Download-TerraformLatest.ps1

[CmdletBinding()]
param (
    [string]$DirectoryPath,
    [switch]$KeepDownload
)
    
process {

    if ($DirectoryPath) {
        Write-Verbose "User requested download location $DirectoryPath"
        if (!(Test-Path -Path $DirectoryPath)) {
            Write-Verbose "User requested download location $DirectoryPath does not exist"
            New-Item -ItemType Directory -Path $DirectoryPath -Force | Out-Null
            Write-Verbose "User requested download location $DirectoryPath created"
        }
    }
    else {
        Write-Verbose "Using script location, $PSScriptRoot, as download and install directory"
        $DirectoryPath = $PSScriptRoot
    }

    $DirectoryPath = Resolve-Path -Path $DirectoryPath
    $TerraformFullPath = Join-Path -Path $DirectoryPath -ChildPath "terraform.exe"

    $downloadPageResponse = Invoke-WebRequest -UseBasicParsing -Uri "https://www.terraform.io/downloads.html"
    [System.Uri]$downloadLink = $downloadPageResponse.Links | `
        Where-Object { $_.href -like "*windows*" -and $_.href -like "*64*" } | `
        Select-Object -ExpandProperty href
        
    $fileName = $downloadLink.Segments | Select-Object -Last 1
    Write-Host "Downloading file $filename"
    $fullArchivePath = (Join-Path -Path $DirectoryPath -ChildPath $fileName)
    Invoke-WebRequest -UseBasicParsing -Uri $downloadLink -OutFile $fullArchivePath
    if (Test-Path -Path $TerraformFullPath) {
        Write-Host "Removing existing terraform.exe"
        Remove-Item -Path $TerraformFullPath -ErrorAction Ignore
    }
    Write-Verbose "Unblocking file $fullArchivePath"
    Unblock-File $fullArchivePath
    Write-Host "Expanding archive $fullArchivePath to directory $DirectoryPath"
    Expand-Archive -Path $fullArchivePath -DestinationPath $DirectoryPath

    if (!$KeepDownload) {
        Write-Verbose "Removing download archive $fullArchivePath"
        Remove-Item -Force -Path $fullArchivePath
    }

    Write-Host "Testing Teraform (showing version information)"
    & $TerraformFullPath --version

}