Tag: powershell

Base64 PowerShell Cmdlet Via Advanced Functions

Robert LohrLeave a comment

Among the many valuable command line utilities on a Linux system is base64, which encodes to and decodes from the Base64 encoding scheme. As much as I like PowerShell…

(Yes, you read that correctly)

…it sorely lacks a base64-equivalent utility, or cmdlet as they are called in PowerShell land. The only solution was to create one myself. Cmdlets are usually written in C#, but you can also employ the concept of advanced functions, which is what I have done.

Here’s the code for converting strings to Base64. The function supports receiving data from a pipeline, or you can call it directly and pass the value as a parameter. More on the usage later.

Function ConvertFrom-Base64
{
    [CmdletBinding()]
    param (
        [Parameter(ValueFromPipeline = $true)]
        [string] $Base64
    )
    
    Process 
    {
        if ($null -ne $Base64) 
        {
            $Bytes = [Convert]::FromBase64String($Base64)
            Write-Output [System.Text.Encoding]::UTF8.GetString($Bytes)
        }
        else 
        {
            Write-Error "No base64-encoded data provided."
        }
    }
}
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How To Execute PowerShell And Bash Scripts In Terraform

Robert LohrLeave a comment

The first thing to know is what Terraform expects of the scripts it executes. It does not work with regular command line parameters and return codes. Instead, it passes a JSON structure via the script’s standard input (stdin) and expects a JSON structure on the standard output (stdout) stream.

The Terraform documentation already contains a working example with explanations for Bash scripts.

#!/bin/bash
set -e

eval "$(jq -r '@sh "FOO=\(.foo) BAZ=\(.baz)"')"

FOOBAZ="$FOO $BAZ"
jq -n --arg foobaz "$FOOBAZ" '{"foobaz":$foobaz}'

I will replicate this functionality for PowerShell on Windows and combine it with the OS detection from my other blog post.

The trick is handling the input. There is a specific way, since Terraform calls your script through PowerShell, something like this echo '{"key": "value"}' | powershell.exe script.ps1.

$json = [Console]::In.ReadLine() | ConvertFrom-Json

$foobaz = @{foobaz = "$($json.foo) $($json.baz)"}
Write-Output $foobaz | ConvertTo-Json

You access the C# Console class’ In property representing the standard input and read a line to get the data Terraform passes through PowerShell to the script. From there, it is all just regular PowerShell. The caveat is that you can no longer call your script as usual. If you want to test it on the command line, you must type the cumbersome command I have shown earlier.

echo '{"json": "object"}' | powershell.exe script.ps1

Depending on how often you work with PowerShell scripts, you may bump into its execution policy restrictions when Terraform attempts to run the script.

│ Error: External Program Execution Failed
│
│   with data.external.script,
│   on main.tf line 8, in data "external" "script":
│    8:   program = [
│    9:     local.shell_name, "${path.module}/${local.script_name}"
│   10:   ]
│
│ The data source received an unexpected error while attempting to execute the program.
│
│ Program: C:\Windows\System32\WindowsPowerShell\v1.0\powershell.exe
│ Error Message: ./ps-script.ps1 : File
│ C:\Apps\Terraform-Run-PowerShell-And-Bash-Scripts\ps-script.ps1
│ cannot be loaded because running scripts is disabled on this system. For more information, see
│ about_Execution_Policies at https:/go.microsoft.com/fwlink/?LinkID=135170.
│ At line:1 char:1
│ + ./ps-script.ps1
│ + ~~~~~~~~~~~~~~~
│     + CategoryInfo          : SecurityError: (:) [], PSSecurityException
│     + FullyQualifiedErrorId : UnauthorizedAccess
│
│ State: exit status 1

You can solve this problem by adjusting the execution policy accordingly. The quick and dirty way is to allow all scripts as is the default on non-Windows PowerShell installations. Run the following as Administrator.

Set-ExecutionPolicy -ExecutionPolicy Unrestricted -Scope LocalMachine

This is good enough for testing and your own use. If you regularly execute scripts that are not your own, you should choose a narrower permission level or consider signing your scripts.

Another potential pitfall is the version of PowerShell in which you set the execution policy. I use PowerShell 7 by default but still encountered the error after applying the unrestricted policy. That is because the version executed by Terraform is 5. That is what Windows starts when you type powershell.exe in a terminal.

PowerShell 7.4.1
PS C:\Users\lober> Set-ExecutionPolicy -ExecutionPolicy Unrestricted -Scope LocalMachine
PS C:\Users\lober> Get-ExecutionPolicy
Unrestricted
PS C:\Users\lober> powershell
Windows PowerShell
Copyright (C) Microsoft Corporation. All rights reserved.

Install the latest PowerShell for new features and improvements! https://aka.ms/PSWindows

PS C:\Users\lober> Get-ExecutionPolicy
Restricted
PS C:\Users\lober> $PsVersionTable

Name                           Value
----                           -----
PSVersion                      5.1.22621.2506
PSEdition                      Desktop
PSCompatibleVersions           {1.0, 2.0, 3.0, 4.0...}
BuildVersion                   10.0.22621.2506
CLRVersion                     4.0.30319.42000
WSManStackVersion              3.0
PSRemotingProtocolVersion      2.3
SerializationVersion           1.1.0.1

Once you set the execution policy in the default PowerShell version, Terraform has no more issues.

A screenshot that shows the Windows Terminal output of the Terraform plan command.

And for completeness sake, here is the Linux output.

A screenshot that shows the Linux terminal output of the Terraform plan command.

You can find the source code on GitHub.

I hope this was useful.

Thank you for reading

How To Add Microsoft Store Games To Steam

Robert LohrLeave a comment

As a gamer, you likely prefer Steam as a game launcher over everything else, notably the Microsoft Store. Steam supports adding non-Steam games, but Microsoft makes it stupidly complicated to run their store content from anywhere else – at least if you do not like Windows shortcuts.

I wanted to add Gears of War 4 to Steam, a game only available in the Microsoft Store. Here is what I did and what should also work for other titles or applications.

First, there is no way around a shortcut. However, it is only temporary and serves as the starting point. If you are lucky, it is all you need. You can delete the shortcut after all is said and done.

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