SNSDevOps.js

var AWS = require("aws-sdk");

var lambda = new AWS.Lambda({
  region: 'ap-southeast-1'
});

function mongodbMonitorResult() {
    return new Promise(function(resolve, reject) {
        lambda.invoke({
          FunctionName: process.env.MongoMonitorLambdaARN,
          Payload: null
        }, function(error, data) {
            if (error) {
                reject(error);
            }
            if(data.Payload) {
                resolve(data.Payload);
            }
        });
    });
}

function transformMongodbObject(members) {
    let membersObject = JSON.parse(members);
    let cwMetrics = [];
    membersObject.map(member => {
        if (member.health !== 1) {
            let deadCluster = "Following MongoDB cluster " + member.name + "(" + member.stateStr + ") is not working anymore.";
            cwMetrics.push(deadCluster);
        }
    });
    return cwMetrics;
}

function sendSNSEmail(eventText) {
    if (eventText.length > 0) {
        let message = "";
        eventText.map((text) => {
            message = message + text + "\n";
        });
        let params = {
            Message: message, 
            Subject: 'MongoDB Replica Status from Lambda',
            TopicArn: process.env.TopicARN
        };
        let publishTextPromise = new AWS.SNS({apiVersion: '2010-03-31'}).publish(params).promise();
        return publishTextPromise.then((data) => {
            return data.MessageId;
        }).catch((err) => {
            return err.stack;
        });   
    } else {
        return 0;
    }
}

exports.handler = function(event, context, callback) {
    mongodbMonitorResult().then(transformMongodbObject).then(sendSNSEmail).then((result) => {
        callback(null, 'success => ' + result);
    }).catch((err) => {
        callback(Error(err));
    })
};