[@aws-cdk/aws-lambda-nodejs] Unable to run lambda locally with `sam local` after updating to aws-cdk@1.61.0

I’m using @aws-cdk/aws-lambda-nodejs to bundle JS lambda code. However, after updating aws-cdk to v1.61.0 (or higher) I can no longer run sam local with the template that cdk synth --no-staging generates. I believe this is because f5c9124 changed asset-staging.ts and now the template uses a different aws:asset:path for nodejs lambdas.

This is the Metadata of a working template:

Metadata:
  aws:cdk:path: TestStack/func/Resource
  aws:asset:path: /Users/lprice/work/playground/demo-aws-cdk-asset-path-bug/.cdk.staging/asset-bundle-IF4IYG
  aws:asset:property: Code

Versus that of a failing template:

Metadata:
  aws:cdk:path: TestStack/func/Resource
  aws:asset:path: asset.eaa6b4d3a12be11c844440afe5ee48ce3999505afaa441be0292009b5f7f2766
  aws:asset:property: Code

As you can see the path is different. When SAM tries to mount the lambda code to the docker image, this new relative path causes it to use a folder that does not contain the lambda code. The result is that when the lambda invoked, the code cannot be found and I get this error:

2020-09-15T14:52:59.899Z	undefined	ERROR	Uncaught Exception 	{"errorType":"Runtime.HandlerNotFound","errorMessage":"index.handler is undefined or not exported","stack":["Runtime.HandlerNotFound: index.handler is undefined or not exported","    at Object.module.exports.load (/var/runtime/UserFunction.js:144:11)","    at Object.<anonymous> (/var/runtime/index.js:43:30)","    at Module._compile (internal/modules/cjs/loader.js:1138:30)","    at Object.Module._extensions..js (internal/modules/cjs/loader.js:1158:10)","    at Module.load (internal/modules/cjs/loader.js:986:32)","    at Function.Module._load (internal/modules/cjs/loader.js:879:14)","    at Function.executeUserEntryPoint [as runMain] (internal/modules/run_main.js:71:12)","    at internal/main/run_main_module.js:17:47"]}
START RequestId: f0477efb-b72d-158b-0cdc-cc3d07557371 Version: $LATEST
END RequestId: f0477efb-b72d-158b-0cdc-cc3d07557371
REPORT RequestId: f0477efb-b72d-158b-0cdc-cc3d07557371	Init Duration: 131.03 ms	Duration: 1.06 ms	Billed Duration: 100 ms	Memory Size: 128 MB	Max Memory Used: 40 MB	

{"errorType":"Runtime.HandlerNotFound","errorMessage":"index.handler is undefined or not exported"}

Reproduction Steps

I created this repo to demonstrate this bug and provide steps to reproduce.

What did you expect to happen?

I expected the lambda to run successfully.

What actually happened?

I see an error when trying to invoke the lambda:

{"errorType":"Runtime.HandlerNotFound","errorMessage":"index.handler is undefined or not exported"}

Environment

• CLI Version : 1.61.0 (build 72e6727)
• Framework Version: 1.61.0 (build 72e6727)
• Node.js Version: v12.18.3
• OS : Mac OS X 10.14.6 (Build: 18G6020)
• Language (Version): Javascript

Edit: Remove --no-staging flag from cdk synth Edit: Undo previous edit.

---

This is 🐛 Bug Report

[ryan-mars]

@priceld If for any reason in the future you need to patch relative paths to assets in a yaml file generated by CDK I’m using this.

I know it’s a little late and the issue is already closed.

const yaml = require('js-yaml')
const fs = require('fs')
const path = require('path')
const { CLOUDFORMATION_SCHEMA } = require('cloudformation-js-yaml-schema')

const yamlPath = path.resolve('template.yaml')
if (!fs.existsSync(yamlPath)) throw `Your YAML isn't there: ${yamlPath}`

const template = yaml.safeLoad(fs.readFileSync(yamlPath, 'utf8'), {
  schema: CLOUDFORMATION_SCHEMA
})

const countPatched = Object.keys(template.Resources)
  .filter((resource) => template.Resources[resource].Type === 'AWS::Lambda::Function')
  .reduce((count, resource) => {
    const oldAssetPath = template.Resources[resource].Metadata['aws:asset:path']
    if (fs.existsSync(path.resolve(oldAssetPath))) {
      console.log(`Skipping ${resource} already a valid path\n${oldAssetPath}`)
      return count
    }
    const newAssetPath = path.resolve('cdk.out', oldAssetPath)
    if (!fs.existsSync(newAssetPath)) throw `There's no there, there: ${newAssetPath}`
    console.log(`Fixing path for ${resource}`)
    console.log(`${oldAssetPath} --> ${newAssetPath}`)
    template.Resources[resource].Metadata['aws:asset:path'] = newAssetPath
    return (count += 1)
  }, 0)

console.log(`Fixed ${countPatched} resources.`)

if (countPatched > 0) {
  console.log(`Writing ${yamlPath}`)
  fs.writeFileSync(yamlPath, yaml.dump(template, { schema: CLOUDFORMATION_SCHEMA }))
} else {
  console.log('Nothing to do, not touching the file.')
}

[priceld]

@jogold I guess it depends on the the purpose of the --no-staging flag. Based on the help documentation, it seems like output shouldn’t be copied at all when using --no-staging but this doesn’t seem to be happening (per #9189).

But @ryan-mars is getting at my point - what I would really like to do (and what I’ve lost the ability to do after v1.61.0) is be able to run sam local with my CDK template and test lambdas locally. I’m not sure if the answer is doing something with aws:asset:path or figuring out how to tell sam local where to search for assets.