AWS SAM and Typescript: building functions and layers

[daniele-salvagni]

Comments for the blog post: https://dsalvagni.com/b/aws-sam-and-typescript-building-functions-and-layers/

[samputer]

Fantastic. Just what I needed - thank you!

Note that I needed to copy any node_modules included in the layer across also.

[daniele-salvagni]

Thank you for bringing this up. You are absolutely right that if the layer has dependencies, they'll also need to be copied over during the build process. I will update this post at some point to also cover this case.

[danhnguyeen]

Hi @daniele-salvagni ,
thanks for your great sharing. I have tried your solution and everything worked well.
But due to we copy everything in node_module, the size of layer will be very large.
I tried to download a very simple layer and extract the zip file, and the layer size is 71MB (because node_module includes typescript package also). So some of my Lambda functions threw bellow error
Function code combined with layers exceeds the maximum allowed size of 262144000 bytes
It means my lambda function + layer is large than the limitation 250MB even my project is still very simple.
Do you have any idea about this case?

[danhnguyeen]

OK, I know why. In your example, I think we should move typescript to devDependencies instead dependencies. It will reduce the package size a lot :)

[daniele-salvagni]

Thanks for catching that mistake @danhnguyeen. Yes, typescript and @types/node should both have been inside devDependencies. I will fix the examples asap

[gittemo]

very useful. Could you be so kind and put up a GH repo with this?

[hafizali05]

@giscus this would be greatly appreciated

[daniele-salvagni]

Hi, I just created a repository on GitHub with a full working example:
https://github.com/daniele-salvagni/aws-sam-ts-functions-layers

[hafizali05]

When in lambda trying to import module from layer, gives module not sound error, can you please suggest ?

[daniele-salvagni]

If the error is local (in your editor) you could create a global package.json where you put the following inside devDependencies so that you editor knows where to look for the module:

"commons": "file:./layers/commons"

You can reference this repo I just added for a full example

[gittemo]

Thank you so much for this ☺️Am 22.05.23, 16:42 schrieb Daniele Salvagni ***@***.***>: Hi, I just created a repository on GitHub with a full working example: https://github.com/daniele-salvagni/aws-sam-ts-functions-layers —Reply to this email directly, view it on GitHub, or unsubscribe.You are receiving this because you commented.Message ID: ***@***.***>

[ahmednmourad]

When you try to copy "commons" folder into "node_modules" there might be a package with the same name, so I would suggest naming "commons" package differently to avoid conflicts.

[sumitbusa]

Hi,

just one question, lets assume i have two files in hello_world functions, instead of only one app.ts.

what will be change, based on current code base i believe it will only compile app.ts instead all present.

[daniele-salvagni]

If the other file is some code imported in app.ts, esbuild will bundle it inside app.js when transpiling it to Javascript, so you don't need to make any changes.

If you want to include other unrelated files inside your lambda, you will need to use a custom Makefile (like I did for the layer) instead of using the provided esbuild integration. Inside your Makefile you could decide to transpile the code with either esbuild or tsc, copy over any other files you need, or run any other command you need to bundle your lambda.

[kostekd]

Fantastic article. Just a little update I believe currently it is possible to specific a format option for esbuild in SAM AWS.

Link to the newest documentation: https://docs.aws.amazon.com/serverless-application-model/latest/developerguide/serverless-sam-cli-using-build-typescript.html

[daniele-salvagni]

Thanks for the heads up, happy to hear that they finally exposed the esbuild options!

[kostekd]

Since reading your article, I've been experimenting with AWS SAM, Lambda layers, and functions. Your article provided a great starting point!

Currently, my entire repository is natively written in TypeScript with ES modules. I'm using Rollup to transpile and bundle my layer.

Maybe in the future, I'll find time to write an updated version of an article like yours!