express-pulse 🫀

A lightweight, highly concurrent infrastructure monitoring middleware for Express.js.

express-pulse provides a plug-and-play /health endpoint that pings your underlying databases and caches simultaneously, returning a load-balancer-friendly JSON report. It is built with zero dependency bloat—you bring your own database drivers, and we handle the monitoring.

Features

• Zero Dependency Bloat: We don't install heavy database drivers. You pass in your existing instances.
• Concurrent Execution: Pings all services simultaneously using Promise.all for zero-bottleneck monitoring.
• Failsafe Design: If a database goes down, your server doesn't crash. The endpoint safely reports a down status.
• Extensible Architecture: Easily write your own monitors for custom third-party APIs or SQL databases.

Installation

npm install express-pulse

Quick Start

Initialize the middleware and pass in your active database or cache clients.

import express from 'express';
import { MongoClient } from 'mongodb';
import { expressPulse, MongoMonitor, RedisMonitor } from 'express-pulse';

const app = express();

// 1. Initialize your databases (Native or Mongoose)
const mongoClient = new MongoClient('mongodb://localhost:27017');
mongoClient.connect();

// 2. Attach the middleware
app.use(expressPulse({
    endpoint: '/health', // Optional: defaults to '/health'
    monitors: [
        new MongoMonitor('Primary-DB', mongoClient),
        // new RedisMonitor('Cache', redisClient)
    ]
}));

app.listen(3000, () => console.log('Server is running...'));

Expected Output

When a load balancer, Kubernetes readiness probe, or monitoring tool hits GET /health, it receives:

{
  "status": "ok",
  "timestamp": "2026-05-22T12:39:25.108Z",
  "services": [
    {
      "name": "Primary-DB",
      "status": "up",
      "latency": 54
    }
  ]
}

Available Built-In Monitors

express-pulse includes zero-dependency adapters for the industry's most popular infrastructure. Just pass your existing, initialized client into the constructor.

NoSQL & Caches:

• MongoMonitor (Supports Native MongoDB & Mongoose)
• RedisMonitor (Supports Redis & ioredis)

Relational Databases (SQL):

• PostgresMonitor (pg)
• MysqlMonitor (mysql2)
• MssqlMonitor (mssql)

Message Brokers & Event Streams:

• RabbitMqMonitor (amqplib - safely uses channels)
• KafkaMonitor (kafkajs - cluster metadata ping)

Search Engines & Cloud:

• ElasticsearchMonitor (@elastic/elasticsearch)
• S3Monitor (AWS S3 / Cloud Storage via HEAD requests)

External Services:

• HttpMonitor (Generic REST API monitor via native fetch)

Writing Custom Monitors

Because express-pulse is built using the Strategy Pattern, you can easily monitor anything by implementing the PulseMonitor interface.

import { PulseMonitor, ServiceHealth } from 'express-pulse';

class StripeApiMonitor implements PulseMonitor {
    async check(): Promise<ServiceHealth> {
        const start = performance.now();
        try {
            await fetch('https://api.stripe.com/health');
            return { name: 'Stripe-API', status: 'up', latency: Math.round(performance.now() - start) };
        } catch (error) {
            return { name: 'Stripe-API', status: 'down', latency: 0 };
        }
    }
}

// Add it to your array!
app.use(expressPulse({
    monitors: [new StripeApiMonitor()]
}));

License

MIT