function Start-AlkamiServiceFabricClusterUpgrade {
<#
.SYNOPSIS
    Updates the Service Fabric runtime version.

.PARAMETER hostname
    A single server from the cluster that needs to be upgraded.
#>
    [CmdletBinding()]
    Param(
        [Parameter(Mandatory = $false)]
        [string]$hostname = "localhost"
    )

    $loglead = Get-LogLeadName;

    Connect-AlkamiServiceFabricCluster -hostname $hostname;

    Write-Host "$loglead Updating Service Fabric runtime version.";

    [array]$versions = (Get-ServiceFabricRegisteredClusterCodeVersion | Select-Object -ExpandProperty CodeVersion | Sort-Object -Descending);
    foreach($version in $versions) {
        Write-Verbose "$loglead Found version $version";
    }

    $largestVersion = $versions[0];
    Write-Host "$loglead Selecting Service Fabric upgrade version $largestVersion. Starting upgrade.";
    Start-ServiceFabricClusterUpgrade -Code -CodePackageVersion $largestVersion -Monitored -FailureAction Rollback;

    Write-Host "$loglead Cluster upgrade started. Progress can be monitored through the dashboard.";
}