HTTP Client with Metrics

This repository provides a simple yet powerful HTTP client for making requests, measuring performance, and recording metrics for observability. The implementation includes support for custom headers, URL templating, and Prometheus metrics.

Features

• Customizable HTTP requests with support for all common HTTP methods.
• Metrics tracking for request counts, durations, and stage-specific timings.
• URL templating for dynamic path construction.
• Error handling with structured response objects.
• Memoization for efficient URL template parsing.

Table of Contents

• Installation
• Usage
  • Creating an HTTP Client
  • Making Requests
  • Metrics Integration

Installation

Install the dependencies using npm:

npm install

Usage

Creating an HTTP Client

Create an instance of HTTPClient with a base URL and default headers:

import { HTTPClient } from "./index";

const client = new HTTPClient({
  baseUrl: "https://api.example.com",
  headers: {
    Authorization: "Bearer YOUR_API_KEY",
  },
});

Making Requests

Use the request method to send HTTP requests. Supported methods include GET, POST, PUT, DELETE, and more.

(async () => {
  try {
    const result = await client.request("GET", "/users/{id}", { id: 123 });
    console.log(result);
  } catch (error) {
    console.error("Request failed:", error);
  }
})();

Metrics Integration

The metrics.ts file provides Prometheus-compatible metrics tracking for HTTP requests. To register the metrics with your Prometheus client, use the registerMetrics function.

import { registerMetrics } from "./metrics";
import { Registry } from "prom-client";

const registry = new Registry();
registerMetrics(registry);

Expose these metrics in your application for monitoring:

app.get("/metrics", async (req, res) => {
  res.set("Content-Type", registry.contentType);
  res.send(await registry.metrics());
});

Upgrading from v1 to v2

The changelog with instructions on upgrading can be found here