What is application monitoring (health-checks, URL availability)?

Application monitoring is a mechanism for checking the status of an application or service in terms of its operability and availability. It is usually implemented through special health-check endpoints (for example, /health or /status) that return information about the application's state.

Such checks allow:

• Ensuring that the service is running and responding to requests.
• Verifying the availability of critical dependencies (databases, external APIs).
• Automating restart or switching to backup instances in case of failures.

An example of a simple health-check in Python using Flask:

from flask import Flask, jsonify
app = Flask(__name__)

@app.route('/health')
def health_check():
    # Here you can add checks for databases, cache systems, etc.
    return jsonify(status='ok')

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

Thus, URL availability is a way of external monitoring, allowing orchestration systems and load balancers to control the application's state.