My First PowerShell : A Simple Story with Dramatic Flair

Recently, I needed an automated way to restart remote servers in my test environment for SentryOne. I knew that this sounded like a PowerShell-ish thing, but I lack what most people call experience when it comes to PowerShell. Maybe that's what everyone calls it?

First Attempt

First, I came across Restart-Computer -ComputerName $ComputerName -Credential $Credential -Force which seemed to be exactly what I needed.

Next, I opened PowerShell and gave it a try:

PowerShell Restart-Computer with Login Popup Window

As shown above, this prompted for credentials to complete the task. Technically, this was what I wanted. However, I wanted to place Restart-Computer in a loop, therefore the popup asking for credentials wouldn't suffice.

Avoiding Popup for Credentials

I discovered that I could use a secure string for the credentials, however, none of the initial examples I found explained how to create the secure string. Way to make me feel even more like a foolish newbie. ;-) A little more searching and I was on my way.

Creating a Secure String

Read-Host "Enter Stuff" -AsSecureString | ConvertFrom-SecureString | Out-File "C:\PowerShell\mysecurestring.txt"

PowerShell Create a Secure String

Voilà! A secure string is created from a string that totally isn't my password. Seriously, I'm not *that* trusting.

PowerShell the Secure String

Using a Secure String

Now that I've created a secure string, I can use it in a credentials object to avoid the popup:

$username = "mconnors"
$password = cat C:\PowerShell\mysecurestring.txt | convertto-securestring
$cred = new-object -typename System.Management.Automation.PSCredential -argumentlist $username, $password
$strComputer = "OA-SQL-100"
Restart-Computer -ComputerName $strComputer -Authentication default -Credential $cred

Clearly this is something that looks more loop-friendly:

PowerShell Using the Secure String

Now it was loop-ready and I wrapped it in a simple for-loop.

The PowerShell Loop

$username = "mconnors"
$password = cat C:\PowerShell\mysecurestring.txt | convertto-securestring
$cred = new-object -typename System.Management.Automation.PSCredential -argumentlist $username, $password
$strComputer = "OA-SQL-"
For ($intInc = 1; $intInc -le 100; $intInc++) {
$serverNameOrIp = $strComputer + $intInc
Write-Host $serverNameOrIp
Restart-Computer -ComputerName $serverNameOrIp -Authentication default -Credential $cred
}

One of the first problems I saw was the computer name was OA-SQL-1 instead of OA-SQL-001. I had a formatting issue to resolve. Padding the zeros into the formatting was easy enough:

$serverNameOrIp = $strComputer + "{0:000}" -f $intInc

Windows PowerShell ISE

Another problem was that pasting the loop into the PowerShell command window and hitting enter didn't look right. It wouldn't run, either. There were '>' for all new lines and it appeared to simply hang when I would execute it. A coworker asked where I was running it and suggested that I use the Windows PowerShell ISE window instead of the more old-school PowerShell command window. I tried that and my loop executed without requiring any changes. Of course, I'd nearly lost my mind at that point...

Output

Once it was working, I made some tweaks to output the computer name and timestamp so I could see the progress. I added a sleep timer so the host machine wouldn't flounder while restarting 100 VMs. I ran into some issues with the SQL Server service timing out on restart across a few random machines. Better to wait a little longer to know they're all safe than discover that during test execution.

As seen above, I was using Write-Host in my script, until I was advised against it. It turns out that Write-Host is kind of bad.

The following script is what I'm excuting now for various ranges of servers. It gets the job done. Could it be improved? Probably. I still have much to learn about PowerShell.

$username = "mconnors"
$password = cat C:\PowerShell\mysecurestring.txt | convertto-securestring
$cred = new-object -typename System.Management.Automation.PSCredential -argumentlist $username, $password
$strComputer = "OA-SQL-"
For ($intInc = 1; $intInc -le 10; $intInc++) {
$serverNameOrIp = $strComputer + "{0:000}" -f $intInc
$CurrentDate = Get-Date
$CurrentDate = $CurrentDate.ToString('hh:mm:ss')
$restartString = '{0} {1}' -f ($serverNameOrIp,$CurrentDate)
Write-Output $restartString
Restart-Computer -ComputerName $serverNameOrIp -Authentication default -Credential $cred
Start-Sleep 30
}

Windows PowerShell ISE showing Restart-Computer Loop

What I believed would be a quick foray into a line or two of PowerShell turned into a larger learning experience.

Things I Know Now

• First, to use Windows PowerShell ISE instead of just PowerShell.
• Second, how to store and access a secure string for credentials.
• Formatting output, such as the padded 0s and desired date/time.
• Speaking of output, why I should use Write-Output instead of Write-Host (thanks, Allen! (b|t)
• Finally, PowerShell might *actually* be cool. I've been hearing that for years, but now I've experienced it!

So I have this small amount of PowerShell knowledge now. It's created intrigue for me. I'm sure it can make my life easier and that I can integrate it into Visual Studio Load and Performance Testing to automate a few more steps for me. I'll be sure to share anything interesting in the future. In addition, I recently met Warren Estes at SQL Saturday Boston and heard wonderful things about his presentation, Get-Session "Powershell 101", so now is the perfect time to ask him to speak at Maine PASS!