Cannot import package in AWS lambda with Nodejs14.x ES module

Question

I have a layer where the path of node_modules is nodejs/node14/node_modules.

Using that layer, and I try to import a package in a Lambda function, say 'aws-cloudfront-sign', like this:

import cfsign from 'aws-cloudfront-sign'

I got error message

Cannot find package 'aws-cloudfront-sign' imported from /var/task/signer.js
Did you mean to import aws-cloudfront-sign/lib/cloudfrontUtil.js?

But if I import the package like this:

import cfsign from '/opt/nodejs/node14/node_modules/aws-cloudfront-sign/lib/cloudfrontUtil.js'

It succeeds.

Do you know why? How could I import the package correctly?

user_1601122 · Answer

This appears to be a bug. It is occurring with layers and the SDK. There are are a number of similar open issues on Github:

As you have worked out, the only workaround at present seems to be the use of absolute paths. E.g.:

import { DynamoDB } from 'aws-sdk;'

fails, whereas

import AWS from '/var/runtime/node_modules/aws-sdk/lib/aws.js';
const { DynamoDB } = AWS;

will work.

I suggest you add your voice to an existing open issue to help ensure it gets attention.