Docker — symple

Docker Compose

services:
  redis:
    image: redis:7-alpine
    ports:
      - "6379:6379"

  symple:
    image: node:22-alpine
    working_dir: /app
    volumes:
      - ./symple-server:/app
    command: npm start
    ports:
      - "4500:4500"
    environment:
      PORT: 4500
      SYMPLE_AUTHENTICATION: "true"
      SYMPLE_DYNAMIC_ROOMS: "false"
      SYMPLE_REDIS_URL: redis://redis:6379
    depends_on:
      - redis

Dockerfile

FROM node:22-alpine
WORKDIR /app
COPY package*.json ./
RUN npm ci --production
COPY . .
EXPOSE 4500
CMD ["node", "server.js"]

Scaling

Run multiple instances behind a load balancer. As long as all instances point to the same Redis, cross-instance messaging works automatically:

services:
  symple:
    deploy:
      replicas: 3
    environment:
      SYMPLE_REDIS_URL: redis://redis:6379

No sticky sessions required -- session tokens are in Redis, and any instance can validate them.

Health checks

The HTTP server responds to any non-WebSocket request. Use it as a health check endpoint:

healthcheck:
  test: ["CMD", "wget", "-q", "--spider", "http://localhost:4500/"]
  interval: 30s
  timeout: 5s
  retries: 3

Production checklist

Enable SSL (SYMPLE_SSL_ENABLED=true) or terminate TLS at the load balancer
Set SYMPLE_AUTHENTICATION=true with Redis for token validation
Set SYMPLE_DYNAMIC_ROOMS=false unless clients need to join rooms at runtime
Set SYMPLE_SESSION_TTL to a reasonable value (e.g. 10080 for one week)
Configure Redis persistence if session durability matters