node-red-contrib-slack-socketmode

A Node-RED node that enables real-time bi-directional communication with Slack using the Slack RTM API (Socket Mode).

This node allows you to:

• Receive messages from any Slack channel, DM or app mention.
• Send messages from Node-RED to Slack using the same authenticated connection.
• Run a persistent background Slack RTM client that automatically reconnects.
• Avoid the need for external tunnels (like ngrok), as Slack Socket Mode requires no public URL.

This package is useful when building:

• ChatOps automations
• Monitoring or alerting pipelines
• IoT → Slack integrations
• Slack assistants connected to industrial SCADA/PLC systems
• Internal automation bots without requiring slash commands or HTTP endpoints

🔧 Installation

Using npm

cd ~/.node-red
npm install node-red-contrib-slack-socketmode

🧩 Node Description

This package provides two main components:

1. Slack RTM Listener Node

Creates a persistent connection to Slack using your SLACK_APP_TOKEN and receives all Slack messages allowed by your app permissions.

Outputs a msg object like:

{ "type": "slack_event", "event": "message", "user": "U1234567", "text": "hello world", "channel": "C9876543", "ts": "1731530820.239629" }

2. Slack RTM Sender Node

Allows you to send Slack messages using:

msg.payload = { channel: "CHANNEL_ID", text: "Your message text" };

⚙️ Slack Configuration (Required)

Follow these steps to configure Slack:

1. Create a Slack App

https://api.slack.com/apps

2. Enable Socket Mode

Slack App → Settings → Socket Mode → Enable

3. Add Required OAuth Scopes

Bot Token Scopes:

app_mentions:read

channels:history

chat:write

groups:history

im:history

mpim:history

4. Install the App into Your Workspace

Slack App → Install App → Install

5. Retrieve Tokens

You will need:

Token Type Purpose SLACK_APP_TOKEN (starts with xapp-) Required for RTM (Socket Mode) SLACK_BOT_TOKEN (starts with xoxb-) Required for sending messages

Insert these tokens in the node configuration inside Node-RED.

🚀 Usage Examples

1. Receiving messages

Connect the Slack RTM Listener node to a debug node.

No payload is required; socket mode starts automatically.

Output example:

{ "type": "slack_event", "event": "message", "user": "U13579", "text": "Temperature is too high!", "channel": "C24680" }

2. Sending messages from Node-RED

Inject:

{ "channel": "C24680", "text": "Hello from Node-RED!" }

Function node "Format message":

msg.payload = { channel: "C24680", text: "Hello from Node-RED!" }; return msg;

Connect it to Slack RTM Sender.

🔄 Auto-Reconnect Feature

The Slack RTM connection automatically:

Reconnects on network failures

Resumes after computer sleep

Handles Slack server restarts

No user intervention is required.

🛠 Advanced Use Cases Trigger flows on keyword if (msg.text.includes("status")) { msg.payload = "System OK"; return msg; } return null;

Forward alerts to Slack

Use MQTT → Function → Slack RTM Sender.

Control Node-RED flows from Slack

Use the Listener node + Switch node.

🧪 Testing

You can verify your Slack tokens by running:

node slack-socket.js

You should see:

Slack Bolt connected in Socket Mode…