Services

Services group related domains into deployable units with technology specifications and deployment strategies.

Basic Syntax

service UserService {
  contexts: Authentication, Profile
  language: nodejs
  data-stores: user_db
  deployment: rolling
}

Multiple Services Block

services {
  UserService {
    contexts: Authentication, Profile
    language: nodejs
    data-stores: user_db, cache
    deployment: rolling
  }

  OrderService {
    contexts: Order, Payment
    language: java
    data-stores: order_db, payment_db
    deployment: canary(50% -> staging, 100% -> production)
  }
}

Service Properties

domains

Comma-separated list of domains this service handles:

contexts: Authentication, Profile, Settings

language

Programming language or platform:

language: nodejs
language: java
language: python
language: golang
language: rust

data-stores

Databases and storage systems:

data-stores: postgres_db, redis_cache, s3_bucket

deployment

Deployment strategy:

// Simple
deployment: rolling
deployment: blue_green

// With routing rules
deployment: canary(50% -> staging, 100% -> production)

Deployment Strategies

Rolling Deployment

Sequential instance updates:

deployment: rolling

Blue-Green Deployment

Parallel environment switching:

deployment: blue_green

Canary Deployment

Gradual rollout with traffic routing:

deployment: canary(
  10% -> canary-production,
  50% -> staging-production,
  100% -> production
)

Complete Example

services {
  APIGateway {
    contexts: Routing, Authentication
    language: nodejs
    data-stores: gateway_cache
    deployment: rolling
  }

  UserService {
    contexts: Profile, Settings, Preferences
    language: golang
    data-stores: user_db, user_cache
    deployment: canary(50% -> staging, 100% -> production)
  }

  OrderService {
    contexts: Order, Cart, Checkout
    language: java
    data-stores: order_db, order_event_store
    deployment: blue_green
  }

  InventoryService {
    contexts: Inventory, Warehouse
    language: rust
    data-stores: inventory_db
    deployment: rolling
  }
}

Best Practices

Group Related Domains

✅ UserService {
  contexts: Authentication, Profile, Settings
}

❌ MixedService {
  contexts: Authentication, Order, Inventory
}

Choose Appropriate Deployment Strategy

• rolling: Safe, standard deployments
• blue_green: Zero-downtime critical services
• canary: Gradual rollout for risky changes