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Overview

Each service in the distributed notification system uses environment variables for configuration. This page provides a complete reference of all variables, their purposes, and default values.

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Variable Loading Priority

Environment variables are loaded in the following order (highest priority first):
  1. Host environment variables (set in shell or CI/CD)
  2. docker-compose.yml environment section
  3. .env.example files (loaded via env_file)

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API Gateway

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Configuration File

Location: api-gateway/.env.example

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Variables

VariableRequiredDefaultDescription
PORTNo8000HTTP server port
RABBITMQ_URLYesamqp://localhost:5672RabbitMQ connection URL
REDIS_HOSTYeslocalhostRedis server hostname
REDIS_PORTNo6379Redis server port
REDIS_TTLNo300Cache TTL in seconds (5 minutes)
THROTTLE_TTLNo60Rate limit window in seconds
THROTTLE_LIMITNo10Max requests per THROTTLE_TTL window
USER_SERVICE_URLYeshttp://localhost:8081User service base URL
TEMPLATE_SERVICE_URLYeshttp://localhost:8082Template service base URL

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Docker Compose Overrides

environment:
  RABBITMQ_URL: amqp://rabbitmq:5672
  REDIS_HOST: redis
  REDIS_PORT: 6379
  USER_SERVICE_URL: http://user-service:8081
  TEMPLATE_SERVICE_URL: http://template-service:8082
  PORT: 8000

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Example Configuration

Development (.env.example): 
# RabbitMQ Configuration
RABBITMQ_URL=amqp://localhost:5672

# Service URLs
USER_SERVICE_URL=http://localhost:8081
TEMPLATE_SERVICE_URL=http://localhost:8082
Production: 
RABBITMQ_URL=amqp://user:[email protected]:5672
REDIS_HOST=redis-prod.example.com
REDIS_PORT=6379
REDIS_TTL=600
THROTTLE_TTL=60
THROTTLE_LIMIT=100
PORT=8000
USER_SERVICE_URL=http://user-service:8081
TEMPLATE_SERVICE_URL=http://template-service:8082
Never commit production credentials to version control. Use secrets management tools or CI/CD secret injection.

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User Service

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Configuration File

Location: user-service/.env.example

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Variables

VariableRequiredDefaultDescription
PORTNo8081HTTP server port
DB_HOSTYeslocalhostPostgreSQL hostname
DB_PORTNo5432PostgreSQL port
DB_USERNAMEYespostgresDatabase username
DB_PASSWORDYesyour_password_hereDatabase password
DB_DATABASEYesnotification_systemDatabase name
DB_SSL_ENABLEDNofalseEnable SSL/TLS for database connection
DB_CA_CERTNocert-102CA certificate identifier for SSL

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Docker Compose Configuration

env_file:
  - ./user-service/.env.example
  - ./user-service/.env  # Optional production overrides
The service uses environment files directly. Database connection can be overridden in the environment section (currently commented out).

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Example Configuration

Development (.env.example): 
# Server Configuration
PORT=8081

# Database Configuration
DB_HOST=localhost
DB_PORT=5432
DB_USERNAME=postgres
DB_PASSWORD=your_password_here
DB_DATABASE=notification_system
DB_SSL_ENABLED=false
DB_CA_CERT=cert-102
Production: 
PORT=8081
DB_HOST=postgres-prod.example.com
DB_PORT=5432
DB_USERNAME=notif_user
DB_PASSWORD=<strong-random-password>
DB_DATABASE=notification_system
DB_SSL_ENABLED=true
DB_CA_CERT=/path/to/ca-certificate.pem
Security Critical: Always change DB_PASSWORD from the default value. Use a strong, randomly generated password (minimum 32 characters).

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Template Service

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Configuration File

Location: Template service uses direct environment configuration in docker-compose.yml

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Variables

VariableRequiredDefaultDescription
PORTNo8002HTTP server port (FastAPI)
Database connection variables inherit from PostgreSQL service configuration

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Docker Compose Configuration

template-service:
  build:
    context: ./template-service
    dockerfile: Dockerfile
  ports:
    - "8002:8002"
  depends_on:
    - postgres
Template service connects to the same PostgreSQL database as the user service.

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Example Configuration

Production: Add environment section to docker-compose for production: 
environment:
  DATABASE_URL: postgresql://postgres:password@postgres:5432/notification_db
  PORT: 8002

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Email Service

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Configuration File

Location: email-service/EmailService/.env.example

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Variables

VariableRequiredDefaultDescription
PORTNo8080HTTP server port
RABBITMQ_HOSTYesrabbitmqRabbitMQ hostname
RABBITMQ_USERYesguestRabbitMQ username
RABBITMQ_PASSYesguestRabbitMQ password
RABBITMQ_EXCHANGEYesnotifications.directExchange name for routing
RABBITMQ_EMAIL_QUEUEYesemail.queueQueue name for email tasks
RABBITMQ_FAILED_QUEUEYesfailed.queueQueue name for failed notifications
REDIS_HOSTYesredisRedis server hostname
USER_SERVICE_URLYeshttp://user_service:80User service base URL
TEMPLATE_SERVICE_URLYeshttp://template_service:80Template service base URL
SMTP_HOSTYesmailhogSMTP server hostname
SMTP_PORTNo1025SMTP server port
SMTP_FROMYes[email protected]Sender email address
SMPT_USERNo(empty)SMTP authentication username
SMPT_PASSNo(empty)SMTP authentication password

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Docker Compose Overrides

environment:
  RABBITMQ_HOST: rabbitmq
  RABBITMQ_USER: guest
  RABBITMQ_PASS: guest
  RABBITMQ_EXCHANGE: notifications.direct
  RABBITMQ_EMAIL_QUEUE: email.queue
  RABBITMQ_FAILED_QUEUE: failed.queue
  REDIS_HOST: redis
  USER_SERVICE_URL: http://user-service:8081
  TEMPLATE_SERVICE_URL: http://template-service:8082
  SMTP_HOST: mailhog
  SMTP_PORT: 1025
  SMTP_FROM: [email protected]
  PORT: 8080

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Example Configuration

Development (.env.example): 
RABBITMQ_HOST=rabbitmq
RABBITMQ_USER=guest
RABBITMQ_PASS=guest
RABBITMQ_EXCHANGE=notifications.direct
RABBITMQ_EMAIL_QUEUE=email.queue
RABBITMQ_FAILED_QUEUE=failed.queue

REDIS_HOST=redis

USER_SERVICE_URL=http://user_service:80
TEMPLATE_SERVICE_URL=http://template_service:80

SMTP_HOST=mailhog
SMTP_PORT=1025
SMTP_FROM=[email protected]

SMPT_USER=
SMPT_PASS=

PORT=8080
Production (with SendGrid): 
RABBITMQ_HOST=rabbitmq-prod.example.com
RABBITMQ_USER=email_service_user
RABBITMQ_PASS=<strong-password>
RABBITMQ_EXCHANGE=notifications.direct
RABBITMQ_EMAIL_QUEUE=email.queue
RABBITMQ_FAILED_QUEUE=failed.queue

REDIS_HOST=redis-prod.example.com

USER_SERVICE_URL=http://user-service:8081
TEMPLATE_SERVICE_URL=http://template-service:8082

SMTP_HOST=smtp.sendgrid.net
SMTP_PORT=587
SMTP_FROM=[email protected]
SMPT_USER=apikey
SMPT_PASS=<sendgrid-api-key>

PORT=8080
Security Critical: In production, replace MailHog with a real SMTP provider and use secure credentials. Never use empty SMTP credentials in production.

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Push Service

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Configuration File

Location: push-service/.env.example

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Variables

VariableRequiredDefaultDescription
PORTNo8004HTTP server port
RABBITMQ_URLYesamqp://localhost:5672RabbitMQ connection URL
USER_SERVICE_URLYeshttp://localhost:8081User service base URL
TEMPLATE_SERVICE_URLYeshttp://localhost:8082Template service base URL
MOCK_PUSH_TOKENNoyour_mock_fcm_token_hereMock FCM token for testing
USER_FALLBACK_ON_ERRORNotrueFallback if user service unavailable
TEMPLATE_FALLBACK_ON_ERRORNotrueFallback if template service unavailable
FIREBASE_PROJECT_IDYes*your_firebase_project_idFirebase project identifier
FIREBASE_CLIENT_EMAILYes*your_firebase_client_emailFirebase service account email
FIREBASE_PRIVATE_KEYYes*your_firebase_private_key_hereFirebase service account private key
*Required for production push notifications

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Docker Compose Overrides

environment:
  RABBITMQ_URL: amqp://rabbitmq:5672
  USER_SERVICE_URL: http://user-service:8081
  TEMPLATE_SERVICE_URL: http://template-service:8082
  PORT: 8004

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Example Configuration

Development (.env.example): 
# RabbitMQ Configuration
RABBITMQ_URL=amqp://localhost:5672

# Service URLs
USER_SERVICE_URL=http://localhost:8081
TEMPLATE_SERVICE_URL=http://localhost:8082

# Server Configuration
PORT=8004

# Mock Configuration (for testing)
MOCK_PUSH_TOKEN=your_mock_fcm_token_here
USER_FALLBACK_ON_ERROR=true
TEMPLATE_FALLBACK_ON_ERROR=true

# Firebase Configuration
FIREBASE_PROJECT_ID=your_firebase_project_id
FIREBASE_CLIENT_EMAIL=your_firebase_client_email
FIREBASE_PRIVATE_KEY=your_firebase_private_key_here
Production: 
RABBITMQ_URL=amqp://push_service:[email protected]:5672
USER_SERVICE_URL=http://user-service:8081
TEMPLATE_SERVICE_URL=http://template-service:8082
PORT=8004

MOCK_PUSH_TOKEN=
USER_FALLBACK_ON_ERROR=false
TEMPLATE_FALLBACK_ON_ERROR=false

FIREBASE_PROJECT_ID=prod-notification-system
FIREBASE_CLIENT_EMAIL=firebase-adminsdk-xyz@prod-notification-system.iam.gserviceaccount.com
FIREBASE_PRIVATE_KEY="-----BEGIN PRIVATE KEY-----\nMIIE...\n-----END PRIVATE KEY-----\n"
Security Critical: Firebase private keys must be kept secure. Use secret management systems (AWS Secrets Manager, HashiCorp Vault, etc.) in production. Never commit these keys to version control.

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Infrastructure Services

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RabbitMQ

VariableRequiredDefaultDescription
RABBITMQ_DEFAULT_USERNoguestDefault username
RABBITMQ_DEFAULT_PASSNoguestDefault password
Docker Compose: 
environment:
  RABBITMQ_DEFAULT_USER: ${RABBITMQ_USER:-guest}
  RABBITMQ_DEFAULT_PASS: ${RABBITMQ_PASS:-guest}

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PostgreSQL

VariableRequiredDefaultDescription
POSTGRES_USERNopostgresDatabase superuser
POSTGRES_PASSWORDYesyour_password_hereSuperuser password
POSTGRES_DBNonotification_dbInitial database name
Docker Compose: 
environment:
  POSTGRES_USER: ${POSTGRES_USER:-postgres}
  POSTGRES_PASSWORD: ${POSTGRES_PASSWORD:-your_password_here}
  POSTGRES_DB: ${POSTGRES_DB:-notification_db}
Security Critical: Change POSTGRES_PASSWORD immediately. Default passwords are a major security vulnerability.

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Redis

Redis container uses default configuration with no authentication. For production: 
command: redis-server --requirepass your-redis-password
Update all services to use: 
REDIS_PASSWORD=your-redis-password

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CI/CD Secrets

GitHub Actions workflows reference these secrets:
SecretUsed ByPurpose
USER_DB_USERCI/CDDatabase username for tests
USER_DB_PASSCI/CDDatabase password for tests
USER_DB_NAMECI/CDTest database name
TEMPLATE_DB_NAMECI/CDTemplate database name
RABBITMQ_URLCI/CDRabbitMQ connection for tests
REDIS_HOSTCI/CDRedis hostname for tests
REDIS_PORTCI/CDRedis port for tests
Configure these in GitHub repository settings: Settings → Secrets and variables → Actions

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Security Best Practices

Never commit sensitive values to version control
  • Use .env files (add to .gitignore)
  • Use secret management tools in production
  • Rotate credentials regularly
Use strong passwords
  • Minimum 32 characters for database passwords
  • Use cryptographically random generators
  • Different passwords for each service
Principle of least privilege
  • Create dedicated database users per service
  • Grant only necessary permissions
  • Use read-only users where applicable
Enable encryption in transit
  • Use TLS for database connections (DB_SSL_ENABLED=true)
  • Use amqps:// for RabbitMQ in production
  • Use rediss:// for Redis with TLS

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Environment Variable Templates

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Development Setup

Create a .env file in the project root: 
# RabbitMQ
RABBITMQ_USER=guest
RABBITMQ_PASS=guest

# PostgreSQL
POSTGRES_USER=postgres
POSTGRES_PASSWORD=dev_password
POSTGRES_DB=notification_db

# Redis
REDIS_HOST=redis
REDIS_PORT=6379

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Production Setup

Use environment-specific files: 
# .env.production
RABBITMQ_USER=prod_rabbitmq_user
RABBITMQ_PASS=<vault:secret/rabbitmq/password>

POSTGRES_USER=prod_db_user
POSTGRES_PASSWORD=<vault:secret/postgres/password>
POSTGRES_DB=notification_db

REDIS_HOST=redis-cluster.example.com
REDIS_PORT=6379
REDIS_PASSWORD=<vault:secret/redis/password>

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Validation

Verify all environment variables are set correctly: 
# Check service configuration
docker compose config

# Verify a specific service
docker compose config api-gateway

# Check environment variables in running container
docker compose exec api-gateway env | grep RABBITMQ
Use docker compose config to debug environment variable substitution issues. It shows the final configuration after all variable replacements.

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