Example DDD/EDA NestJS application with OpenTelemetry tracing, Prometheus metrics and Grafana dashboards

Getting Started Guide

Prerequisites

• Node.js (v18 or later)
• Docker and Docker Compose
• npm or yarn

Setup and Installation

1. Clone the repository

git clone https://github.com/AndreyShashlovDev/eda-otel-grafana.git
cd eda-otel-grafana

2. Install dependencies

npm install

3. Start the infrastructure services

# Start Kafka, PostgreSQL, Prometheus, Grafana and Jaeger
docker-compose up -d

4. Configure environment variables

Ensure the config/development.env file exists with the following variables:

NODE_ENV=development
API_PORT=3000
API_HOST=localhost
KAFKA_BROKERS=localhost:29092
KAFKA_CLIENT_ID=eda-shop-app
KAFKA_GROUP_ID=eda-shop-group
DB_HOST=localhost
DB_PORT=5433
DB_USERNAME=user
DB_PASSWORD=password
DB_DATABASE=orders_db

5. Start the application services

# In one terminal - start the API Gateway
npm run start:dev api-gateway

# In another terminal - start the Order Service
npm run start:dev order-service

Monitoring and Observability

• Kafka UI: http://localhost:8080
• Jaeger UI (Distributed Tracing): http://localhost:16686
• Grafana (Dashboards): http://localhost:3001 (user: admin, password: admin)
• Prometheus (Metrics): http://localhost:9090

Testing the API

Create a new order:

curl -X POST http://localhost:3000/orders \
  -H "Content-Type: application/json" \
  -d '{
    "userId": "user123",
    "items": [
      {
        "productId": "prod-1",
        "name": "Sample Product",
        "price": 99.99,
        "quantity": 1
      }
    ],
    "total": 99.99
  }'

Get an order (replace order-id with an actual ID):

curl http://localhost:3000/orders/order-id

Project Structure

• apps/api-gateway: Frontend API for client requests
• apps/order-service: Microservice for order processing
• libs/common: Shared code, DTOs, and entities
• libs/telemetry: OpenTelemetry configuration and utilities
• config: Environment configuration files
• docker-compose.yml: Infrastructure service definitions

Architecture

This project demonstrates:

• Domain-Driven Design (DDD) principles
• Event-Driven Architecture (EDA) with Kafka
• Distributed tracing with OpenTelemetry
• Metrics collection with Prometheus
• Visualization with Grafana dashboards