powershell

Requirements

• Assuming you have minimum of Powershell 5.1. If you don’t, you should be on that at the minimum. Just install chocolatey, and then run choco upgrade powershell powershell-core -y --source chocolatey and you should have both 5.1 and core ready to go if your Windows version supports it. If you are on Windows 7 as a developer, there is no 🌮 for you, just get upgraded already.
• Anything manipulating system might need admin, so run as admin in prompt.
• Install-Module PSFramework // I use this module for better logging and overall improvements in my quality of life. It’s high quality, used by big projects like DbaTools and developed by a Powershell MVP with lots of testing. Forget regular Write-Verbose commands and just use the Write-PSFMessage -Level Verbose -Message 'TacoBear' instead.

PSFramework

I use PSFramework on all my instances, as it’s fantastic expansion to some core areas with PowerShell. This great module (along with other ancillary supporting ones like PSModuleDevelopment are well tested and usable for solving some issues in a much more elegant and robust manner than what is natively offered.

A few key elements it can help with are:

• Improving Configuration and variable handling without complex scope issues
• Improving overall logging and troubleshooting
• Improving object manipulation
• Runspace usability enhancements
• Scripted properties

Development (Optional)

1. Install VSCode (Users)
2. choco upgrade vscode-powershell -y or install in extension panel in VSCode. If you are using ISE primarily…. move on already.

String Formatting

Math & Number Conversions

Date & Time Conversion

Converting dates to Unix Epoc time can be challenging without using the correct .NET classes. There is some built in functionality for converting dates such as (Get-Date).ToUniversalTime() -UFormat '%s' but this can have problems with time zone offsets. A more consistent approach would be to leverage the following. This was very helpful to me in working with Grafana and InfluxDb which commonly leverage Unix Epoc time format with seconds or milliseconds precision.

$CurrentTime = [DateTimeOffset]::new([datetime]::now,[DateTimeOffset]::Now.Offset);

# Unix Epoc time starts from this date
$UnixStartTime = [DateTimeOffset]::new(1970, 1, 1, 0, 0, 0,[DateTimeOffset]::Now.Offset);

# To Use This Now On Timestamp you could run the following
$UnixTimeInMilliseconds = [Math]::Floor( ((get-date $CurrentTime) - $UnixStartTime).TotalMilliseconds)

# To Use with Different Time just change the `$CurrentTime` to another value like so
$UnixTimeInMilliseconds = [Math]::Floor( ((get-date $MyDateValue) - $UnixStartTime).TotalMilliseconds)

Credential Management

Setup for BetterCredentials

First, don’t store anything as plain text in your files. That’s a no no. Secondly, try using BetterCredentials. This allows you to use Windows Credential Manager to store your credentials and then easily pull them back in for usage later in other scripts you run. I’ve found it a great way to manage my local credentials to simplify my script running.

Install-Module BetterCredentials -Force -AllowClobber

Creating a Credential

Then to create credentials try using this handy little filter/function

<#
.Description
	Quick helper function for passing in credentials to create. Why filter? Planned on using with pipeline. Right now just using arguments in examples below.
#>
filter CredentialCreator
{
    [cmdletbinding()]
    param(
     [string]$UserName
    ,[string]$Pass
    ,[string]$Target
    )
    [string]$CalcTarget = ($Target,$UserName -ne '')[0]
    $SetCredentialSplat = @{
        Credential = [pscredential]::new($UserName,($Pass | ConvertTo-SecureString -AsPlainText -Force))
        Target = $CalcTarget
        Description = "BetterCredentials cached credential for $CalcTarget"
        Persistence = 'LocalComputer'
        Type = 'Generic'
    }
    BetterCredentials\Set-Credential @SetCredentialSplat
    Write-PSFMessage -Level Important -Message "BetterCredentials cached credential for $CalcTarget"

}

Example on using this quick function (if you don’t want to use my quick helper, then just use code in the function as an example).

#----------------------------------------------------------------------------#
#                   Example On Using to Create Credentials                   #
#----------------------------------------------------------------------------#
$pass = Read-Host 'Enter Network Pass'
CredentialCreator -UserName "$ENV:USERDOMAIN\$ENV:UserName" -Pass $pass -Target "$ENV:USERDOMAIN\$ENV:UserName"
CredentialCreator -UserName "TacoBear" -Pass 'TacoBearEatsThings' -Target "azure-tacobear-api"

Clearing all credentials in credential repo

Find-Credential * | Remove-Credential

Using Credentials in a Script

Using with credential object

Do-Something -Credential (Find-Credential 'azure-tacobear-api')

Extracting out the raw name and password for things that won’t take the credential object, but want the password as a string (uggh)

$cred = Find-Credential 'azure-tacobear-api'
$UserName = $cred.GetNetworkCredential().UserName   #Note that this could be an access key if you wanted.
$AccessKey = $cred.GetNetworkCredential().Password

Using Basic Authorization With REST

When leveraging some api methods you need to encode the header with basic authentication to allow authenticated requests. This is how you can do that in a script without having to embed the credentials directly, leveraging BetterCredentials as well.

#seems to work for both version 5.1 and 6.1
param(
    $Uri = ''
)

Import-Module BetterCredentials
$cred = Find-Credential 'mycredentialname'
$AccessId = $cred.GetNetworkCredential().UserName
$AccessKey = $cred.GetNetworkCredential().Password
$Headers = @{
    Authorization = 'Basic ' + [Convert]::ToBase64String([Text.Encoding]::ASCII.GetBytes( ('{0}:{1}' -f $AccessId, $AccessKey) ))
}
$results = Invoke-RestMethod -Uri $Uri -Header $Headers
$results

Load Functions from a Folder

Prefer to use modules, but for quick adhoc work, you can organize your work in a folder and use a subfolder called functions. I find this better than trying to create one large script file with multiple functions in it.

$FunctionsFolder = Join-Path $toolsDir 'functions'
Get-ChildItem -Path $FunctionsFolder -Filter *.ps1 | ForEach-Object {
    Write-PSFMessage -Level Verbose -Message "Loading: $($_.FullName)"
    . "$($_.FullName)"
}

Select Object Manipulation

Expanding Nested Objects

One thing that I’ve had challenges with is expanding nested objects with AWSPowershell, as a lot of the types aren’t formatted for easy usage without expansion. For example, when expanding the basic results of Get-EC2Instance you can try to parse out the state, but it won’t behave as expected.

For example, if you run:

(Get-EC2Instance -Filter $ec2Filter).Instances | Select-Object InstanceId, State

Trying to expand gets you the state, but now you don’t have the original object alongside it.

PSFramework makes this easy to work with by simply referencing the object properties for parsing in the Select-PSFObject statement.

(Get-EC2Instance -Filter $ec2Filter).Instances | Select-PSFObject InstanceId, 'State.Code as StateCode', 'State.Name as StateName'

The result is exactly you’d you need to work with

Get / Set Accessors in PowerShell

In C# you use get/set accessors to have more control over your properties. In PowerShell, thanks to PSFramework, you can simplify object pipelines by using Select-PSFObject to do the equivalent and have a scripted property that handles a script block to provide a scripted property on your object.

For example, in leveraging AWS Profiles, I wanted to get a region name mapped to a specific profile as a default region. You can do this in a couple steps using ForEach-Object and leverage [pscustomobject], or you can simplify it greatly by running Select-PSFObject like this:

Get-AWSCredentials -ListProfileDetail  |  Select-PSFObject -Property ProfileName -ScriptProperty @{
    region = @{
        get = {
            switch ($this.ProfileName)
            {
                'taco1' {'us-east-1'}
                'taco2' {'us-east-1'}
                'taco3' {'us-east-1'}
                'taco4' {'eu-west-1'}
                'taco5' {'us-west-2'}
                'taco6' {'us-east-1'}
                default {'us-east-1'}
            }
        }
    }
}

Another good example might be the desire to parse out the final key section from S3, to determine what the file name would actually be for easier filtering or searching. In this case, a simple script property could parse out the name, and then return the last item in the array using Powershell’s shortcut of $array[-1] to get the last item.

Get-S3Object -BucketName 'tacoland' | Select-PSFObject -ScriptProperty @{
    BaseName = @{
        get  = {
            (($this.Name  -split '/')[-1])
        }
    }
}