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How to Monitor Your Bun Application with Vigilmon

#bunjs #javascript #monitoring #webdev

How to Monitor Your Bun Application with Vigilmon

Bun is the fast all-in-one JavaScript runtime — built-in bundler, test runner, package manager, and server. If you're running production services with Bun, you need uptime monitoring. This guide shows you how to add health checks to any Bun application and monitor it with Vigilmon.

Why Monitor Bun Applications?

  • Bun apps can crash silently without a process manager
  • Runtime panics don't always show up in logs immediately
  • Memory leaks in long-running Bun servers need early detection
  • Users hitting a dead endpoint is worse than getting an alert

Adding a Health Check Endpoint to Your Bun Server

Basic Bun.serve Health Check 

// server.ts
const server = Bun.serve({
  port: 3000,
  async fetch(req) {
    const url = new URL(req.url);

    // Health check endpoint
    if (url.pathname === '/health') {
      return new Response(JSON.stringify({
        status: 'ok',
        uptime: process.uptime(),
        timestamp: new Date().toISOString(),
        runtime: 'bun',
        version: Bun.version,
      }), {
        headers: { 'Content-Type': 'application/json' },
      });
    }

    // Your app routes here
    return new Response('Hello from Bun!');
  },
});

console.log(`Listening on http://localhost:${server.port}`);
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With Database Check 

import { Database } from 'bun:sqlite';

const db = new Database('app.db');

const server = Bun.serve({
  port: 3000,
  async fetch(req) {
    const url = new URL(req.url);

    if (url.pathname === '/health') {
      try {
        // Test database connectivity
        db.query('SELECT 1').get();

        return new Response(JSON.stringify({
          status: 'ok',
          database: 'connected',
          uptime: process.uptime(),
        }), {
          status: 200,
          headers: { 'Content-Type': 'application/json' },
        });
      } catch (error) {
        return new Response(JSON.stringify({
          status: 'error',
          database: 'disconnected',
          error: error.message,
        }), {
          status: 503,
          headers: { 'Content-Type': 'application/json' },
        });
      }
    }

    return new Response('Hello Bun!');
  },
});
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With Elysia Framework 

import { Elysia } from 'elysia';

const app = new Elysia()
  .get('/health', () => ({
    status: 'ok',
    runtime: 'bun',
    version: Bun.version,
    uptime: process.uptime(),
    timestamp: new Date().toISOString(),
  }))
  .get('/', () => 'Hello Elysia!')
  .listen(3000);

console.log(`Elysia running at http://localhost:${app.server?.port}`);
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With Hono on Bun 

import { Hono } from 'hono';

const app = new Hono();

app.get('/health', (c) => {
  return c.json({
    status: 'ok',
    runtime: 'bun',
    uptime: process.uptime(),
    timestamp: new Date().toISOString(),
  });
});

app.get('/', (c) => c.text('Hello Hono on Bun!'));

export default {
  port: 3000,
  fetch: app.fetch,
};
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Heartbeat Monitoring for Bun Background Workers

If you have background workers in Bun (using Bun.CronJob or manual intervals), send heartbeats to Vigilmon:

// worker.ts
const HEARTBEAT_URL = 'https://vigilmon.online/api/heartbeat/YOUR_MONITOR_ID';

async function processJobs() {
  // Your job processing logic
  await processQueue();

  // Send heartbeat to Vigilmon
  await fetch(HEARTBEAT_URL, { method: 'POST' }).catch(console.error);
}

// Run every minute
setInterval(processJobs, 60_000);

console.log('Worker started');
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Setting Up Vigilmon Monitoring

  1. Sign up at vigilmon.online
  2. Add a new monitor → paste your health endpoint URL (e.g., https://api.yourdomain.com/health)
  3. Configure alerts: email, Slack, or webhook
  4. Set check interval: 1 min or 5 min
  5. Add SSL monitoring for your domain

Vigilmon checks from multiple regions, so you'll know if your Bun app is down before your users do.

Keeping Bun Running in Production

Bun needs a process manager to restart on crashes:

# Using PM2
npm install -g pm2
pm2 start "bun run server.ts" --name my-bun-app
pm2 save
pm2 startup
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# Using systemd
sudo nano /etc/systemd/system/bun-app.service
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[Unit]
Description=Bun Application
After=network.target

[Service]
Type=simple
User=www-data
WorkingDirectory=/var/www/app
ExecStart=/usr/local/bin/bun run server.ts
Restart=always
RestartSec=5

[Install]
WantedBy=multi-user.target
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sudo systemctl enable bun-app
sudo systemctl start bun-app
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Complete Monitoring Checklist for Bun Apps

  • [ ] /health endpoint returning 200 with JSON status
  • [ ] Database connectivity check in health endpoint
  • [ ] External dependency checks (Redis, external APIs)
  • [ ] Uptime monitor on Vigilmon (1-min interval)
  • [ ] SSL certificate monitor for your domain
  • [ ] Heartbeat monitor for cron jobs / background workers
  • [ ] Process manager (PM2 or systemd) for auto-restart
  • [ ] Alert channels configured (email + Slack)

Summary

Monitoring a Bun application is straightforward:

  1. Add /health endpoint (returns 200 when healthy)
  2. Connect to Vigilmon (paste the URL, done)
  3. Configure alerts
  4. Run Bun under a process manager

Vigilmon handles the rest — multi-region checks every minute, instant alerts if your Bun app goes down, SSL expiry warnings.

Start monitoring your Bun app free →

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