Bug: Invoking a lambda function is giving me an error 'cannot find module' even though module exists

[kkchu791]

After building and starting the local sam server, I'm noticing after I run my lambda GetBlocksByDateRangeFunction, I get this error in the console.

Invalid lambda response received: Invalid API Gateway Response Keys: {'trace', 'errorMessage', 'errorType'} in {'errorType': 'Runtime.ImportModuleError', 'errorMessage': "Error: Cannot find
module 'something'\nRequire stack:\n- /var/runtime/index.mjs", 'trace': ["Runtime.ImportModuleError: Error: Cannot find module 'something'", 'Require stack:', '- /var/runtime/index.mjs', '
at _loadUserApp (file:///var/runtime/index.mjs:997:17)', '    at async UserFunction.js.module.exports.load (file:///var/runtime/index.mjs:1032:21)', '    at async start
(file:///var/runtime/index.mjs:1195:23)', '    at async file:///var/runtime/index.mjs:1201:1']}

Steps to reproduce:

I'm not sure how I got this behavior to happen.

Observed result:

2023-06-25 11:58:45,415 | Constructed Event 1.0 to invoke Lambda. Event: {'version': '1.0', 'httpMethod': 'GET', 'body': None, 'resource': '/kevin', 'requestContext': {'resourceId': '123456',
'apiId': '1234567890', 'resourcePath': '/kevin', 'httpMethod': 'GET', 'requestId': '04e1e7ee-a920-462e-ac8d-3589db2ff535', 'accountId': '123456789012', 'stage': 'Prod', 'identity': {'apiKey':
None, 'userArn': None, 'cognitoAuthenticationType': None, 'caller': None, 'userAgent': 'Custom User Agent String', 'user': None, 'cognitoIdentityPoolId': None, 'cognitoAuthenticationProvider':
None, 'sourceIp': '127.0.0.1', 'accountId': None}, 'extendedRequestId': None, 'path': '/kevin', 'protocol': 'HTTP/1.1', 'domainName': '127.0.0.1:3001', 'requestTimeEpoch': 1687719488,
'requestTime': '25/Jun/2023:18:58:08 +0000'}, 'queryStringParameters': None, 'multiValueQueryStringParameters': None, 'headers': {'User-Agent': 'PostmanRuntime/7.32.3', 'Accept': '*/*',
'Postman-Token': '6f0a0ea9-75de-4839-a840-947f37c83019', 'Host': '127.0.0.1:3001', 'Accept-Encoding': 'gzip, deflate, br', 'Connection': 'keep-alive', 'X-Forwarded-Proto': 'http',
'X-Forwarded-Port': '3001'}, 'multiValueHeaders': {'User-Agent': ['PostmanRuntime/7.32.3'], 'Accept': ['*/*'], 'Postman-Token': ['6f0a0ea9-75de-4839-a840-947f37c83019'], 'Host':
['127.0.0.1:3001'], 'Accept-Encoding': ['gzip, deflate, br'], 'Connection': ['keep-alive'], 'X-Forwarded-Proto': ['http'], 'X-Forwarded-Port': ['3001']}, 'pathParameters': None,
'stageVariables': None, 'path': '/kevin', 'isBase64Encoded': False}
2023-06-25 11:58:45,419 | Found one Lambda function with name 'GetBlocksByDateRangeFunction'
2023-06-25 11:58:45,424 | Invoking src/handlers/something.somethingHandler (nodejs18.x)
2023-06-25 11:58:45,425 | No environment variables found for function 'GetBlocksByDateRangeFunction'
2023-06-25 11:58:45,426 | Resolving code path. Cwd=/Users/kirkchu/pairup/ourtracks-node-api/.aws-sam/build,
CodeUri=/Users/kirkchu/pairup/ourtracks-node-api/.aws-sam/build/GetBlocksByDateRangeFunction
2023-06-25 11:58:45,427 | Resolved absolute path to code is /Users/kirkchu/pairup/ourtracks-node-api/.aws-sam/build/GetBlocksByDateRangeFunction
2023-06-25 11:58:45,427 | Code /Users/kirkchu/pairup/ourtracks-node-api/.aws-sam/build/GetBlocksByDateRangeFunction is not a zip/jar file
2023-06-25 11:58:45,465 | Using local image: public.ecr.aws/lambda/nodejs:18-rapid-x86_64.

2023-06-25 11:58:45,466 | Mounting /Users/kirkchu/pairup/ourtracks-node-api/.aws-sam/build/GetBlocksByDateRangeFunction as /var/task:ro,delegated, inside runtime container
2023-06-25 11:58:46,369 | Starting a timer for 3 seconds for function 'GetBlocksByDateRangeFunction'
START RequestId: 56b06cbc-5a48-4570-886f-f9e589e8b906 Version: $LATEST
2023-06-25T18:58:46.658Z	undefined	ERROR	Uncaught Exception 	{"errorType":"Runtime.ImportModuleError","errorMessage":"Error: Cannot find module 'something'\nRequire stack:\n- /var/runtime/index.mjs","stack":["Runtime.ImportModuleError: Error: Cannot find module 'something'","Require stack:","- /var/runtime/index.mjs","    at _loadUserApp (file:///var/runtime/index.mjs:997:17)","    at async UserFunction.js.module.exports.load (file:///var/runtime/index.mjs:1032:21)","    at async start (file:///var/runtime/index.mjs:1195:23)","    at async file:///var/runtime/index.mjs:1201:1"]}
25 Jun 2023 18:58:46,687 [ERROR] (rapid) Init failed error=Runtime exited with error: exit status 129 InvokeID=
2023-06-25T18:58:46.957Z	undefined	ERROR	Uncaught Exception 	{"errorType":"Runtime.ImportModuleError","errorMessage":"Error: Cannot find module 'something'\nRequire stack:\n- /var/runtime/index.mjs","stack":["Runtime.ImportModuleError: Error: Cannot find module 'something'","Require stack:","- /var/runtime/index.mjs","    at _loadUserApp (file:///var/runtime/index.mjs:997:17)","    at async UserFunction.js.module.exports.load (file:///var/runtime/index.mjs:1032:21)","    at async start (file:///var/runtime/index.mjs:1195:23)","    at async file:///var/runtime/index.mjs:1201:1"]}
END RequestId: 191afcfa-7165-4e0d-a437-efa1c55904c9
REPORT RequestId: 191afcfa-7165-4e0d-a437-efa1c55904c9	Init Duration: 0.94 ms	Duration: 567.76 ms	Billed Duration: 568 ms	Memory Size: 128 MB	Max Memory Used: 128 MB
2023-06-25 11:58:47,270 | Cleaning all decompressed code dirs
2023-06-25 11:58:47,272 | Lambda returned empty body!
2023-06-25 11:58:47,273 | Invalid lambda response received: Invalid API Gateway Response Keys: {'errorType', 'trace', 'errorMessage'} in {'errorType': 'Runtime.ImportModuleError',
'errorMessage': "Error: Cannot find module 'something'\nRequire stack:\n- /var/runtime/index.mjs", 'trace': ["Runtime.ImportModuleError: Error: Cannot find module 'something'", 'Require
stack:', '- /var/runtime/index.mjs', '    at _loadUserApp (file:///var/runtime/index.mjs:997:17)', '    at async UserFunction.js.module.exports.load (file:///var/runtime/index.mjs:1032:21)', '
at async start (file:///var/runtime/index.mjs:1195:23)', '    at async file:///var/runtime/index.mjs:1201:1']}

Expected result:

I'm expecting it to not return an error and not to say Cannot Find Module since the module does exist.

Additional environment details (Ex: Windows, Mac, Amazon Linux etc)

Mac

1. OS: MacOS Big Sur
2. sam --version: SAM CLI, version 1.88.0
3. AWS region: us-west-2

# Paste the output of `sam --info` here

{
  "version": "1.88.0",
  "system": {
    "python": "3.11.4",
    "os": "macOS-11.2.2-x86_64-i386-64bit"
  },
  "additional_dependencies": {
    "docker_engine": "20.10.23",
    "aws_cdk": "Not available",
    "terraform": "Not available"
  },
  "available_beta_feature_env_vars": [
    "SAM_CLI_BETA_FEATURES",
    "SAM_CLI_BETA_BUILD_PERFORMANCE",
    "SAM_CLI_BETA_TERRAFORM_SUPPORT",
    "SAM_CLI_BETA_RUST_CARGO_LAMBDA"
  ]
}```

`Add --debug flag to command you are running`

[kkchu791]

Approaches I've tried:

1. Deleted all docker images and containers involving sam
2. Change the name of the resource and it began to work. When I switched it back to the original name, I got the error.
3. Updated Sam-Cli to the latest version

[sriram-mv]

Thanks for creating this issue, can you share your template and how your code is structured?

Change the name of the resource and it began to work. When I switched it back to the original name, I got the error.

This is super interesting, do you see any changes in the artifacts within .aws-sam/ directory once you change the name of the resource?

[kkchu791]

template.yaml

AWSTemplateFormatVersion: '2010-09-09'
Transform: AWS::Serverless-2016-10-31

# More info about Globals: https://github.com/awslabs/serverless-application-model/blob/master/docs/globals.rst
Globals:
  Function:
    Runtime: nodejs18.x
    Timeout: 180
    Architectures: x86_64
    Environment:
      Variables:
        DB_HOST: process.env.DB_HOST
        DB_USER: process.env.DB_USER
        DB_PASSWORD: process.env.DB_PASSWORD
        DB_DATABASE: process.env.DB_DATABASE
        DB_PORT: process.env.DB_PORT
  Api:
    Cors:
      AllowMethods: "'*'"
      AllowHeaders: "'*'"
      AllowOrigin: "'*'"

Resources:
  GetBlocksByDateRangeFunction:
    Type: AWS::Serverless::Function
    Properties:
      Handler: src/handlers/blocks/get-blocks-by-date-range.getBlocksByDateRangeHandler
      Runtime: nodejs18.x
      Architectures:
        - x86_64
      Events:
        Api:
          Type: Api
          Properties:
            Path: /blocks
            Method: GET

  GetOpenBlocksByDateRangeFunction:
    Type: AWS::Serverless::Function
    Properties:
      Handler: ./src/handlers/blocks/get-open-blocks-by-date-range.getOpenBlocksByDateRangeHandler
      Architectures:
        - x86_64
      Events:
        Api:
          Type: HttpApi
          Properties:
            Path: /blocks/open
            Method: GET

  CreateBlockFunction:
    Type: AWS::Serverless::Function
    Properties:
      Handler: src/handlers/blocks/create-block.createBlockHandler
      Architectures:
        - x86_64
      Events:
        Api:
          Type: HttpApi
          Properties:
            Path: /blocks
            Method: POST

  # UpdateBlockFunction:
  #   Type: AWS::Serverless::Function
  #   Properties:
  #     Handler: src/handlers/blocks/update-block.updateBlockHandler
  #     Architectures:
  #       - x86_64
  #     Events:
  #       Api:
  #         Type: HttpApi
  #         Properties:
  #           Path: /blocks/{id}
  #           Method: PUT

Outputs:
  WebEndpoint:
    Description: API Gateway endpoint URL for Prod stage
    Value: !Sub "https://${ServerlessHttpApi}.execute-api.${AWS::Region}.amazonaws.com/Prod/"

[kkchu791]

[kkchu791]

I don't see to many changes in the artifacts for .aws-sam besides the function name changing to the new one I changed it to. See in screenshots that the function name is now getBlockssByDateRangeFunction instead of getBlocksByDateRangeFunction.

[dineshnagumothu]

Facing the same issue on M1 Mac. Started initially well, then suddenly got the error with no code changes.

Changed the name of the resource and starts working again.

[cunneen]

I also have this problem (also an M1 Mac), but unlike @dineshnagumothu , renaming the resource didn't work for me.

I strongly suspect the issue is with the lambda runtime harness within the docker image; The error I get is :

node:internal/modules/cjs/loader:1031
  throw err;
  ^

Error: Cannot find module '/var/runtime/index.js'
    at Function._resolveFilename (node:internal/modules/cjs/loader:1028:15)
    at Function._load (node:internal/modules/cjs/loader:873:27)
    at Function.executeUserEntryPoint [as runMain] (node:internal/modules/run_main:81:12)
    at node:internal/main/run_main_module:22:47 {
  code: 'MODULE_NOT_FOUND',
  requireStack: []
}
22 Sep 2023 08:49:50,052 [ERROR] (rapid) Init failed error=Runtime exited with error: exit status 1 InvokeID=

But if I open a terminal session to the Docker container (which is left running), the /var/runtime/ folder contains an index.mjs file but not an index.js file.

The docker image seems to be this one:

public.ecr.aws/sam/emulation-nodejs16.x:rapid-1.50.0-x86_64

[cunneen]

In my case above, I discovered that I had an outdated version of the SAM CLI that was installed via homebrew, in addition to the one I'd installed via the MacOS package installer.

After uninstalling both, and installing the latest (v1.97.0), debugging my lambda function works nicely for me.

[ldu2]

I’m running into a similar issue on my Mac, OS Ventura 13.6. It happens to all three hello-world ts apps, nodejs14, 16 and 18.

One interesting thing is that after starting the app (any of the three), the first hit to the /hello endpoint gives the classic Error: Cannot find module ‘app’\nRequire stack:\n-/var/runtime/index.mjs”,”stack….
Then the consecutive hits give a different error: Invalid lambda response received: Lambda response must be a valid json.

My sam cli is v1.97.0. I installed with the brew initially, same version, same error. Uninstall that and installed through pkg file. Same error.

This error didn’t happened to me on the most popular python version of the hello world app.

Please let me know if there’s any fix for this issue. It doesn’t seems like there’s any obvious issue on my side. (If you know what I mean) Also removing images and changing resources name didn’t work.

[erikhuisman]

This error happens to me on the sample project:

• hello world
• node18 & node16 (others i did not try)
• hello world typescript

No problem invoking and run the api for the plain js version