Configuration Overview
The distributed notification system requires proper configuration of messaging, caching, and database infrastructure. This guide covers the setup and configuration of each component.
RabbitMQ Setup
RabbitMQ serves as the message broker for asynchronous communication between services.
Container Configuration
rabbitmq:
image: rabbitmq:3.11-management
container_name: rabbitmq
environment:
RABBITMQ_DEFAULT_USER: ${RABBITMQ_USER:-guest}
RABBITMQ_DEFAULT_PASS: ${RABBITMQ_PASS:-guest}
ports:
- "5673:5672" # AMQP protocol
- "15673:15672" # Management UI
volumes:
- rabbitmq_data:/var/lib/rabbitmq
restart: unless-stopped
healthcheck:
test: ["CMD", "rabbitmq-diagnostics", "ping"]
interval: 5s
timeout: 10s
retries: 5
start_period: 10s
Exchanges and Queues
The system uses a direct exchange pattern:
| Component | Name | Type | Purpose |
|---|
| Exchange | notifications.direct | Direct | Routes messages to specific queues based on routing keys |
| Queue | email.queue | Durable | Stores email notification tasks |
| Queue | failed.queue | Durable | Stores failed notification attempts for retry |
| Queue | push.queue | Durable | Stores push notification tasks |
Routing Keys
email.created -> email.queue
push.created -> push.queue
*.failed -> failed.queue
Connection URLs
Internal (Docker network):
External (host machine):
Management UI
Access the RabbitMQ management interface:
http://localhost:15673
Username: guest
Password: guest
Change default credentials in production deployments. The guest/guest credentials should only be used for local development.
Service Integration
Email Service Configuration:
RABBITMQ_HOST=rabbitmq
RABBITMQ_USER=guest
RABBITMQ_PASS=guest
RABBITMQ_EXCHANGE=notifications.direct
RABBITMQ_EMAIL_QUEUE=email.queue
RABBITMQ_FAILED_QUEUE=failed.queue
RABBITMQ_URL=amqp://rabbitmq:5672
Redis Configuration
Redis provides caching and rate limiting capabilities.
Container Configuration
redis:
image: redis:7-alpine
container_name: redis
ports:
- "6379:6379"
volumes:
- redis_data:/data
restart: unless-stopped
Connection Details
Internal (Docker network):
External (host machine):
Host: localhost
Port: 6379
Usage Patterns
| Service | Use Case | TTL |
|---|
| API Gateway | Response caching | 300s (5 minutes) |
| API Gateway | Rate limiting | 60s (1 minute) |
| Email Service | Template caching | Variable |
| User Service | User preference caching | Variable |
Service Integration
REDIS_HOST=redis
REDIS_PORT=6379
REDIS_TTL=300
Persistence
Redis data is persisted to the redis_data volume. By default, Redis uses RDB snapshots:
- Snapshots created every 60s if at least 1000 keys changed
- Snapshots created every 300s if at least 100 keys changed
- Snapshots created every 900s if at least 1 key changed
PostgreSQL Setup
PostgreSQL serves as the primary database for user and template data.
Container Configuration
postgres:
image: postgres:15
environment:
POSTGRES_USER: ${POSTGRES_USER:-postgres}
POSTGRES_PASSWORD: ${POSTGRES_PASSWORD:-your_password_here}
POSTGRES_DB: ${POSTGRES_DB:-notification_db}
ports:
- "5432:5432"
volumes:
- pgdata:/var/lib/postgresql/data
restart: unless-stopped
Database Schema
The system creates a single database (notification_db) with separate schemas for each service:
- User Service: User accounts, preferences, notification settings
- Template Service: Notification templates, variables, metadata
Connection Details
Internal (Docker network):
Host: postgres
Port: 5432
Database: notification_db
User: postgres
Password: your_password_here
Host: localhost
Port: 5432
Database: notification_db
User: postgres
Password: your_password_here
SSL Configuration
For production deployments, enable SSL/TLS:
DB_SSL_ENABLED=true
DB_CA_CERT=/path/to/ca-cert.pem
The default password your_password_here MUST be changed for production deployments. Use strong, randomly generated passwords.
Service Integration
User Service:
DB_HOST=postgres
DB_PORT=5432
DB_USERNAME=postgres
DB_PASSWORD=your_password_here
DB_DATABASE=notification_system
DB_SSL_ENABLED=false
MailHog Setup
MailHog is an SMTP testing tool for local development.
Container Configuration
mailhog:
image: mailhog/mailhog
container_name: mailhog
ports:
- "1025:1025" # SMTP server
- "8025:8025" # Web UI
restart: unless-stopped
Access Points
SMTP Server:
Host: mailhog (or localhost)
Port: 1025
Authentication: None
Email Service Integration
For production, replace MailHog with a real SMTP provider (SendGrid, AWS SES, etc.) and configure proper credentials.
Service Dependencies
The depends_on configuration ensures proper startup order:
Dependency Graph
Startup Order
- Infrastructure (postgres, redis, rabbitmq, mailhog) - Start first
- Data Services (user-service, template-service) - Wait for postgres
- Gateway Services (api-gateway, email-service, push-service) - Wait for all dependencies
Health Check Dependencies
The email service uses a health check dependency:
email-service:
depends_on:
rabbitmq:
condition: service_healthy
redis:
condition: service_started
mailhog:
condition: service_started
- Email service waits for RabbitMQ health check to pass
- Starts after Redis and MailHog containers are running
- Prevents connection failures during startup
Add health checks to all services in production for better orchestration and automatic recovery.
Configuration Files
Each service loads configuration from:
.env.example files (loaded via env_file)environment section (overrides .env.example)- Host environment variables (highest priority)
Priority Order
Host ENV variables > docker-compose environment > .env.example
Development vs Production
Create separate .env files for different environments:
# Development
user-service/.env.development
# Production
user-service/.env.production
docker-compose.yml to use the appropriate file:
env_file:
- ./user-service/.env.production
Monitoring and Debugging
Check Service Health
# Check all containers
docker compose ps
# Inspect specific service
docker compose logs -f email-service
# Check RabbitMQ queues
docker exec rabbitmq rabbitmqctl list_queues
# Check Redis keys
docker exec redis redis-cli KEYS '*'
# Connect to PostgreSQL
docker exec -it postgres psql -U postgres -d notification_db
Common Configuration Issues
| Issue | Symptom | Solution |
|---|
| Service can’t connect to RabbitMQ | Connection refused errors | Wait for RabbitMQ health check, verify RABBITMQ_URL |
| Redis connection timeout | Cache misses, timeout errors | Check REDIS_HOST and REDIS_PORT |
| PostgreSQL authentication failed | Login errors | Verify DB_USERNAME and DB_PASSWORD |
| Email service crashes on startup | Immediate restart loop | Check all required environment variables are set |
Always verify service connectivity before deploying. Use docker compose logs to debug startup issues.