Have I written this PowerShell script well enough to balance simplicity and performance?

Question

I have a script that checks remote servers for tomcat and the associated java versions. It takes about 60 seconds to run against a list of about 16 servers. I'm just curious if the script is as efficient as realistically possible. I'm far from a PowerShell pro but I'm satisfied with the outcome. Just checking for where there is room for improvement.

$Servers = 'server1','server2','etc'
$Output = @()
 
foreach ($Server in $Servers)
{
$SName = gwmi -Class Win32_Service -ComputerName $Server -Filter {Name LIKE 'Tomcat%'}
IF ($SName -ne $null) {
    $Output += [PSCustomObject]@{
        Server_name = $SName.PSComputerName
        Service_name = $SName.Name
        Service_status = $SName.State
        Tomcat_version = "$(Get-Content -Path ("\\"+$SName.PSComputerName+"\"+"$($SName.PathName.ToString())".Substring(0,$SName.Pathname.LastIndexOf("\")-3)+"\webapps\ROOT\RELEASE-NOTES.txt" -replace ":", "$") | Select-String -Pattern 'Apache Tomcat Version ')".TrimStart()
        Java_Version = (Invoke-Command -ComputerName $Server -ScriptBlock {(GCI -Path "$((Get-ItemProperty -Path 'HKLM:\SOFTWARE\WOW6432Node\Apache Software Foundation\Procrun 2.0\Tomcat9\Parameters\Java').Jvm)").VersionInfo.ProductName})
}
}
 Else {}
 }

 $Output | Select Server_name, Service_name,Service_status, Tomcat_Version, Java_Version | Format-Table -AutoSize

1. Can I simplify things anymore?
2. Is the time to completion decent for what is being performed?

Answer 1

• Invoke-Command allows you to connect with multiple computers at the same time which should be more efficient.
• += is pretty bad, please read: Why should I avoid using the increase assignment operator (+=) to create a collection
• You're querying WMI first and then if service is there you are using Invoke-Command, mind as well, connect once to the remote host and check everything.

I personally would do something like this

$Servers = 'server1','server2','etc'

$scriptBlock = {
    
    # Since you're querying each server, and then if the service is there you Invoke-Command,
    # mind as well Invoke-Command at first and if the service is there enter the If condition,
    # else close the connection.
    $tomcatServ = Get-CimInstance -Class Win32_Service -Filter "Name LIKE 'Tomcat%'"
    if($tomcatServ)
    {
        ##### This part is pretty confusing for someone reading your code, if you show us how does
        ##### RELEASE-NOTES.txt looks we may be able to improve it and simplified it a bit
        $path = $tomcatServ.PathName.Substring(0,$tomcatServ.PathName.LastIndexOf("\")-3)
        $path = Join-Path $path -ChildPath "webapps\ROOT\RELEASE-NOTES.txt"
        $tomCatVer = ((Get-Content $path) -replace ":", "$" | Select-String -Pattern 'Apache Tomcat Version ').TrimStart()
        
        ##### This part is a bit confusing too
        $key = 'HKLM:\SOFTWARE\WOW6432Node\Apache Software Foundation\Procrun 2.0\Tomcat9\Parameters\Java'
        $javaVer = GetChild-Item -Path ((Get-ItemProperty -Path $key).Jvm).VersionInfo.ProductName
        #####

        [PSCustomObject]@{
            Server_name = $env:ComputerName
            Service_name = $tomcatServ.Name
            Service_status = $tomcatServ.State
            Tomcat_version = $tomCatVer
            Java_Version = $javaVer
        }
    }
}

$Output = Invoke-Command -ComputerName $Servers -ScriptBlock $scriptBlock -HideComputerName
$Output | Select-Object * -ExcludeProperty RunspaceID | Format-Table -AutoSize