode, it connects out to Slack — there is no public endpoint to expose.

• Create a Slack app and enable Socket Mode (Settings → Socket Mode).
• Generate an app-level token (Basic Information → App-Level Tokens) with the connections:write scope — this is the xapp-… token.
• Under Event Subscriptions, subscribe to the bot message events (e.g. message.channels). With Socket Mode on there is no Request URL to set.
• Copy .env.example to .env and fill in:
  • SLACK_BOT_TOKEN — the bot token (xoxb-…)
  • SLACK_APP_TOKEN — the app-level token (xapp-…)
  • RELAY_TOKEN — a shared secret the Sonos Proxy must also use (generate with openssl rand -hex 32)
• Run bun install, then bun run dev (defaults to port 3000).
• Set up Sonos Proxy pointed at ws://localhost:3000 with the same RELAY_TOKEN.
• Enjoy!

Deployment

See the Makefile... make sure you are in the expected subscription by running az account set --subscription YOUR_SUBSCRIPTION_ID.

The relay uses WebSockets, which are disabled by default on Azure App Service — run make websockets to enable them, and make appsettings to set SLACK_BOT_TOKEN, SLACK_APP_TOKEN, and RELAY_TOKEN on the web app. (SLACK_SIGNING_SECRET is no longer used now that the bot runs in Socket Mode.)

Resources

• Slack Bolt API
• Block Kit Builder
• Sonos Proxy
• node-sonos-http-api