Amazon API Gateway Interview Questions and Answers for 10 years experience

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100 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 "front door" for applications to access backend services, handling tasks like request routing, authentication, authorization, throttling, and monitoring.

  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 roll out changes gradually. Stages isolate configurations and prevent accidental disruptions to production environments.

  3. Describe the various API Gateway integration types.

    • Answer: API Gateway supports several integration types, including HTTP, AWS Service, AWS Lambda, and Mock. HTTP integrates with any HTTP endpoint; AWS Service integrates directly with other AWS services; AWS Lambda invokes Lambda functions; and Mock returns predefined responses for testing purposes.

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

    • Answer: API Gateway provides several ways to secure APIs, including using AWS IAM, Cognito User Pools/Identity Pools, OAuth 2.0, and custom authorizers (Lambda functions) for fine-grained control. You can also use API keys for basic authentication.

  5. Explain the concept of API Gateway throttling and rate limiting.

    • Answer: Throttling limits the rate of requests to your API to prevent overload. Rate limiting is a more granular form of throttling that can apply different limits based on factors like API key or client IP address. API Gateway helps manage these limits to ensure high availability and prevent abuse.

  6. How do you monitor API Gateway performance?

    • Answer: API Gateway provides CloudWatch metrics, logs, and dashboards for monitoring key performance indicators like latency, request counts, error rates, and throughput. This allows you to identify bottlenecks and optimize API performance.

  7. What are custom authorizers in API Gateway, and when would you use them?

    • Answer: Custom authorizers are Lambda functions that handle authentication and authorization logic beyond the built-in methods. Use them for complex authorization scenarios requiring access control based on custom logic or data sources not directly integrated with API Gateway.

  8. Explain API Gateway caching.

    • Answer: API Gateway caching improves performance by storing frequently accessed responses. This reduces latency and load on backend services. You can configure caching at the method level, controlling cache size, invalidation, and TTL (Time To Live).

  9. How do you handle request transformations in API Gateway?

    • Answer: API Gateway allows you to transform requests (e.g., adding headers, mapping parameters) before they reach the backend. This is crucial for adapting requests to the backend's expectations or for enforcing consistent request formats.

  10. Describe response transformations in API Gateway.

    • Answer: Similar to request transformations, response transformations modify responses from the backend before they are returned to the client. This allows you to format responses consistently, mask sensitive data, or add metadata.

  11. How do you handle errors in API Gateway?

    • Answer: API Gateway allows you to define error handling logic, either through default error handling or by mapping HTTP status codes to specific responses. This ensures consistent error handling and provides meaningful feedback to clients.

  12. Explain the use of API Gateway request validators.

    • Answer: Request validators check incoming requests against predefined schemas (JSON Schema or OpenAPI). They prevent malformed requests from reaching the backend, improving security and reliability.

  13. How do you manage API Keys in API Gateway?

    • Answer: API Keys are used for simple authentication. You generate and manage them in the API Gateway console, associating them with usage plans to control access and usage quotas.

  14. What are usage plans in API Gateway?

    • Answer: Usage plans define quotas and throttling limits for API Keys. This enables granular control over API usage and prevents abuse or unexpected costs.

  15. Describe API Gateway's role in serverless architectures.

    • Answer: API Gateway is a cornerstone of serverless architectures. It acts as the entry point for serverless functions (Lambda), handling requests and routing them to the appropriate functions, abstracting away the complexities of server management.

  16. How do you deploy API Gateway changes?

    • Answer: Changes are deployed to specific stages. This allows for testing in non-production environments before releasing to production, minimizing the risk of disruptions.

  17. Explain the importance of API Gateway logging and tracing.

    • Answer: Logging and tracing are essential for monitoring, debugging, and troubleshooting API performance and security. They provide insights into request flow, errors, and latency issues.

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

    • Answer: API Gateway integrates seamlessly with many AWS services, such as Lambda, DynamoDB, S3, and more. This integration simplifies building complex applications and workflows.

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

    • Answer: Best practices include designing RESTful APIs, using appropriate HTTP methods, implementing proper error handling, using versioning, and employing security measures.

  20. How do you handle large-scale API traffic with API Gateway?

    • Answer: API Gateway is designed for scalability. It automatically scales to handle large volumes of traffic. Proper configuration of throttling and caching is crucial for optimizing performance under heavy load.

  21. What are the different pricing models for API Gateway?

    • Answer: API Gateway pricing is based on API calls, data transferred, and usage of features like caching and custom authorizers. A pay-as-you-go model applies, with costs varying based on usage.

  22. How do you secure your API Gateway endpoints using VPC Link?

    • Answer: VPC Link enables you to connect your API Gateway to resources within your Virtual Private Cloud (VPC), improving security by isolating your backend services from the public internet.

  23. Explain the concept of API Gateway's integration requests and responses.

    • Answer: Integration requests are how API Gateway formats requests sent to your backend, and integration responses are how API Gateway formats the responses returned to the client. These allow for mapping and transformation between different formats.

  24. How do you manage different versions of your API using API Gateway?

    • Answer: API Gateway supports API versioning through different stages and paths. This allows you to deploy different versions of your API concurrently and manage the lifecycle of each version.

  25. Describe the use of API Gateway's mapping templates.

    • Answer: Mapping templates define transformations for requests and responses using Velocity Template Language (VTL). They are used for data mapping, request/response modification, and custom logic during integration.

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

    • Answer: CORS is configured in API Gateway to allow requests from specific origins. This is crucial for enabling web applications running on different domains to access your API.

  27. Explain how to implement JWT (JSON Web Token) authentication with API Gateway.

    • Answer: JWT authentication typically uses a custom authorizer to verify the JWT signature and extract claims. This provides a standard and secure mechanism for verifying user identity.

  28. How do you use API Gateway to create a RESTful API?

    • Answer: API Gateway naturally supports RESTful API design principles, allowing you to define resources, methods (GET, POST, PUT, DELETE), and paths using a straightforward interface.

  29. Describe the benefits of using API Gateway over self-managing APIs.

    • Answer: API Gateway offers scalability, security features, monitoring tools, and ease of management, reducing the operational burden compared to self-managing APIs.

  30. How do you handle WebSocket connections using API Gateway?

    • Answer: API Gateway WebSockets allows for real-time, bidirectional communication between clients and backend services, enabling features like chat applications and real-time dashboards.

  31. Explain how to use API Gateway with Serverless Application Model (SAM).

    • Answer: SAM simplifies deploying and managing serverless applications, including API Gateway, using declarative YAML or JSON templates.

  32. Describe your experience with API Gateway's integration with CloudFormation.

    • Answer: CloudFormation allows for infrastructure-as-code deployment and management of API Gateway, providing version control and automation capabilities.

  33. How do you troubleshoot common API Gateway issues?

    • Answer: Troubleshooting involves reviewing CloudWatch logs and metrics, checking API Gateway configurations, verifying backend service health, and using debugging tools to pinpoint the root cause.

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

    • Answer: Security considerations include proper authentication and authorization, input validation, preventing injection attacks, and regularly reviewing and updating security configurations.

  35. Explain your experience with deploying and managing API Gateway using the AWS CLI.

    • Answer: The AWS CLI provides programmatic control over API Gateway, allowing for automated deployments, configuration changes, and monitoring.

  36. How do you optimize API Gateway performance for different use cases?

    • Answer: Optimization strategies include using caching, appropriate integration types, request/response transformations, and proper throttling configurations based on the specific needs of each API.

  37. Describe your experience with integrating API Gateway with different database technologies.

    • Answer: Integration typically involves using a backend service (e.g., Lambda function) to interact with the database, with API Gateway acting as the API endpoint.

  38. How do you handle scaling challenges with API Gateway?

    • Answer: API Gateway automatically scales, but optimizing backend services and properly configuring throttling is crucial for handling unexpected traffic spikes.

  39. What is your experience with using API Gateway's integration with CDK (AWS Cloud Development Kit)?

    • Answer: CDK allows for defining and deploying API Gateway resources using familiar programming languages, providing more flexibility and control than CloudFormation.

  40. Explain how to use API Gateway with different programming languages for backend integration.

    • Answer: API Gateway supports integration with various languages through services like Lambda (supporting numerous languages) or direct HTTP integration with services written in any language.

  41. How do you ensure API Gateway high availability and disaster recovery?

    • Answer: API Gateway is inherently highly available. For disaster recovery, consider using multiple regions and configuring failover mechanisms for backend services.

  42. Describe your experience with API Gateway's role in implementing microservices architecture.

    • Answer: API Gateway acts as the central access point for multiple microservices, routing requests to the appropriate service, simplifying communication and management.

  43. How do you monitor and analyze API Gateway logs for security incidents?

    • Answer: Analyzing logs for suspicious activity, such as unauthorized access attempts, unusual request patterns, or error rates, is crucial for identifying and responding to security incidents.

  44. Explain your approach to designing and implementing a secure API using API Gateway.

    • Answer: A secure API design incorporates authentication, authorization, input validation, output sanitization, and regular security audits to protect against various threats.

  45. How do you handle API Gateway updates and maintenance without affecting production?

    • Answer: Using different stages allows for testing and deploying updates in non-production environments before releasing to production, minimizing disruptions.

  46. Describe your experience with using API Gateway's built-in metrics for performance tuning.

    • Answer: Built-in metrics provide insights into latency, error rates, and throughput, allowing for identification of bottlenecks and optimization of API performance.

  47. How do you troubleshoot slow API responses in API Gateway?

    • Answer: Troubleshooting slow responses involves examining logs, metrics, and tracing information to identify whether the issue stems from API Gateway itself, the backend service, or network latency.

  48. Explain your experience with integrating API Gateway with third-party services.

    • Answer: Integration with third-party services is typically handled through HTTP integration, ensuring proper authentication and handling of requests and responses.

  49. How do you handle large request and response payloads in API Gateway?

    • Answer: Handling large payloads may involve using binary media types, optimizing backend services for efficient data handling, and potentially implementing request/response compression.

  50. What are some advanced features of API Gateway that you have utilized?

    • Answer: Advanced features might include VPC Link, WebSockets, fine-grained access control with custom authorizers, and sophisticated mapping templates for complex data transformations.

  51. Describe your approach to managing the lifecycle of an API using API Gateway.

    • Answer: Managing the API lifecycle involves planning, designing, building, testing, deploying, monitoring, and iterating based on feedback and performance data.

  52. How do you ensure the scalability and reliability of your APIs built on API Gateway?

    • Answer: Scalability and reliability are ensured by proper configuration of throttling, caching, backend service scaling, and robust error handling and monitoring.

  53. Explain your experience with using API Gateway for both RESTful and WebSocket APIs.

    • Answer: Both RESTful and WebSocket APIs leverage API Gateway's capabilities, but each requires a different configuration and approach to handle requests and responses appropriately.

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