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Mastering AWS API Gateway with AWS APIGateway-integration: Practical Examples and Best Practice

Updated: Aug 28, 2024



API Gateway is a crucial component in modern application architectures, especially when building microservices or serverless applications. Here are some of the key reasons why you might want to use an API Gateway:

Centralised Management: API Gateway provides a centralised interface for managing all of your APIs. This makes it easier to maintain and monitor your APIs, as you can do everything from one place.
Security: API Gateway provides several features to secure your APIs, such as IAM roles and policies, resource policies, CORS, API keys and usage plans, and integration with AWS WAF. These features help protect your APIs from unauthorised access and common web exploits.
Performance: API Gateway provides optional caching capabilities to improve performance. By caching the responses from your backend, API Gateway can reduce the number of calls made to your backend, and thus reduce latency for your users.
Scalability: API Gateway handles all the tasks involved in accepting and processing concurrent API calls, including traffic management, authorization and access control, monitoring, and API version management. This allows your applications to scale effortlessly.
Integration with Other AWS Services: API Gateway integrates seamlessly with other AWS services like AWS Lambda, Amazon DynamoDB, Amazon SNS, and more. This makes it easier to build and manage applications that use these services.

API Gateway is a fully managed service by Amazon Web Services (AWS) that makes it easy for developers to create, publish, maintain, monitor, and secure APIs at any scale. One of the key features of API Gateway is the ability to integrate directly with other AWS services, and this is where the x-amazon-apigateway-integration extension comes into play. This extension is used in the OpenAPI definition to set up the integration between the API Gateway and the backend AWS service.


In this blog post, we'll explore some examples of how to use X-Amazon-APIGateway Integration and discuss some best practices to follow when using it.




~ Integration with AWS Lambda


AWS Lambda is a serverless computing service that lets you run your code without provisioning or managing servers.


Here's an example of how you can set up an integration with Lambda using x-amazo


n-apigateway-integration:

paths:
  /myapi:
    post:
      x-amazon-apigateway-integration:
        uri:
          Fn::Sub: arn:aws:apigateway:${AWS::Region}:lambda:path/2015-03-31/functions/${MyLambdaFunction.Arn}/invocations
        responses:
          default:
            statusCode: "200"
        passthroughBehavior: "when_no_match"
        httpMethod: "POST"
        type: "aws_proxy"

In this example, the uri field is used to specify the ARN (Amazon Resource Name) of the Lambda function to be invoked. The responses field maps the response from the backend to the response that API Gateway returns to the client. The passthroughBehavior field determines what API Gateway does when it doesn't find a defined response for the backend. The httpMethod field specifies th


e HTTP method to use when calling the backend. The type field specifies the integration type, which in this case is aws_proxy for Lambda proxy integration.



~ Integration with Amazon DynamoDB


Amazon DynamoDB is a key-value and document database that delivers single-digit millisecond performance at any scale.


Here's an example of how you can set up an integration with DynamoDB:


paths:
  /myapi:
    put:
      x-amazon-apigateway-integration:
        uri:
          Fn::Sub: arn:aws:apigateway:${AWS::Region}:dynamodb:action/PutItem
        credentials: ${MyDynamoDBRole.Arn}
        responses:
          default:
            statusCode: "200"
        requestTemplates:
          application/json: |
            {
              "TableName": "MyTable",
              "Item": {
                "id": {
                  "S": "$input.params('id')"
                },
                "value": {
                  "S": "$input.params('value')"
                }
              }
            }
        httpMethod: "POST"
        type: "aws"

In this example, the uri field is used to specify the action to be performe


d on DynamoDB. The credentials field is used to specify the IAM role that has permissions to perform the action. The requestTemplates field is used to transform the incoming request into the format required by DynamoDB.


Best Practices

  1. Use the Correct Integration Type: AWS API Gateway supports several types of integrations, including aws, aws_proxy, http, http_proxy, and mock. Make sure to use the correct type for your use case.

  2. Secure Your APIs: Always use IAM roles with the least privileges necessary for the credentials field. This minimizes the potential damage if your API is compromised.

  3. Use Stage Variables: Stage variables are name-value pairs that you can define as configuration attributes associated with a deployment stage of an API Gateway API. You can use these variables to manage your uri and credentials fields across different stages of your API.

  4. Handle Errors Properly: Make sure to define responses for all possible HTTP status codes that your backend can return. This ensures that your API behaves predictably when errors occur.

  5. Use Mapping Templates: Mapping templates can transform the incoming request into the format required by your backend and transform the response from your backend into the format required by your API. This decouples your API from your backend and makes your API more flexible.

By following these best practices and understanding how to use the x-amazon-apigateway-integration extension, you can create robust and secure APIs with


AWS API Gateway.




~ Integration with Custom Microservices API

Illustration of AWS API Gateway connecting various microservices in a cloud architecture.

If you have a custom microservice running on an EC2 instance or within a Docker container on ECS or EKS, you can also use the x-amazon-apigateway-integration extension to set up an HTTP integration.


Here's an example:

paths:
  /myapi:
    get:
      x-amazon-apigateway-integration:
        uri: 
          Fn::Sub: http://${EC2Instance.PublicIp}:8080/myapi
        responses:
          default:
            statusCode: "200"
        httpMethod: "GET"
        type: "http"

In this example, the uri field is used to specify the URL of your custom microservice. The httpMethod field specifies the HTTP method to use when calling the backend. The type field specifies the integration type, which in this case is http for HTTP integration.

Please note that this is a simplified example. In a real-world scenario, you would likely have a load balancer in front of your microservices, and you would use the DNS name of the load balancer in the uri field. Also, you would likely use HTTPS for secure communication.



Best Practices

  1. Use Load Balancers: If you have multiple instances of your microservice for high availability or load balancing, make sure to use a load balancer and use the DNS name of the load balancer in the uri field.

  2. Use HTTPS: To secure the communication between API Gateway and your microservice, use HTTPS instead of HTTP. You can use AWS Certificate Manager to create a free SSL certificate for your load balancer.

  3. Use VPC Links: If your microservice is running within a VPC, you can use VPC Links to allow API Gateway to access it. This ensures that the traffic between API Gateway and your microservice stays within the AWS network, which is more secure and has lower latency.

  4. Handle Errors Properly: Make sure to define responses for all possible HTTP status codes that your microservice can return. This ensures that your API behaves predictably when errors occur.

By following these best practices and understanding how to use the x-amazon-apigateway-integration extension, you can create robust and secure APIs with AWS API Gateway that integrate with your custom microservices.



Importing a custom API into Amazon API Gateway using the OpenAPI standard is a straightforward process.


A step-by-step guide on how to:


~ Create Your OpenAPI Definition: The first step is to create an OpenAPI definition for your API. This definition describes your API's resources, methods, input parameters, output responses, and the x-amazon-apigateway-integration settings for integrating with your backend. You can write this definition in either JSON or YAML format.

~ Validate Your OpenAPI Definition: Before importing your definition into API Gateway, it's a good idea to validate it using an OpenAPI validator. This can help catch any syntax errors or inconsistencies in your definition.

~ Log in to the AWS Management Console: Navigate to the API Gateway service.

~ Create a New API: Click on "Create API". Then, select "Import" and choose the "REST API" option.

~ Import Your OpenAPI Definition: Click on "Choose File" and select your OpenAPI definition file. Then, click on "Import" to import your API.

~ Review Your API: After importing, you should see your API's resources and methods in the API Gateway console. You can click on each resource and method to view its details. Make sure everything looks correct.

~ Deploy Your API: Before your API can handle requests, you need to deploy it. To do this, click on "Actions" and select "Deploy API". You'll be asked to choose or create a new stage for your deployment.

~ Test Your API: After deploying, you'll be given an Invoke URL for your API. You can use this URL to test your API and make sure it's working correctly.

Remember, the OpenAPI definition is a powerful tool for defining and managing your APIs. It allows you to define your API's interface and the x-amazon-apigateway-integration settings in a machine-readable format, which can be version-controlled and shared across your team. This makes it easier to collaborate on API development and ensures consistency across different environments.


In conclusion, the x-amazon-apigateway-integration extension is a powerful tool for integrating your APIs with various AWS services and custom microservices. By understanding its usage and following the best practices we've outlined, you can create robust, secure, and efficient APIs. Remember, the journey to mastering API Gateway doesn't stop here. Keep exploring, keep learning, and keep innovating. If you have any questions or need further assistance, don't hesitate to reach out. We're here to help you succeed in your cloud journey. If you found this blog post helpful, please share it with your colleagues and friends. Stay tuned for more insightful content on AWS and cloud computing. Happy coding!

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