Deployment Architecture

This document describes ChatRoom's deployment options and architecture.

Single Instance Deployment

Docker Compose

services:
  postgres:
    image: postgres:16
    environment:
      POSTGRES_DB: chatroom
      POSTGRES_USER: chatroom
      POSTGRES_PASSWORD: ${DB_PASSWORD}
    volumes:
      - pgdata:/var/lib/postgresql/data

  app:
    build: .
    ports:
      - "8080:8080"
    environment:
      DATABASE_DSN: postgres://chatroom:${DB_PASSWORD}@postgres:5432/chatroom
      JWT_SECRET: ${JWT_SECRET}
    depends_on:
      - postgres

  prometheus:
    image: prom/prometheus
    ports:
      - "9090:9090"
    volumes:
      - ./prometheus.yml:/etc/prometheus/prometheus.yml

volumes:
  pgdata:

Kubernetes Deployment

Key Kubernetes Resources

# Deployment
apiVersion: apps/v1
kind: Deployment
metadata:
  name: chatroom
spec:
  replicas: 3
  template:
    spec:
      containers:
      - name: chatroom
        image: chatroom:latest
        ports:
        - containerPort: 8080
        envFrom:
        - configMapRef:
            name: chatroom-config
        - secretRef:
            name: chatroom-secret
        livenessProbe:
          httpGet:
            path: /healthz
            port: 8080
        readinessProbe:
          httpGet:
            path: /ready
            port: 8080

Horizontal Scaling

Implemented

1. PostgreSQL NOTIFY: Cross-instance message broadcast
2. Session Persistence: ws_sessions table stores online status
3. Stateless API: All instances share the same database

Optional Optimizations

Option	Description
Sticky Sessions	Ensure WebSocket connections route to the same instance
Redis Session	Replace Postgres NOTIFY, higher throughput
Message Queue	Kafka/RabbitMQ for high message volume

Environment Variables

Variable	Default	Description
PORT	8080	HTTP listen port
DATABASE_DSN	-	Database connection string
JWT_SECRET	-	JWT signing secret (must be set in production)
ENV	dev	Runtime environment
ACCESS_TOKEN_TTL_MINUTES	15	Access Token validity period
REFRESH_TOKEN_TTL_DAYS	7	Refresh Token validity period
WS_TICKET_TTL_SECONDS	60	WebSocket Ticket validity period
ALLOWED_ORIGINS	-	CORS whitelist (comma-separated)
POD_ID	-	Instance identifier (distributed scenario)

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