Health check endpoints in Flask - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ component_behavior

intermediate

What is the output of this Flask health check endpoint?

Consider this Flask app code snippet for a health check endpoint. What will the endpoint return when accessed?

Flask

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

@app.route('/health')
def health_check():
    return jsonify(status='ok', uptime=12345), 200

# Assume the server is running and /health is accessed

A {"status":"ok","uptime":12345}

B Internal Server Error

C 404 Not Found

D status=ok, uptime=12345

💡 Hint

Flask's jsonify returns JSON with correct headers.

The endpoint returns a JSON response with keys 'status' and 'uptime' and HTTP status 200.

📝 Syntax

intermediate

Which option causes a syntax error in this Flask health check route?

Identify which Flask route definition will cause a syntax error.

Flask

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

# Four route definitions below

A @app.route('/health')\ndef health()\n return jsonify(status='ok')

B @app.route('/health')\ndef health():\n return jsonify(status='ok')\n print('done')

C @app.route('/health')\ndef health():\n return jsonify(status='ok')

D @app.route('/health')\ndef health():\n return jsonify(status='ok', code=200)

💡 Hint

Check for missing colons in function definitions.

Option A is missing a colon after the function definition, causing a syntax error.

❓ state_output

advanced

What is the HTTP status code returned by this health check endpoint?

Given this Flask health check endpoint, what HTTP status code will the client receive?

Flask

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

@app.route('/health')
def health_check():
    response = jsonify(status='ok')
    response.status_code = 503
    return response

A 500

B 200

C 404

D 503

💡 Hint

The status_code attribute sets the HTTP status code.

The code sets response.status_code to 503, so the client receives HTTP 503 Service Unavailable.

🔧 Debug

advanced

Why does this Flask health check endpoint raise a TypeError?

Examine the code and identify why it raises a TypeError when accessed.

Flask

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

@app.route('/health')
def health_check():
    data = {'status': 'ok'}
    return jsonify(data, 200)

A Missing return statement causes TypeError

B The dictionary 'data' is not JSON serializable

C jsonify() does not accept multiple positional arguments like (data, 200)

D Flask app is not instantiated properly

💡 Hint

Check the signature of jsonify function.

jsonify expects keyword arguments or a single dict, not multiple positional arguments. Passing (data, 200) causes TypeError.

🧠 Conceptual

expert

Which option best describes the purpose of a health check endpoint in Flask?

Select the most accurate description of why a health check endpoint is used in a Flask application.

A To authenticate users before accessing the main app routes

B To provide a simple URL that returns the app's status for monitoring systems

C To serve the main homepage content of the Flask app

D To handle all errors and exceptions globally

💡 Hint

Think about monitoring and uptime checks.

Health check endpoints are lightweight URLs that return app status, used by monitoring tools to verify the app is running.