Scalable Web Sockets | Redis + Kafka + Postgres

This is a simple example of sclaing Web Sockets using Redis Pub/Sub, Kafka and Postgres.

Architecture

flowchart LR
  subgraph Clients
    McTechie(Client 1)
    AnonUser2(Client 2)
    AnonUser3(Client 3)
    AnonUser4(Client 4)
    AnonUser5(Client 5)
  end

  subgraph Servers
    McTechie(Client 1) <-->|Socket Conn.| Server_1(Server 1)
    AnonUser2(Client 2) <-->|Socket Conn.| Server_1(Server 1)
    AnonUser3(Client 3) <-->|Socket Conn.| Server_1(Server 1)
    AnonUser4(Client 4) <-->|Socket Conn.| Server_2(Server 2)
    AnonUser5(Client 5) <-->|Socket Conn.| Server_2(Server 2)
  end

  subgraph Scaling Mechanism
    subgraph Pub/Sub Layer
      Server_1 <-->|Pub/Sub| Redis(Redis Service)
      Server_2 <-->|Pub/Sub| Redis(Redis Service)
    end

    subgraph Kafka Layer
      Server_1 -->|Produces| KafkaTopic(Kafka Topic)
      Server_2 -->|Produces| KafkaTopic(Kafka Topic)
      KafkaTopic <-->|Consumes| KafkaConsumer(Consumer Service)
      KafkaConsumer(Consumer Service) -->|Write| Postgres(Postgres DB)
    end
  end

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Tech Stack

• Node.js (Server)
• Redis (Sync messages between multiple servers)
• Kafka (Gather messages with a high throughput and allow consumption)
• Drizzle (ORM for Postgres)

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How to run

This project requires Node.js, Redis, Kafka and Postgres to run.

Part 1: Redis & Kafka

You can use Docker to run Redis and Kafka, or use a local / cloud service.

docker compose up -d

Don't forget to add the following environment variables in the .env file:

REDIS_URL=
KAFKA_BROKER_URL=

Part 2: Postgres

You can either use the Docker Compose Postgres container, or spin it up locally, or a third-party service. I've used Vercel's Postgres service.

Make sure to add the following environment variables in the .env file:

POSTGRES_URL=
POSTGRES_PRISMA_URL=
POSTGRES_URL_NON_POOLING=
POSTGRES_USER=
POSTGRES_HOST=
POSTGRES_PASSWORD=
POSTGRES_DATABASE=

Part 3: Server

# Clone the repository
git clone https://github.com/McTechie/scalable-websockets.git

# Change directory
cd scalable-websockets

# Install pnpm (Skip if already installed)
npm i -g pnpm

# Install dependencies
pnpm install

# Run the server
pnpm dev

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Demo

Client 1

Client 2

Message Broadcast [Client 1]

Message Received [Client 2]

Server Logs