AWS API Gateway Interview Questions

An API management tool known as an API gateway sits in between a client and a group of backend services. An API gateway serves as a proxy server to admit all app programming interface (API) requests, collect all necessary services, and provide the desired outcome.

By using API gateways, most entrepreneurship APIs are deployed. Authentication process, rate limiting, and statistical data are common tasks that API gateways take care of on behalf of a system of API services. 

Before we begin the interview questions, let us go through the features of the AWS API gateway. The most prominent ones are:

• Both stateful (WebSocket) and stateless (REST) APIs are supported.
• It includes a developer portal that the API's creator can use to publish their APIs.
• It has high-level, adaptable authentication techniques, such as Amazon Cognito user pools, Lambda authorizer functions, and AWS Identity and Access Management policies.
• It includes Canary discharge deployments that assist in implementing the changes safely.
• The Cloudtail feature aids in logging and keeping track of API usage and related changes.
• It has the capability to use CloudFormation templates, which aid in the API creation process.
• The ability to set alarms for various situations is made possible by CloudWatch, which assists in providing access to logging and executing these logs.
• Additionally, it permits customized domain

The demand for AWS API gateway professionals is quite high in the market, therefore, we have curated some important and most-asked interview questions that will help you bag your dream job.

For better understanding, the types of questions asked are divided into two categories. They are:

1. Freshers
2. Experienced
3. FAQs

Top 10 Frequently Asked AWS API Gateway Interview Questions

1. What constitutes the core elements of the Amazon API Gateway?
2. What services offered by AWS are compatible with API Gateway?
3. How then can you cache an API endpoint's responses?
4. What are some recommended techniques for creating APIs?
5. What does "throttling" refer to, and how might you combat it?
6. Why is an AWS API gateway necessary?
7. What is the API lifecycle for Amazon API Gateway?
8. What does an Amazon API Gateway resource mean?
9. What does an Amazon API Gateway resource policy entail?
10. What does an Amazon API Gateway Lambda authorizer do?

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AWS API Gateway Interview Questions for Freshers

1. An API gateway is what?

An API gateway is indeed a type of proxy server that stands in the way of communication between apps and backend services. An API gateway manages client requests, sends them to the proper backend service, receives the response, and then sends the client the response. Additional features like verification, caching and rate limiting can also be offered by API gateways.

2. How does a microservices architecture's API gateway operate?

All client requests enter through the API gateway. It is in charge of providing any required authentication and authorization, as well as of direct requests to the correct microservice. The API gateway also takes care of any interdisciplinary issues, like monitoring and logging.

3. Can you describe the process for using AWS API Gateway to create a basic REST API?

You must create a new API, a resource for the API, a technique for the resource, and implement the API in order to create a straightforward REST API using AWS API Gateway. You will then be given an endpoint by the API Gateway so that you can access the API.

4. What are some benefits of combining microservices architectures with API gateways?

When using microservices architectures, API gateways can offer a number of benefits. They may contribute to the creation of a single point of access for all microservices, which might also facilitate traffic management and monitoring. They can assist with traffic routing to suitable microservices and with authentication and security for all microservices.

5. What constitutes the core elements of the Amazon API Gateway?

The following are Amazon API Gateway's primary elements:

• the actual API Gateway service
• The API Gateway SDK, 
• API Gateway console
• API Gateway API

6. How are your APIs configured for authentication and authorization?

You must combine the two when constructing authorization and authentication for APIs. While authorization determines the level of permission each user has, authentication ensures that only authorized users can access the API.

7. How would you monitor log data using Amazon's CloudWatch service?

True tracking of Amazon Web Services (AWS) applications and resources is offered by the web service Amazon CloudWatch. To gather and monitor metrics, set alarms,log files and instantly respond to changes in the AWS resources, use Amazon CloudWatch.

8. What services offered by AWS are compatible with API Gateway?

DynamoDB, Lambda, and S3 are just a few of the AWS services that can be used with API Gateway.

9. Which security standards are compatible with AWS API Gateway?

OAuth 2.0,, SSL/TLS, and IAM are just a few of the security protocols that AWS API Gateway supports.

10. How then can you cache an API endpoint's responses?

Using a content delivery network is one way to store reactions from an API endpoint in a cache (CDN). Your API endpoint's static content can be cached by a CDN, which will speed up delivery to users. The use of a reverse proxy server is another method for caching responses. Without repeatedly making requests to the API endpoint, a reverse proxy server can store API responses and come back to users.

AWS API Gateway Interview Questions for Experienced:

1. What are some recommended techniques for creating APIs?

The use of a consistent naming convention, clear and precise documentation, and offering multiple ways to access the API are some best practices when designing APIs.

2. What are some typical issues that arise for developers when using API Gateways?

When using API Gateways, developers frequently run into the following issues:

• Lack of documentation or inadequate documentation
• Lack of assistance from the gateway provider
• Limited functionality
• Poor performance of the gateway

These can all make it difficult to understand how they work.

3. What distinguishes private, public, and partner APIs from one another?

Private APIs are accessible only within a company and are not available to the general public. Anyone can use public APIs, which are typically well-documented. Partner APIs typically have had some level of access control and are only for use by approved partners.

4. What does "throttling" refer to, and how might you combat it?

Limiting the volume of traffic that can pass through an API gateway is the procedure of throttling. This can be done for a number of reasons, such as to enforce rate limits for specific users or to avoid overburdening the backend that API is connecting to. Throttling can take many different forms, such as limiting the number of queries that can be made per second or capping the overall number of information that can be transferred in a given amount of time.

5. How does CORS (cross-origin resource sharing) work with Amazon API Gateway?

By enabling developers to specify which origins are permitted to access their API, Amazon API Gateway manages CORS. This is accomplished by configuring a CORS policy that can be done using either the API Gateway console or the REST API. Once a CORS policy has been established, API Gateway would then automatically add the required headers to API responses so that browsers can decide whether or not people should be permitted access to the resources.

6. What occurs if an API request goes over the rate limits or concurrent throttle limits set on the API?

The API Gateway will send an error message to the client if an API request exceeds the simultaneous throttle limit or rate boundaries imposed on an API. The client will then have to decide whether to try again later or wait for the throttle restriction to reset.

7. For APIs made with Amazon API Gateway, is it possible to set up a "custom domain name"?

For APIs made with Amazon API Gateway, it is possible to generate a custom domain name. A new Domain Name System (DNS) documentation that directs the unique domain name towards the Amazon API Gateway endpoint can be created to accomplish this.

8. Do all API requests generate logs? If so, where exactly?

An API does log each and every request that is made. The logs, which are typically kept in a database, can be used to monitor API performance and usage.

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9. Why should I pick Amazon API Gateway over competing products like Apigee or the Microsoft Azure API Management Service?

Amazon API Gateway is often preferred over the other API management tools for a variety of reasons, but one of the main ones is that it is completely handled by Amazon, so you don't have to worry about scaling or maintaining the service yourself. Additionally, building serverless applications is made simple by the integration of Amazon API Gateway with other AWS services such as Lambda and DynamoDB. Last but not least, Amazon API Gateway provides a free tier of providers so you can get started without paying anything.

10. When integrating an HTTP proxy with Amazon API Gateway, when should I use the "mock integration" option?

If you want to come back a predetermined reaction from the API without having to create any backend infrastructure, the "mock integration" option should be utilized. To send requests to a backend HTTP server, you should use the HTTP proxy integration option.

11. Why is an AWS API gateway necessary?

To make setting up the body mapping template for API Gateway easier, it is possible to provide such a schema or model again for payload. The features that API Gateway adds to OpenAPI to support the creation of SDKs and API documentation are included in its REST API management features.

Related Article: AWS Configuration

12. Is the gateway for the Amazon API secure?

Yes: Because all APIs created with Amazon API Gateway just expose HTTPS endpoints, it is safe to use. The Amazon API Gateway does not support HTTP endpoints that are not encrypted.

13. How does the AWS Gateway API function?

The documentation for API Gateway states that it controls every aspect of accepting and handling tens of thousands of API calls at once. Examples of these tasks include traffic control, permission and security systems, monitoring, and API versioning.

14. In API Gateway, what does API Caching mean?

The responses to our endpoints can be cached by users by enabling API prefetching in Amazon API Gateway. Caching enables us to decrease the number of calls to our endpoint even while reducing request latency for the API. The default TTL setting for API caching is 300 seconds. TTL has a maximum setting of 3600 seconds.

15. What advantages does an API Gateway offer?

• To stop attacks, Cost Effective Requests are throttled.
• Caching API
• A connection to the monitoring service CloudWatch is made through an Amazon API Gateway.
• Scalable
• Users could indeed authorize Access in API Gateway to ensure security. IAM is connected to a gateway that offers resources like AWS credentials.

16. What steps are required in working with API Gateway and AWS Lambda?

The steps involved in using API Gateway and AWS Lambda are as follows:

• HTTP Gateway
• IAM role creation for permission
• AWS Lambda function creation
• Develop an API Gateway
• Lambda function and API Gateway integration
• Data transmission to API Gateway

Related Article: AWS Lambda Tutorial

17. Describe a resource.

A resource is a typed object that belongs to our API domain. Each resource has a data model, connections to other resources, the ability to respond to requests using various methods, and the ability to define assets as variables to thwart requests for several child resources.

18. AWS Lambda Function: What Is It?

Amazon offers AWS Lambda, which is used to upload codes or business logic to the Aws platform and also manages it. This uploading code is referred to as a Lambda Function, and we can use it as an event-driven service that is triggered by changes to data in an S3 bucket or a Dynamodb table, for example, as an AWS API gateway's backend.

19. How can we build HTTP APIs using API Gateway?

HTTP APIs are made for cost-effective, low-latency integrations with services, including HTTP endpoints and AWS Lambda.

Additionally, HTTP claims to support CORS and automatic deployments, as well as OIDC and OAuth authorization.

REST APIs from earlier generations currently offer more options.

With less latency and expenditure than RESTAPIs, HTTP APIs make it possible to build RESTful APIs.

Additionally, it aids in having to send requests to any routing protocol HTTP endpoints from AWS Lambda functions.

Additionally, we are able to develop an HTTP API that works with AWS lambda on the function.

20. How are API Gateway APIs called?

The app developer assists with working with the executeapi API Gateway Service component, which is used to invoke API that has been created or implemented in an API Gateway. There are various ways to call an API and these underpinning programming entities are revealed by the created API.

Most Common AWS API Gateway FAQs

1. What kinds of API are there?

Two categories of API exist:

It is necessary for API proxy features and API management features in a single solution, and API Gateway also provides REST APIs. RESTful APIs are used to optimize serverless caseloads and HTTP backends using HTTP APIs.

Applications for real-time, two-way communication, such as chat apps and broadcasting dashboards, are built using WEBSOCKET APIs.

Additionally, it keeps a steady connection to handle message transfers between our clients and our backend service.

Related Article: Elasticsearch Update API

2. How to troubleshoot the AWS/ApiGateway 5XXError in AWS API Gateway & Lambda?

To enable API Gateway to force logs to CloudWatch, we must create an IAM role:

{

    "Version": "2012-10-17",

    "Statement": [

        {

            "Effect": "Allow",

            "Action": [

                "logs:CreateLogGroup",

                "logs:CreateLogStream",

                "logs:DescribeLogGroups",

                "logs:DescribeLogStreams",

                "logs:PutLogEvents",

                "logs:GetLogEvents",

                "logs:FilterLogEvents"

            ],

            "Resource": "*"

        }

    ]

3. How can API Gateway and SQS be combined?

The setting for the method is as follows:

PostMethod:

    Type: "AWS::ApiGateway::Method"

    Properties:

      ApiKeyRequired: "true"

      HttpMethod: "POST"

      ResourceId: !Ref "SomeResource"

      RestApiId: !Ref "SomeRestApi"

      Integration:

        IntegrationHttpMethod: "POST"

        IntegrationResponses:

        - StatusCode: 200

        Type: "AWS"

        Uri: "arn:aws:apigateway:${AWS::Region}:sqs:action/SendMessage"

4. What distinguishes Lambda from the AWS Gateway API?

The URI for the endpoint to be called is AWS API Gateway. Unlike Lambda, which is the calculated function called from S3,  API Gateway or SNS.

5. Can we track calls to the Amazon API Gateway?

You can use the metrics dashboard provided by API Gateway to track calls made to your services after an API has been published and is being used. Through the integration of Amazon CloudWatch, the API Gateway dashboard offers you backend performance metrics for API calls, latency information, and error rates. In addition to receiving error, access, or debug logs in CloudWatch Logs, you can enable detailed metrics for every method in your APIs.

6. What scenarios allow for the use of HTTP APIs?

Constructing proxy APIs for AWS Lambda or indeed any HTTP endpoint is what HTTP APIs are best for.

Constructing contemporary APIs with OIDC and OAuth 2 authorization

Levels of responsibility that are likely to rise significantly

7. Amazon API Gateway: Why Use It?

Developers can use Amazon API Gateway, a straightforward, adaptable, fully managed, pay-as-you-go service, to build and manage reliable APIs for application back ends. You can focus on developing the core business services by using API Gateway to quickly and affordably launch new services.

8. What is the API lifecycle for Amazon API Gateway?

Every REST API can also have multiple stages when using Amazon API Gateway. Stages are designed to assist with the project cycle of an API; for instance, after your APIs have been built, you can deploy people to a development stage or a production stage when they are ready for use.

9. What does an Amazon API Gateway stage mean?

Stages in Amazon API Gateway are comparable to tags. They specify the route that allows access to the deployment. You could designate a development stage, for instance, and deploy one's cars API there.

10. What does Amazon API Gateway's WebSocket routing entail?

The messages are correctly routed to a particular integration using WebSocket forwarding in Amazon API Gateway. When defining the WebSocket API, you must clearly state a routing key and an integration backend to use. A characteristic in the body text is the routing key. Additionally, for non-matching routing keys, a default integration can be set. For more information on routing, consult the documentation.

11. How do I use the backend service to send messages to clients who are connected?

A special URL, known as the callback URL, is formed for each new client linked to the WebSocket API. This callback URL can be used to communicate with the client from the backend system.

12. What is the largest message size that the WebSocket APIs support?

The largest message size that can be sent is 128 KB. Other restrictions on WebSocket APIs are listed in the documentation.

13. What features are included with API Gateway's HTTP APIs as standard?

OIDC, CORS support and OAuth2 support for authorization and authorization, and stage-based automatic deployments are all features that come standard with HTTP APIs.

14. How can I create an HTTP API by importing an OpenAPI definition?

Using OpenAPI 3, you can import an API definition. Routes, integrations, and API models will be made as a result. 

15. In Amazon API Gateway, can I create HTTPS endpoints?

Yes, only HTTPS endpoints are exposed by all APIs built with Amazon API Gateway. HTTP endpoints that are not encrypted are not supported by Amazon API Gateway. By default, Amazon API Gateway gives the API an internal domain that uses the Amazon API Gateway certificate automatically.

16. What types of data are supported by Amazon API Gateway?

For REST,HTTP and WebSocket APIs, APIs built on Amazon API Gateway could indeed accept whatever payloads sent over HTTPS. XML, JSON, query string parameters, and request headers are examples of common data formats.

17. What does an Amazon API Gateway resource mean?

A resource is a worded object that belongs to the domain of your API. Each resource may be linked to other resources, have relationships to certain other resources, and be responsive to various methods. Resources can also be defined as variables to block requests for many child resources.

18. What do Amazon API Gateway stage variables mean?

You can specify key/value pairs of configuration values linked to a stage using stage variables. These values can be included in your API configuration, much like environment variables. Instead of hardcoding the HTTP endpoint for the method integration, you could define it as a stage variable and use it in your API configuration, allowing you to use a distinct endpoint for each stage.

19. What does an Amazon API Gateway resource policy entail?

You can restrict the ability of a specific principal (typically an IAM user or role) to invoke an API by attaching a Resource Policy, a JSON policy document, to the API. You can restrict API calls to specific source IP address variances or CIDR blocks or allow users from different AWS accounts to safely access your API by using a resource policy. In the Amazon API Gateway, resource policies can be combined with REST APIs.

20. What does an Amazon API Gateway Lambda authorizer do?

AWS Lambda functions are called lambda authorizers. Utilizing a bearer token auth strategy, such as OAuth, you can authorize access to APIs with custom request authorizers. When an API is named, API Gateway checks to see if a Lambda authorizer has been set up. If it has, API Gateway then uses the authorization token to call the Lambda function.

Advantages of AWS API Gateway

1. Authentication:

It is possible to verify API calls using an API gateway. In this manner, the client only needs to authenticate once at the gateway even if they need to access data from various services. This lowers latency and guarantees that authentication procedures are uniform throughout the application.

2. Validation of Input:

Simple logic can also be carried out by API gateways. When it comes to input validation, this entails making sure that the client's request is complete and in the appropriate format before it is sent to the service that will ultimately obtain the requested data.

3. Metrics gathering:

The API gateway is the best place to gather analytics because it handles all requests. For instance, an API gateway can count the number of requests being made by a user or related to a specific microservice. Additionally, this enables the use of API gateways for rate limiting: if a user sends too many queries, the gateway can dismiss them rather than forward them to a service.

4. Transformation of a response:

Frequently, various users and devices require access to various types of information. For instance, internal clients may require more information than external clients, while mobile devices may require less data than desktop devices. This can be taken into account by using an API gateway, which essentially presents a distinct API. 

Key Upshots:

An API gateway can be characterized in a variety of ways. An API gateway is a layer that sits between your clients and services; you can refer to it as a reverse proxy, a single point of entry, or an interface. Clients send requests to an API gateway rather than directly to individual services. The appropriate service receives the requests after being forwarded by the API gateway.