Cannot find module 'cfn-response': AWS Lambda nodejs10.x

Confirm by changing [ ] to [x] below to ensure that it’s a bug:

• I’ve gone though Developer Guide and API reference
• I’ve checked AWS Forums and StackOverflow for answers
• I’ve searched for previous similar issues and didn’t find any solution

Describe the bug When updating my Lambda functions from nodejs8.10 to nodejs10.x - as per request from AWS Lambda operational notification - I get the error “Cannot find module ‘cfn-response’”, which completely breaks my CloudFormation deployment. If I rollback the same deployed lambda to nodejs8.10 it works again.

Is the issue in the browser/Node.js? AWS Labmda using Node.js 10.x

If on Node.js, are you running this on AWS Lambda? Yes!

Details of the browser/Node.js version nodejs10.x

SDK version number The one used by AWS Lambda - I guess always the latest.

To Reproduce (observed behavior)

var cfnresp = require('cfn-response')

exports.handler = async (event) => {
    // TODO implement
    const response = {
        statusCode: 200,
        body: JSON.stringify('Hello from Lambda!'),
    };
    return response;
};

Expected behavior

Response:
{
  "statusCode": 200,
  "body": "\"Hello from Lambda!\""
}

Request ID:
"565f6238-fd8c-4b9c-bfab-bebca1dd0e2d"

Screenshots

Response:
{
  "errorType": "Runtime.ImportModuleError",
  "errorMessage": "Error: Cannot find module 'cfn-response'",
  "trace": [
    "Runtime.ImportModuleError: Error: Cannot find module 'cfn-response'",
    "    at _loadUserApp (/var/runtime/UserFunction.js:100:13)",
    "    at Object.module.exports.load (/var/runtime/UserFunction.js:140:17)",
    "    at Object.<anonymous> (/var/runtime/index.js:45:30)",
    "    at Module._compile (internal/modules/cjs/loader.js:778:30)",
    "    at Object.Module._extensions..js (internal/modules/cjs/loader.js:789:10)",
    "    at Module.load (internal/modules/cjs/loader.js:653:32)",
    "    at tryModuleLoad (internal/modules/cjs/loader.js:593:12)",
    "    at Function.Module._load (internal/modules/cjs/loader.js:585:3)",
    "    at Function.Module.runMain (internal/modules/cjs/loader.js:831:12)",
    "    at startup (internal/bootstrap/node.js:283:19)"
  ]
}

Request ID:
"f5fe7e20-65c6-4cb6-adb2-e2a80bfb9968"

Function Logs:
START RequestId: f5fe7e20-65c6-4cb6-adb2-e2a80bfb9968 Version: $LATEST
2019-11-14T04:27:27.919Z	undefined	ERROR	Uncaught Exception	{"errorType":"Runtime.ImportModuleError","errorMessage":"Error: Cannot find module 'cfn-response'","stack":["Runtime.ImportModuleError: Error: Cannot find module 'cfn-response'","    at _loadUserApp (/var/runtime/UserFunction.js:100:13)","    at Object.module.exports.load (/var/runtime/UserFunction.js:140:17)","    at Object.<anonymous> (/var/runtime/index.js:45:30)","    at Module._compile (internal/modules/cjs/loader.js:778:30)","    at Object.Module._extensions..js (internal/modules/cjs/loader.js:789:10)","    at Module.load (internal/modules/cjs/loader.js:653:32)","    at tryModuleLoad (internal/modules/cjs/loader.js:593:12)","    at Function.Module._load (internal/modules/cjs/loader.js:585:3)","    at Function.Module.runMain (internal/modules/cjs/loader.js:831:12)","    at startup (internal/bootstrap/node.js:283:19)"]}
END RequestId: f5fe7e20-65c6-4cb6-adb2-e2a80bfb9968
REPORT RequestId: f5fe7e20-65c6-4cb6-adb2-e2a80bfb9968	Duration: 1905.42 ms	Billed Duration: 2000 ms	Memory Size: 128 MB	Max Memory Used: 24 MB	
Unknown application error occurred
Runtime.ImportModuleError

[RLThomaz]

It seems that in Node.js 10.x we need to specify the relative path to actually find cfn-response. So this code snipet below should work just fine:

var cfnresp = require('./cfn-response')

exports.handler = async (event) => {
    // TODO implement
    const response = {
        statusCode: 200,
        body: JSON.stringify('Hello from Lambda!'),
    };
    return response;
};

If that is the issue/solution, can you please close this ticket and update the documentation? The documentation actually tells us to use it like the first example.

Editing: I have one more concern.

So cfn-response is basically required for CloudFormation, hence the name. How does CloudFormation “ZipFile” - under the Lambda resource - actually knows when to upload cfn-response.js? Is it also going to upload it when we require it as './cfn-response'?

[prashantalhat]

thanks @RLThomaz you saved my day. I was facing this issue when updating my nodejs runtime from 8 to 10.