Node Consul Service

A robust Node.js service that integrates with HashiCorp Consul for service discovery and configuration management. This service provides a comprehensive solution for managing distributed systems and microservices architecture, making it easier to handle service communication, health checks, and configuration management in a distributed environment.

Table of Contents

• Features
• Prerequisites
• Installation
• Initialization
• API Documentation
• Examples
• Contributing
• License

Features

• Service Registration & Discovery: Automatically register and discover services in your distributed system
• Health Checking: Built-in health check mechanisms for service monitoring
• Service Communication: Simplified inter-service communication with automatic load balancing
• Service Instance Management: Easy management of multiple service instances
• Data Linking: Efficient data aggregation and linking across services
• Caching Support: Optional caching mechanism for improved performance

Prerequisites

• Node.js (v14 or higher)
• HashiCorp Consul server
• npm or yarn package manager

Installation

# Using npm
npm install node-consul-service

# Using yarn
yarn add node-consul-service

Initialization

Service Initialization

Before using any functions from the library, you must initialize the client first. You can initialize the client by passing configuration options:

const { initClient } = require('node-consul-service');

await initClient({
  host: 'localhost',
  port: 8500,
  secure: false,
  token: 'your-token',           // Optional
  datacenter: 'dc1',            // Optional
  retryAttempts: 3,             // Number of connection retry attempts
  retryDelay: 1000              // Delay between retries in milliseconds
});

Initialization Features

• Automatic Retry: Attempts to connect multiple times on failure
• Connection Verification: Verifies successful connection before proceeding
• State Management: Tracks initialization state to prevent multiple initializations
• Error Handling: Clear and helpful error messages

Complete Usage Example

const { initClient, registerService } = require('node-consul-service');

async function startService() {
  try {
    // Initialize client
    await initClient({
      host: 'localhost',
      port: 8500,
      retryAttempts: 3
    });

    // Register service
    await registerService({
      name: 'my-service',
      id: 'my-service-1',
      port: 3000
    });

    console.log('✅ Service started successfully');
  } catch (error) {
    console.error('❌ Failed to start service:', error);
    process.exit(1);
  }
}

startService();

API Documentation

Core Functions

Service Registration

const { registerService } = require('node-consul-service');

await registerService({
  name: 'service-name',
  id: 'service-id',
  port: 3000,
  address: 'localhost',
  check: {
    name: 'service health check',
    http: 'http://localhost:3000/health',
    interval: '10s',
    timeout: '5s',
    deregistercriticalserviceafter: '1m'
  }
});

Service Communication

const { callService } = require('node-consul-service');

// Simple GET request
const result = await callService('service-name', '/endpoint');

// POST request with data
const response = await callService('service-name', {
  method: 'POST',
  path: '/endpoint',
  data: { key: 'value' }
});

Service Discovery

const { 
  listServices,
  getServiceInstances,
  getRandomServiceInstance 
} = require('node-consul-service');

// List all registered services
const services = await listServices();

// Get all instances of a specific service
const instances = await getServiceInstances('service-name');

// Get a random instance of a service
const instance = await getRandomServiceInstance('service-name');

Data Linking

The dataLink function provides a powerful way to aggregate and link data from multiple services efficiently.

const { dataLink } = require('node-consul-service');

const data = [
  { userId: '123', name: 'John' },
  { userId: '456', name: 'Jane' }
];

const schema = [
  {
    Field: 'userId',           // Field name in the original data
    service: 'user-service',   // Target service name
    path: '/api/users/batch',  // API endpoint path
    cacheGetter: async (ids) => {
      // Optional function to get data from cache
      return await cache.getUsers(ids);
    }
  }
];

const result = await dataLink(data, schema);

Schema Properties

• Field: Field name in the original data that contains the identifier
• service: Name of the service to be called
• path: API endpoint path in the target service
• cacheGetter: Optional function to get data from cache before calling the service

Examples

Basic Service Setup

const { registerService, callService } = require('node-consul-service');

// Register your service
await registerService({
  name: 'my-service',
  id: 'my-service-1',
  port: 3000,
  address: 'localhost',
  check: {
    http: 'http://localhost:3000/health',
    interval: '10s'
  }
});

// Call another service
const response = await callService('other-service', '/api/data');

Advanced Data Linking

const { dataLink } = require('node-consul-service');

// Complex data linking example
const orders = [
  { orderId: '1', userId: '123', productId: 'P1' },
  { orderId: '2', userId: '456', productId: 'P2' }
];

const schema = [
  {
    Field: 'userId',
    service: 'user-service',
    path: '/api/users/batch'
  },
  {
    Field: 'productId',
    service: 'product-service',
    path: '/api/products/batch'
  }
];

const enrichedOrders = await dataLink(orders, schema);

Contributing

We welcome contributions! Please feel free to submit a Pull Request. For major changes, please open an issue first to discuss what you would like to change.

1. Fork the repository
2. Create your feature branch (git checkout -b feature/amazing-feature)
3. Commit your changes (git commit -m 'Add some amazing feature')
4. Push to the branch (git push origin feature/amazing-feature)
5. Open a Pull Request

License

This project is licensed under the MIT License - see the LICENSE file for details.