Working with AWS Lambda and Lambda Layers in AWS SAMThe introduction of serverless technology has enabled developers to shed the burden of managing infrastructure and concentrate on their application
To Nha Notes | May 15, 2024, 2:14 p.m.
The introduction of serverless technology has enabled developers to shed the burden of managing infrastructure and concentrate on their application code. AWS Lambda has taken on that management by providing isolated, event-driven compute environments for the execution of application code. To use a Lambda function, a developer just needs to package their code and any dependencies into a zip file and upload that file to AWS. However, as serverless applications get larger and more functions are required for those applications, there is a need for the ability to share code across multiple functions within the application.
To meet this need, AWS released Lambda layers, providing a mechanism to externally package dependencies that can be shared across multiple Lambda functions. Lambda layers reduces lines of code and size of application artifacts and simplifies dependency management. Along with the release of Lambda layers, AWS also released support for layers in the AWS Serverless Application Model (SAM) and the AWS SAM command line interface (CLI). SAM is a template specification that enables developers to define a serverless application in clean and simple syntax. The SAM CLI is a command line tool that operates on SAM templates and application code. SAM can now define Lambda layers with the AWS::Serverless::LayerVersion type. The SAM CLI can build and test your layers locally as well as package, deploy, and publish your layers for public consumption.
How layers work
To understand how SAM CLI supports layers, you need to understand how layers work on AWS. When a Lambda function configured with a Lambda layer is executed, AWS downloads any specified layers and extracts them to the /opt directory on the function execution environment. Each runtime then looks for a language-specific folder under the /opt directory.
Lambda layers can come from multiple sources. You can create and upload your own layers for sharing, you can implement an AWS managed layer such as SciPi, or you can grab a third-party layer from an APN Partner or another trusted developer. The following image shows how layers work with multiple sources.
References
https://aws.amazon.com/blogs/compute/working-with-aws-lambda-and-lambda-layers-in-aws-sam/
https://docs.aws.amazon.com/lambda/latest/dg/chapter-layers.html
https://blowstack.com/blog/how-to-use-aws-lambda-layers-with-sam
https://docs.aws.amazon.com/serverless-application-model/latest/developerguide/building-layers.html