Setup python, pyenv-win and poetry on Windows

setup-pyenv-poetry-windows.ps1

[CmdletBinding()]
param (
    [Parameter(Mandatory=$true)]
    [string] $PythonVersion
)

$ErrorActionPreference = "Stop"
$ProgressPreference = "SilentlyContinue"
Set-StrictMode -Version Latest


function _runCommand {
    [CmdletBinding()]
    param (
        [Parameter(Mandatory=$true, Position=0)]
        [string] $Command,
        [switch] $PassThru
    )

    if ($PassThru) {
        $res = Invoke-Expression $Command
    }
    else {
        Invoke-Expression $Command
    }

    if ($LASTEXITCODE -ne 0) {
        $msg = "'$Command' reported a non-zero status code [$LASTEXITCODE] - check previous output{0}"
        if ($PassThru) {
            Write-Error ($msg -f "`n$res")
        }
        else {
            Write-Error ($msg -f ".")
        }
    }

    if ($PassThru) {
        return $res
    }
}
function _addToUserPath {
    [CmdletBinding()]
    param (
        [Parameter(Mandatory=$true, Position=0)]
        [string] $AppName,
        [Parameter(Mandatory=$true, Position=1)]
        [string[]] $PathsToAdd
    )

    $currentPathEntries = $env:PATH -split ";" | Select-Object -Unique | Where-Object { ![string]::IsNullOrEmpty($_) }

    $missingPathEntries = @()
    foreach ($pathToAdd in $PathsToAdd) {
        Write-Verbose "Checking PATH entry for $pathToAdd"
        if ($pathToAdd -notin $currentPathEntries) {
            Write-Verbose "Not found, will add to PATH"
            $missingPathEntries += $pathToAdd
        }
    }
    if ($missingPathEntries.Count -gt 0) {
        Write-Host "$($AppName): Updating %PATH%..." -f Green
        # Update the user-scoped PATH environment variable
        $currentUserPaths = [System.Environment]::GetEnvironmentVariable("PATH", [System.EnvironmentVariableTarget]::User) -split ";" | Select-Object -Unique | Where-Object { ![string]::IsNullOrEmpty($_) }
        $updatedUserPath = $missingPathEntries + $currentUserPaths
        [System.Environment]::SetEnvironmentVariable("PATH", ($updatedUserPath -join ";").TrimEnd(";"), [System.EnvironmentVariableTarget]::User)
        
        # Update PATH in the current session, so we don't need to restart the console
        $env:PATH = ($missingPathEntries + $currentPathEntries) -join ";"
    }
    else {
        Write-Host "$($AppName): PATH already setup." -f Cyan
    }
}

Write-Host "#################################################" -f White
Write-Host "## Python, pyenv & poetry Windows setup script ##" -f White
Write-Host "#################################################" -f White

# Install pyenv
if (!(Test-Path $HOME/.pyenv)) {
    # Explicitly check whether running Windows PowerShell, as '$IsWindows' is only available for PowerShell Core
    if ($PSVersionTable.PSEdition -eq 'Desktop' -or $IsWindows) {
        Write-Host "pyenv: Installing for Windows..." -f Green
        if (!(Get-Command git -ErrorAction Ignore)) {
            Write-Error "Git is required to install pyenv. Please install git and re-run this script."
        }
        & git clone https://github.com/pyenv-win/pyenv-win.git $HOME/.pyenv
        if ($LASTEXITCODE -ne 0) {
            Write-Error "git reported a non-zero status code [$LASTEXITCODE] - check previous output."
        }
    }
    else {
        Write-Error "This script currently only supports Windows."
    }
}
else {
    Write-Host "pyenv: Already installed." -f Cyan
}

# Add pyenv to PATH
_addToUserPath "pyenv" @(
    "$HOME\.pyenv\pyenv-win\bin"
    "$HOME\.pyenv\pyenv-win\shims"
)

# Install default pyenv python version
$pyenvVersions = _runCommand "pyenv versions" -PassThru | Select-String $PythonVersion
if (!($pyenvVersions)) {
    Write-Host "pyenv: Installing python version $PythonVersion..." -f Green
    _runCommand "pyenv install $PythonVersion"
}
else {
    Write-Host "pyenv: Python version $PythonVersion already installed." -f Cyan
}

# Set pyenv global version
$globalPythonVersion = _runCommand "pyenv global" -PassThru
if ($globalPythonVersion -ne $PythonVersion) {
    Write-Host "pyenv: Setting global python version: $PythonVersion" -f Green
    _runCommand "pyenv global $PythonVersion"
}
else {
    Write-Host "pyenv: Global python version already set: $globalPythonVersion" -f Cyan
}

if (!(Get-Command poetry -ErrorAction Ignore)) {
    $downloadPath = "$HOME/Downloads/install-poetry.py"
    Write-Host "python-poetry: Installing..." -f Green
    Invoke-WebRequest -Uri "https://install.python-poetry.org" `
                      -UseBasicParsing `
                      -OutFile $downloadPath
    try {
        _runCommand "pyenv exec python `"$downloadPath`""
    }
    finally {
        Remove-Item $downloadPath
    }
}
else {
    Write-Host "python-poetry: Already installed." -f Cyan
}

# Add poetry to PATH
_addToUserPath "python-poetry" @("$HOME\AppData\Roaming\Python\Scripts")

# Test poetry is available
_runCommand "poetry --version"

Write-Host "####################" -f Green
Write-Host "## Setup Complete ##" -f Green
Write-Host "####################" -f Green

I just manually set my path within the same command prompt.

I tried editing the environment variables through the UI and adding the paths to pyenv-win/bin and pyenv-win/shims (lines 99-100) but that still didn't work.

If it isn't much trouble, could you share the command that you ran in the command prompt to set your path?
What location did you add to PATH? @the4amfriend

I just manually set my path within the same command prompt.

I tried editing the environment variables through the UI and adding the paths to pyenv-win/bin and pyenv-win/shims (lines 99-100) but that still didn't work.

If it isn't much trouble, could you share the command that you ran in the command prompt to set your path? What location did you add to PATH? @the4amfriend

I have the same problem and am quite new to windows. Could use a pointer her too :)

Hi, I have the same problem with cscript not being found. The script overwrites previously set PATH variables loaded from machine scope by just getting those of the current user.

I had the exact same problem. I checked my path variable in the shell I ran the script, and I could see that pyenv-win/bin and pyenv-win/shims prepended, but the rest was somehow messed up. Rather than fix the path in that shell, I opened a new shell and ran the script again. That appears to have worked, at least I saw no errors.
This is all new to me, so I cannot yet say everything is fully functional.

One way of fixing the cscript error (Win 10). To me opening in a new shell did not fix this one.

1. Get the current PATH variable content
   [System.Environment]::GetEnvironmentVariable("PATH", [System.EnvironmentVariableTarget]::User)

2. Reset the PATH with added path to cscript C:\windows\system32\ <- must have the backward slash at the end
   (modify according to your environment paths from the previous command)
   [System.Environment]::SetEnvironmentVariable("PATH","C:\Users\NNN.pyenv\pyenv-win\shims;C:\Users\xxx.pyenv\pyenv-win\bin;C:\Users\NNN\AppData\Roaming\pypoetry;C:\windows\system32\", [System.EnvironmentVariableTarget]::User)

3. Reload the Path environment variable to the PS
   $env:PATH = [System.Environment]::GetEnvironmentVariable("PATH", [System.EnvironmentVariableTarget]::User)

4. Run the setup again
   .\setup-pyenv-poetry-windows.ps1

Thanks for your comments @tab1tha, @the4amfriend, @gtheys, @toolsche, @fsuchy, @armbck

I finally got around to revisiting this and have fixed (hopefully!) the PATH handling - the change should ensure that your existing PATH entries are left intact, regardless of their scope.