API Metrics System

A lightweight middleware for gathering and displaying API metrics.

Features

• Express Middleware: Track request method, URL, status code, response time, user agent, IP, and more.
• Elasticsearch Storage: Persist metrics to Elasticsearch for querying.
• Metrics Dashboard: Built-in Express dashboard to visualize metrics over time.
• CLI Tool: Quick config initialization.

Prerequisites

• Node.js 18+
• Elasticsearch 8.x running locally or remotely

Installation

npm install api-metrics-system

Configuration

Initialize the config file in your project:

npx api-metrics-system init

Edit config/ams.json:

{
  "dashboardPort": 4322,
  "elastic": {
    "enable": true,
    "node": "http://localhost:9200",
    "username": "elastic",
    "password": "elastic",
    "index": "ams"
  }
}

Usage

import express from 'express';
import { setTracking, startTracking, loadDashboard } from 'api-metrics-system';

const app = express();
app.use(express.json());


// Use the middleware on routes you want to track
app.get('/api/users', setTracking, (req, res) => {
  res.json({ users: [] });
});

app.listen(3000, async() =>{
  // Initialize clients (call once at startup)
    await startTracking();

  // Optional: start the metrics dashboard
    await loadDashboard();
});

Metrics Dashboard

Access the dashboard at http://localhost:<dashboardPort> (default: 4322).

API Endpoint

GET /api/v1/metrics

Query Parameters:

| Parameter | Description | |-----------|-------------| | preset | Time range preset: 1h, 24h, 7d, 30d | | from | ISO date string (requires to) | | to | ISO date string (requires from) |

Example:

GET /api/v1/metrics?preset=24h
GET /api/v1/metrics?from=2024-01-01T00:00:00Z&to=2024-01-02T00:00:00Z

Response:

{
  "appliedFilter": { "from": "...", "to": "..." },
  "hitsOverTime": [{ "timestamp": "...", "count": 150 }],
  "statusDistribution": [{ "status": "200", "count": 120 }],
  "slowestEndpoints": [{ "url": "/api/users", "avgResponseTimeMs": 45 }],
  "mostHitEndpoints": [{ "url": "/api/users", "count": 200 }],
  "errorRate": 2.5
}

CLI Commands

api-metrics-system init     # Initialize config/ams.json in current directory

License

ISC