Where Does the Convention of Using /healthz for Application Health Checks Come From?

Introduction

The /healthz endpoint is a widely used convention for application health checks. It provides a simple way for systems to verify the health of an application or service. But where does this convention come from, and why has it become so popular?

In this guide, you'll learn about the origins of /healthz, its purpose, and how it fits into modern software development practices.

The Origins of /healthz

The /healthz convention originated in the Kubernetes ecosystem. Kubernetes uses /healthz endpoints to check the health of system components like the API server. Over time, this convention was adopted by developers for their own applications.

Why /healthz?

• Simplicity: The /healthz endpoint is easy to implement and understand.
• Standardization: Using a common endpoint name makes it easier for tools and systems to integrate.
• Backward Compatibility: The z in /healthz was added to avoid conflicts with existing /health endpoints.

+-------------------+
|   Application     |
|                   |
| +---------------+ |
| |   /healthz    | |
| +---------------+ |
| +---------------+ |
| |   Monitoring  | |
| +---------------+ |
| +---------------+ |
| |   Alerts      | |
| +---------------+ |
+-------------------+

Implementing /healthz in Your Application

Example in Node.js

const express = require('express');
const app = express();

app.get('/healthz', (req, res) => {
  res.status(200).send('OK');
});

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

This code creates a simple /healthz endpoint that returns a 200 status code and an OK message.

Example in Python

from flask import Flask
app = Flask(__name__)

@app.route('/healthz')
def healthz():
    return "OK", 200

if __name__ == '__main__':
    app.run(port=3000)

This Python example achieves the same functionality using Flask.

Best Practices for Health Checks

• Keep It Lightweight: Ensure the /healthz endpoint responds quickly and doesn't perform heavy operations.
• Use HTTP Status Codes: Return 200 for healthy and 500 for unhealthy states.
• Monitor Regularly: Integrate /healthz checks into your monitoring tools.

Conclusion

The /healthz convention has become a standard for application health checks due to its simplicity and effectiveness. By implementing /healthz in your applications, you can provide a reliable way for systems to monitor and ensure the health of your services.