change CName lambda

changeCName.js

var AWS = require('aws-sdk');
var route53 = new AWS.Route53();


exports.handler = async (event) => {
    console.log("Invoking CName change Script");
    var ec2 = new AWS.EC2();
    let vpnUrl;

    var data = await ec2.describeClientVpnEndpoints({}).promise();

    if (data.ClientVpnEndpoints.length > 0) {
        console.log(data.ClientVpnEndpoints[0].DnsName);
        vpnUrl = data.ClientVpnEndpoints[0].DnsName;
        return route53.changeResourceRecordSets(getParameters(event.cname, event.dnsZoneId, vpnUrl)).promise();
    } else {
        throw "No active VPN Endpoint! No DNS modification needed.";
    }
};

function getParameters(cname, hostedZoneId, vpnUrl) {
    return {
        ChangeBatch: {
            "Comment": "Auto generated CName Record for VPN Endpoint",
            "Changes": [
                {
                    "Action": "UPSERT",
                    "ResourceRecordSet": {
                        "Name": cname,
                        "Type": "CNAME",
                        "TTL": 300,
                        "ResourceRecords": [
                            {
                                "Value": vpnUrl
                            }
                        ]
                    }
                }
            ]
        },
        HostedZoneId: hostedZoneId
    };
}