NodeJs unable to callback AWS Secrets Manager response

Question

I'm trying to use AWS Secrets Manager to fetch my RDS credentials,
The Secrets Manager SDK is able to get the Secret properly,
But I am unable to export it back to my calling file.

I have 2 files -
1. index.js -

var mysql = require('mysql');
var secretsManager = require('./secrets-manager');

exports.handler = (event, context, callback) => {

    secretsManager.getDbCredentialFromSecretsManager(function(err,creds) {
        if (err) {
            console.log(err);
            callback(err, null);
        }
        else{
            console.log("Creds ", creds);
            var connection = mysql.createConnection(creds);

            connection.connect(function(err) {
                if (err) {
                  console.error(err.stack);
                  callback(err,null);
                }
                else{
                    callback(null,connection);
                }
            });
        }
    });

}

2. secrets-manager.js -

var AWS = require('aws-sdk');
var constants = require('/opt/nodejs/utils/constants');

module.exports = {
    getRDSCredsFromSM
};

function getRDSCredsFromSM (callback) {
    var response = {};

    let secretName = "secretId";

    var client = new AWS.SecretsManager({
        region: constants.aws.region
    });

    client.getSecretValue({SecretId: secretName}, function(err, data) {

        if (err) {
            console.log(err);
            callback(err, null);
        }
        else {
            if ('SecretString' in data) {
                let secret = data.SecretString;
                secret = JSON.parse(secret);

                console.log("secret",secret);
                callback(null, secret);
            } else {
                let buff = new Buffer(data.SecretBinary, 'base64');
                let decodedBinarySecret = buff.toString('ascii');
                callback(null, decodedBinarySecret);
            }
        }
    });
}

I feel there's some mistake from me on Node side,
Which is why the callback isn't working properly,
The Lambda Timesout,
And the logs show nothing in creds variable -

console.log("Creds ", creds);

Answer 1

Working code -

let async = require('async');
let AWS = require('aws-sdk');

module.exports = {
    getDbCredentialFromSecretsManager
};

const TAG = '[SECRETS-MANAGER-UTIL->';

function getDbCredentialFromSecretsManager (constants, callback) {
    let response = {};
    const METHOD_TAG = TAG + 'getDbCredentialFromSecretsManager->';

    async.waterfall([
        function(callback) {
            let client = new AWS.SecretsManager({
                region: constants.aws.region
            });

            client.getSecretValue({SecretId: constants.aws.sm}, function(err, data) {
                if (err) {
                    console.log(METHOD_TAG,err);
                    callback(err, null);
                }
                else {
                    console.log(METHOD_TAG, 'Secrets Manager call successful');
                    if ('SecretString' in data) {
                        let secret = data.SecretString;
                        secret = JSON.parse(secret);
                        response.user = secret.username;
                        response.password = secret.password;
                        response.host = secret.host;
                        response.database = constants.db.database;
                        callback(null, response);
                    } else {
                        let buff = new Buffer(data.SecretBinary, 'base64');
                        let decodedBinarySecret = buff.toString('ascii');
                        callback(null, decodedBinarySecret);
                    }
                }
            });
        }
    ],
    function(err, response) {
        if (err) {
            console.log(METHOD_TAG, err);
            callback(err, response);
        } 
        else {
            callback(null, response);
        }
    });
}