API Gateway Best Practises - amazon-web-services

We are looking at utilising aws api gateway for better management of APIs. However, at a enterprise level, what will be the best practise? Will a common API gateway for to be used by all app teams be necessary (In this case, we might need a administrator for this common API gateway which adds to overhead) or should each app team build their own API gateway and administration of their API calls?
Hope to have someone share their experiences.

I have used AWS API gateway for different web/mobile application projects. let me try to answer your questions one by one here.
Limitations Based Design
API gateway comes with limitations. You can find answers based on these limitations.
For eg: There is a soft limit on "Resources per API" and its set at 300 which can be increased up to 500 max. This means that in future, if more than 500 resources are needed, new API gateway needs to be created.
So, it's better to logically segregate the APIs and have different API gateways depending on the purpose.
Throttle limit per region across REST APIs, WebSocket APIs, and WebSocket callback APIs is limited (Soft) to 10,000 requests per second (RPS) with an additional burst capacity provided by the token bucket algorithm, using a maximum bucket capacity of 5,000 requests.
So based on traffic API gateway needs to be designed.
There are many such limitations https://docs.aws.amazon.com/apigateway/latest/developerguide/limits.html
Features Based Design
API Gateway uses OPEN API standards and facilitates XML/JSON import and export features. So if a new API Gateway is created with a swagger file from an application, its better not to mix it with other applications.
There are many features like 1)Enable API cache, 2)Enable throttling, 3) Web Application Firewall 4) Client Certificate which cannot be common for all APis in an enterprise. So again, it's better to have separate APIs based on the requirements.
AWS API Gateway is engineered with different logging mechanisms and each API gateway implementation will need a tailored approach.
SDK generation comes very handy for mobile development and again there is no use of bundling all apis into one SDk and providing access.
So my suggestion is to use multiple API gateways, for an enterprise based on specific needs.

Related

How to give access to API behing AWS Api Gateway from our SDK

we use Aws Api Gateway to protect our apis.
We want to create an sdk for developers. The idea is to have In app purchase in their apps and call our apis in order to start payment.
We are trying to have a way to connect machine from machine. The first machine will be an sdk integrated in Android games and the second will be our back end protected by the api gateway.
The sdk should have a the authorization to consume the api.
Today we don't know how to do it, even after discussing with many architects.
The sdk is not going to have user and password, because it is not a user, so no way to generate the classic access token.
How could we achieve this use case ?
Thanks
The sdk should have a the authorization to consume the api. Today we don't know how to do it, even after discussing with many architects.
There are three possible ways to have a protected API Gateway. AWS Cognito and AWS Lambda. The third option, API Keys, is a little bit different than the previous two.
With Cognito, you create user pools and API Gateway automatically handles authorization when a request is received.
With Lambda, you create your own custom authorization logic.
I generally prefer the Lambda approach due to the ease of use but it depends on the use-case.
With the API Key option, you create API Keys for specific routes and API Gateway checks them through the request headers. I think any use-case that requires this can be handled with the Lambda option as well.
What you are describing doesn't sound difficult to achieve.
You will generate an API key and you will give them to the developers that will use your API.
In your SDK, you can accept the API key as an initialization parameter and provide it in the requests to API Gateway.

Difference in use case between application load balancer and API gateway

I’m trying to pick up API gateway.
What are the different use cases for alb vs API gateway? I’ll be honest to say that I am not completely familiar with the concept of an API. I know we can invoke it backend, and the analogy that it’s a restaurant menu. However, beyond that, I am not clear what the difference is. Is it that applications using ALB has a user interface, but not API gateway? I tried reading through documentation on the features, but got even more lost. As such, I am hoping someone can share the use cases for both services so that I can visualise what it’s used for and the reason for the features. Thanks!
API GW is focused on API and has some additional options - e.g. API definition via swagger, execution of a lambda function, converting the call to an event bridge event, support of authenticators (iam, cognito), multiple deployment stages etc.
The load balancer listens on a port and that's about it.
Q: In what cases would you require these API GW features as opposed to just using an ALB?
A: One obvious benefit is a serverless or "low code". Let's say you want an API which processes asynchronous requests.
It is possible to create an API endpoint which queues all incoming requests to a SQS queue with just one AWS CLI command with no programming (provided the resources do exist):
https://docs.aws.amazon.com/apigateway/latest/developerguide/http-api-develop-integrations-aws-services.html
Each API endpoint can be served by a different AWS resource including EC2/ALB.
ALB is well suited for things like traditional monolithic applications (LAMP, Java application servers etc.)

HTTP APIs enable you to create RESTful APIs with lower latency and lower cost than REST APIs

I am reading AWS API gateway documentation.
There is a sentence confusing me
HTTP APIs enable you to create RESTful APIs with lower latency and lower cost than REST APIs.
here is the link to the page containing this sentence
What is the difference between RESTful and REST here? Because in many places I read that it's the same
API Gateway offers multiple modes for using it
HTTP
REST
Websockets
These are all capabilities that API gateway offers. What they are saying it that if you want to develop a REST service it is better to use the HTTP options instead of the REST one.
Most likely they will suggest to use lambdas and maybe dynamodb and go down a serverless routes, but that's not mandatory.

How to charge users by usage?

I’m building a service and I’m planning to charge a fixed price for each lambda call.
How to count requests per client if the lambda function being called is the same? I’m planning to pass a client id
You can use API Gateway Usage Plans for your requirement.
After you create, test, and deploy your APIs, you can use API Gateway usage plans to make them available as product offerings for your customers. You can configure usage plans and API keys to allow customers to access selected APIs at agreed-upon request rates and quotas that meet their business requirements and budget constraints. If desired, you can set default method-level throttling limits for an API or set throttling limits for individual API methods.
A usage plan specifies who can access one or more deployed API stages and methods—and also how much and how fast they can access them. The plan uses API keys to identify API clients and meters access to the associated API stages for each key. It also lets you configure throttling limits and quota limits that are enforced on individual client API keys.
Read this docs for more detail explanation.
You can use api gateway https://aws.amazon.com/api-gateway/
"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. APIs act as the "front door" for applications to access data, business logic, or functionality from your backend services."
It provides you with statistics about usage as well as different options like limit numbers of requests per api_key, etc

Application Load Balancers vs API Gateway

AWS comes with a service called Application Load Balancer and it could be a trigger to a lambda function. The way to call such a lambda function is by sending an HTTP/HTTPS request to ALB.
Now my question is how this is any different from using the API Gateway? And when should one use ALB over API Gateway (or the way around)?
One of the biggest reasons we use API gateway in front of our lambda functions instead of using an ALB is the native IAM (Identity and Access Management) integration that API GW has. We don't have to do any of the identity work ourselves, it's all delegated to IAM, and in addition to that, API GW has built-in request validation including validation of query string parameters and headers. In a nutshell, there are so many out of the box integrations what come with API GW, you wind up having to do a lot more work if you go the route of using an ALB.
It seems that the request/response limit is lower when using ALB, and WebSockets are not supported:
The maximum size of the request body that you can send to a Lambda
function is 1 MB. For related size limits, see HTTP Header Limits.
The maximum size of the response JSON that the Lambda function can
send is 1 MB.
WebSockets are not supported. Upgrade requests are rejected with an
HTTP 400 code.
See: https://docs.aws.amazon.com/elasticloadbalancing/latest/application/lambda-functions.html
Payload limit with API Gateway is discussed here: Request payload limit with AWS API Gateway
Also the article already mentioned by #matesio provides information about additional things to consider when choosing between ALB and API Gateway.
Notable tweet referenced in the mentioned article:
If you are building an API and want to leverage AuthN/Z, request
validation, rate limiting, SDK generation, direct AWS service backend,
use #APIGateway. If you want to add Lambda to an existing web app
behind ALB you can now just add it to the needed route.
(From: Dougal Ballantyne, the Head of Product for Amazon API Gateway)
API gateways usually are richer in functionality than Load balancers. In addition to load balancing, API gateways often capable to do the following:
Content based based routing (some calls to v1 and some calls to v2 and so on, based on certain criteria)
IAM related functionality (eg: access validation )
Security (eg: SSL offloading, DDOS attack prevention, security credentials translation - eg: translating particular type of token to another, etc)
Payload translation (eg: XML to Json, etc)
Additionally, API gateways may be available in appliance form - and appliances are usually of low-latency, far more secure, etc.
I am not aware of specific features of AWS API gateway, but the above ones are general features of any API gateway. Nevertheless, when you have an option to use either LB or API gateway to offer a service on internet, API gateway is usually a better option, unless there are specific reasons to choose otherwise.