Powershell Script to create multiple Solr instances in the same machine

I use low effort solr installs whenever i need to create a Solr instance. Recently, i encountered a scenario wherein i had to run multiple instances of solr in the same machine. So, modified the low effort solr installs script in order to create separate service instances pointing to separate solr folders. Here is the list of minor changes -

Code in github.

Copy from below this line:
Param(
    $solrVersion = "7.5.0",
$installSubFolder = "instance-5", #provide client name or project name to make it unique
    $installFolder = "C:\solr\$installSubFolder",
    $solrPort = "8987",
    $solrHost = "solr",
    $solrSSL = $true,
    $nssmVersion = "2.24",
    $JREVersion = "1.8.0_221",
$solrSvcName="solr-$installSubFolder-$solrVersion" #change here to make the service name unique
)

$JREPath = "C:\Program Files\Java\jre$JREVersion" ## Note that if you're running 32bit java, you will need to change this path
$solrName = "solr-$solrVersion"
$solrRoot = "$installFolder\$solrName"
$nssmRoot = "$installFolder\nssm-$nssmVersion"
$solrPackage = "https://archive.apache.org/dist/lucene/solr/$solrVersion/$solrName.zip"
$nssmPackage = "https://nssm.cc/release/nssm-$nssmVersion.zip"
$downloadFolder = "~\Downloads"

## Verify elevated
## https://superuser.com/questions/749243/detect-if-powershell-is-running-as-administrator
$elevated = [bool](([System.Security.Principal.WindowsIdentity]::GetCurrent()).groups -match "S-1-5-32-544")
if($elevated -eq $false)
{
    throw "In order to install services, please run this script elevated."
}

function downloadAndUnzipIfRequired
{
    Param(
        [string]$toolName,
        [string]$toolFolder,
        [string]$toolZip,
        [string]$toolSourceFile,
        [string]$installRoot
    )

    if(!(Test-Path -Path $toolFolder))
    {
        if(!(Test-Path -Path $toolZip))
        {
            Write-Host "Downloading $toolName..."
            Start-BitsTransfer -Source $toolSourceFile -Destination $toolZip
        }

        Write-Host "Extracting $toolName to $toolFolder..."
        Expand-Archive $toolZip -DestinationPath $installRoot
    }
}
# download & extract the solr archive to the right folder
$solrZip = "$downloadFolder\$solrName.zip"
downloadAndUnzipIfRequired "Solr" $solrRoot $solrZip $solrPackage $installFolder

# download & extract the nssm archive to the right folder
$nssmZip = "$downloadFolder\nssm-$nssmVersion.zip"
downloadAndUnzipIfRequired "NSSM" $nssmRoot $nssmZip $nssmPackage $installFolder

# Ensure Java environment variable
$jreVal = [Environment]::GetEnvironmentVariable("JAVA_HOME", [EnvironmentVariableTarget]::Machine)
if($jreVal -ne $JREPath)
{
    Write-Host "Setting JAVA_HOME environment variable"
    [Environment]::SetEnvironmentVariable("JAVA_HOME", $JREPath, [EnvironmentVariableTarget]::Machine)
}

# if we're using HTTP
if($solrSSL -eq $false)
{
    # Update solr cfg to use right host name
    if(!(Test-Path -Path "$solrRoot\bin\solr.in.cmd.old"))
    {
        Write-Host "Rewriting solr config"

        $cfg = Get-Content "$solrRoot\bin\solr.in.cmd"
        Rename-Item "$solrRoot\bin\solr.in.cmd" "$solrRoot\bin\solr.in.cmd.old"
        $newCfg = $newCfg | % { $_ -replace "REM set SOLR_HOST=192.168.1.1", "set SOLR_HOST=$solrHost" }
        $newCfg | Set-Content "$solrRoot\bin\solr.in.cmd"
    }
}

# Ensure the solr host name is in your hosts file
if($solrHost -ne "localhost")
{
    $hostFileName = "c:\\windows\system32\drivers\etc\hosts"
    $hostFile = [System.Io.File]::ReadAllText($hostFileName)
    if(!($hostFile -like "*$solrHost*"))
    {
        Write-Host "Updating host file"
        "`r`n127.0.0.1`t$solrHost" | Add-Content $hostFileName
    }
}

# if we're using HTTPS
if($solrSSL -eq $true)
{
    # Generate SSL cert
    $existingCert = Get-ChildItem Cert:\LocalMachine\Root | where FriendlyName -eq "$solrName"
    if(!($existingCert))
    {
        Write-Host "Creating & trusting an new SSL Cert for $solrHost"

        # Generate a cert
        # https://docs.microsoft.com/en-us/powershell/module/pkiclient/new-selfsignedcertificate?view=win10-ps
        $cert = New-SelfSignedCertificate -FriendlyName "$solrName" -DnsName "$solrHost" -CertStoreLocation "cert:\LocalMachine" -NotAfter (Get-Date).AddYears(10)

        # Trust the cert
        # https://stackoverflow.com/questions/8815145/how-to-trust-a-certificate-in-windows-powershell
        $store = New-Object System.Security.Cryptography.X509Certificates.X509Store "Root","LocalMachine"
        $store.Open("ReadWrite")
        $store.Add($cert)
        $store.Close()

        # remove the untrusted copy of the cert
        $cert | Remove-Item
    }

    # export the cert to pfx using solr's default password
    if(!(Test-Path -Path "$solrRoot\server\etc\solr-ssl.keystore.pfx"))
    {
        Write-Host "Exporting cert for Solr to use"

        $cert = Get-ChildItem Cert:\LocalMachine\Root | where FriendlyName -eq "$solrName"
 
        $certStore = "$solrRoot\server\etc\solr-ssl.keystore.pfx"
        $certPwd = ConvertTo-SecureString -String "secret" -Force -AsPlainText
        $cert | Export-PfxCertificate -FilePath $certStore -Password $certpwd | Out-Null
    }

    # Update solr cfg to use keystore & right host name
    if(!(Test-Path -Path "$solrRoot\bin\solr.in.cmd.old"))
    {
        Write-Host "Rewriting solr config"

        $cfg = Get-Content "$solrRoot\bin\solr.in.cmd"
        Rename-Item "$solrRoot\bin\solr.in.cmd" "$solrRoot\bin\solr.in.cmd.old"
        $newCfg = $cfg | % { $_ -replace "REM set SOLR_SSL_KEY_STORE=etc/solr-ssl.keystore.jks", "set SOLR_SSL_KEY_STORE=$certStore" }
        $newCfg = $newCfg | % { $_ -replace "REM set SOLR_SSL_KEY_STORE_PASSWORD=secret", "set SOLR_SSL_KEY_STORE_PASSWORD=secret" }
        $newCfg = $newCfg | % { $_ -replace "REM set SOLR_SSL_TRUST_STORE=etc/solr-ssl.keystore.jks", "set SOLR_SSL_TRUST_STORE=$certStore" }
        $newCfg = $newCfg | % { $_ -replace "REM set SOLR_SSL_TRUST_STORE_PASSWORD=secret", "set SOLR_SSL_TRUST_STORE_PASSWORD=secret" }
        $newCfg = $newCfg | % { $_ -replace "REM set SOLR_HOST=192.168.1.1", "set SOLR_HOST=$solrHost" }
        $newCfg | Set-Content "$solrRoot\bin\solr.in.cmd"
    }
}

# install the service & runs
$svc = Get-Service "$solrSvcName" -ErrorAction SilentlyContinue
if(!($svc))
{
    Write-Host "Installing Solr service"
    &"$installFolder\nssm-$nssmVersion\win64\nssm.exe" install "$solrSvcName" "$solrRoot\bin\solr.cmd" "-f" "-p $solrPort"
    $svc = Get-Service "$solrSvcName" -ErrorAction SilentlyContinue
}
if($svc.Status -ne "Running")
{
    Write-Host "Starting Solr service"
    Start-Service "$solrSvcName"
}

# finally prove it's all working
$protocol = "http"
if($solrSSL -eq $true)
{
    $protocol = "https"
}

Invoke-Expression "start $($protocol)://$($solrHost):$solrPort/solr/#/"