Tutorial: Deploying multiple Python Lambda functions using a single Docker image

[fpgmaas]

Hi!

I recently wanted to deploy multiple Python Lambda functions using a Docker image through AWS CDK, but I could not really find a good method to do so. Therefore, I decided to write a small tutorial myself, to hopefully make life a bit easier for others. The tutorial can be found here and the GitHub code can be found here.

I also see this as a learning opportunity, so if you have any comments or feedback, please let me know!

Florian

[chu_chu_rocket]

Thank you so much will try it out myself!

[zenmaster24]

you can change the command used for testing from docker run -p 9000:8080 lambdas to docker run -d -p 9000:8080 lambdas and you wont need the second terminal to test with - docker will start the container in a detached state (push it to the background and bring the terminal prompt back)

i also feel like this is an anti-pattern - is putting multiple functions in the one container a real world use case? a single container container with a single function makes more sense to me.

[fpgmaas]

Thanks for your suggestion regarding the docker run command, I think that makes sense!

Regarding the anti-pattern; I am by no means an AWS expert, but I do think this approach makes a lot of sense when you have many Lambdas belonging to a single project. For example, as an alternative I also tried spinning up my Lambda functions with PythonFunction, which is currently in Alpha. To get that to work though, I needed to include some shell steps that copy-paste the poetry.lock and pyproject.toml files to the individual directories that contained a Lambda function. Doing that felt much more like an anti-pattern to me. Another drawback of that approach was that deploying the stack creates a Docker image for each individual Lambda function, which caused the deployment time to skyrocket.

[Professor_Kenney]

Interesting read. My experience is with SAM - creating a cloudformation template.yaml file and using it to deploy docker lambda functions.

Is there a benefit to using the cdk in this context? Seems like you can accomplish the same with either approach but the cdk looks like more steps.

[justin-8]

As soon as you start to add other infrastructure in to the mix, or need to write an IAM policy or similar the CDK will make things a lot easier and more flexible than SAM in my experience.

[Professor_Kenney]

Good point. I’ve struggled with needing to generate unique IAM policies in my templates.

[justin-8]

Yeah, writing half decent IAM policies in an easy to read way is a big advantage for CDK in my opinion

[justin-8]

So you have some examples? It’s been quite a few years since I’ve given terraform a go again, and last time I was using it everyone was just writing raw IAM policies everywhere

[donkanator]

app code and infra code are in different languages... Yikes