original file name: Codeium Chat - AuRp8cuTN1u6EUbG5bsurMJgcMzrOqO6.md summary: The conversation is about a user who successfully deployed a CDK stack to AWS but encountered errors when testing the signUp function in the deployed API. The user received an error message stating "User pool client YOUR_COGNITO_APP_CLIENT_ID does not exist." They sought assistance and were advised to ensure the Lambda function code retrieves the User Pool Client ID dynamically and to review the API Gateway integration.

Note: This is purely the output of the chat conversation and does not contain any raw data, codebase snippets, etc. used to generate the output.

User at 4:31 pm, Jun 28, 2024

I have created this CDK stack and deployed it successfully to AWS:

// cdk/lib/cdk-stack.ts

import {
 aws_cognito as cognito,
 aws_s3 as s3,
 aws_lambda as lambda,
 aws_iam as iam,
 aws_apigateway as apigateway,
 aws_cloudfront as cloudfront
} from "aws-cdk-lib";
import { Construct } from 'constructs';
import * as cdk from 'aws-cdk-lib';

const lambdaRuntime = lambda.Runtime.NODEJS_16_X;

export class HandTermCdkStack extends cdk.Stack {
 constructor(scope: Construct, id: string, props?: cdk.StackProps) {
  super(scope, id, props);

  // Cognito User Pool
  const userPool = new cognito.UserPool(this, 'HandTermUserPool', {
   userPoolName: 'HandTermUserPool',
   selfSignUpEnabled: true,
   userVerification: {
    emailSubject: 'Verify your email for our app!',
    emailBody: 'Hello {username}, Thanks for signing up to our app! Your verification code is {####}',
    emailStyle: cognito.VerificationEmailStyle.CODE,
   },
   signInAliases: {
    email: true
   },
   passwordPolicy: {
    minLength: 8,
    requireUppercase: true,
    requireLowercase: true,
    requireDigits: true,
    requireSymbols: true,
   },
   autoVerify: { email: true }
  });

  // Cognito User Pool Client
  const userPoolClient = userPool.addClient('AppClient', {
   authFlows: {
    userSrp: true,
   },
   generateSecret: false,
  });

  // Cognito Identity Pool
  const identityPool = new cognito.CfnIdentityPool(this, 'HandTermIdentityPool', {
   identityPoolName: 'HandTermIdentityPool',
   allowUnauthenticatedIdentities: false,
   cognitoIdentityProviders: [{
    clientId: userPoolClient.userPoolClientId,
    providerName: userPool.userPoolProviderName,
   }],
  });

  // S3 Bucket for User Logs
  const logsBucket = new s3.Bucket(this, 'HandTermHistoryBucket', {
   bucketName: 'handterm-history',
   blockPublicAccess: s3.BlockPublicAccess.BLOCK_ALL,
   encryption: s3.BucketEncryption.S3_MANAGED,
  });

  // Lambda Execution Role
  const lambdaExecutionRole = new iam.Role(this, 'LambdaExecutionRole', {
   assumedBy: new iam.CompositePrincipal(
    new iam.ServicePrincipal('lambda.amazonaws.com'),
    new iam.ServicePrincipal('edgelambda.amazonaws.com')
   ),
   managedPolicies: [
    iam.ManagedPolicy.fromAwsManagedPolicyName('service-role/AWSLambdaBasicExecutionRole'),
    iam.ManagedPolicy.fromAwsManagedPolicyName('AmazonS3FullAccess'),
   ],
  });

  // Lambda@Edge Function for HttpOnly Cookies
  const lambdaAtEdge = new lambda.Function(this, 'LambdaAtEdgeFunction', {
   runtime: lambdaRuntime, // Note: Ensure you're using a runtime supported by Lambda@Edge
   handler: 'app.lambdaHandler', // Adjusted to point to the transpiled JS file and handler
   code: lambda.Code.fromAsset('lambda/handtermEdgeFunction/'), // Pointing to the directory
   role: lambdaExecutionRole,
   memorySize: 128,
   description: 'A Lambda@Edge function for HttpOnly Cookies',
  });

  // Assuming lambdaAtEdge is your authentication Lambda function
  const api = new apigateway.RestApi(this, 'HandTermApi', {
   restApiName: 'HandTerm Service',
   description: 'This service serves authentication requests.',
  });

  const authLambdaIntegration = new apigateway.LambdaIntegration(lambdaAtEdge, {
   requestTemplates: { "application/json": '{ "statusCode": "200" }' }
  });

  api.root.addMethod('POST', authLambdaIntegration); // Adding a POST method

  const signUpLambda = new lambda.Function(this, 'SignUpFunction', {
   runtime: lambdaRuntime,
   handler: 'signUp.handler',
   code: lambda.Code.fromAsset('lambda/authentication'),
  });

  const signUpIntegration = new apigateway.LambdaIntegration(signUpLambda);
  const signUpResource = api.root.addResource('signup');
  signUpResource.addMethod('POST', signUpIntegration);

  // Outputs
  new cdk.CfnOutput(this, 'UserPoolId', { value: userPool.userPoolId });
  new cdk.CfnOutput(this, 'UserPoolClientId', { value: userPoolClient.userPoolClientId });
  new cdk.CfnOutput(this, 'IdentityPoolId', { value: identityPool.ref });
  new cdk.CfnOutput(this, 'BucketName', { value: logsBucket.bucketName });
  new cdk.CfnOutput(this, 'LambdaAtEdgeFunctionName', { value: lambdaAtEdge.functionName });
  new cdk.CfnOutput(this, 'ApiEndpoint', { value: api.url });
 }
}

const app = new cdk.App();
new HandTermCdkStack(app, 'HandTermCdkStack');

I get this response when I deploy it:

🕐[16:06:41]❯ cdk deploy --region us-east-1 --profile mark
Debugger listening on ws://127.0.0.1:57838/6ee5a61c-e090-4751-87d1-626b4722dd94
For help, see: https://nodejs.org/en/docs/inspector
Debugger attached.
Waiting for the debugger to disconnect...

✨ Synthesis time: 8.7s

HandTermCdkStack: deploying... [1/1]
HandTermCdkStack: creating CloudFormation changeset...

 ✅ HandTermCdkStack (no changes)

✨ Deployment time: 2.95s

Outputs:
HandTermCdkStack.ApiEndpoint = https://u4ceo7qshi.execute-api.us-east-1.amazonaws.com/prod/
HandTermCdkStack.BucketName = handterm-history
HandTermCdkStack.HandTermApiEndpoint4157FF52 = https://u4ceo7qshi.execute-api.us-east-1.amazonaws.com/prod/
HandTermCdkStack.IdentityPoolId = us-east-1:81f5ef2e-abee-4324-8eb9-3f3bf46d561f
HandTermCdkStack.LambdaAtEdgeFunctionName = HandTermCdkStack-LambdaAtEdgeFunction29DB2087-zctkKM9ApxIy
HandTermCdkStack.UserPoolClientId = 5v7fgpudlhl7kdagmhcej6rlku
HandTermCdkStack.UserPoolId = us-east-1_3uSNUrQbE
Stack ARN:
arn:aws:cloudformation:us-east-1:318364255844:stack/HandTermCdkStack/3a165d20-3598-11ef-b7c5-121014da84d9

✨ Total time: 11.65s

But when I go to the deployed API and run this test data on the signUp function:

{
  "username": "testuser",
  "password": "FastTrack#1",
  "email": "[email protected]"
}

I get this error:

Response body
"User pool client YOUR_COGNITO_APP_CLIENT_ID does not exist."
Response headers
{
  "X-Amzn-Trace-Id": "Root=1-667f45b5-71fdfde66d813b4ef2cdc1e5;Parent=49134b43f1fe263b;Sampled=0;lineage=b7b1ca60:0"
}
Logs
Execution log for request 70941c11-c41b-4427-b286-00a20026bfed
Fri Jun 28 23:22:29 UTC 2024 : Starting execution for request: 70941c11-c41b-4427-b286-00a20026bfed
Fri Jun 28 23:22:29 UTC 2024 : HTTP Method: POST, Resource Path: /signup
Fri Jun 28 23:22:29 UTC 2024 : Method request path: {}
Fri Jun 28 23:22:29 UTC 2024 : Method request query string: {}
Fri Jun 28 23:22:29 UTC 2024 : Method request headers: {}
Fri Jun 28 23:22:29 UTC 2024 : Method request body before transformations: {
    "username": "testuser",
    "password": "FastTrack#1",
    "email": "[email protected]"
}
Fri Jun 28 23:22:29 UTC 2024 : Endpoint request URI: https://lambda.us-east-1.amazonaws.com/2015-03-31/functions/arn:aws:lambda:us-east-1:318364255844:function:HandTermCdkStack-SignUpFunctionCFE784C5-qDLsuBvd1ODa/invocations
Fri Jun 28 23:22:29 UTC 2024 : Endpoint request headers: {X-Amz-Date=20240628T232229Z, x-amzn-apigateway-api-id=u4ceo7qshi, Accept=application/json, User-Agent=AmazonAPIGateway_u4ceo7qshi, Host=lambda.us-east-1.amazonaws.com, X-Amz-Content-Sha256=a18d0c096ebdf904914d914efd6e93c84170189bf875730c5e6428b3aa5b30e7, X-Amzn-Trace-Id=Root=1-667f45b5-71fdfde66d813b4ef2cdc1e5, x-amzn-lambda-integration-tag=70941c11-c41b-4427-b286-00a20026bfed, Authorization=*********************************************************************************************************************************************************************************************************************************************************************************************************************************************411315, X-Amz-Source-Arn=arn:aws:execute-api:us-east-1:318364255844:u4ceo7qshi/test-invoke-stage/POST/signup, X-Amz-Security-Token=IQoJb3JpZ2luX2VjEGcaCXVzLWVhc3QtMSJGMEQCIDyd6Q10UQslrq64qXpKG0zaWctUT8+ntexj+Xh+2k6vAiAlMAWlHwCbaR0tjwRq2A5zMrU83Db1a/IzVnysPyIY+SqzBQggEA [TRUNCATED]
Fri Jun 28 23:22:29 UTC 2024 : Endpoint request body after transformations: {"resource":"/signup","path":"/signup","httpMethod":"POST","headers":null,"multiValueHeaders":null,"queryStringParameters":null,"multiValueQueryStringParameters":null,"pathParameters":null,"stageVariables":null,"requestContext":{"resourceId":"3s0u3o","resourcePath":"/signup","httpMethod":"POST","extendedRequestId":"aGfUVHH0IAMFp1g=","requestTime":"28/Jun/2024:23:22:29 +0000","path":"/signup","accountId":"318364255844","protocol":"HTTP/1.1","stage":"test-invoke-stage","domainPrefix":"testPrefix","requestTimeEpoch":1719616949095,"requestId":"70941c11-c41b-4427-b286-00a20026bfed","identity":{"cognitoIdentityPoolId":null,"cognitoIdentityId":null,"apiKey":"test-invoke-api-key","principalOrgId":null,"cognitoAuthenticationType":null,"userArn":"arn:aws:iam::318364255844:user/mark","apiKeyId":"test-invoke-api-key-id","userAgent":"Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/126.0.0.0 Safari/537.36 Edg/126.0.0.0","accountId":"318364 [TRUNCATED]
Fri Jun 28 23:22:29 UTC 2024 : Sending request to https://lambda.us-east-1.amazonaws.com/2015-03-31/functions/arn:aws:lambda:us-east-1:318364255844:function:HandTermCdkStack-SignUpFunctionCFE784C5-qDLsuBvd1ODa/invocations
Fri Jun 28 23:22:29 UTC 2024 : Received response. Status: 200, Integration latency: 86 ms
Fri Jun 28 23:22:29 UTC 2024 : Endpoint response headers: {Date=Fri, 28 Jun 2024 23:22:29 GMT, Content-Type=application/json, Content-Length=91, Connection=keep-alive, x-amzn-RequestId=a5542a24-7b2a-4e23-a3d2-ed786e3338a6, x-amzn-Remapped-Content-Length=0, X-Amz-Executed-Version=$LATEST, X-Amzn-Trace-Id=root=1-667f45b5-71fdfde66d813b4ef2cdc1e5;parent=49134b43f1fe263b;sampled=0;lineage=b7b1ca60:0}
Fri Jun 28 23:22:29 UTC 2024 : Endpoint response body before transformations: {"statusCode":400,"body":"\"User pool client YOUR_COGNITO_APP_CLIENT_ID does not exist.\""}
Fri Jun 28 23:22:29 UTC 2024 : Method response body after transformations: "User pool client YOUR_COGNITO_APP_CLIENT_ID does not exist."
Fri Jun 28 23:22:29 UTC 2024 : Method response headers: {X-Amzn-Trace-Id=Root=1-667f45b5-71fdfde66d813b4ef2cdc1e5;Parent=49134b43f1fe263b;Sampled=0;lineage=b7b1ca60:0}
Fri Jun 28 23:22:29 UTC 2024 : Successfully completed execution
Fri Jun 28 23:22:29 UTC 2024 : Method completed with status: 400

Codeium at 4:31 pm, Jun 28, 2024

The error message you're encountering, "User pool client YOUR_COGNITO_APP_CLIENT_ID does not exist," suggests that the Lambda function responsible for handling the signUp operation is referencing an incorrect or placeholder Cognito App Client ID. This typically happens when the function's code or its environment variables include a placeholder or an incorrectly hardcoded value meant to represent the Cognito User Pool Client ID.

Given the provided code and the error message, here are a few steps to troubleshoot and potentially resolve this issue:

1. Verify Lambda Function Code: Check the code of the Lambda function that is handling the signUp process. Ensure it retrieves the User Pool Client ID dynamically rather than using a hardcoded value. If you're using environment variables in your Lambda function to store the User Pool Client ID, make sure they're set correctly.

2. Environment Variables: If your signUp Lambda function relies on environment variables to get the User Pool Client ID, ensure that these variables are correctly set up during the deployment. You can pass the User Pool Client ID as an environment variable to your Lambda function like so:

const signUpLambda = new lambda.Function(this, 'SignUpFunction', {
  runtime: lambdaRuntime,
  handler: 'signUp.handler',
  code: lambda.Code.fromAsset('lambda/authentication'),
  environment: {
    USER_POOL_CLIENT_ID: userPoolClient.userPoolClientId,
  },
});

This snippet ensures that the signUp Lambda function has access to the User Pool Client ID via an environment variable named USER_POOL_CLIENT_ID. Adjust the environment variable name and access pattern in your Lambda function's code accordingly.

3. Lambda Function Deployment: After making changes to your CDK stack or Lambda function, ensure you redeploy your stack to apply these changes. You can redeploy your stack using the AWS CDK CLI with the same cdk deploy command you used initially.

4. Review API Gateway Integration: Ensure that the API Gateway integration with your Lambda function is correctly configured and that the request and response are correctly mapped. Misconfiguration here might lead to unexpected behavior, although based on the error message, it's less likely the cause.

5. Testing and Logs: Utilize AWS CloudWatch Logs to inspect the logs generated by your Lambda function during invocation. These logs can provide additional insights into the execution flow and potentially highlight where the incorrect User Pool Client ID is being referenced.

By following these steps, you should be able to identify and correct the issue causing the "User pool client YOUR_COGNITO_APP_CLIENT_ID does not exist" error.

User at 4:40 pm, Jun 28, 2024

Ok, I've redeployed and now i get this error:

Response body
{"message": "Internal server error"}
Response headers
{
  "x-amzn-ErrorType": "InternalServerErrorException"
}
Logs
Execution log for request fa541ae3-83b6-4664-b341-3d2696a2a57a
Fri Jun 28 23:38:27 UTC 2024 : Starting execution for request: fa541ae3-83b6-4664-b341-3d2696a2a57a
Fri Jun 28 23:38:27 UTC 2024 : HTTP Method: POST, Resource Path: /
Fri Jun 28 23:38:27 UTC 2024 : Method request path: {}
Fri Jun 28 23:38:27 UTC 2024 : Method request query string: {}
Fri Jun 28 23:38:27 UTC 2024 : Method request headers: {}
Fri Jun 28 23:38:27 UTC 2024 : Method request body before transformations: {
    "username": "testuser",
    "password": "FastTrack#1",
    "email": "[email protected]"
}
Fri Jun 28 23:38:27 UTC 2024 : Endpoint request URI: https://lambda.us-east-1.amazonaws.com/2015-03-31/functions/arn:aws:lambda:us-east-1:318364255844:function:HandTermCdkStack-LambdaAtEdgeFunction29DB2087-zctkKM9ApxIy/invocations
Fri Jun 28 23:38:27 UTC 2024 : Endpoint request headers: {X-Amz-Date=20240628T233827Z, x-amzn-apigateway-api-id=u4ceo7qshi, Accept=application/json, User-Agent=AmazonAPIGateway_u4ceo7qshi, Host=lambda.us-east-1.amazonaws.com, X-Amz-Content-Sha256=bebb259478bb968f731ca06186f4019590842bb731c9179e01d58b18b92fc866, X-Amzn-Trace-Id=Root=1-667f4973-564cc743869048d5a86cfcb4, x-amzn-lambda-integration-tag=fa541ae3-83b6-4664-b341-3d2696a2a57a, Authorization=*********************************************************************************************************************************************************************************************************************************************************************************************************************************************5c0ab7, X-Amz-Source-Arn=arn:aws:execute-api:us-east-1:318364255844:u4ceo7qshi/test-invoke-stage/POST/, X-Amz-Security-Token=IQoJb3JpZ2luX2VjEGcaCXVzLWVhc3QtMSJHMEUCIQCZg4N1HhwdFv++h71Eo6DLxhFE1uhR2nM5iwwfEptyIwIgUYtdKLtRhwKjKYZWdxQx9Yi2sqBcMy1l31g1+mGlMMwqsQUIIBAAGgwz [TRUNCATED]
Fri Jun 28 23:38:27 UTC 2024 : Endpoint request body after transformations: {"resource":"/","path":"/","httpMethod":"POST","headers":null,"multiValueHeaders":null,"queryStringParameters":null,"multiValueQueryStringParameters":null,"pathParameters":null,"stageVariables":null,"requestContext":{"resourceId":"p1xomh011j","resourcePath":"/","httpMethod":"POST","extendedRequestId":"aGhqKHt4IAMF1Dg=","requestTime":"28/Jun/2024:23:38:27 +0000","path":"/","accountId":"318364255844","protocol":"HTTP/1.1","stage":"test-invoke-stage","domainPrefix":"testPrefix","requestTimeEpoch":1719617907941,"requestId":"fa541ae3-83b6-4664-b341-3d2696a2a57a","identity":{"cognitoIdentityPoolId":null,"cognitoIdentityId":null,"apiKey":"test-invoke-api-key","principalOrgId":null,"cognitoAuthenticationType":null,"userArn":"arn:aws:iam::318364255844:user/mark","apiKeyId":"test-invoke-api-key-id","userAgent":"Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/126.0.0.0 Safari/537.36 Edg/126.0.0.0","accountId":"318364255844","caller":"AI [TRUNCATED]
Fri Jun 28 23:38:27 UTC 2024 : Sending request to https://lambda.us-east-1.amazonaws.com/2015-03-31/functions/arn:aws:lambda:us-east-1:318364255844:function:HandTermCdkStack-LambdaAtEdgeFunction29DB2087-zctkKM9ApxIy/invocations
Fri Jun 28 23:38:28 UTC 2024 : Received response. Status: 200, Integration latency: 284 ms
Fri Jun 28 23:38:28 UTC 2024 : Endpoint response headers: {Date=Fri, 28 Jun 2024 23:38:28 GMT, Content-Type=application/json, Content-Length=313, Connection=keep-alive, x-amzn-RequestId=b50e7f7f-1612-4b55-8f04-aee9a0754c44, X-Amz-Function-Error=Unhandled, x-amzn-Remapped-Content-Length=0, X-Amz-Executed-Version=$LATEST, X-Amzn-Trace-Id=root=1-667f4973-564cc743869048d5a86cfcb4;parent=169bdbc2838c6fdb;sampled=0;lineage=79b7a1d3:0}
Fri Jun 28 23:38:28 UTC 2024 : Endpoint response body before transformations: {"errorType":"TypeError","errorMessage":"Cannot read properties of undefined (reading '0')","trace":["TypeError: Cannot read properties of undefined (reading '0')","    at Runtime.lambdaHandler [as handler] (/var/task/app.js:6:35)","    at Runtime.handleOnceNonStreaming (file:///var/runtime/index.mjs:1173:29)"]}
Fri Jun 28 23:38:28 UTC 2024 : Lambda execution failed with status 200 due to customer function error: Cannot read properties of undefined (reading '0'). Lambda request id: b50e7f7f-1612-4b55-8f04-aee9a0754c44
Fri Jun 28 23:38:28 UTC 2024 : Method completed with status: 502

Codeium at 4:40 pm, Jun 28, 2024

The new error message you're encountering, "Cannot read properties of undefined (reading '0')" within your Lambda function, indicates a runtime error in the JavaScript code of your Lambda function. This kind of error usually happens when trying to access a property or an index on a variable that hasn't been defined or initialized.

Given the stack trace provided in the logs, the error occurs in your Lambda function's handler, specifically at app.js:6:35. This suggests that somewhere around the 6th line of your app.js file, the code tries to access an index or property on a variable that is undefined.

Here's a general approach to troubleshoot and potentially fix the issue:

1. Review the Lambda Function Code: Open the app.js file within your Lambda function's project directory. Look around line 6 (the exact line might differ slightly depending on additional comments or whitespace) for any operations that access properties or indices, such as someVariable[0] or someVariable.property.

2. Check for Undefined Variables: Determine if the variable being accessed is or could be undefined at the time of access. This could happen for several reasons, such as:

   • The variable is supposed to hold data from an external source (e.g., an API call or database query) that did not return as expected.
   • There was a logical flaw that prevented the variable from being correctly assigned.
   • The variable is dependent on conditional logic that did not execute as anticipated.

3. Safe Access: Implement checks to ensure the variable is defined before accessing its properties or indices. For example, if you're accessing an array element, you can check if the array is defined and has elements:

if (arrayVariable && arrayVariable.length > 0) {
  // Safe to access arrayVariable[0]
} else {
  // Handle the case where the array is undefined or empty
}

4. Logging for Debugging: Add logging statements before the line where the error occurs to print out the variable's value. This can help you understand why it's undefined:

console.log("Variable value:", variable);

5. Update and Deploy: After making the necessary changes, update your Lambda function code and redeploy it. You can use the AWS Management Console, AWS CLI, or the AWS CDK (if you're managing your function through CDK) to deploy the updated code.

6. Retest: After deploying the updated function, retest the operation that triggered the error to see if the issue is resolved.

Remember, the goal is to identify why the variable is undefined at the point of access and either ensure it's properly defined or safely handle cases where it might not be.

User at 4:49 pm, Jun 28, 2024

I think that's referring to this app.ts

// cdk/lambda/handtermEdgeFunction/app.ts

import { CloudFrontResponseEvent, CloudFrontResponseHandler, CloudFrontResponseResult } from 'aws-lambda';

export const lambdaHandler: CloudFrontResponseHandler = async (event: CloudFrontResponseEvent): Promise<CloudFrontResponseResult> => {
 const response = event.Records[0].cf.response;
 const headers = response.headers;

 // Set HttpOnly Cookie
 headers['set-cookie'] = [{
  key: 'Set-Cookie',
  value: `handterm-history=YourCookieValue; Path=/; Secure; HttpOnly;`
 }];

 return response;
};

That is the file that I see in the Lambda function associated with the signUp endpoint.

We had been trying to use theLambda function with CloudFront, but I am not sure if that's currently the case.

Codeium at 4:49 pm, Jun 28, 2024

Given the app.ts code you've provided for the Lambda function, and considering the error message related to accessing properties of undefined (Cannot read properties of undefined (reading '0')), the issue is likely related to the structure of the event object the Lambda function receives. This error typically occurs when the Lambda function expects a certain event structure but receives something different.

In the context of Lambda@Edge, which is what your app.ts Lambda function is designed for, it's important to remember that Lambda@Edge functions can be triggered by four different CloudFront events: viewer request, viewer response, origin request, and origin response. Your function is set to handle a response from CloudFront (CloudFrontResponseEvent), modifying the response headers before they're sent back to the client.

The error you're encountering could arise if the Lambda function is not being triggered by CloudFront as expected, or if the event structure is somehow different from what's anticipated. Here are some steps to troubleshoot and potentially resolve the issue:

1. Verify Lambda@Edge Trigger: Ensure that the Lambda function is correctly associated with a CloudFront distribution and that it's triggered on the expected event type (e.g., origin response or viewer response). If you initially set this up for testing with API Gateway or another trigger, the event structure would be different, leading to the error you're seeing.

2. Check Event Structure: If you're invoking the Lambda function manually (e.g., for testing purposes) or using a different trigger than Lambda@Edge, ensure that the event structure passed to the function matches what CloudFront would send. This involves mimicking the event.Records[0].cf.response structure.

3. Conditional Execution: If this Lambda function might be used in contexts other than Lambda@Edge (though typically not recommended due to the specific nature of Lambda@Edge functions), you can add conditional logic to handle different event structures. However, ensure that the primary use case remains intact for Lambda@Edge.

4. Review Lambda@Edge and CloudFront Configuration: If the Lambda function is meant to be used exclusively with CloudFront, review your CloudFront distribution settings in the AWS Management Console to ensure the function is associated with the correct distribution and event type. Remember, changes to Lambda@Edge associations with CloudFront distributions can take some time to propagate globally.

5. Deploy and Test: After verifying the configuration or making changes, redeploy your Lambda function and test it again by accessing a resource through your CloudFront distribution to ensure it's triggered correctly and the error is resolved.

Given the specific nature of Lambda@Edge functions and their tight integration with CloudFront, it's crucial to ensure that their deployment and triggers are correctly configured to match the expected event structure. If the Lambda function is not meant to be used with CloudFront anymore, consider updating its configuration or using a different Lambda function for your signUp endpoint that's designed to handle the event structure you're testing with.

User at 4:54 pm, Jun 28, 2024

The Lambda function is created by the above cdk-stack

  // Lambda@Edge Function for HttpOnly Cookies
  const lambdaAtEdge = new lambda.Function(this, 'LambdaAtEdgeFunction', {
   runtime: lambdaRuntime, // Note: Ensure you're using a runtime supported by Lambda@Edge
   handler: 'app.lambdaHandler', // Adjusted to point to the transpiled JS file and handler
   code: lambda.Code.fromAsset('lambda/handtermEdgeFunction/'), // Pointing to the directory
   role: lambdaExecutionRole,
   memorySize: 128,
   description: 'A Lambda@Edge function for HttpOnly Cookies',
  });

I have added some logging to that Lambda and will see in a moment what it outputs.

Codeium at 4:54 pm, Jun 28, 2024

Adding logging to your Lambda function is a great step towards identifying the root cause of the issue. By examining the logs, you can get a clearer picture of what the function is receiving in the event object and where exactly the execution might be going awry.

Here are a few tips to keep in mind while you're reviewing the logs:

1. Inspect the Event Structure: Pay close attention to the structure of the event object logged by your Lambda function. Lambda@Edge functions expect a specific event structure that includes Records, cf, and response properties for handling HTTP responses. Verify that the event object matches this structure.

2. Look for Undefined Variables: If you encounter Cannot read properties of undefined (reading '0') errors, it indicates that the expected event.Records array might be missing or different from what's anticipated. This can happen if the function is triggered in a way that doesn't provide the expected event format.

3. Verify Lambda@Edge Trigger: Ensure that the function is indeed being triggered by CloudFront events. Lambda@Edge functions are designed to be triggered by CloudFront viewer request/response or origin request/response events. If your function is being triggered by another source, the event format might not be compatible.

4. Understand the Context: Lambda@Edge functions can be executed in response to different types of CloudFront events. Understanding whether your function is being triggered as expected (e.g., on viewer response or origin response) can help you identify discrepancies in the event structure or logic within your handler.

5. Error Handling: Consider adding more robust error handling to your Lambda function to gracefully handle unexpected event formats or missing properties. This can prevent your function from throwing errors and provide more meaningful feedback for troubleshooting.

6. CloudWatch Logs: Lambda@Edge function logs are stored in Amazon CloudWatch in the AWS Region closest to the location where the function is executed. Make sure you're checking the correct CloudWatch log group in the appropriate region to see the logs generated by your function.

After you've reviewed the logs and identified any issues with the event structure or function logic, you can make the necessary adjustments to your Lambda function code, redeploy it, and test it again.

If you encounter specific log entries that are unclear or if the issue persists, feel free to share more details, and I'll do my best to provide further assistance.

User at 5:37 pm, Jun 28, 2024

I've added a log here, but it doesn't seem to output anything when I call it in the web ui.

Codeium at 5:38 pm, Jun 28, 2024

If your Lambda@Edge function isn't outputting logs when you expect it to—especially in response to interactions with your web UI—there are several potential reasons and troubleshooting steps to consider:

Lambda@Edge logs are sent to the AWS region nearest to the location where the function is executed, not necessarily the region where the Lambda function is deployed. Make sure you're checking CloudWatch Logs in all possible regions to locate the logs. This can sometimes mean manually checking several regions or writing a script to automate the search.

Ensure that your CloudFront distribution is correctly configured to trigger the Lambda function. This includes checking the behavior settings to ensure they're linked to the right version of your Lambda@Edge function. Changes to CloudFront distributions can take several minutes to propagate, so it's also worth waiting a bit after making any adjustments.

Only published versions (not the $LATEST version) of Lambda@Edge functions can be associated with CloudFront distributions. Ensure you're working with a published version of your Lambda function and that the ARN used in the CloudFront distribution matches this version.

If your Lambda@Edge function is designed to execute under specific conditions—such as certain path patterns or headers—ensure that your requests from the web UI meet these conditions. For example, if the function triggers based on specific path patterns, verify that the requests from your UI are to URLs that match these patterns.

Ensure that the IAM role associated with your Lambda@Edge function has the necessary permissions. This includes permissions to write logs to CloudWatch. The role should include the AWSLambdaBasicExecutionRole policy or a custom policy with similar permissions.

After updating your Lambda function or CloudFront distribution settings, verify that all changes have fully propagated and that the function is deployed correctly. You can check the status in the AWS Management Console.

As a troubleshooting step, consider manually invoking the Lambda function with a simulated CloudFront event to see if it logs as expected. This can help differentiate between issues with the function itself and issues with how it's triggered by CloudFront.

If you've mentioned interacting with a web UI and expecting the Lambda@Edge function to log, ensure there's no confusion about the integration points. Lambda@Edge functions are triggered by CloudFront events, not directly by web UI interactions unless those interactions generate requests that go through CloudFront.

After checking these areas, if you still can't see logs from your Lambda@Edge function, you might want to review the function's code to ensure logging statements are correctly placed and that there are no conditions preventing the logging code from executing. If the issue persists, consider reaching out to AWS Support for more direct assistance, especially if you suspect a configuration or service issue.

User at 6:31 pm, Jun 28, 2024

I was looking at the wrong error message. I was looking looking at the response in the web UI from / POST instead of the /signUp POST

When I POST to the /signUp I get this:

Response body
"User pool client YOUR_COGNITO_APP_CLIENT_ID does not exist."
Response headers
{
  "X-Amzn-Trace-Id": "Root=1-667f61bf-143d9d1a6074eee360fe1986;Parent=4d9e402316c7eb96;Sampled=0;lineage=b7b1ca60:0"
}
Logs
Execution log for request bdcfe011-56f8-445a-9397-23e571f818f2
Sat Jun 29 01:22:07 UTC 2024 : Starting execution for request: bdcfe011-56f8-445a-9397-23e571f818f2
Sat Jun 29 01:22:07 UTC 2024 : HTTP Method: POST, Resource Path: /signup
Sat Jun 29 01:22:07 UTC 2024 : Method request path: {}
Sat Jun 29 01:22:07 UTC 2024 : Method request query string: {}
Sat Jun 29 01:22:07 UTC 2024 : Method request headers: {}
Sat Jun 29 01:22:07 UTC 2024 : Method request body before transformations: {
"username": "testuser",
"password": "FastTrack#1",
"email": "[email protected]"
}
Sat Jun 29 01:22:07 UTC 2024 : Endpoint request URI: https://lambda.us-east-1.amazonaws.com/2015-03-31/functions/arn:aws:lambda:us-east-1:318364255844:function:HandTermCdkStack-SignUpFunctionCFE784C5-qDLsuBvd1ODa/invocations

And that is the same thing that the useAuth.http is telling me:

HTTP/1.1 400 Bad Request
Content-Type: application/json
Content-Length: 61
Connection: close
Date: Sat, 29 Jun 2024 00:42:19 GMT
x-amzn-RequestId: 27919a6c-b5e6-421c-a112-eece82f2e302
x-amz-apigw-id: aGrA0GiLoAMEW8w=
X-Amzn-Trace-Id: Root=1-667f586b-5eb620216e4bc6fc02daa0a4;Parent=336945d200625872;Sampled=0;lineage=b7b1ca60:0
X-Cache: Error from cloudfront
Via: 1.1 4ae7b0eb7d78fd970f14597219365f98.cloudfront.net (CloudFront)
X-Amz-Cf-Pop: LAX3-C4
X-Amz-Cf-Id: RBW7QS7-C1VZ94ryUAAXOFO-hKfHHi84KkT5WJ6CBJ8l1gwC03HAbQ==

"User pool client YOUR_COGNITO_APP_CLIENT_ID does not exist."

Codeium at 6:32 pm, Jun 28, 2024

The error message "User pool client YOUR_COGNITO_APP_CLIENT_ID does not exist." indicates a configuration issue with your AWS Cognito setup. Specifically, it suggests that the application client ID being used to make requests to Cognito does not match any client ID in the specified user pool. Here are some steps to troubleshoot and resolve this issue:

• Ensure that the YOUR_COGNITO_APP_CLIENT_ID placeholder is replaced with the actual App Client ID from your Cognito User Pool. This value should not be the placeholder but the real ID that you get from the Cognito console.
• If you are using environment variables or configuration files to store the App Client ID, verify that these are correctly set up and that the application is correctly loading these values.

• Go to the AWS Cognito console, select your User Pool, and then go to the App clients section. Make sure that the App Client ID used in your request matches one of the App Client IDs listed in your User Pool.
• If the App Client ID does not exist, you might need to create a new App Client or use an existing one that is correctly configured.

• Check that the App Client settings in Cognito are correctly configured for your use case. For example, ensure that the App Client is enabled for the necessary authentication flows.
• If you are using any features like custom authentication flows, make sure that the App Client is correctly set up to support these.

• Once you have confirmed or updated the App Client ID in Cognito, make sure to update your application's configuration with the correct ID. This includes updating any environment variables, configuration files, or hardcoded values within your application code.
• In the context provided by src\lib\useAuth.http, ensure that the variable or placeholder {{ $dotenv API_URL }} correctly includes the actual Cognito App Client ID in the POST requests to /signup and /signin endpoints.

• After making the necessary changes, redeploy your application if needed and test the signup process again to ensure that the correct Cognito App Client ID is being used and that the error is resolved.

• If your application uses API Gateway and Lambda functions to interact with Cognito, ensure that the Lambda function handling the /signup POST request is correctly extracting and using the Cognito App Client ID.
• Review the integration between API Gateway and your Lambda function to ensure that the App Client ID is being passed correctly from the client-side requests through to Cognito.

Following these steps should help you resolve the issue related to the Cognito App Client ID, allowing your application to successfully interact with AWS Cognito for user authentication operations.

User at 6:40 pm, Jun 28, 2024

This is my current cdk/lib/cdk-stack.ts

// cdk/lib/cdk-stack.ts

import {
 aws_cognito as cognito,
 aws_s3 as s3,
 aws_lambda as lambda,
 aws_iam as iam,
 aws_apigateway as apigateway,
 aws_cloudfront as cloudfront
} from "aws-cdk-lib";
import { Construct } from 'constructs';
import * as cdk from 'aws-cdk-lib';

const lambdaRuntime = lambda.Runtime.NODEJS_16_X;

export class HandTermCdkStack extends cdk.Stack {
 constructor(scope: Construct, id: string, props?: cdk.StackProps) {
  super(scope, id, props);

  // Cognito User Pool
  const userPool = new cognito.UserPool(this, 'HandTermUserPool', {
   userPoolName: 'HandTermUserPool',
   selfSignUpEnabled: true,
   userVerification: {
    emailSubject: 'Verify your email for our app!',
    emailBody: 'Hello {username}, Thanks for signing up to our app! Your verification code is {####}',
    emailStyle: cognito.VerificationEmailStyle.CODE,
   },
   signInAliases: {
    email: true
   },
   passwordPolicy: {
    minLength: 8,
    requireUppercase: true,
    requireLowercase: true,
    requireDigits: true,
    requireSymbols: true,
   },
   autoVerify: { email: true }
  });

  // Cognito User Pool Client
  const userPoolClient = userPool.addClient('AppClient', {
   authFlows: {
    userSrp: true,
   },
   generateSecret: false,
  });

  // Cognito Identity Pool
  const identityPool = new cognito.CfnIdentityPool(this, 'HandTermIdentityPool', {
   identityPoolName: 'HandTermIdentityPool',
   allowUnauthenticatedIdentities: false,
   cognitoIdentityProviders: [{
    clientId: userPoolClient.userPoolClientId,
    providerName: userPool.userPoolProviderName,
   }],
  });

  // S3 Bucket for User Logs
  const logsBucket = new s3.Bucket(this, 'HandTermHistoryBucket', {
   bucketName: 'handterm-history',
   blockPublicAccess: s3.BlockPublicAccess.BLOCK_ALL,
   encryption: s3.BucketEncryption.S3_MANAGED,
  });

  // Lambda Execution Role
  const lambdaExecutionRole = new iam.Role(this, 'LambdaExecutionRole', {
   assumedBy: new iam.CompositePrincipal(
    new iam.ServicePrincipal('lambda.amazonaws.com'),
    new iam.ServicePrincipal('edgelambda.amazonaws.com')
   ),
   managedPolicies: [
    iam.ManagedPolicy.fromAwsManagedPolicyName('service-role/AWSLambdaBasicExecutionRole'),
    iam.ManagedPolicy.fromAwsManagedPolicyName('AmazonS3FullAccess'),
   ],
  });

  // Lambda@Edge Function for HttpOnly Cookies
  const lambdaAtEdge = new lambda.Function(this, 'LambdaAtEdgeFunction', {
   runtime: lambdaRuntime, // Note: Ensure you're using a runtime supported by Lambda@Edge
   handler: 'app.lambdaHandler', // Adjusted to point to the transpiled JS file and handler
   code: lambda.Code.fromAsset('lambda/handtermEdgeFunction/'), // Pointing to the directory
   role: lambdaExecutionRole,
   memorySize: 128,
   description: 'A Lambda@Edge function for HttpOnly Cookies',
  });

  // Assuming lambdaAtEdge is your authentication Lambda function
  const api = new apigateway.RestApi(this, 'HandTermApi', {
   restApiName: 'HandTerm Service',
   description: 'This service serves authentication requests.',
  });

  const authLambdaIntegration = new apigateway.LambdaIntegration(lambdaAtEdge, {
   requestTemplates: { "application/json": '{ "statusCode": "200" }' }
  });

  api.root.addMethod('POST', authLambdaIntegration); // Adding a POST method

  const signUpLambda = new lambda.Function(this, 'SignUpFunction', {
   runtime: lambdaRuntime,
   handler: 'signUp.handler',
   code: lambda.Code.fromAsset('lambda/authentication'),
   environment: {
    USER_POOL_CLIENT_ID: userPoolClient.userPoolClientId,
   }
  });

  const signUpIntegration = new apigateway.LambdaIntegration(signUpLambda);
  const signUpResource = api.root.addResource('signup');
  signUpResource.addMethod('POST', signUpIntegration);

  // Outputs
  new cdk.CfnOutput(this, 'UserPoolId', { value: userPool.userPoolId });
  new cdk.CfnOutput(this, 'UserPoolClientId', { value: userPoolClient.userPoolClientId });
  new cdk.CfnOutput(this, 'IdentityPoolId', { value: identityPool.ref });
  new cdk.CfnOutput(this, 'BucketName', { value: logsBucket.bucketName });
  new cdk.CfnOutput(this, 'LambdaAtEdgeFunctionName', { value: lambdaAtEdge.functionName });
  new cdk.CfnOutput(this, 'ApiEndpoint', { value: api.url });
 }
}

const app = new cdk.App();
new HandTermCdkStack(app, 'HandTermCdkStack');

Is the Cognito App client id configured wrongly in there?

Also, is there any way in the output section to output the Cognito App client id to the .env file?

Codeium at 6:40 pm, Jun 28, 2024

Reviewing your cdk-stack.ts, the setup for the Cognito App Client ID and its usage looks correct. You're passing the userPoolClient.userPoolClientId directly to the Lambda function's environment, which is a standard way to provide such configurations:

environment: {
    USER_POOL_CLIENT_ID: userPoolClient.userPoolClientId,
}

This approach should correctly set the environment variable USER_POOL_CLIENT_ID for the Lambda function, assuming the deployment completes successfully without errors.

If the error "User pool client YOUR_COGNITO_APP_CLIENT_ID does not exist." is occurring, it suggests a potential mismatch or configuration issue at the point where the App Client ID is being consumed, which might happen if:

• The environment variable is not being correctly accessed in the Lambda function code.
• The Lambda function code is using a placeholder (YOUR_COGNITO_APP_CLIENT_ID) instead of the environment variable.
• There's a delay or issue with the AWS CDK deployment that prevents the latest environment variables from being correctly applied.

1. Verify Lambda Code: Check your Lambda function code (signUp.handler) to ensure it's correctly referencing process.env.USER_POOL_CLIENT_ID and not a hardcoded placeholder.

2. Deployment Check: Ensure your AWS CDK stack has been successfully deployed after adding or updating the environment variable. Sometimes, changes might not propagate if the deployment encountered issues.

3. Manual Verification: After deployment, you can manually verify the Lambda environment variables in the AWS Console to ensure the USER_POOL_CLIENT_ID is set correctly.

The AWS CDK does not natively support directly writing outputs to a .env file. However, you can achieve this by capturing the outputs after deployment and using external scripts. Here’s a basic approach:

1. Capture Outputs: Use the AWS CLI to capture the outputs of your stack after deployment:

aws cloudfront describe-stacks --stack-name HandTermCdkStack --query "Stacks[0].Outputs"

2. Process and Write to .env: Process the JSON output from the above command with a script (e.g., in Node.js, Python, or Bash) to extract the desired values and format them into a .env file.

const { exec } = require('child_process');
const fs = require('fs');

exec('aws cloudformation describe-stacks --stack-name HandTermCdkStack --query "Stacks[0].Outputs"', (error, stdout, stderr) => {
    if (error) {
        console.error(`exec error: ${error}`);
        return;
    }

    const outputs = JSON.parse(stdout);
    const envContents = outputs.map(output => `${output.OutputKey}=${output.OutputValue}`).join('\n');

    fs.writeFileSync('.env', envContents);
});

This script is a basic example; you may need to adjust it based on your environment and specific requirements.

Ensure that any scripts or processes that write sensitive information (like Cognito App Client IDs) to .env files are secured and managed appropriately to avoid unintentional disclosure of sensitive data.

User at 7:03 pm, Jun 28, 2024

I am looking for inappropriately hardcoded strings and I noticed this on in cdk/lambda/handtermEdgeFunction/app.ts

import { CloudFrontResponseEvent, CloudFrontResponseHandler, CloudFrontResponseResult } from 'aws-lambda';

export const lambdaHandler: CloudFrontResponseHandler = async (event: CloudFrontResponseEvent): Promise<CloudFrontResponseResult> => {
 console.log('event:', JSON.stringify(event, null, 2));
 const response = event.Records[0].cf.response;
 const headers = response.headers;

 // Set HttpOnly Cookie
 headers['set-cookie'] = [{
  key: 'Set-Cookie',
  value: `handterm-history=YourCookieValue; Path=/; Secure; HttpOnly;`
 }];

 return response;
};

I don't know if the YourCookieValue is correct.

Codeium at 7:03 pm, Jun 28, 2024

The string YourCookieValue in the code snippet you provided for cdk/lambda/handtermEdgeFunction/app.ts is indeed a placeholder and should be replaced with a dynamic value that suits your application's requirements. This value is intended to represent the actual cookie value you want to set in the user's browser.

In a real-world scenario, the cookie value (YourCookieValue) is typically dynamic and could represent a session identifier, authentication token, or any other value that you need to securely transmit to the client without exposing it to JavaScript access (hence the use of HttpOnly flag).

Here is an approach to dynamically set a cookie value:

1. Generate or Retrieve a Dynamic Value: Depending on your application's logic, this value could be generated within the Lambda function (e.g., a session ID) or retrieved from another source (e.g., a database or authentication service).

2. Securely Transmit Sensitive Information: If the cookie is used for session management or authentication, ensure the value is securely generated and cannot be guessed or forged. For example, use secure, random identifiers, or JWT tokens signed with a secret.

3. Example Modification:

Assuming you have a function generateCookieValue that returns a string representing the dynamic value for the cookie, your Lambda function could look like this:

import { CloudFrontResponseEvent, CloudFrontResponseHandler, CloudFrontResponseResult } from 'aws-lambda';

// Example function to generate a dynamic cookie value
function generateCookieValue(): string {
  // Your logic here. This is just a placeholder implementation.
  return 'secureRandomValue';
}

export const lambdaHandler: CloudFrontResponseHandler = async (event: CloudFrontResponseEvent): Promise<CloudFrontResponseResult> => {
  console.log('event:', JSON.stringify(event, null, 2));
  const response = event.Records[0].cf.response;
  const headers = response.headers;

  // Set HttpOnly Cookie with a dynamic value
  headers['set-cookie'] = [{
    key: 'Set-Cookie',
    value: `handterm-history=${generateCookieValue()}; Path=/; Secure; HttpOnly;`
  }];

  return response;
};

In this example, generateCookieValue would be replaced with your actual logic for generating or retrieving the cookie's value. The key point is to replace the placeholder YourCookieValue with a dynamic value that suits your application's logic and security requirements.

This approach ensures that the cookie value set by your Lambda@Edge function is not static and can be tailored to your application's needs, enhancing both functionality and security.

User at 7:09 pm, Jun 28, 2024

Do I have to fetch the generatedCookieValue from Cognito? Does it have to match something else or will it be used later to look something up?

Codeium at 7:10 pm, Jun 28, 2024

The necessity to fetch generatedCookieValue from AWS Cognito, or whether it needs to match something else, largely depends on what you intend to achieve with this cookie. There are a few common use cases for setting cookies in the context of AWS Cognito and web applications:

If you're using the cookie for session management (e.g., to maintain a user's signed-in state), the cookie value typically represents a session identifier or a token. In the context of AWS Cognito:

• Cognito Tokens: After a successful authentication, Cognito provides JWT tokens (idToken, accessToken, and optionally refreshToken). These tokens can be used to maintain and manage a user's session.
• Custom Session Handling: If you're implementing custom session handling logic, the cookie value might be a session ID that you generate and manage on your server or within your infrastructure.

In some scenarios, cookies are used to manage or preserve state across requests. For example:

• Cross-site Request Forgery (CSRF) Protection: A unique token to mitigate CSRF attacks.
• Redirection After Sign-In: Storing the intended URL to redirect the user after a successful authentication.

Cognito itself manages user sessions through tokens provided as part of the authentication response. You do not typically need to fetch or store these tokens in cookies yourself if you're using Cognito's hosted UI or directly interacting with Cognito from the client side. However, in server-side or Lambda@Edge scenarios where direct client interaction is limited, you might choose to:

• Store Cognito Tokens in Cookies: For a server-rendered application, you might pass Cognito tokens to the client via secure, HttpOnly cookies.
• Custom Cookie Values: In cases where you're not directly storing Cognito tokens but need to maintain session state or other information, the cookie value can be something you generate (e.g., a reference to data stored elsewhere, like a session store or database).

• Security: Ensure that any sensitive information stored in cookies is properly secured. Use the HttpOnly, Secure, and, where appropriate, SameSite attributes to enhance security.
• Compliance: Be mindful of privacy and data protection regulations (like GDPR or CCPA) when handling cookies and personal information.
• Lookup: If a cookie is used to store a reference ID (e.g., session ID), ensure that your application logic or backend services can correctly interpret this ID to retrieve the associated data or validate the session.

In summary, whether you need to fetch a value from Cognito for your cookie depends on your specific requirements for authentication, session management, or state management within your application's architecture.

User at 7:18 pm, Jun 28, 2024

The promary purpose of this Lambda@Edge function is to provide HttpOnly Cookies to prevent XSS risks.

So, that seems like a use case where I would have to interact with Cognito from the Lambda function, but I don't know how to do that part.

Codeium at 7:19 pm, Jun 28, 2024

If the primary purpose of your Lambda@Edge function is to set HttpOnly cookies to mitigate Cross-Site Scripting (XSS) risks, particularly in the context of AWS Cognito, there are generally two approaches you might consider:

After a user successfully authenticates with Cognito, your application will receive JWT tokens (ID token, access token, and refresh token). You can set these tokens as HttpOnly cookies to securely transmit them to the client. Here's how you might interact with Cognito and set cookies in a Lambda function:

The Lambda@Edge function would typically be triggered after a user authenticates and a redirection from Cognito occurs. This can be challenging to handle directly with Lambda@Edge due to its limited trigger types (Viewer Request, Viewer Response, Origin Request, Origin Response).

A common pattern is to set up a redirect or a callback URL that points to an API Gateway endpoint, which then triggers a Lambda function to process authentication tokens. However, directly handling this with Lambda@Edge without an intermediary service is not straightforward.

Once you have the authentication tokens, you would set them as HttpOnly cookies in the HTTP response. Note that directly handling Cognito tokens at Lambda@Edge is not a typical use case due to the nature of Lambda@Edge executions and the way Cognito redirects and handles tokens.

If you're not directly handling Cognito tokens but want to use custom sessions managed by your application, you would:

After validating a user's authentication with Cognito (which might happen via API calls from your application's backend or through user interaction with Cognito's hosted UI), generate a session identifier in your backend.

Store this session identifier and its associated information (such as user attributes or token expiry) in a secure, server-side session store (e.g., Redis, DynamoDB).

Use Lambda@Edge to set this session identifier as an HttpOnly cookie in the HTTP response. This cookie is then used in subsequent requests to identify the session.

Here's a simplified example of how you might set an HttpOnly cookie in a Lambda@Edge function without direct integration with Cognito:

exports.handler = (event, context, callback) => {
    const { request, response } = event.Records[0].cf;

    // Example: Set a simple HttpOnly cookie
    const cookieValue = 'exampleSessionId=123456; Path=/; Secure; HttpOnly;';

    // Ensure there's a 'set-cookie' header and add the cookie
    const headers = response.headers;
    headers['set-cookie'] = headers['set-cookie'] || [];
    headers['set-cookie'].push({ value: cookieValue });

    return callback(null, response);
};

Directly interacting with Cognito from Lambda@Edge to handle authentication tokens is not typical due to the flow of information from Cognito to the client usually being managed client-side or via redirects to server endpoints.

For most use cases involving authentication and session management with Cognito, consider using a server-side application or AWS API Gateway to handle the token exchange and session cookie setup, rather than directly using Lambda@Edge. Lambda@Edge is best suited for tasks that need to be performed closer to the user, like content customization and basic request/response modifications.

User at 8:14 pm, Jun 28, 2024

Ok, so I think I should be using your first approach.

Can you help me modify my CDK to do that?

Codeium at 8:15 pm, Jun 28, 2024

To modify your AWS CDK setup for the first approach—setting Cognito tokens as HttpOnly cookies via a Lambda function and API Gateway, instead of directly using Lambda@Edge—follow these steps. This approach involves capturing the tokens after a user authenticates with Cognito and then securely setting them as HttpOnly cookies through a Lambda function that's invoked via API Gateway.

You'll create a new Lambda function that will be responsible for receiving authentication tokens, setting them as HttpOnly cookies, and then redirecting the user.

1. Lambda Function: Add this Lambda function to your cdk-stack.ts. This function will be triggered by API Gateway after a successful authentication with Cognito.

const tokenHandlerLambda = new lambda.Function(this, 'TokenHandlerFunction', {
    runtime: lambda.Runtime.NODEJS_16_X,
    handler: 'tokenHandler.handler',
    code: lambda.Code.fromAsset('lambda/tokenHandler'),
    environment: {
        // Add any required environment variables here
    }
});

Make sure to create a corresponding tokenHandler.js (or .ts if you're using TypeScript) file in your lambda/tokenHandler directory with the logic to handle the tokens and set cookies.

Create an API Gateway endpoint that triggers the tokenHandlerLambda. This endpoint will be used as the redirect URI in your Cognito User Pool Client settings.

1. API Gateway Endpoint: Modify the existing API Gateway setup or create a new one specifically for handling the redirect URI.

const api = new apigateway.RestApi(this, 'HandTermApi', {
    restApiName: 'HandTerm Service',
    description: 'This service serves authentication requests.',
});

const tokenHandlerIntegration = new apigateway.LambdaIntegration(tokenHandlerLambda);
const authCallbackResource = api.root.addResource('auth');
authCallbackResource.addMethod('GET', tokenHandlerIntegration); // Assuming the redirect URI includes a GET request

Update the Cognito User Pool Client's callback URLs to include the API Gateway endpoint created above. This step ensures that Cognito redirects to your Lambda function after authentication.

1. Callback URL Update: When adding or updating the User Pool Client in your CDK stack, include the API Gateway endpoint URL as part of the callback URLs.

const userPoolClient = userPool.addClient('AppClient', {
    authFlows: {
        userSrp: true,
    },
    generateSecret: false,
    // Add your API Gateway endpoint URL to the list of callback URLs
    callbackUrls: [`https://${api.restApiId}.execute-api.${this.region}.amazonaws.com/prod/auth`]
});

In your tokenHandler Lambda function, implement the logic to:

• Extract the tokens from the query parameters.
• Set the tokens as HttpOnly cookies in the response headers.
• Redirect the user to your application's main page or dashboard.

• Securely Handling Tokens: Ensure the implementation securely handles tokens, especially if they're JWT tokens from Cognito.
• CORS Configuration: If your web application is hosted on a different domain than your API Gateway, configure CORS settings accordingly.
• Deployment and Testing: After making these changes, deploy your CDK stack, configure your web application to use the new authentication flow, and thoroughly test the authentication process.

This setup leverages API Gateway and Lambda to securely handle authentication tokens, providing flexibility and enhancing security by using HttpOnly cookies.

User at 8:35 pm, Jun 28, 2024

In the userPoolClient code I get this error:

Object literal may only specify known properties, and 'callbackUrls' does not exist in type 'UserPoolClientOptions'.ts(2353)
⚠ Error (TS2353) | 
Object literal may only specify known properties, and callbackUrls does not exist in type  UserPoolClientOptions 
 .

Also, in the tokenHandler, how do I extract the token from the query parameters? Do you know where the querystring will be coming from and what it's parameters will be named?

Codeium at 8:36 pm, Jun 28, 2024

Your error indicates that the callbackUrls property isn't recognized within the UserPoolClientOptions type, which is accurate for the AWS CDK's addClient method on a UserPool object. My mistake on that guidance. The callbackUrls are actually a part of an App Client's settings when dealing with OAuth flows, particularly when utilizing the Cognito Hosted UI. If you're directly handling tokens without utilizing OAuth flows or the Cognito Hosted UI, you would typically manage redirection and token handling within your application logic or through API Gateway as an intermediary, not directly in the UserPoolClient configuration.

If you intend to use OAuth 2.0 features, including callback URLs with a Cognito User Pool App Client, you would typically set this up in the AWS Management Console or via AWS CLI/API for an existing App Client since the CDK currently does not support directly setting callbackUrls on the UserPoolClient. However, when integrating with API Gateway and Lambda for token handling, direct callback URLs configuration in CDK might not be necessary as described previously.

Regarding extracting tokens from the query parameters in your tokenHandler Lambda function, when Cognito redirects to your specified callback URL after authentication, it appends tokens to the URL as query parameters. The exact parameters depend on the OAuth flow used. For example:

• code (Authorization Code Grant): Cognito returns an authorization code that you can exchange for tokens.
• id_token, access_token, and refresh_token (Implicit Grant): Cognito returns the tokens directly in the URL.

Here's how you might extract query parameters in a Node.js Lambda function:

exports.handler = async (event) => {
    // Extract query string parameters from the event
    const queryParams = event.queryStringParameters;
    
    // Example for Authorization Code Grant
    const code = queryParams.code;

    // Example for Implicit Grant
    const idToken = queryParams.id_token;
    const accessToken = queryParams.access_token;
    const refreshToken = queryParams.refresh_token;

    // Your logic here to handle the tokens or code

    // Example response to set cookies and redirect
    const response = {
        statusCode: 302,
        headers: {
            'Set-Cookie': `idToken=${idToken}; Secure; HttpOnly; Path=/`,
            'Location': 'https://yourapplication.com/dashboard'
        },
        body: ''
    };
    return response;
};

When handling tokens, especially in URL query parameters:

• Be cautious with the Implicit Grant flow, as returning tokens in the URL can expose them to potential risks.
• Consider using the Authorization Code Grant flow for better security. You would exchange the code for tokens server-side where it's safer.
• Ensure any redirect URIs and origins are configured correctly to prevent unauthorized redirects.

Adjust your approach based on the specific OAuth flow you're using and how you plan to handle tokens within your application. If you're not using the Cognito Hosted UI or OAuth features, your token handling and redirection logic will be custom implemented within your application and Lambda functions, using API Gateway as the bridge for HTTP requests.

User at 8:46 pm, Jun 28, 2024

Should I remove the Lambda@Edge function, then?

  // Lambda@Edge Function for HttpOnly Cookies
  const lambdaAtEdge = new lambda.Function(this, 'LambdaAtEdgeFunction', {
   runtime: lambdaRuntime, // Note: Ensure you're using a runtime supported by Lambda@Edge
   handler: 'app.lambdaHandler', // Adjusted to point to the transpiled JS file and handler
   code: lambda.Code.fromAsset('lambda/handtermEdgeFunction/'), // Pointing to the directory
   role: lambdaExecutionRole,
   memorySize: 128,
   description: 'A Lambda@Edge function for HttpOnly Cookies',
  });

If I understood you correctly, it would be easier to integrate with Cognito without using a Lambda@Edge function and CloudFront.

Codeium at 8:47 pm, Jun 28, 2024

Yes, based on your scenario—where the primary goal is to securely handle authentication tokens and set HttpOnly cookies as part of an authentication flow with AWS Cognito—it might be simpler and more straightforward to remove the Lambda@Edge function and not use CloudFront for this specific part of your authentication logic.

Lambda@Edge is powerful for use cases requiring manipulation of HTTP requests or responses at the edge locations closest to the end-users, such as SEO optimizations, URL rewrites, or adding security headers. However, when dealing with authentication tokens from Cognito, especially if you need to perform operations like token validation, exchange, or setting secure cookies based on authentication results, using a standard AWS Lambda function triggered by API Gateway (as previously discussed) provides a more direct and manageable approach.

Here's why a standard Lambda function with API Gateway might serve better for your needs:

• Easier Debugging and Logging: Standard Lambda functions offer more straightforward debugging and logging compared to Lambda@Edge, which can be crucial for authentication flows.
• Direct Integration with AWS Services: Directly integrating with Cognito and other AWS services without the restrictions and nuances of Lambda@Edge.
• Simpler Configuration: Managing API Gateway and Lambda configurations is generally more straightforward than dealing with CloudFront distributions and Lambda@Edge, especially for authentication logic.

If you decide to remove the Lambda@Edge function, ensure that any resources or triggers associated with it are also updated or removed accordingly. For example, if you have a CloudFront distribution configured to trigger the Lambda@Edge function, you would need to update or remove that configuration. Here’s a brief guide:

1. Remove Lambda@Edge from CloudFront Distribution:

   • Go to the AWS Management Console, navigate to your CloudFront distribution, and remove any associations with the Lambda@Edge function.

2. Update or Remove the Lambda@Edge function in CDK:

   • You can safely remove the Lambda@Edge function declaration from your cdk-stack.ts if it's no longer needed.
   • Ensure to remove or update any references to this function within your CDK stack to avoid deployment errors.

3. Redeploy Your CDK Stack:

   • After making changes, redeploy your CDK stack to apply them.

4. Verification:

   • Verify that the changes have been successfully applied and that there are no lingering dependencies or errors related to the removed Lambda@Edge function.

5. Focus on Standard Lambda and API Gateway:

   • Concentrate your efforts on implementing the authentication flow using a standard Lambda function triggered by API Gateway, as this will give you more flexibility and control over handling Cognito's authentication tokens and setting HttpOnly cookies.

By focusing on a standard Lambda function and API Gateway for handling the authentication flow, you should find it easier to implement, manage, and debug your authentication logic in integration with AWS Cognito.

User at 9:07 pm, Jun 28, 2024

I added the api code you posted above, but there doesn't seem to be any authorizor associated with it.

Don't I need to associate it with the Cognito HandTermUserPool?

Also, doesn't the tokenHandler need a role with policies associated with it?

Codeium at 9:08 pm, Jun 28, 2024

You're correct on both counts. Integrating API Gateway with Cognito for authentication and ensuring your Lambda function has the appropriate permissions are important steps for securing your application and enabling it to interact with AWS services.

To use your Cognito User Pool to authorize API requests, you can set up a Cognito User Pool Authorizer in API Gateway. This authorizer will inspect incoming tokens for their authenticity and scope, granting or denying access based on the token's validity.

Here's how you can add a Cognito User Pool Authorizer to your API Gateway in the AWS CDK setup:

// Assuming `api` is your RestApi object and `userPool` is your Cognito User Pool
const cognitoAuthorizer = new apigateway.CognitoUserPoolsAuthorizer(this, 'CognitoAuthorizer', {
  cognitoUserPools: [userPool],
  identitySource: 'method.request.header.Authorization',
  authorizerName: 'CognitoAuthorizer'
});

// Use the authorizer for your endpoint
authCallbackResource.addMethod('GET', tokenHandlerIntegration, {
  authorizer: cognitoAuthorizer,
  authorizationType: apigateway.AuthorizationType.COGNITO,
});

This setup configures API Gateway to use the Cognito User Pool as an authorizer, expecting the Authorization header to contain a valid JWT token issued by Cognito.

For your tokenHandler Lambda function to interact with AWS services (e.g., fetching user information from Cognito or writing logs to CloudWatch), you need to assign it an IAM role with the appropriate permissions.

Here's an example of how you could define a role for your Lambda function in CDK, granting it basic execution permissions and any additional policies you require:

const lambdaRole = new iam.Role(this, 'TokenHandlerLambdaRole', {
  assumedBy: new iam.ServicePrincipal('lambda.amazonaws.com'),
  managedPolicies: [
    iam.ManagedPolicy.fromAwsManagedPolicyName('service-role/AWSLambdaBasicExecutionRole'), // Basic Lambda execution role
    // Add additional policies as needed
  ],
});

// Then, when you define your Lambda function:
const tokenHandlerLambda = new lambda.Function(this, 'TokenHandlerFunction', {
  runtime: lambda.Runtime.NODEJS_16_X,
  handler: 'tokenHandler.handler',
  code: lambda.Code.fromAsset('lambda/tokenHandler'),
  role: lambdaRole, // Assign the role here
  environment: {
    // Environment variables here
  }
});

This setup ensures that your tokenHandler Lambda function has the necessary permissions to execute and perform its intended actions. Adjust the policies according to the specific AWS services and actions your Lambda function needs to interact with.

By adding a Cognito User Pool as an authorizer to your API Gateway and ensuring your Lambda function has an appropriate role, you strengthen the security and functionality of your application. Ensure you tailor the IAM policies to your application's specific needs to maintain the principle of least privilege.

User at 9:21 pm, Jun 28, 2024

There's something you said that I didn't understand but I want to know how to do:

"Consider using the Authorization Code Grant flow for better security. You would exchange the code for tokens server-side where it's safer."

Codeium at 9:21 pm, Jun 28, 2024

Certainly! The Authorization Code Grant flow is a part of the OAuth 2.0 protocol, which is designed for scenarios where the client application needs to perform actions on behalf of the user, but the user's credentials should not be shared with the application. This flow is particularly beneficial for web applications, as it allows the application to authenticate the user without handling sensitive information directly, enhancing security, especially against attacks like Cross-Site Scripting (XSS) and Cross-Site Request Forgery (CSRF).

Here's a high-level overview of how the Authorization Code Grant flow works with AWS Cognito and how you can implement it:

First, you redirect the user to the Cognito hosted sign-in page. The URL for this page includes query parameters specifying the details of the authentication request, such as the client_id of your Cognito User Pool App Client, the response_type (set to code for the Authorization Code Grant flow), and the redirect_uri (where Cognito will send the user after authentication).

https://your_user_pool_domain/login?response_type=code&client_id=your_app_client_id&redirect_uri=https://your_callback_url

The user enters their credentials on the Cognito hosted login page. After authentication, Cognito redirects the user to the redirect_uri specified in the initial request, appending an authorization code to the URL as a query parameter.

https://your_callback_url?code=AUTHORIZATION_CODE

Your backend (or a server-side component) captures the authorization code from the query parameters and makes a request to Cognito’s token endpoint to exchange it for the user’s tokens (ID token, access token, and refresh token). This request must include the authorization code, your app client ID, your app client secret (if you have one), and the grant type (authorization_code).

// Example of exchanging the authorization code for tokens in Node.js
const axios = require('axios');
const querystring = require('querystring');

async function getToken(authorizationCode) {
  const tokenResponse = await axios.post('https://your_user_pool_domain/oauth2/token', querystring.stringify({
    grant_type: 'authorization_code',
    client_id: 'your_app_client_id',
    redirect_uri: 'https://your_callback_url',
    code: authorizationCode,
    // Include client_secret if your app client has one
  }), {
    headers: {
      'Content-Type': 'application/x-www-form-urlencoded'
    }
  });

  return tokenResponse.data; // Contains id_token, access_token, and refresh_token
}

With the tokens obtained, you can now authenticate API requests, retrieve user information, or manage sessions in your application.

• Client Secret: If your app client is configured with a client secret, ensure it's securely stored and not exposed, especially in client-side code.
• Redirect URI Validation: Ensure the redirect_uri used in both the authorization request and token exchange request matches one of the URIs registered with the Cognito User Pool App Client to prevent redirect attacks.
• Token Validation: Always validate the tokens received from Cognito before using them to ensure they are authentic and haven’t been tampered with.

By following the Authorization Code Grant flow, you significantly enhance the security of your application by avoiding exposure of sensitive information and tokens to the client side and leveraging Cognito's capabilities to manage user authentication and token issuance securely.

User at 10:12 pm, Jun 28, 2024

My application is a text-based TUI, so redirecting to a web page would break the text-based nature of the interface.

Do we need to add a post-auth trigger to the Cognito in the CDK?

Codeium at 10:12 pm, Jun 28, 2024

For a text-based Terminal User Interface (TUI) application, leveraging web-based authentication flows like the Authorization Code Grant with redirects indeed doesn't match the user experience you're aiming for. Since the application operates within a terminal environment, a more suitable approach involves directly handling authentication without web redirects, possibly using the Cognito User Pool's USER_PASSWORD_AUTH flow for simplicity.

Given this context, you wouldn't need to implement a post-authentication trigger in Cognito for handling redirection or token exchanges as you would in a web-based OAuth flow. Instead, you might focus on securely managing the user's credentials and tokens directly within your TUI application's backend logic.

For direct authentication from a TUI, you can use the AWS SDK to interact with Cognito. Your application will:

1. Prompt the user for their username and password within the terminal interface.
2. Use the AWS SDK to submit these credentials to Cognito.
3. Handle the response from Cognito, which will include tokens upon successful authentication.

Here's a simplified example using the AWS SDK for JavaScript:

import { CognitoIdentityServiceProvider } from 'aws-sdk';

const cognito = new CognitoIdentityServiceProvider({ region: 'us-east-1' });

async function authenticateUser(username: string, password: string) {
  const params = {
    AuthFlow: 'USER_PASSWORD_AUTH',
    ClientId: 'YOUR_COGNITO_APP_CLIENT_ID',
    AuthParameters: {
      USERNAME: username,
      PASSWORD: password,
    },
  };

  try {
    const authResult = await cognito.initiateAuth(params).promise();
    console.log('Authentication successful', authResult);
    // Handle the authResult which includes tokens
  } catch (error) {
    console.error('Authentication failed', error);
  }
}

A Post-Authentication Lambda Trigger in Cognito is used to add custom logic after a user is authenticated but before tokens are generated. This can be useful for:

• Customizing token claims
• Implementing custom logging or analytics
• Enforcing additional security checks

For your TUI application, whether you need a post-authentication trigger depends on your specific requirements beyond the initial authentication logic. If your application simply needs to authenticate users and possibly retrieve user sessions or information without additional processing after authentication, you might not need this trigger.

However, if you find a use case for a post-authentication trigger, here's how you could add one in your CDK stack:

import * as lambda from 'aws-cdk-lib/aws-lambda';
import * as cognito from 'aws-cdk-lib/aws-cognito';

// Assuming userPool is your existing Cognito UserPool instance

const postAuthLambda = new lambda.Function(this, 'PostAuthLambda', {
  runtime: lambda.Runtime.NODEJS_14_X, // Use the runtime appropriate for your Lambda's code
  handler: 'postAuth.handler', // Update with your handler information
  code: lambda.Code.fromAsset('path/to/your/lambda/code'),
  // Additional configuration as needed
});

userPool.addTrigger(cognito.UserPoolOperation.POST_AUTHENTICATION, postAuthLambda);

For a TUI application, directly interacting with AWS Cognito via the SDK for authentication aligns better with the text-based interaction model than implementing web-based OAuth flows. The choice to use a post-authentication trigger should be guided by the specific needs for customization or processing after a user's authentication succeeds.

User at 10:19 pm, Jun 28, 2024

Would your example above "Authenticating Directly from the TUI" allow us to use HttpOnly Cookies?

I am under the understanding that HttpOnly Cookies are a good way of preventing XSS and more secure private partitioning of user content.

Codeium at 10:19 pm, Jun 28, 2024

In the context of a text-based Terminal User Interface (TUI) application, the concept of using HttpOnly cookies directly for managing session tokens isn't applicable in the same way it is for web applications. HttpOnly cookies are specifically a security feature for web browsers, designed to make certain cookies inaccessible to JavaScript, thereby mitigating certain types of cross-site scripting (XSS) attacks. Since a TUI application operates outside of a web browser environment, the mechanism for securely storing and transmitting session information will differ.

For TUI applications, especially those running in a terminal or command-line environment, secure management of session tokens (such as those obtained from AWS Cognito) involves:

1. Secure Storage: Storing the session tokens securely on the client-side. Depending on the operating system and environment, this could involve:

   • Using secure storage mechanisms provided by the operating system, such as the Keychain on macOS, Credential Locker on Windows, or Secret Service on Linux.
   • Encrypting tokens before storing them in a file system location with restricted access permissions.

2. Secure Transmission: Ensuring that any communication between the TUI application and your backend services (or directly with AWS services) happens over secure channels (e.g., HTTPS).

Given the constraints and environment of a TUI application, here are some guidelines for handling tokens securely:

• Token Retrieval: When your TUI application authenticates a user via AWS Cognito (as in the previous example), ensure the communication occurs over HTTPS.
• Token Storage: If you need to store tokens locally to maintain the session, use the most secure storage options available in your environment. Avoid storing tokens in plain text or in easily accessible locations.
• Token Usage: Use the tokens securely to make authenticated requests to your backend or AWS services. Ensure these requests are also made over HTTPS.

Imagine a TUI application that needs to authenticate users and then perform actions on AWS on behalf of those users:

1. Authentication: The application uses the AWS SDK to authenticate users with Cognito, retrieving tokens upon successful authentication.
2. Session Management: The application stores these tokens securely using the operating system's secure storage mechanism.
3. Making Requests: When the application needs to make requests to your backend or directly to AWS services, it retrieves the tokens from secure storage, includes them in the request headers, and ensures the request is made over HTTPS.

While HttpOnly cookies are not directly applicable to TUI applications, the principles of secure token storage and secure communication remain critically important. Focus on leveraging secure storage facilities provided by the operating system for storing tokens and ensure all communications that transmit sensitive information or authentication tokens are encrypted using HTTPS.

User at 10:25 pm, Jun 28, 2024

We are miscommunicating to each other. When I am talking about my application being a TUI, I mean an @xterm/xterm browser-based static site that creates a text-based environment and a text-based game in the web browser, using React and TypeScript.

It is in that context that I am attempting to secure user logins and ensure data privacy between users by implementing HttpOnly Cookies.

Does that seem like a reasonable use case?

Codeium at 10:25 pm, Jun 28, 2024

Thank you for clarifying the context of your application. Given that your application is a browser-based TUI using @xterm/xterm with React and TypeScript, the use of HttpOnly cookies becomes highly relevant and is indeed a reasonable and recommended approach for handling session tokens and enhancing security.

In a web browser context, HttpOnly cookies are an effective measure to protect your application against XSS attacks because they ensure that the cookies cannot be accessed through client-side scripts. This significantly reduces the risk of unauthorized access to user sessions even if an attacker can inject malicious scripts into your web pages.

Given your setup, here’s how you can work with HttpOnly cookies for session management:

1. Server-Side Token Handling: After a user authenticates, your server (or a serverless backend like AWS Lambda) should handle the token exchange with AWS Cognito. Once you receive authentication tokens from Cognito, you decide which information needs to be stored in cookies.

2. Setting HttpOnly Cookies: When your backend sends the authentication response back to the browser, set the session tokens (or session identifiers) as HttpOnly cookies in the response headers. This can be done in your AWS Lambda function that's acting as the backend for authentication. Here’s an example of setting a cookie in a Lambda function response:

   const response = {
       statusCode: 200,
       headers: {
           'Set-Cookie': `sessionId=${yourSessionId}; HttpOnly; Secure; Path=/;`,
           // Additional headers as necessary
       },
       body: JSON.stringify({
           message: 'Authentication successful',
           // Any other response payload
       }),
   };
   return response;

3. Secure Attributes: Note the Secure attribute in the cookie, which ensures the cookie is only sent over HTTPS, further enhancing security. The Path=/ attribute specifies that the cookie is accessible for every request to your domain.

4. Client-Side Handling: On the client side, your React application does not directly access these HttpOnly cookies. Instead, each subsequent request to your server (or serverless backend) will automatically include these cookies (thanks to the browser's cookie handling), where you can validate the session and perform authorized actions.

5. Logout and Session Expiry: Ensure you implement mechanisms for users to log out and to automatically expire sessions after a certain period or inactivity. This can involve server-side logic to invalidate session identifiers or tokens.

• Content Security Policy (CSP): Enhance your application's security by implementing a Content Security Policy header to reduce the risk of XSS attacks.
• Cross-Site Request Forgery (CSRF): Although HttpOnly cookies are not accessible via JavaScript, ensure your application is also protected against CSRF attacks. This might involve CSRF tokens or validating the Origin and Referer headers for state-changing requests.
• Cross-Origin Resource Sharing (CORS): Be mindful of your CORS policy to ensure your application does not inadvertently allow unsafe cross-origin requests.

Implementing HttpOnly cookies in a browser-based TUI application for secure session management is indeed a good practice. Ensure you follow best practices for security and privacy to protect user data and sessions effectively.