Install a custom version of Python within the Jenkins current WORKSPACE.

deploy_jenkins_slave_python.ps1

# Usage: powershell ".\deploy_jenkins_slave_python.ps1"

# Stop the execution on the first error
$ErrorActionPreference = "Stop"

# Ensure we have a working WORKSPACE and a defined Python version
if (-Not ($Env:PYTHON_VERSION)) {
	echo "PYTHON_VERSION not defined. Aborting."
	exit 1
} elseif (-Not ($Env:WORKSPACE)) {
	echo "WORKSPACE not defined. Aborting."
	exit 1
}

function download($url, $output) {
	# Download one file and save its content to a given file name
	echo ">>> Downloading $url"
	echo "             to $output"
	$curl = New-Object System.Net.WebClient
	$curl.DownloadFile($url, $output)
}

function install_python {
	$output = "$($Env:WORKSPACE)\python-$($Env:PYTHON_VERSION).msi"
  $python_dir = "$($Env:WORKSPACE)\python-$($Env:PYTHON_VERSION)"
	$url = "https://www.python.org/ftp/python/$($Env:PYTHON_VERSION)/python-$($Env:PYTHON_VERSION).msi"
	
	echo "    PYTHON_VERSION = $Env:PYTHON_VERSION"
	echo "    WORKSPACE      = $Env:WORKSPACE"
  echo "    PYTHON_DIR     = $PYTHON_DIR"

	if (-Not (Test-Path $python_dir)) {
		download $url $output
		echo ">>> Installing Python"
		# As the installation write some keys into regedit, we need to uninstall Python before installing a new one.
		# If we do not do that, the next installation will be incomplete.
		# BTW this issue will no occur with Python 3.
		Start-Process msiexec -ArgumentList "/x `"$output`" /passive" -wait
		Start-Process msiexec -ArgumentList "/i `"$output`" /passive ADDLOCAL=`"pip_feature`" TARGETDIR=`"$python_dir`"" -wait
	}
}

install_python