Effect CQRS + Event Sourcing Template

A production-ready TypeScript template implementing CQRS (Command Query Responsibility Segregation) and Event Sourcing patterns using Domain-Driven Design (DDD) and Hexagonal Architecture. Built with Effect and Nx.

🎯 What is This?

This is a template project demonstrating:

• ✅ DDD - Domain-Driven Design with bounded contexts
• ✅ CQRS - Separate write (commands) and read (queries) models
• ✅ Event Sourcing - Complete audit trail of state changes
• ✅ Hexagonal Architecture - Pluggable adapters for infrastructure
• ✅ Clean Architecture - Testable, maintainable, technology-agnostic
• ✅ Type Safety - Full TypeScript with Effect for typed error handling

Perfect for building scalable, maintainable event-driven applications.

🚀 Quick Start

Fastest Option: Docker (Recommended)

# Clone the repository
git clone <repo-url>
cd create-node-ddd-app

# Start with in-memory adapters (fastest)
./docker.sh dev

# Or start with PostgreSQL (event store + projections)
./docker.sh postgres

# View all available commands
./docker.sh

The API will be available at:

• Dev mode: http://localhost:3000
• PostgreSQL: http://localhost:3002

Visit /docs for interactive Swagger API documentation.

Local Development

# Install dependencies
pnpm install

# Build the application
pnpm nx run runner:build

# Run the application
node apps/runner/dist/index.js

Expected output (abridged):

🔧 Application Configuration:
  ├─ Environment: development
  ├─ Event Store: memory
  ├─ Event Bus: memory
  ├─ Auth Provider: memory
  ├─ Telemetry: noop
  ├─ Projections:
  │   └─ PostListView: memory
  └─ Servers:
      ├─ HTTP REST: enabled (port 3000)
      ├─ Web SSR: enabled (port 3001)
      ├─ gRPC: disabled
      └─ WebSocket: disabled

✅ Runner: Application started successfully
🚀 CQRS + Event Sourcing architecture active
   🌐 REST API: http://localhost:3000
   📚 Swagger Docs: http://localhost:3000/docs

With zero configuration, the runner seeds a canonical in-memory PostListView projection (set PROJECTION_DEFAULT=none to opt out).

📋 Table of Contents

Core Documentation

• docs/SETUP.md - Complete setup and development guide
• docs/ARCHITECTURE.md - System design and patterns
• docs/TESTING.md - Testing strategy and execution
• docs/SECURITY.md - Security guidelines
• docs/TELEMETRY.md - Observability with SigNoz

Product & Planning

• docs/product/VISION.md - Product vision and goals
• docs/product/ROADMAP.md - Development roadmap
• docs/product/user-stories/ - Feature requirements

Architecture Decisions

• docs/decisions/ - Architecture Decision Records (ADRs)
• docs/rfcs/ - Request for Comments

For LLM Agents

• CLAUDE.md - LLM-specific navigation and rules

🔄 CQRS + Event Sourcing Flow

┌─────────────┐
│   Client    │
└──────┬──────┘
       │
       ▼
┌─────────────────────────────────────┐
│    REST API (port 3000)              │
│  Commands       │       Queries      │
└────────┬────────┴────────┬───────────┘
         │                 │
         ▼                 ▼
┌──────────────────┐  ┌──────────────┐
│  Write Model     │  │  Read Model  │
│ (PostService)    │  │(QueryDB)     │
│      ↓           │  │      ↑       │
│  EventStore ─────┼──┼─→ Projector  │
└──────────────────┘  └──────────────┘
         │                 ▲
         └───────────────┬─┘
               EventBus
          (Effect Queue)

💾 API Examples

Create a Post (Command)

curl -X POST http://localhost:3000/posts \
  -H "Content-Type: application/json" \
  -d '{
    "aggregateId": "post-001",
    "userId": "user-123",
    "title": "My First Post",
    "content": "Testing CQRS and Event Sourcing!"
  }'

Get a Post (Query)

curl http://localhost:3000/posts/post-001

List All Posts (Query)

curl http://localhost:3000/posts

Publish a Post (Command)

curl -X POST http://localhost:3000/posts/post-001/publish

🏗️ Architecture at a Glance

packages/
├── domain/
│   ├── shared-kernel/          # Core domain primitives (zero dependencies)
│   ├── debate-domain/          # Post aggregate, events, commands, queries
│   └── auth-domain/            # Authentication models
├── application/
│   ├── app/                    # Cross-cutting ports, API definitions, error mapping
│   ├── debate-application/     # PostService, PostProjector, contract tests
│   └── auth-application/       # AuthService, AuthorizationService
└── infrastructure/
    ├── eventstore-inmemory-adapter/   # Event persistence (dev/test)
    ├── eventstore-postgres-adapter/   # Event persistence (production)
    ├── database-inmemory-adapter/     # CQRS read model (dev/test)
    ├── database-postgres-adapter/     # CQRS read model (production)
    ├── event-queue-adapter/           # Event bus (Effect Queue)
    ├── http-rest-adapter/             # REST API + Swagger
    └── ...                            # auth, telemetry, grpc, websocket, web-ssr

apps/
└── runner/                     # Composition root (wires everything)

Key Principle: Domain is stable. Infrastructure is replaceable. Runner is sacrificial.

🔧 Configuration

The application is configured via environment variables:

# Event persistence (write model)
EVENT_STORE=memory              # memory, postgres (eventstoredb: planned)

# Async event distribution
EVENT_BUS=memory                # memory (rabbitmq, kafka: planned)

# Read model projections (one block per projection)
# Zero-config boots a canonical in-memory PostListView projection.
PROJECTION_DEFAULT=memory                # memory, postgres, none (opt out of seeding)
PROJECTION_POST_LIST_VIEW_TYPE=memory    # memory, postgres (mongodb: planned)
# For postgres: PROJECTION_POST_LIST_VIEW_HOST / _PORT / _DATABASE / _USER / _PASSWORD

# Server configuration
HTTP_ENABLED=true
HTTP_PORT=3000
GRPC_ENABLED=false
GRPC_PORT=50051
WEBSOCKET_ENABLED=false
WEBSOCKET_PORT=8080

# Telemetry
TELEMETRY_PROVIDER=noop         # noop, signoz

See SETUP.md for detailed configuration guide.

🧪 Testing

# Run all tests
pnpm nx run-many -t test

# Run tests for a specific package
pnpm nx run debate-domain:test

# Run tests with coverage
pnpm nx run shared-kernel:test:coverage

# End-to-end tests
pnpm test:e2e

See TESTING.md for the testing strategy (contract tests, integration tests, coverage expectations per package).

📦 Build and Deploy

Build

pnpm nx run-many -t build

Docker

# Development
./docker.sh dev

# Production setup with PostgreSQL
./docker.sh postgres

# Infrastructure only (for local Node.js debugging)
./docker.sh infra postgres mongodb

See SETUP.md for complete Docker documentation.

🎓 Learning Resources

For Architects

Start with ARCHITECTURE.md to understand:

• System design philosophy
• Design patterns used
• Dependency management
• Why each architectural decision was made

For Developers

Start with SETUP.md to:

• Get your environment running
• Understand the development workflow
• Learn Docker setup and commands
• Configure environment variables

For QA Engineers

See TESTING.md for:

• How to run tests
• Testing strategies
• API endpoint testing examples
• CQRS flow verification

🛠️ Common Tasks

Run the app locally with debugger

# Terminal 1: Start infrastructure
./docker.sh infra postgres

# Terminal 2: Generate environment config
./docker.sh env:local

# Terminal 3: Build and run with inspector
pnpm nx run runner:build
node --inspect apps/runner/dist/index.js

# Connect debugger in Chrome: chrome://inspect

Test multiple adapters

# In-memory (no infrastructure needed)
pnpm nx run-many -t test

# PostgreSQL setup (integration tests)
./docker.sh infra postgres
pnpm nx run-many -t test

# SigNoz observability
./docker.sh infra postgres signoz
# View traces at http://localhost:3301

Add a new feature

1. Define domain logic in packages/domain/
2. Define application services and ports in packages/application/
3. Implement adapter in packages/infrastructure/ if needed
4. Wire in apps/runner/src/lib/factories.ts

🐛 Troubleshooting

Port Already in Use

HTTP_PORT=4000 node apps/runner/dist/index.js

"Adapter Not Implemented" Error

Use in-memory adapters:

EVENT_STORE=memory EVENT_BUS=memory PROJECTION_DEFAULT=memory node apps/runner/dist/index.js

Docker Issues

# Clean up everything
./docker.sh clean

# Check service health
./docker.sh health

# View logs
./docker.sh logs

📚 Additional Documentation

All documentation is organized under the docs/ folder:

Category	Description
docs/ARCHITECTURE.md	System design, patterns, principles
docs/TESTING.md	Testing strategy and execution
docs/SETUP.md	Development setup and environment
docs/SECURITY.md	Security guidelines
docs/TELEMETRY.md	Observability with SigNoz
docs/decisions/	Architecture Decision Records
docs/rfcs/	Request for Comments
docs/product/	Vision, roadmap, user stories
docs/templates/	Document templates (RFC, ADR, LOG)
docs/logs/	Operational logs
docs/archive/	Historical documentation
docker/README.md	Docker reference

🤝 Contributing

Contributions welcome! Please ensure:

• Architecture principles are maintained
• Tests pass and coverage doesn't decrease
• Documentation is updated
• Commits follow the project style

📄 License

MIT © Riccardo Agnoletto — see ADR-2026-07-06-repository-license.

Projects generated with create-node-ddd-app are yours: no attribution or license obligation attaches to scaffolded output.

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Built with ❤️ using Effect, Nx, and TypeScript