Introduction to is-reachable

The is-reachable package for Node.js is an essential tool for network applications. It allows developers to easily verify if a server or remote endpoint is reachable. This can be extremely useful for applications requiring network diagnostics, uptime monitoring, or just checking the status of a remote service.

Installation

  npm install is-reachable

Basic Usage

Using is-reachable is straightforward. Import the module and call the function with the URL you wish to check.

  const isReachable = require('is-reachable');

  (async () => {
    console.log(await isReachable('https://google.com')); // true
  })();

Checking Multiple Endpoints

You can also check multiple endpoints at once by passing an array of URLs.

  const isReachable = require('is-reachable');

  (async () => {
    const urls = [
      'https://google.com',
      'https://github.com',
      'https://nonexistent.domain'
    ];
    
    const results = await Promise.all(urls.map(url => isReachable(url)));
    console.log(results); // [true, true, false]
  })();

Using with Configuration Options

The is-reachable package also supports several configuration options.

  const isReachable = require('is-reachable');

  (async () => {
    const options = {
      timeout: 5000,
      retries: 2
    };
    
    console.log(await isReachable('https://google.com', options)); // true
  })();

Building an Uptime Monitoring App

Here’s an example of a basic uptime monitoring application using the is-reachable package.

  const isReachable = require('is-reachable');
  const nodemailer = require('nodemailer');

  const urlsToCheck = [
    'https://google.com',
    'https://github.com',
    'https://nonexistent.domain'
  ];

  const transporter = nodemailer.createTransport({
    service: 'gmail',
    auth: {
      user: 'your-email@gmail.com',
      pass: 'your-email-password'
    }
  });

  const checkUrls = async () => {
    for (const url of urlsToCheck) {
      const reachable = await isReachable(url);
      if (!reachable) {
        await transporter.sendMail({
          from: 'your-email@gmail.com',
          to: 'admin@example.com',
          subject: `Alert: ${url} is down`,
          text: `The URL ${url} is currently unreachable.`
        });
      }
    }
  };

  // Set an interval to check the URLs periodically
  setInterval(checkUrls, 300000); // Check every 5 minutes

This script will check the specified URLs every 5 minutes and send an email alert if any of them are unreachable.

With these examples, you should be well-equipped to use is-reachable in your own network-related applications.

Happy coding!

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