Health check endpoints in FastAPI - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ component_behavior

intermediate

What is the output of this FastAPI health check endpoint?

Consider this FastAPI endpoint code for a health check. What will the client receive when accessing /health?

FastAPI

from fastapi import FastAPI

app = FastAPI()

@app.get("/health")
async def health_check():
    return {"status": "ok", "uptime": 12345}

A "status: ok, uptime: 12345"

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

C HTTP 404 Not Found error

D An empty JSON object {}

💡 Hint

Look at the return statement inside the endpoint function.

The endpoint returns a dictionary with keys status and uptime. FastAPI automatically converts this dictionary to JSON in the response.

📝 Syntax

intermediate

Which option correctly defines a FastAPI health check endpoint?

Select the code snippet that correctly defines a GET endpoint at /health returning JSON {"status": "healthy"}.

A

@app.get("/health")
async def health():
    return {"status": "healthy"}

B

app.get("/health")
async def health():
    return {"status": "healthy"}

C

@app.get("/health")
def health():
    print({"status": "healthy"})

D

@app.get("/health")
async def health():
    return "status: healthy"

💡 Hint

Remember the decorator syntax and that the function must return a dictionary for JSON.

Option A uses the correct decorator @app.get("/health") and returns a dictionary, which FastAPI converts to JSON.

Option A misses the decorator symbol '@'. Option A returns None and prints instead of returning. Option A returns a string, not JSON.

❓ state_output

advanced

What is the response status code of this health check endpoint?

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

FastAPI

from fastapi import FastAPI

app = FastAPI()

@app.get("/health")
async def health_check():
    return {"status": "ok"}

A 500

B 404

C 200

D 302

💡 Hint

FastAPI returns 200 OK by default for successful GET requests.

When a FastAPI endpoint returns a dictionary without specifying a status code, the default HTTP status code is 200 (OK).

🔧 Debug

advanced

Why does this health check endpoint cause a runtime error?

Examine this FastAPI endpoint code. Why will it cause an error when accessed?

FastAPI

from fastapi import FastAPI

app = FastAPI()

@app.get("/health")
async def health_check():
    return status: "ok"

A SyntaxError due to invalid return statement syntax

B TypeError because 'status' is undefined

C RuntimeError because async function is missing await

D No error, returns JSON {"status": "ok"}

💡 Hint

Look carefully at the return statement syntax.

The return statement uses invalid syntax. It should return a dictionary like {"status": "ok"}, but instead it uses a colon without braces, causing a SyntaxError.

🧠 Conceptual

expert

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

Choose the most accurate description of why a health check endpoint is used in FastAPI applications.

A To log detailed error messages when the app crashes

B To authenticate users before they access the main application features

C To serve the main homepage content of the application

D To provide a simple URL that external systems can call to verify the app is running and responsive

💡 Hint

Think about monitoring and uptime checks.

A health check endpoint is a simple URL that monitoring tools or load balancers call to confirm the app is alive and working. It does not handle authentication or serve main content.