23.8. API Gateway integration with AWS Lambda: Permissions and roles management in AWS IAM for Lambda and API Gateway

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23.8. API Gateway integration with AWS Lambda: Managing permissions and roles in AWS IAM for Lambda and API Gateway

The integration of API Gateway with AWS Lambda is a powerful combination that enables the development and deployment of scalable serverless applications. However, to make the most of these technologies, it is essential to properly understand and manage permissions and roles in AWS Identity and Access Management (IAM) for Lambda and API Gateway.

Permissions Management in AWS IAM

AWS IAM is a service that helps you control access to AWS resources. In the context of Lambda and API Gateway, IAM permissions define who or what can invoke your Lambda functions and who can access and manage your APIs.

Permissions are defined by IAM policies, which are JSON documents that specify the allowed actions, the resources on which the actions can be performed, and the optional conditions under which the actions are allowed or denied. For example, a policy might allow a Lambda function to be invoked only from a certain API Gateway, or a user can manage APIs but not invoke Lambda functions.

Role Management in AWS IAM

IAM roles are a way to delegate permissions to AWS entities or federated users. For Lambda and API Gateway, you can create IAM roles that allow these services to assume permissions on your behalf to access other AWS resources.

For example, you can create an IAM role that allows your Lambda function to access an Amazon S3 bucket or an Amazon DynamoDB table. Similarly, you can create an IAM role that allows your API Gateway to call other APIs or AWS services.

API Gateway integration with AWS Lambda

When you integrate API Gateway with AWS Lambda, you can create RESTful or WebSocket APIs that trigger Lambda functions in response to HTTP or WebSocket requests. This allows you to develop serverless applications that can automatically scale to meet demand and you only pay for what you use.

To integrate API Gateway with Lambda, you need to add a permission to your Lambda function resource that allows API Gateway to invoke it. This is done by adding a permission policy to the Lambda function resource that allows the "lambda:InvokeFunction" action from the "apigateway.amazonaws.com" principal.

Additionally, you may need to create an IAM role for API Gateway that allows it to invoke your Lambda function. This role must have a policy attached that allows the "lambda:InvokeFunction" action on your Lambda function resource.

Conclusion

Managing permissions and roles in AWS IAM for Lambda and API Gateway is a crucial part of developing serverless applications on AWS. By understanding how permissions and roles work and how to configure them correctly, you can ensure that your applications are secure, scalable, and efficient.

With the right combination of permissions and roles, you can build powerful applications that make the most of AWS Lambda and API Gateway. Whether you are a beginner or an experienced backend developer, we hope this guide has provided useful insight into how to manage permissions and roles in AWS IAM for these services.

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