AWS lambda layers error when call API "cannot find module" - amazon-web-services

Question

I try to use layers of AWS Lambda, watched a tutorial about it, but I get an error "cannot find module ..."
service: aws-nodejs
package:
exclude:
- .gitignore
- package.json
- .git/**
provider:
name: aws
profile: sandbox
runtime: nodejs12.x
layers:
testLayer:
path: testLayer
compatibleRuntimes:
- nodejs12.x
allowedAccounts:
- '*'
functions:
hello:
handler: handler.hello
layers:
- arn:aws:lambda:us-east-1:*:layer:testLayer:15
events:
- http:
path: test
method: get
cors: true
When i deploy it, i don't have any errors in my terminal, and on AWS, i see my layer and when i download it, i have my package.json with moment dependency, and the node_modules folder with moment
my handler.js looks like this :
'use strict';
module.exports.hello = async (event, context) => {
const moment = require('moment')
const a = moment('2016-01-01')
return {
statusCode: 200,
body: JSON.stringify({
message: 'Hey' + a
}),
};
};
My files structure :
testLayer/
node_modules/
moment/
package.json
serverless.yml
handler.js
package.json
Do you have any idea of what i doing wrong ?

Answer 1

Yes, it's possible that your node modules are there in your lambda layer and yet lambda is throwing error of "cannot find module..".
This may be happening because the zip that you have created is not as per directory structure mentioned in AWS documentation.
As per official documentation :
Including Library Dependencies in a Layer You can move runtime
dependencies out of your function code by placing them in a layer.
Lambda runtimes include paths in the /opt directory to ensure that
your function code has access to libraries that are included in
layers.
To include libraries in a layer, place them in one of the folders
supported by your runtime.
Node.js – nodejs/node_modules, nodejs/node8/node_modules (NODE_PATH)
Example AWS X-Ray SDK for Node.js
nodejs/node_modules/aws-xray-sdk
Make sure your zip contains correct directory structure else try importing your modules from /opt/your_node_module_directory

Answer 2

You can check node paths that provided by lambda with:
console.log(process.env.NODE_PATH);
After seeing the absolute path, you should set your import according to it. In my case it was:
import axios from '/opt/nodejs/node_modules/axios/index.js';