Amazon web services – Solved: MySQL PROTOCOL_CONNECTION_LOST Error with AWS CDK CustomResource, Lambda

I am using AWS CDK for defining AWS infrastructure.
I have database-stack that defines RDS(MySQL) instance and have set up AWSCustomResource like below to run table-creation.sql when the Database instance is deployed for the first time.

Everytime, the instance is launched, the table is not created in the instance showing error:

2023-06-11T14:23:19.813Z    8155569d-cd7e-4fc4-833c-db7da6afbf3d    INFO    Error: Connection lost: The server closed the connection.
    at Protocol.end (/var/task/index.js:9350:17)
    at Socket.<anonymous> (/var/task/index.js:9907:32)
    at Socket.<anonymous> (/var/task/index.js:10233:14)
    at Socket.emit (node:events:525:35)
    at Socket.emit (node:domain:489:12)
    at endReadableNT (node:internal/streams/readable:1358:12)
    at processTicksAndRejections (node:internal/process/task_queues:83:21)
    --------------------
    at Protocol._enqueue (/var/task/index.js:9374:52)
    at Protocol.handshake (/var/task/index.js:9304:27)
    at PoolConnection.connect (/var/task/index.js:9925:22)
    at Pool.getConnection (/var/task/index.js:10330:20)
    at Pool.query (/var/task/index.js:10447:12)
    at /var/task/index.js:10997:22
    at new Promise (<anonymous>)
    at Runtime.handler (/var/task/index.js:10996:18)
    at processTicksAndRejections (node:internal/process/task_queues:96:5) {
  fatal: true,
  code: 'PROTOCOL_CONNECTION_LOST'
}

To solve this, I tried looking into this post which seemed relevant: nodejs mysql Error: Connection lost The server closed the connection
But the solution didn’t work for me and other posts as well.

Also I noticed the solutions were mostly with NodeJS without AWS Lambda functions.
I tried many things and I am wondering what could be the possible problems and how to solve this issue. Any advice would be thankful.

Here are the AWS CDK defined database-stack.ts with AWSCustomResource to run a lambda function at its creation and rds-init.ts which is lambda function code for creating tables.

database-stack.ts

// Create Lambda Function to initialize the DB with tables and data.
        const rdsLambdaFunction = new NodejsFunction(this, "rdsLambdaFN", {
            entry: "./src/lambda_functions/rds-init.ts",
            runtime: Runtime.NODEJS_16_X,
            timeout: Duration.minutes(3), // Preventing coldstart time
            functionName: "rds-init-function",
            environment: {
                DB_ENDPOINT_ADDRESS: dbProxy.endpoint,
                DB_NAME: "vegafoliodb",
                DB_SECRET_ARN: instance.secret?.secretFullArn || "", // Not Fetching Password directly but via SecretARN for security :)
            },
            vpc,
            vpcSubnets: vpc.selectSubnets({
                subnetType: ec2.SubnetType.PRIVATE_WITH_EGRESS,
            }),
            bundling: {
                // Use Command Hooks to include table-creation.sql file in the bundle
                commandHooks: {
                    beforeBundling(inputDir: string, outputDir: string) {
                        return [
                            `cp ${inputDir}/src/lambda_functions/table-creation.sql ${outputDir}`,
                        ];
                    },

                    afterBundling(inputDir: string, outputDir: string) {
                        return [];
                    },

                    beforeInstall(inputDir: string, outputDir: string) {
                        return [];
                    },
                },

                externalModules: [
                    "aws-sdk", // No Need to include AWS SDK as we are using native aws-sdk.
                ],
            },
            securityGroups: [dbSG],
        });

// Custom Resource to invoke Lambda Function on db stack creation creation
        new AwsCustomResource(this, "rdsInitCustomResource", {
            onCreate: {
                service: "Lambda",
                action: "invoke",
                parameters: {
                    FunctionName: rdsLambdaFunction.functionArn,
                    InvocationType: "RequestResponse",
                },
                physicalResourceId: PhysicalResourceId.of(
                    "rdsInitCustomResource"
                ),
            },
            policy: AwsCustomResourcePolicy.fromSdkCalls({
                resources: [rdsLambdaFunction.functionArn],
            }),
            role: customResourcerole,
        });

rds-init.ts

// Custom Resource to invoke Lambda Function on db stack creation creation
        new AwsCustomResource(this, "rdsInitCustomResource", {
            onCreate: {
                service: "Lambda",
                action: "invoke",
                parameters: {
                    FunctionName: rdsLambdaFunction.functionArn,
                    InvocationType: "RequestResponse",
                },
                physicalResourceId: PhysicalResourceId.of(
                    "rdsInitCustomResource"
                ),
            },
            policy: AwsCustomResourcePolicy.fromSdkCalls({
                resources: [rdsLambdaFunction.functionArn],
            }),
            role: customResourcerole,
        });