Functions with HTTP triggers in Azure - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is an HTTP trigger in Azure Functions?

An HTTP trigger starts an Azure Function when it receives an HTTP request, like when you open a webpage or call an API.

beginner

How does an Azure Function respond to an HTTP trigger?

It processes the request and sends back a response, such as data or a status message, just like a web server replying to a browser.

intermediate

What HTTP methods can trigger an Azure Function?

Common methods include GET (to get data), POST (to send data), PUT, DELETE, and others, depending on what the function is set to accept.

intermediate

Why use HTTP triggers in serverless functions?

They let you run code only when needed, saving resources and costs, and make it easy to build APIs or webhooks without managing servers.

advanced

How do you secure an Azure Function with an HTTP trigger?

You can use keys, tokens, or Azure Active Directory to control who can call the function, protecting it from unwanted access.

What happens when an HTTP request triggers an Azure Function?

A The function shuts down

B The function sends an email

C The function runs and returns a response

D The function creates a virtual machine

An HTTP trigger causes the function to run and respond to the request.

Which HTTP method is commonly used to retrieve data from an Azure Function?

A GET

B POST

C DELETE

D PUT

GET is used to request data without changing anything.

How can you restrict access to an HTTP-triggered Azure Function?

A By deleting the function

B By turning off the function

C By changing the function name

D By using function keys or authentication tokens

Function keys and tokens control who can call the function.

What is a benefit of using HTTP triggers in serverless functions?

A They require manual server management

B They run code only when needed, saving costs

C They always run continuously

D They cannot respond to web requests

HTTP triggers run functions on demand, which saves resources and money.

Which of these is NOT a typical HTTP method for Azure Functions?

A CONNECT

B POST

C GET

D DELETE

CONNECT is rarely used in Azure Functions; GET, POST, and DELETE are common.

Explain how an HTTP trigger works in Azure Functions and why it is useful.

Think about how a website or app calls a function to get or send data.

Describe methods to secure an Azure Function that uses an HTTP trigger.

Consider how you keep a door locked so only certain people can enter.

Practice

1. What does an HTTP trigger do in an Azure Function?

easy

A. It stores data for the function to use later.

B. It runs the function when it receives a web request.

C. It schedules the function to run at specific times.

D. It sends emails automatically when triggered.

Solution

1. Step 1: Understand the role of HTTP triggers

   HTTP triggers start a function when a web request is received.

2. Step 2: Compare with other triggers

   Other triggers like timers schedule functions, but HTTP triggers respond to web calls.

3. Final Answer:

   It runs the function when it receives a web request. -> Option B

4. Quick Check:

   HTTP trigger = runs on web request [OK]

Hint: HTTP trigger means function runs on web request [OK]

Common Mistakes:

• Confusing HTTP trigger with timer trigger
• Thinking HTTP trigger stores data
• Assuming HTTP trigger sends emails

2. Which of the following is the correct way to define an HTTP trigger in an Azure Function's function.json file?

easy

A. "bindings": [{ "type": "httpTrigger", "direction": "in", "authLevel": "function", "methods": ["get"] }]

B. "bindings": [{ "type": "timerTrigger", "direction": "in", "schedule": "0 */5 * * * *" }]

C. "bindings": [{ "type": "blobTrigger", "direction": "in", "path": "samples-workitems/{name}" }]

D. "bindings": [{ "type": "queueTrigger", "direction": "in", "queueName": "myqueue-items" }]

Solution

1. Step 1: Identify HTTP trigger binding

   The correct binding type for HTTP trigger is "httpTrigger" with direction "in".

2. Step 2: Check authLevel and methods

   authLevel "function" and methods ["get"] are valid properties for HTTP triggers.

3. Final Answer:

   "bindings": [{ "type": "httpTrigger", "direction": "in", "authLevel": "function", "methods": ["get"] }] -> Option A

4. Quick Check:

   HTTP trigger binding = type "httpTrigger" [OK]

Hint: HTTP trigger binding uses type "httpTrigger" in function.json [OK]

Common Mistakes:

• Using timerTrigger or blobTrigger instead of httpTrigger
• Missing authLevel property
• Wrong direction value

3. Given this Azure Function code snippet, what will be the HTTP response body when a GET request is sent?

import logging
import azure.functions as func

def main(req: func.HttpRequest) -> func.HttpResponse:
    name = req.params.get('name')
    if not name:
        return func.HttpResponse("Please pass a name", status_code=400)
    return func.HttpResponse(f"Hello, {name}!")

medium

A. Hello, Alice!

B. Hello, World!

C. Error 404 Not Found

D. Please pass a name

Solution

1. Step 1: Check request parameter handling

   The function looks for 'name' in query parameters. If missing, it returns a 400 response with message "Please pass a name".

2. Step 2: Analyze given request

   The question states a GET request is sent but does not mention a 'name' parameter, so name will be None.

3. Final Answer:

   Please pass a name -> Option D

4. Quick Check:

   No name param = "Please pass a name" response [OK]

Hint: If no 'name' param, function returns error message [OK]

Common Mistakes:

• Assuming default name is 'Alice' or 'World'
• Ignoring the 400 status code response
• Confusing request body with query parameters

4. You have this function.json snippet for an HTTP triggered Azure Function:

{
  "bindings": [
    {
      "type": "httpTrigger",
      "direction": "in",
      "authLevel": "anonymous",
      "methods": ["post"]
    },
    {
      "type": "httpTrigger",
      "direction": "out"
    }
  ]
}

What is the error in this configuration?

medium

A. The output binding type should be "http" not "httpTrigger".

B. The output binding type "http" is invalid; it should be "httpResponse".

C. The output binding type "http" is invalid; it should be "httpTrigger".

D. The output binding type should be "http" with direction "in".

Solution

1. Step 1: Review input and output bindings

   The input binding uses "httpTrigger" which is correct for HTTP triggers.

2. Step 2: Identify output binding error

   The output binding incorrectly uses "httpTrigger"; it should be "http" with direction "out" for HTTP responses.

3. Final Answer:

   The output binding type should be "http" not "httpTrigger". -> Option A

4. Quick Check:

   HTTP output binding = type "http" [OK]

Hint: HTTP output binding uses type "http", not "httpTrigger" [OK]

Common Mistakes:

• Using "httpTrigger" as output binding type incorrectly
• Confusing input and output binding types
• Setting wrong direction for output binding

5. You want to create an Azure Function with an HTTP trigger that only allows calls with a function key (authLevel set to "function") and responds with JSON containing a greeting message using the "name" query parameter and returns a JSON error message if the "name" query parameter is missing. Which of the following code snippets correctly implements this behavior?

hard

A. import azure.functions as func

def main(req: func.HttpRequest) -> func.HttpResponse:
name = req.params.get('name')
if not name:
return func.HttpResponse('Missing name', status_code=400)
return func.HttpResponse(f'{"message": "Hello, {name}!"}', mimetype='application/json')

B. import azure.functions as func

def main(req: func.HttpRequest) -> func.HttpResponse:
name = req.get_json().get('name')
if not name:
return func.HttpResponse('Missing name', status_code=400)
return func.HttpResponse(f'Hello, {name}!')

C. import azure.functions as func
import json

def main(req: func.HttpRequest) -> func.HttpResponse:
name = req.params.get('name')
if not name:
return func.HttpResponse(json.dumps({'error': 'Missing name'}), status_code=400, mimetype='application/json')
return func.HttpResponse(json.dumps({'message': f'Hello, {name}!'}), mimetype='application/json')

D. import azure.functions as func
import json

def main(req: func.HttpRequest) -> func.HttpResponse:
name = req.params.get('name')
return func.HttpResponse(json.dumps({'message': f'Hello, {name}!'}), mimetype='text/plain')

Solution

1. Step 1: Check authLevel and input handling

   authLevel "function" is set in function.json (not shown), so code must handle query param 'name' safely.

2. Step 2: Validate JSON response and error handling

   import azure.functions as func import json def main(req: func.HttpRequest) -> func.HttpResponse: name = req.params.get('name') if not name: return func.HttpResponse(json.dumps({'error': 'Missing name'}), status_code=400, mimetype='application/json') return func.HttpResponse(json.dumps({'message': f'Hello, {name}!'}), mimetype='application/json') uses json.dumps to create proper JSON for both error ({'error': 'Missing name'}) and success ({'message': f'Hello, {name}!'}), with mimetype='application/json' and status_code=400 for errors.

3. Step 3: Compare other options

   A returns plain text error and f-string JSON-like string; C uses get_json() instead of params; D uses text/plain mimetype.

4. Final Answer:

   Uses json.dumps and mimetype='application/json' for both success and error JSON responses. -> Option C

5. Quick Check:

   json.dumps for JSON error and success with application/json mimetype [OK]

Hint: Use json.dumps and mimetype 'application/json' for JSON responses [OK]

Common Mistakes:

• Returning JSON as plain string without json.dumps
• Using wrong mimetype for JSON
• Reading JSON body instead of query parameters