aws lambda dynamic dns records updation upon ec2 instance state change

lambda-route53-dyn-dns.js

const AWS = require('aws-sdk')

let params = {
    InstanceIds: [
        "i-something"
    ]
};

let route53params = {
    "HostedZoneId": "", // zone id
    "ChangeBatch": {
        "Changes": [{
            "Action": "UPSERT",
            "ResourceRecordSet": {
                "Name": "", // domain
                "Type": "A",
                "TTL": 10,
                "ResourceRecords": [{
                    "Value": "ip" // this will get updated below
                }]
            }
        }]
    }
};

exports.handler = function(event, context) {
    //console.log('r53-1 event log start')
    //console.log('event is: ' + JSON.stringify(event))
    let ec2 = new AWS.EC2();

    ec2.describeInstances(params, function(err, data) {
        console.log('inside describeInstance')
        if (err) {
            console.log('error in describeInstance')
            console.log(err, err.stack); // an error occurred
        }

        else {
            // console.log('data is: ' + JSON.stringify(data)); // successful response
            var ip = data.Reservations[0].Instances[0].PublicIpAddress
            console.log('ip is: ' + ip)
        }

        var route53 = new AWS.Route53()

        route53params.ChangeBatch.Changes[0].ResourceRecordSet.ResourceRecords[0].Value = ip
        console.log('route53params ip is: ' + route53params.ChangeBatch.Changes[0].ResourceRecordSet.ResourceRecords[0].Value)

        route53.changeResourceRecordSets(route53params, function(err, data) {
            console.log('err is: ', err, 'data is: ', data)
            context.done(null, 'Function finished')
        });
    });
};