PowerShell script for configuring Performance Counters access in Sitecore 9

Configure-AppPoolAccessToPerformanceMonitoring.ps1

function IISReset {
    [CmdletBinding(SupportsShouldProcess = $true)]
    Param
    (
        [string]$Reason,
        [int]$TryNumber = 0,
        [switch]$Force
    )

    if ($Force -or $PSCmdlet.ShouldProcess("IIS", $Reason)) {
        $process = Start-Process "iisreset.exe" -NoNewWindow -Wait -PassThru

        if (($process.ExitCode -gt 0) -and ($TryNumber -lt 3) ) {
            Write-Warning "IIS Reset failed. Retrying..."
            $newTryNumber = $TryNumber + 1
            IISReset -Reason $Reason -TryNumber $newTryNumber -Force
        }
    }
}

function AddAppPoolUserToGroups {
    [CmdletBinding()]
    Param
    (
        [string[]]$AppPools,
        [string[]]$Groups
    )

    $needIISReset = $false

    foreach ($gr in $Groups) {
        $group = [ADSI]"WinNT://$Env:ComputerName/$gr,group"
        $members = $group.psbase.invoke("Members") | ForEach-Object {$_.GetType().InvokeMember("Name", 'GetProperty', $null, $_, $null)}

        foreach ($pool in $AppPools) {
            if ($members -contains $pool) {
                Write-Warning "'$pool' AppPool user exists in '$gr' group"
            }
            else {
                Write-Output "Adding '$pool' AppPool user to '$gr' group..."
        
                $ntAccount = New-Object System.Security.Principal.NTAccount("IIS APPPOOL\$pool")
                $strSID = $ntAccount.Translate([System.Security.Principal.SecurityIdentifier])
                $user = [ADSI]"WinNT://$strSID"
                $group.Add($user.Path)
                $needIISReset = $true
    
                Write-Output "Adding '$pool' AppPool user to '$gr' group done."
            }
        }
    }

    if ($needIISReset -eq $true) {
        IISReset -Reason "Groups changes will take effect after IIS Reset. Do it now?" -Confirm
    }
}

$pools = @("APP_POOL_NAME")
$groups = @("Performance Log Users", "Performance Monitor Users")

AddAppPoolUserToGroups -AppPools $pools -Groups $groups