Updates a route53 entry with the public hostname of the current EC2 instance. Usage: `Update-R53ForCurrentHost "servers.example.com" "s01"`

Update-R53ForCurrentHost.psm1

function Update-R53ForCurrentHost {
    param($zoneName, $subdomain)

    Import-Module AWSPowershell
    
    Write-Output "Updating R53 record for $subdomain.$zoneName"
    $publicHostname = Invoke-WebRequest `
        -Uri http://169.254.169.254/latest/meta-data/public-hostname
    
    Write-Output "New HostName is:$publicHostname"
    $hostedZone = Get-R53HostedZones | Where-Object Name -eq ($zoneName + ".")

    # Set ResourceRecordSet
    $resourceName = $subdomain + "." + $zoneName + "."
    $resourceRecordSet = New-Object Amazon.Route53.Model.ResourceRecordSet
    $resourceRecordSet.Name = $resourceName
    $resourceRecordSet.Type = "CNAME"
    $resourceRecordSet.ResourceRecords = New-Object Amazon.Route53.Model.ResourceRecord ($publicHostname)
    $resourceRecordSet.TTL = 300

    # Set Action
    Write-Output "Checking for status of: $resourceName"
    if (((Get-R53ResourceRecordSet -HostedZoneId $hostedZone.id).ResourceRecordSets | Where-Object Name -eq $resourceName | Measure-Object).Count -eq 0) {
        Write-Output "Domain does not exist... Creating new domain"
        $action = [Amazon.Route53.ChangeAction]::CREATE
    }
    else {
        Write-Output "Domain exists... Updating domain"
        $action = [Amazon.Route53.ChangeAction]::UPSERT
    }

    # Set Change 
    $change = New-Object Amazon.Route53.Model.Change ($action, $resourceRecordSet)

    # Execute
    Write-Output "Updating...."
    Edit-R53ResourceRecordSet -HostedZoneId $hostedZone.Id -ChangeBatch_Change $change
    Write-Output "Update Done"

}