<#
.SYNOPSIS
    Perform steps to migrate all ESXi hosts in a cluster to another vCenter Server.
.DESCRIPTION
    Use this script to migrate all ESXi hosts in a cluster to another vCenter Server.
    After the host is migrated the running VMs are moved to the folder they were in on the source vCenter Server.
    The folders must be available before this script is used.

    This script assumes availability of the following modules:
    - VMware-PowerCli
.PARAMETER
    - Cluster: name of the cluster to migrate.
.EXAMPLE
    .\Migrate-Hosts.ps1 -Cluster <clustername>
.NOTES
    Script name: Migrate-Hosts.ps1
    Author:      Jeroen Buren
    DateCreated: 03-03-2020
#>

[CmdletBinding(SupportsShouldProcess=$true)]

param(
    [parameter(Mandatory=$true,HelpMessage="Which cluster do you want to migrate?")][string]$Cluster,
    [parameter(Mandatory=$true,HelpMessage="What is the root folder for VMs?")][string]$RootFolder
)

####################################################################################
#                                                                                  #
# Functions                                                                        #
#                                                                                  #
####################################################################################

function Get-ScriptDirectory {
  $Invocation = (Get-Variable MyInvocation -Scope 1).Value
  Split-Path $Invocation.MyCommand.Path
}

function Log {
  param(
    [Parameter(Mandatory=$true)][String]$Message,
    [Parameter(Mandatory=$true)][ValidateSet("Info","Debug","Warn","Error")][String]$Type,
    [Parameter(Mandatory=$true)][ValidateSet("Console","LogFile","Both")][String]$OutputMode
  )

  $dateTimeString = Get-Date -Format "yyyy-MM-dd HH:mm:sszz"
  $output = ($dateTimeString + " " + $type.ToUpper() + " " + $message)
  if ($outputMode -eq "Console" -OR $outputMode -eq "Both") {
    Write-Host $output
  }
  if ($outputMode -eq "LogFile" -OR $outputMode -eq "Both") {
    try {
      Add-Content $logFile -Value $output -ErrorAction Stop
    }
    catch {
      Log ("Failed to write to log file: """ + $logFile + """.") -OutputMode Console -Type Error
      Log ("[" + $_.Exception.GetType().FullName + "] " + $_.Exception.Message) -OutputMode Console -Type Error
    }
  }
}

filter Get-FolderPath {
    $_ | Get-View | % {
        $row = "" | select Name, Path
        $row.Name = $_.Name

        $current = Get-View -Server $SourcevCenter $_.Parent
        $path = $_.Name
        do {
            $parent = $current
            if($parent.Name -ne "vm"){$path = $parent.Name + "\" + $path}
            $current = Get-View -Server $SourcevCenter $current.Parent
        } while ($current.Parent -ne $null)
        $row.Path = $path
        $row
    }
}

####################################################################################
#                                                                                  #
# Variables                                                                        #
#                                                                                  #
####################################################################################

# Logfile
Set-Variable logFile ((Get-ScriptDirectory) + "\Migrate-Hosts.log") -Option Constant -ErrorAction SilentlyContinue
$SourcevCenter = "<source vcenter>"
$DestinationvCenter = "<destination vcenter>"

####################################################################################
#                                                                                  #
# Main Code                                                                        #
#                                                                                  #
####################################################################################

Log -Message "Script started" -Type Info -OutputMode LogFile

$cred = Get-Credential -Message "Enter valid ESXi host credentials"

# Connect source vCenter Server
Connect-VIserver -Server $SourcevCenter | Out-Null
Log -Message "Connected to source vCenter Server" -Type Info -OutputMode Both

# Connect destination vCenter Server
Connect-VIServer -Server $DestinationvCenter | Out-Null
Log -Message "Connected to destination vCenter Server" -Type Info -OutputMode Both

# Get DRS Host rules from cluster
$DRSVmHostRules = Get-DrsVMHostRule -Cluster $Cluster -Server $SourcevCenter

# Get DRS VM rules from cluster
$rules = @()
foreach ($rule in Get-DrsRule -Cluster $Cluster -Server $SourcevCenter) {
  $line = ($rule.Name + "," + $rule.Enabled + "," + $rule.Type)
  foreach ($vmId in $rule.VMIds) {
    $line += ("," + (Get-View -Id $vmId).Name)
  }
$rules += $line
$rules | Out-File D:\Scripts\VMware\Temp\$Cluster-DRSRules.txt
}

# Get DRS VM groups from cluster
Get-DrsClusterGroup -Cluster $Cluster -Type VMGroup -Name "VM DRS Group 1" -Server $SourcevCenter | Select -ExpandProperty Member | Select Name | Export-Csv "D:\Scripts\VMware\Temp\$Cluster-1.csv" -NoTypeInformation
Get-DrsClusterGroup -Cluster $Cluster -Type VMGroup -Name "VM DRS Group 2" -Server $SourcevCenter | Select -ExpandProperty Member | Select Name | Export-Csv "D:\Scripts\VMware\Temp\$Cluster-2.csv" -NoTypeInformation

# Start migration
foreach ($esxi in Get-Cluster -Name $Cluster -Server $SourcevCenter | Get-VMHost) {
  Log -Message "Migrating host $($esxi.Name)" -Type Info -OutputMode Both

  # Get folderpath from VMs on host
  $report = @()
  $report = Get-VMHost $esxi -Server $SourcevCenter | Get-VM | Get-Folderpath
  $report | Export-Csv "D:\Scripts\VMware\Temp\$($esxi)-VMs-With-FolderPath.csv" -NoTypeInformation
  Log -Message "Exported folder paths from VMs" -Type Info -OutputMode Both

  # Disconnect host from source vCenter
  Set-VMHost -Server $SourcevCenter -VMHost $esxi -State Disconnected -Confirm:$false
  Log -Message "Disconnected host $($esxi.Name) from source vCenter Server" -Type Info -OutputMode Both

  # Remove host from source vCenter
  Remove-VMHost -Server $SourcevCenter -VMHost $esxi -Confirm:$false
  Log -Message "Removed host $($esxi.Name) from source vCenter Server" -Type Info -OutputMode Both

  # Add host to destination vCenter
  Try {Add-VMHost -Server $DestinationvCenter -Name $esxi.Name -Credential $cred -Location "Datacenter" -Force}
  Catch {Log -Message "Oops... Something went wrong..." -Type Error -OutputMode Both}
  Log -Message "Added host $($esxi.Name) to destination vCenter Server" -Type Info -OutputMode Both

  # Move host to cluster
  Try {Move-VMHost -Server $DestinationvCenter -VMHost $(Get-VMHost -Name $esxi.Name -Server $DestinationvCenter) -Destination $Cluster}
  Catch {Log -Message "Oops... Something went wrong..." -Type Error -OutputMode Both}
  Log -Message "Moved host $($esxi.Name) to cluster $Cluster" -Type Info -OutputMode Both

  # Move VMs to folder and start with next host
  $VMfolder = @()
  $VMfolder = Import-Csv "D:\Scripts\VMware\Temp\$($esxi)-VMs-With-FolderPath.csv" | Sort-Object -Property Path

  foreach ($guest in $VMfolder) {
      $key = @()
      $key =  Split-Path $guest.Path | split-path -leaf
      if ($key -eq "Datacenter") {
        Log -Message "Moving $($guest.Name) to folder $RootFolder" -Type Info -OutputMode Both
        Move-VM (Get-VM $guest.Name -Server $DestinationvCenter) -InventoryLocation (Get-Folder -Name $RootFolder -Type VM -Server $DestinationvCenter) | Out-Null
      }
      else {
        Log -Message "Moving $($guest.Name) to folder $key" -Type Info -OutputMode Both
      Move-VM (Get-VM $guest.Name -Server $DestinationvCenter) -InventoryLocation (Get-Folder $key -Server $DestinationvCenter -Location $RootFolder) -ErrorAction SilentlyContinue | Out-Null
      }
  }
}

# Create DRS Cluster Host Groups
$Hosts1 = Get-Cluster -Name $Cluster -Server $DestinationvCenter | Get-VMHost | where {$_.Name.Substring(4,1) -eq "0"}
$Hosts2 = Get-Cluster -Name $Cluster -Server $DestinationvCenter | Get-VMHost | where {$_.Name.Substring(4,1) -eq "1"}

Log -Message "Creating DRS Host Groups" -Type Info -OutputMode Both
New-DrsClusterGroup -Name "Host DRS Group 1" -Cluster $Cluster -VMHost $Hosts1 | Out-Null
New-DrsClusterGroup -Name "Host DRS Group 2" -Cluster $Cluster -VMHost $Hosts2 | Out-Null

# Create DRS Cluster VM Groups
$VMsAMS = @()
$VMsWSN = @()

foreach ($vm in Import-Csv "D:\Scripts\VMware\Temp\$Cluster-1.csv") {$VMs1 += Get-VM -Name $vm.Name -Server $DestinationvCenter}
foreach ($vm in Import-Csv "D:\Scripts\VMware\Temp\$Cluster-2.csv") {$VMs2 += Get-VM -Name $vm.Name -Server $DestinationvCenter}

Log -Message "Creating DRS VM Groups" -Type Info -OutputMode Both
New-DrsClusterGroup -Name "VM DRS Group 1" -Cluster $Cluster -Server $DestinationvCenter -VM $VMs1 | Out-Null
New-DrsClusterGroup -Name "VM DRS Group 2" -Cluster $Cluster -Server $DestinationvCenter -VM $VMs2 | Out-Null

# Enable DRS on the cluster
Set-Cluster -Cluster $Cluster -Server $DestinationvCenter -DrsEnabled $true -Confirm:$false | Out-Null

# Create DRS Host rules
foreach ($rule in $DRSVmHostRules) {
  $VMGroup = Get-DrsClusterGroup -Name $rule.VMGroup -Cluster $Cluster -Type VMGroup -Server $DestinationvCenter
  $VMHostGroup = Get-DrsClusterGroup -Name $rule.VMHostGroup -Cluster $Cluster -Type VMHostGroup -Server $DestinationvCenter
  New-DrsVMHostRule -Name $rule.Name -Enabled $true -Cluster $Cluster -VMGroup $VMGroup -VMHostGroup $VMHostGroup -Type ShouldRunOn -Server $DestinationvCenter | Out-Null
}

# Create DRS VM rules
foreach ($rule in $rules) {
  $rulearr = $rule.Split(",")
  if ($rulearr[1] -eq "True") {$enabled = $true}
  if ($rulearr[2] -eq "VMAntiAffinity") {$together = $false}
  New-DrsRule -Server $DestinationvCenter -Name $rulearr[0] -Cluster $Cluster -Enabled $enabled -KeepTogether $together -VM (Get-VM -Name ($rulearr[3..($rulearr.Count -1)]) -Server $DestinationvCenter)
}

# Disconnect from vCenter Servers
Disconnect-VIServer -Server $SourcevCenter -Confirm:$false
Disconnect-VIServer -Server $DestinationvCenter -Confirm:$false

Log -Message "Script Ended" -Type Info -OutputMode LogFile