Supabase node.js proxy server

index.js

const { Socket } = require('@supabase/realtime-js');
const WebSocket = require('ws');

const wss = new WebSocket.Server({ port: 3000 });

wss.on('connection', function connection(ws) {
  ws.send('Connection established.');
});

const socket = new Socket(process.env.REALTIME_URL || 'http://localhost:4000/socket') 
socket.connect()
socket.channel('realtime:public')
  .join()
  .channel
  .on('*', payload => {
    wss.clients.forEach(function each(client) {
      if (client.readyState === WebSocket.OPEN) {
        client.send(JSON.stringify({
          "type": payload.table,
          "operation": payload.type,
          "object": payload.record != null ? payload.record : payload.old_record
        }));
      }
    });
  })

package.json

{
  "name": "realtime-proxy",
  "scripts": {
    "dev": "node index.js"
  },
  "version": "1.0.0",
  "main": "index.js",
  "license": "MIT",
  "dependencies": {
    "@supabase/realtime-js": "^0.9.0",
    "bufferutil": "^4.0.1",
    "express": "^4.17.1",
    "utf-8-validate": "^5.0.2",
    "ws": "^7.3.0"
  }
}

restart-realtime.sh

#!/bin/bash
docker rm -f realtime || true
docker run -d -p 4000:4000 --name=realtime \
  -e DB_HOST='docker.for.mac.host.internal' \
  -e DB_NAME="$POSTGRES_DB" \
  -e DB_USER='postgres' \
  -e DB_PASSWORD='' \
  -e DB_PORT="$POSTGRES_PORT" \
  -e PORT=4000 \
  -e HOSTNAME='localhost' \
  -e SECRET_KEY_BASE='SOMETHING_SUPER_SECRET' \
  supabase/realtime

Run instructions:
Disclaimer: this works for me on Mac

0. Have Docker and node/npm/yarn installed
1. Save files to folder of your choice
2. yarn install
3. Refer to https://github.com/supabase/realtime#database-set-up for preparing database (maybe restart db server afterwards)
4. Set POSTGRES_DB and POSTGRES_PORT env vars somehow or replace with hardcoded values in restart-realtime.sh
5. ./restart-realtime.sh
6. yarn run dev

To test:

• Use some websocket test client, i.e. WebSocket Test Client Chrome extension or WebSocket Client from Mac AppStore
• Connect to ws://localhost:3000
• Change something in the database, i.e. use pgAdmin or plain psql
• See adjusted JSON that got send in test client