Layers in AWS Lambda function

In AWS Lambda, "layers" refer to a way to centrally manage and share code and dependencies across multiple Lambda functions.

A Lambda layer is a .zip file archive that contains supplementary code or data. Layers usually contain library dependencies, a custom runtime, or configuration files.

Layers allow you to package libraries, dependencies, and custom runtime components separately from your Lambda function code.

Here are some key points about layers in AWS Lambda:

1. Code and Dependencies Separation: Layers enable you to keep your Lambda function code focused on business logic while managing shared libraries, dependencies, and runtime components separately.

2. Reuse and Versioning: You can reuse layers across multiple Lambda functions, which helps in maintaining consistency and reduces the size of your deployment packages. Layers support versioning, allowing you to manage updates and rollback changes when necessary.

3. Custom Runtimes: Layers can also include custom runtimes, which extend the capabilities of Lambda beyond the standard runtimes provided by AWS (such as Node.js, Python, Java, etc.). This allows you to use languages or libraries that are not natively supported by AWS Lambda.

4. Size and Limits: Each AWS Lambda function can use up to 5 layers simultaneously. The size of all layers combined with your function code cannot exceed the unzipped deployment package size limit

5. Implementation: Layers are implemented as .zip archives that are uploaded to AWS Lambda. They are then referenced by Lambda functions either through the AWS Management Console, AWS CLI, or AWS SDKs.

6. Benefits: Using layers can streamline development, especially in scenarios where multiple functions share common dependencies or where you want to extend Lambda's capabilities with custom runtimes or additional libraries.

Overall, layers in AWS Lambda provide a mechanism for better code management, reuse of components, and extending Lambda's functionality, making it easier to maintain and deploy serverless applications.