How to provide custom backend code in AWS so that a Lambda function can import it-CodePudding

Imagine a basic Lambda Function like this:

#!/usr/bin/env python
# -*- coding: utf-8 -*-
"""This is an example Lambda Function which imports MyFancyClass from the
backend.
"""

from typing import Any, Dict

from project_name.module import MyFancyClass

def lambda_handler(event: Dict[str, Any], context: Any) -> Dict[str, Any]:
    """Standard Lambda event handler."""
    del context

    class_instance = MyFancyClass('some initial value')
    result = class_instance.special_method(event)
    return result

I could not manage to find an easy explanation how the code setup in AWS works such that you provide a backend code repo from where the Lambda function can import Python modules.

I read about Lambda Layers, but deploying all dependencies as a ZIP-file every time I make a change in the backend does not seem to be the smooth process I envision.

I much rather believe there must be a way to set up a CI/CD - pipeline on AWS where the code repo is managed AWS CodeCommit. With that, you push changes to the remote backend repo, it gets updated and finally, when the Lambda function is executed it accesses the up-to-date backend code.

But maybe, zipping the backend code and deploying it as a Lambda layer is really the only way. And if so, I would like to know how this can be combined with a CI/CD-pipeline repo in the most convenient way.

CodePudding user response：

You have to package the dependencies either into the Lambda deployment zip file, or into a Lambda Layer zip file, and deploy that to AWS Lambda. An AWS Lambda function cannot pull dependencies dynamically at run time, it has to have those dependencies included as part of the deployment, or as a deployed Layer that it depends on.

You need to configure your CI/CD platform to build and deploy a new version of your Lambda deployment (or Lambda layer deployment) whenever you push changes to the source code repository.

But maybe, zipping the backend code and deploying it as a Lambda layer is really the only way.

Yes that is the only way.

And if so, I would like to know how this can be combined with a CI/CD-pipeline repo in the most convenient way.

That last question is extremely broad.

In general you would have a CI/CD pipeline that is triggered by updates to your source code repository, builds a new version of your Lambda function or Lambda layer, and then deploys that update to AWS Lambda. If you need specific help with a specific step in that process, ask that as a separate question.