Terraform Lightweight Install Script

Install-Terraform.ps1

echo "Starting Terraform Install"
function Install-Terraform {
    [CmdletBinding()]
    param (
        [String]$tfVersion = '0.12',
        $InstallPath = '.',
        $os = 'windows',
        $arch = 'amd64'
    )

    if ($ENV:TF_VERSION) {$tfVersion = $ENV:TF_VERSION}
    $tfAvailableVersions = (Invoke-Restmethod -UseBasicParsing 'https://releases.hashicorp.com/terraform/index.json').versions    

    #If a minor release was provided (e.g. 12.0), find the latest bugfix version available
    if ($tfVersion -match '^\d+\.\d+$') {
        $tfSearchVersion = [version]$tfVersion
        #Exclude Prereleases
        $tfAvailableVersionNums = [version[]]($tfAvailableVersions.psobject.properties.name | Where-Object {$PSItem -match '^\d+\.\d+\.\d+$'})
        [string]$tfVersion = $tfAvailableVersionNums | where minor -eq $tfSearchVersion.Minor | Sort-Object -descending | Select-Object -first 1
    }

    $tfSelectedVersion = $tfAvailableVersions.$tfVersion
    if (-not $TFSelectedVersion) {write-error "TF Version $TFVersion was not found on the terraform server"; return}
    $tfDownloadUri = $tfSelectedVersion.builds | where os -eq $os | where arch -eq $arch | Select-Object -first 1 | % url
    ("Selected Version: " + $tfSelectedVersion.version)
    "Downloading $tfDownloadUri"
    $DownloadPath= [io.path]::GetTempFileName()
    #TODO: Hash Verification
    if ($PSEdition -eq 'Desktop') {
        #Fixes performance problem with Invoke-WebRequest
        $ProgressPreference = 'Continue'
    }
    
    iwr -useb $tfDownloadUri -OutFile $DownloadPath
    $ResolvedInstallPath = resolve-path $InstallPath
    "Extracting terraform to $ResolvedInstallPath"
    $tfZipPath = Join-Path (Split-Path $DownloadPath -Parent) 'terraform.zip'
    Move-Item $DownloadPath $tfZipPath
    Expand-Archive -Path $tfZipPath -DestinationPath $InstallPath -Force
    if (($ResolvedInstallPath) -notin $env:PATH.split([IO.Path]::PathSeparator)) {write-warning "$ResolvedInstallPath was not found in your PATH environment variable. Call terraform directly with $(join-path $ResolvedInstallPath 'terraform')"}
}

#Run the last function in this file unless this script is dotsourced, using any arguments provided
if ($myinvocation.Line -notmatch '^\. ') {
    $command = 'beginblock','processblock','endblock' | foreach {
        $myInvocation.mycommand.scriptblock.ast.$PSItem.statements
    } | Where-Object {$PSItem -is [Management.Automation.Language.FunctionDefinitionAst]} | % name | Select-Object -last 1
    $myargs = $myinvocation.UnboundArguments
    [ScriptBlock]$invokeScriptBlock = [Scriptblock]::Create("$command $myargs")
    invoke-command $invokeScriptBlock
}