Resources and methods in AWS - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ service_behavior

intermediate

API Gateway Resource and Method Behavior

You create an API Gateway REST API with a resource path /items and add a GET method integrated with a Lambda function. What happens when a client sends a POST request to /items?

A The API Gateway returns a 405 Method Not Allowed error because POST method is not defined on the resource.

B The API Gateway forwards the POST request to the Lambda function configured for GET method.

C The API Gateway automatically creates a POST method and returns a 200 OK response.

D The API Gateway returns a 404 Not Found error because POST method is not supported.

💡 Hint

Think about how API Gateway handles HTTP methods that are not explicitly configured on a resource.

API Gateway only allows HTTP methods that are explicitly defined on a resource. If a client sends a request with an undefined method, API Gateway returns a 405 Method Not Allowed error.

❓ Architecture

intermediate

Designing Resources and Methods for Versioning

You want to design an API Gateway REST API that supports two versions: v1 and v2. Which resource structure best supports this versioning?

A Use a single resource <code>/api</code> and add a query parameter <code>version</code> to distinguish versions.

B Create two top-level resources: <code>/v1</code> and <code>/v2</code>, each with their own methods and integrations.

C Create one resource <code>/</code> and use different HTTP headers to specify the version.

D Create separate APIs for v1 and v2 instead of using resources.

💡 Hint

Consider how resource paths can represent different API versions clearly.

Using separate resource paths like /v1 and /v2 clearly separates versions and allows independent method configurations for each version.

❓ security

advanced

Securing Methods with IAM Authorization

You configure a POST method on a resource in API Gateway and set the authorization type to IAM. What must a client do to successfully invoke this method?

A Sign the request with AWS credentials using Signature Version 4 signing process.

B Include an API key in the request header.

C Send the request without any authentication; IAM authorization is automatic.

D Provide a valid OAuth 2.0 token in the Authorization header.

💡 Hint

Think about how IAM authorization works with API Gateway methods.

When IAM authorization is enabled, clients must sign their requests using AWS Signature Version 4 with valid AWS credentials to be authorized.

❓ Configuration

advanced

Configuring a Mock Integration Method

You want to create a GET method on a resource that returns a fixed JSON response without calling any backend. Which integration type should you configure?

A Set the integration type to HTTP and point to a dummy URL that returns the JSON.

B Set the integration type to AWS Service and call a service that returns the JSON.

C Set the integration type to MOCK and configure a method response with a static mapping template.

D Set the integration type to AWS Lambda and use a Lambda function that returns the JSON.

💡 Hint

Consider how to return a response directly from API Gateway without backend calls.

MOCK integration allows API Gateway to return a response directly using mapping templates without invoking any backend service.

✅ Best Practice

expert

Optimizing API Gateway Resource and Method Structure for Caching

You want to enable caching for a GET method on a resource but only cache responses when the query parameter type is present. How should you configure caching keys?

A Enable caching on the method without specifying cache key parameters; all requests are cached.

B Caching cannot be configured based on query parameters in API Gateway.

C Enable caching and include all query string parameters as cache keys.

D Enable caching on the method and configure the cache key parameters to include <code>method.request.querystring.type</code> only.

💡 Hint

Think about how API Gateway cache keys can be customized to include specific request parameters.

API Gateway allows specifying which request parameters are used as cache keys. Including only method.request.querystring.type caches responses based on that parameter.

Practice

1. What does a resource represent in AWS API Gateway?

easy

A. A URL path that clients can access

B. A backend database connection

C. A security policy for API access

D. A method to deploy the API

Solution

1. Step 1: Understand the role of resources in API Gateway

   Resources define the URL paths that clients use to reach your API endpoints.

2. Step 2: Differentiate resources from other components

   Resources are not backend connections, security policies, or deployment methods; they are URL paths.

3. Final Answer:

   A URL path that clients can access -> Option A

4. Quick Check:

   Resource = URL path [OK]

Hint: Resources are the API's URL paths clients call [OK]

Common Mistakes:

• Confusing resources with backend services
• Thinking resources are security settings
• Mixing resources with deployment steps

2. Which HTTP method is correctly defined in AWS API Gateway to retrieve data?

easy

A. GET

B. POST

C. DELETE

D. PUT

Solution

1. Step 1: Identify the HTTP method for data retrieval

   GET is the standard HTTP method used to retrieve or read data from a resource.

2. Step 2: Confirm other methods' purposes

   POST creates data, DELETE removes data, and PUT updates data, so they are not for retrieval.

3. Final Answer:

   GET -> Option A

4. Quick Check:

   GET = retrieve data [OK]

Hint: GET method is for reading data from resources [OK]

Common Mistakes:

• Using POST instead of GET to fetch data
• Confusing DELETE with data retrieval
• Mixing PUT with GET for reading data

3. Given this API Gateway setup: a resource /items with a POST method integrated to a Lambda function. What happens when a client sends a POST request to /items?

medium

A. The API Gateway returns a static mock response

B. The API Gateway returns a 404 Not Found error

C. The Lambda function is triggered to process the request

D. The request is ignored because POST is not allowed

Solution

1. Step 1: Understand the integration of POST method with Lambda

   The POST method on the /items resource is connected to a Lambda function, so requests trigger that function.

2. Step 2: Analyze the client request effect

   When a client sends a POST request to /items, API Gateway forwards it to Lambda for processing.

3. Final Answer:

   The Lambda function is triggered to process the request -> Option C

4. Quick Check:

   POST + Lambda integration = Lambda triggered [OK]

Hint: POST method triggers Lambda if integrated [OK]

Common Mistakes:

• Assuming POST is not allowed without checking method setup
• Thinking API Gateway returns 404 if resource exists
• Confusing mock responses with Lambda integration

4. You created a resource /users and added a GET method, but clients get a 403 Forbidden error when calling it. What is the most likely cause?

medium

A. The client is using POST instead of GET

B. The resource path is misspelled

C. The API Gateway is not deployed

D. The method does not have an integration configured

Solution

1. Step 1: Check method integration setup

   A 403 Forbidden often means the method exists but lacks proper integration or permissions.

2. Step 2: Rule out other causes

   If the resource path was misspelled, the error would be 404. If API Gateway was not deployed, the error would differ. Using POST instead of GET would cause a 405 Method Not Allowed.

3. Final Answer:

   The method does not have an integration configured -> Option D

4. Quick Check:

   403 Forbidden = missing integration or permissions [OK]

Hint: 403 often means method lacks integration or permissions [OK]

Common Mistakes:

• Confusing 403 with 404 or 405 errors
• Ignoring deployment status
• Assuming client method is always correct

5. You want to create an API with a resource /orders that supports both GET and POST methods. The GET method returns a mock response, and the POST method triggers a Lambda function. Which configuration correctly sets this up?

hard

A. Create /orders resource; add GET and POST methods both with MOCK integration

B. Create /orders resource; add GET method with MOCK integration; add POST method with Lambda integration

C. Create /orders resource; add GET method with Lambda integration; add POST method with MOCK integration

D. Create /orders resource; add GET and POST methods both with Lambda integration

Solution

1. Step 1: Match method to integration type

   The GET method should use MOCK integration to return a static response without backend calls.

2. Step 2: Configure POST method to trigger Lambda

   The POST method must be integrated with Lambda to process incoming data.

3. Step 3: Verify the correct combination

   Create /orders resource; add GET method with MOCK integration; add POST method with Lambda integration correctly assigns MOCK to GET and Lambda to POST on the /orders resource.

4. Final Answer:

   Create /orders resource; add GET method with MOCK integration; add POST method with Lambda integration -> Option B

5. Quick Check:

   GET=MOCK, POST=Lambda [OK]

Hint: GET with MOCK, POST with Lambda for mixed behavior [OK]

Common Mistakes:

• Swapping MOCK and Lambda integrations between methods
• Using same integration for both methods incorrectly
• Forgetting to create the resource before methods