PowerCLI: Migrate templates during the Enter Maintenance Mode task

Normally when you put a host into Maintenance mode the templates will stay on the host instead of being migrate to a different host. This can be very annoying if you are performing maintenance on the vSphere host and a colleague needs to deploy a VM from the template. I am running vSphere 4.1 update 1. I don’t know if this is still the case with vSphere 5. The host in Maintenance mode will look like this:

So to fix this annoying “issue” I have created a PowerCLI function to place the vSphere host into maintenance mode and if there are Templates registered on the vSphere host, the Templates will be moved to another host in the Cluster.

Function Enter-MaintenanceMode{
<#
.SYNOPSIS   Enter Maintenance mode 
.DESCRIPTION   The function starts the Enter Maintenance task and also migrates the Templates to another host.
.NOTES   Author:  Arne Fokkema
.PARAMETER vmHost
   One vmHosts.
.EXAMPLE
   PS> Enter-MaintenanceMode<vmHost Name>
.EXAMPLE
  PS> Get-VMHost <vmHost Name> | Enter-MaintenanceMode
#>

[CmdletBinding()]
param(
    [parameter(ValueFromPipeline = $true,
    position = 0,
    Mandatory = $true,
    HelpMessage = "Enter the vmHost to start the Enter Maintenance mode task")]
    $vmHost
)    

    $templates = Get-VMHost $vmHost | Get-Template
    if($templates -eq $null){
        $tplMigrate = $false
    }
    else{
        $tplMigrate = $true
    }
    
    $targetVMHost = Get-VMHost -Location (Get-Cluster -VMHost (Get-VMhost $vmHost)).Name | Where {$_.Name -ne $vmHost} | Sort Name | Select -First 1
    if($tplMigrate -eq $true){
        foreach($tpl in $templates){
            Write-Host "Converting template $($tpl.Name) to VM" -ForegroundColor Yellow
            $vm = Set-Template -Template (Get-Template $tpl) -ToVM 
            
            Write-Host "Moving template $($tpl.Name) to vmHost: $($targetVMHost)" -ForegroundColor Yellow
            Move-VM -VM $vm -Destination (Get-VMHost $targetVMHost) -Confirm:$false | Out-Null
            
            Write-Host "Converting template $($tpl.Name) back to template" -ForegroundColor Yellow
            ($vm | Get-View).MarkAsTemplate() | Out-Null    
        }    
    }
    Write-Host "Enter Maintenance mode $($vmHost)" -ForegroundColor Yellow
    Set-VMHost $vmHost -State Maintenance | Out-Null
}

You can run the script like this:

Enter-MaintenanceMode esx07

Or from the pipeline:

Get-VMHost esx07 | Enter-MaintenanceMode

The output will be the same:

And the host is completely empty and ready for maintenance: