API Gateway

Question 1

Which AWS service is designed for creating, publishing, maintaining, monitoring, and securing REST, HTTP, and WebSocket APIs at any scale?

Answer 1

API Gateway - highly available, scalable, and fully managed AWS service

Question 2

What are the key features of API Gateway?

Answer 2

• Authorization
• Throttling
• Caching
• CORS
• Request/Response transformation
• OpenAPI specification support
• Direct service integration, and more

Question 3

Can API Gateway be integrated with on-premises endpoints?

Answer 3

API Gateway can connect directly to AWS services like DynamoDB, SNS, Step Functions, Lambda, AWS-hosted and on-premises endpoints

Question 4

Can you describe the typical flow of a request through API Gateway?

Answer 4

Request:
Clients -> API Gateway (Authorize, Validate, Transform) -> Backend Services

Response:
Backend Services -> API Gateway (Return, Prepare, Transform) -> Clients

Question 5

What functionalities are available when API Gateway is connected to CloudWatch?

Answer 5

When integrated with CloudWatch, API Gateway provides detailed logging and metrics for requests and responses

Question 6

What authentication methods does API Gateway support?

Answer 6

• Authorization via Cognito User Pools
• Custom authorization through Lambda functions, allowing to integrate custom identity providers (IDP)

Question 7

What types of endpoints does API Gateway offer?

Answer 7

API Gateway supports three types of endpoints:

• Private: Accessible only within a VPC through interface endpoints
• Regional: Ideal for clients within the same AWS region
• Edge-optimized: Routes requests to the nearest CloudFront Point of Presence (PoP)

Question 8

What AWS API Gateway component represents a logical reference to its lifecycle state?

Answer 8

Stage (e.g., dev, prod, beta, v2).

Each stage has its own deployment and is identified by a unique URL
- api.domain.com/dev
- api.domain.com/prod

Question 9

What are the minimum and maximum cache sizes supported by API Gateway?

Answer 9

API Gateway allows caching from 500MB to 237GB

Question 10

What are the minimum and maximum cache TTL values supported by API Gateway?

Answer 10

• Min TTL 0s
• Max TTL 3600s (1h)
• Default TTL of 300s (5m)

Question 11

Is caching configured per API Gateway instance?

Answer 11

Caching is configured per stage and can be encrypted

Question 12

What are the components of an AWS API Gateway invoke URL?

Answer 12

• Endpoint DNS name
• Stage
• Resource

https://1nj7l16t37.execute-api.us-east-1.amazonaws.com/stage/resource

Question 13

What are the phases of AWS API Gateway integration?

Answer 13

• Method Request
• Integration Request
• Integration Response
• Method Response

Question 14

What types of integration does AWS API Gateway support?

Answer 14

Requires integration request and response configuration:
- AWS: Exposes AWS service actions
- HTTP: Exposes HTTP backend endpoints

Does not requires integration request and response configuration:
- AWS_PROXY: Directly invokes an AWS Lambda function
- HTTP_PROXY: Exposes HTTP backend endpoints without transformation
- MOCK: Returns a response without calling a backend service

Question 15

What AWS API Gateway component (script) modifies request parameters, body, or headers in non-proxy integrations?

Answer 15

Mapping Templates

Question 16

What language is used in AWS API Gateway Mapping Templates?

Answer 16

Velocity Template Language (VTL)

Question 17

What is a common use case for AWS API Gateway Mapping Templates?

Answer 17

Converting REST API requests to SOAP API format for integration

Question 18

What action must be performed to make AWS API Gateway updates live and callable by users?

Answer 18

Deployment to a new or existing stage

Question 19

Can a deployed AWS API Gateway stage be updated after changes are made?

Answer 19

Yes, a stage can be overwritten with new changes or rolled back

Question 20

What key-value pairs can be defined as configuration attributes associated with an AWS API Gateway Stage and used in API setup and Mapping Templates?

Answer 20

Stage Variables

Question 21

What specification defines a standard, language-agnostic interface for HTTP APIs, enabling both humans and computers to discover and understand the service’s capabilities without access to source code, documentation, or network traffic inspection?

Answer 21

OpenAPI Specification (OAS)

Question 22

How OpenAPI Specification files can be used by AWS API Gateway service?

Answer 22

• To import an API
• To export an API

Question 23

What key-value pair defines configuration attributes associated with an AWS API Gateway Stage Deployment, functioning like environment variables and usable in API setup and mapping templates?

Answer 23

Stage Variables

• HTTP integration URI: `http://${stageVariables.varName}/resource/operation
• Mapping template: `{“name”: “${stageVariables.varName” }.

Question 24

What AWS API Gateway feature can enhance API performance by reducing the number of calls to your endpoint and improving request latency?

Answer 24

API Caching

Question 25

How can a client invalidate a cache entry and reload it from the AWS API Gateway integration endpoint?

Answer 25

By sending a request with the `Cache-Control: max-age=0` header