Use existing Lambda layer(AWS) in Serverless(framework) project - aws-lambda

Question

I am migrating existing lambda functions created using the AWS GUI to a serverless framework project for better version control.
Few functions have layers, now I am trying to add the layer in the config file by directly using the ARN of the layer. This layer was created using the GUI, not using the framework.
functions:
functionName:
handler: handlerFile.handler
layers:
- arn:aws:lambda:...:...:layer:layername:version # Using the ARN directly here, no layer config present in this project
Now when I try to deploy the project, I am getting Module not found. Can't resolve 'sharp', so the layer is not working and unable to access the modules, the sharp library is in the layer. node_modules doesn't exist or is not a directory All the online tutorials and documentation add the layer files manually in the project and deploy a new layer and then use that, is it not possible to use the ARN of an existing layer? It is happening at the webpack compilation step of deployment. This is the webpack config file
module.exports = {
target : 'node',
mode: 'none'
}
The layer uses the folder structure mentioned in the docs, it also works fine in the existing lambda function that I created in the GUI. I am using multiple layers, so I didn't want to add the layer files in the serverless project to keep it clean. The last thing to try would be to manually create layer directories and deploy the layers first using the serverless framework and then it might work(though not sure)
Is it possible to use the ARN of an existing layer directly in the serverless function config given that the layers have already been created using the GUI and not using the framework?
Serverless framework version : 3
Layer type: nodejs 16

Answer 1

Yes, it is possible to use existing layers exactly in the way you added them, you should be able to use both existing layers via ARN and ones created by the Framework. Could you please share the full error and tell us what version of the Framework are you using?
On the side note - module not found might suggest that handler cannot be found. I see you have hanlerFile in config instead of (probably) handlerFile. Maybe this typo is causing the problem here?