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Difficulty: EasyAPI Development and Integration with Amazon API Gateway

A developer is configuring a new API endpoint using Amazon API Gateway that integrates with a backend AWS Lambda function using a Lambda proxy integration. Which two requirements must be met to ensure that client requests are correctly processed and the API returns valid responses? (Select TWO.)

  1. The Lambda function must return a JSON payload containing the 'statusCode', 'headers', and 'body' fields to API Gateway.Answer
  2. API Gateway automatically formats the client request details into a single JSON object and passes it to the Lambda function.Answer
  3. C
    The developer must write Velocity Template Language (VTL) mapping templates in API Gateway to map the client request payload to the Lambda function.
  4. D
    The backend Lambda function must programmatically invoke a Cognito User Pool token endpoint to validate incoming client identity tokens.
  5. E
    The developer only needs to enable Cross-Origin Resource Sharing (CORS) on the API Gateway resource, as API Gateway automatically adds the required CORS headers to the Lambda proxy response.

Answer

The Lambda function must return a JSON payload containing the 'statusCode', 'headers', and 'body' fields to API Gateway, and API Gateway automatically formats the client request details into a single JSON object and passes it to the Lambda function.
With Lambda proxy integration, API Gateway automatically packages the incoming HTTP request details (headers, query parameters, stage variables, path parameters, and request body) into a single JSON object and passes it as the event payload to the backend Lambda function. In return, the Lambda function must return a JSON response structured with 'statusCode', 'headers', and 'body' fields so that API Gateway can map them to the corresponding client HTTP response.

Step-by-Step Solution

1
Understand the behavior of Lambda proxy integration in API Gateway.
In a Lambda proxy integration, the incoming request is passed directly to the Lambda function as a structured JSON object, meaning no mapping templates are needed.
This establishes that API Gateway handles request forwarding automatically without developer-defined templates.
2
Identify the response requirements for Lambda proxy integration.
The Lambda function must return a specific JSON response format including 'statusCode', 'headers', and 'body' so that API Gateway can parse it and formulate the HTTP response.
Failing to return this format results in a 502 Bad Gateway error from API Gateway.
3
Determine the correct choices based on these integration principles.
The two correct answers are that API Gateway automatically formats request details into a JSON object, and the Lambda function must return a JSON payload with 'statusCode', 'headers', and 'body' fields.
These choices accurately describe the input and output requirements for Lambda proxy integration.

Key Concept

API Gateway Lambda Proxy Integration Requirements
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Topics

API Development and Integration with Amazon API Gateway

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