Amazon API Gateway Interview Questions and Answers for 2 years experience

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Amazon API Gateway Interview Questions & Answers

  1. What is Amazon API Gateway?

    • Answer: Amazon API Gateway is a fully managed service that makes it easy for developers to create, publish, maintain, monitor, and secure APIs at any scale. It acts as a reverse proxy, handling requests from clients and routing them to the appropriate backend services (like AWS Lambda, EC2 instances, etc.).

  2. Explain the different API Gateway deployment stages.

    • Answer: API Gateway allows you to deploy your API to different stages (e.g., dev, test, prod). This enables you to manage different versions of your API concurrently and easily roll back to previous versions if needed. Each stage has its own endpoint URL.

  3. How do you handle authentication and authorization in API Gateway?

    • Answer: API Gateway offers various authentication methods, including Amazon Cognito, IAM, custom authorizers (using Lambda functions), and OAuth 2.0. Authorization is handled through request validators, authorizers, and IAM roles, allowing fine-grained control over API access.

  4. Describe the concept of API Gateway request mapping templates.

    • Answer: Request mapping templates allow you to transform the incoming request from a client before it reaches the backend. You can use Velocity Template Language (VTL) to modify headers, paths, query parameters, and the request body. This is useful for data transformation or adding contextual information.

  5. Explain API Gateway response mapping templates.

    • Answer: Similar to request mapping templates, response mapping templates transform the response from the backend before it's sent to the client. This allows you to modify the response structure, add headers, or remove unnecessary data. They are also written in VTL.

  6. How do you handle errors in API Gateway?

    • Answer: API Gateway provides error handling capabilities. You can configure error responses to return specific HTTP status codes and custom error messages. You can also use CloudWatch to monitor errors and identify potential issues.

  7. What are custom authorizers in API Gateway and how do they work?

    • Answer: Custom authorizers are Lambda functions that verify the identity of the client making the request. API Gateway invokes the Lambda function, which evaluates the request and returns a policy document indicating whether the request is authorized or not.

  8. Explain the different caching strategies in API Gateway.

    • Answer: API Gateway supports caching to improve performance and reduce the load on backend services. You can configure caching at the method level, specifying the cache TTL (time to live) and cache key parameters. This caches responses from the backend for faster delivery to clients.

  9. How do you monitor API Gateway performance?

    • Answer: API Gateway integrates with Amazon CloudWatch, providing detailed metrics on API usage, latency, error rates, and throttling. CloudWatch dashboards and alarms can be used to monitor performance and detect anomalies.

  10. What is throttling in API Gateway?

    • Answer: Throttling is a mechanism to limit the rate of requests to your API. This prevents your API from being overwhelmed by a large number of requests and ensures consistent performance. You can configure throttling limits at the API, stage, or method level.

  11. How do you integrate API Gateway with other AWS services?

    • Answer: API Gateway seamlessly integrates with many AWS services, including Lambda, EC2, S3, DynamoDB, and more. You can configure your API to forward requests to these services and handle responses accordingly.

  12. Explain the concept of API Gateway integrations.

    • Answer: Integrations define how API Gateway connects to backend services. They specify the integration type (e.g., HTTP, AWS service), integration endpoint, request mapping templates, and response mapping templates.

  13. What is the difference between HTTP API and REST API in API Gateway?

    • Answer: REST APIs are designed for building RESTful APIs and offer more features and customization options, but are slightly more expensive. HTTP APIs are designed for lightweight, high-performance HTTP APIs and offer better cost optimization, but have fewer features than REST APIs.

  14. How do you handle request validation in API Gateway?

    • Answer: API Gateway allows you to define request validators to ensure that incoming requests conform to specific schemas and constraints. This helps prevent invalid requests from reaching your backend services. You can define validation rules using JSON Schema.

  15. Describe the use of API Gateway with Serverless applications.

    • Answer: API Gateway is a perfect complement to serverless applications, acting as the front-end for Lambda functions. It handles routing, authentication, authorization, and scaling, allowing developers to focus on building the business logic of their applications.

  16. How do you deploy an API Gateway API?

    • Answer: You can deploy an API Gateway API using the AWS Management Console, AWS CLI, or AWS SDKs. Deployment creates a new stage for the API, making it accessible via its unique endpoint URL.

  17. Explain the role of API Gateway in Microservices architecture.

    • Answer: In a microservices architecture, API Gateway acts as a central point of entry for all clients, aggregating requests to multiple microservices. It provides a unified interface for accessing various backend services.

  18. How do you manage API keys in API Gateway?

    • Answer: API Gateway allows you to generate and manage API keys for authentication and authorization. You can assign API keys to specific users or clients, and control their access to different API resources.

  19. What are some best practices for designing API Gateway APIs?

    • Answer: Best practices include designing RESTful APIs, using appropriate HTTP methods, defining clear error handling, implementing robust security measures, and utilizing caching strategies for performance optimization.

  20. Explain the concept of request parameters in API Gateway.

    • Answer: Request parameters are values passed in the API request, which can be part of the URL path, query string, headers, or request body. API Gateway uses these parameters to route requests and customize behavior.

  21. How do you use API Gateway with AWS Lambda for asynchronous processing?

    • Answer: API Gateway can be configured to integrate with Lambda functions asynchronously. This allows API Gateway to return a response immediately, while Lambda processes the request in the background. This is useful for long-running tasks.

  22. What are the different types of integration requests in API Gateway?

    • Answer: API Gateway supports various integration request types including HTTP, AWS Service Proxy, Mock, and AWS Lambda.

  23. Describe how to use AWS CloudWatch to monitor API Gateway metrics.

    • Answer: CloudWatch provides various metrics like count, latency, error rate and more, and can be visualized via dashboards. Alarms can be setup for threshold breaches.

  24. Explain the concept of API Gateway usage plans.

    • Answer: Usage plans define quotas and throttling limits for API access. They allow you to control how many requests clients can make to your API.

  25. How do you handle authentication and authorization using IAM roles with API Gateway?

    • Answer: IAM roles allow you to grant API access based on identity. The identity is verified against the IAM policies. It's commonly used in serverless architectures.

  26. Describe the process of creating a REST API in API Gateway.

    • Answer: It involves defining resources and methods, setting up integrations with backends, configuring authentication and authorization, and deploying to stages.

  27. How do you test an API Gateway API?

    • Answer: You can test using the API Gateway console's built-in tester, Postman, or other API testing tools, by sending requests to the API endpoint.

  28. Explain the importance of API documentation in API Gateway.

    • Answer: Well-documented APIs are crucial for developers using your APIs. API Gateway supports generating API documentation using tools like Swagger.

  29. How do you handle CORS (Cross-Origin Resource Sharing) in API Gateway?

    • Answer: Configure CORS settings in API Gateway to allow requests from specific origins, methods, and headers.

  30. What are some common security considerations when using API Gateway?

    • Answer: Authentication, authorization, input validation, output encoding, protection against common attacks like DDoS and OWASP top 10.

  31. Explain how to implement rate limiting with API Gateway.

    • Answer: Use throttling settings in API Gateway to limit the number of requests per second or minute to prevent abuse and ensure service stability.

  32. How do you handle large payloads in API Gateway?

    • Answer: Use binary media types and configure appropriate request and response mapping templates to efficiently handle large binary data.

  33. Describe the process of deploying an API to different environments (dev, test, prod) in API Gateway.

    • Answer: Create different stages (dev, test, prod) in API Gateway and deploy the API to each stage. Each stage will have its own independent endpoint.

  34. How do you manage API versions in API Gateway?

    • Answer: Use different stages to manage different versions of your API. Each stage can represent a specific version, allowing for concurrent deployment of different versions.

  35. Explain the importance of using request validators and response validators in API Gateway.

    • Answer: They ensure that requests conform to predefined schemas and responses are formatted correctly, improving data integrity and reducing errors.

  36. How do you troubleshoot common issues in API Gateway?

    • Answer: Use CloudWatch logs and metrics to identify errors and performance bottlenecks. Check integration logs, and examine request and response data for clues.

  37. What are some common integration patterns used with API Gateway?

    • Answer: Proxy integration, direct integration, Lambda integration, and integration with other AWS services like SQS, Kinesis.

  38. How do you handle different HTTP methods (GET, POST, PUT, DELETE) in API Gateway?

    • Answer: Define separate methods (GET, POST, PUT, DELETE) for each resource within your API to handle different HTTP verbs appropriately.

  39. Explain how to use API Gateway with a VPC-based backend.

    • Answer: Configure a VPC Link to allow API Gateway to access your backend resources within a VPC.

  40. How do you implement logging and monitoring for API Gateway?

    • Answer: Use CloudWatch Logs to capture logs from API Gateway and CloudWatch metrics for performance monitoring.

  41. Describe the use of API Gateway with OpenAPI (Swagger) specifications.

    • Answer: OpenAPI (Swagger) specifications can be imported into API Gateway to define the API structure and generate API documentation automatically.

  42. How do you manage and deploy different versions of your API using API Gateway?

    • Answer: Use different API stages to manage and deploy different versions of the API. This allows for parallel deployment and rollback capabilities.

  43. Explain how to use API Gateway with different authentication mechanisms (e.g., OAuth 2.0, AWS IAM).

    • Answer: Configure API Gateway to use Authorizers, integrating with Cognito or using custom authorizers for OAuth 2.0 or IAM.

  44. Describe the use of Lambda proxy integrations in API Gateway.

    • Answer: Lambda proxy integration simplifies integration with Lambda functions, forwarding the entire request to the Lambda function.

  45. How do you handle request transformation and response transformation in API Gateway?

    • Answer: Use request mapping templates and response mapping templates (using VTL) to transform requests and responses between API Gateway and the backend.

  46. Explain how to implement request validation using JSON Schema in API Gateway.

    • Answer: Define a JSON Schema to specify the expected request structure and configure API Gateway to validate incoming requests against the schema.

  47. How do you monitor and troubleshoot API Gateway deployments?

    • Answer: Monitor CloudWatch logs and metrics for errors during deployment. Review deployment status and rollback if necessary.

  48. Describe how to use API Gateway with AWS SAM (Serverless Application Model).

    • Answer: Define API Gateway resources in your SAM template for easy deployment and management of API Gateway APIs as part of a serverless application.

  49. Explain the concept of API Gateway quotas and limits.

    • Answer: API Gateway has quotas and limits on various aspects, such as the number of APIs, stages, methods, and requests per second. Understanding these limits is crucial for scalability planning.

  50. How do you optimize API Gateway performance?

    • Answer: Use caching, optimize mapping templates, utilize appropriate integration types, and properly configure throttling and rate limiting.

  51. Describe your experience with API Gateway's integration with other AWS services beyond Lambda.

    • Answer: [Candidate should provide specific examples of integrations with services like S3, DynamoDB, EC2, etc. and describe their experience.]

  52. How have you handled API Gateway's scaling needs in your previous projects?

    • Answer: [Candidate should describe their approach to handling increased traffic and how they ensured API Gateway's scalability and availability.]

  53. What are some common challenges you've faced while working with API Gateway, and how did you overcome them?

    • Answer: [Candidate should describe specific challenges and their problem-solving approach, demonstrating their troubleshooting skills and experience.]

  54. Discuss your experience with API Gateway's cost optimization strategies.

    • Answer: [Candidate should describe their understanding of API Gateway's pricing model and their approach to optimizing costs.]

  55. Have you used any third-party tools or libraries with API Gateway? If yes, which ones and why?

    • Answer: [Candidate should list any relevant tools and justify their use based on specific needs and benefits.]

  56. Explain your understanding of API Gateway's role in ensuring the security and compliance of your APIs.

    • Answer: [Candidate should highlight their understanding of security best practices and how API Gateway features contribute to security and compliance requirements.]

  57. Describe a situation where you had to debug a complex issue related to API Gateway. What was your approach?

    • Answer: [Candidate should present a detailed account of a challenging scenario and articulate their systematic debugging process.]

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