One of the more relevant and cost saving tasks when working in Azure Cloud is fast and efficient shutdown and startup of virtual machines. Some of the options available could be to :

a) Iterate through a csv list of VMs or Resource Group  of VMs and serially shutdown or startup the VMs. This can be accomplished using a Foreach loop. A Downside of this option is that it’s slow and could take a while depending on the number of VMs. In my lab test, the shutdown and startup 60 VMs took almost 3 hours at 3 minutes per VM for each action.

b) A better option would be to execute the shutdown/startup scripts on the VMs in parallel. Using the Foreach -Parallel in a Powershell workflow took less time, but almost 2 hours to shutdown and startup 60 VMs. Too much time. This function can only be deployed as a Runbook set to run on a schedule. While this met the requirement for automation, we also wanted a solution that could be run easily from a laptop as a function or module.

c) Of course there’s also the option of using the Web based portal to shutdown and startup 60 VMs or more. Well this is simply not a viable and scalable option.

While researching the most efficient and fastest way to accomplish this task,  I came upon the Invoke-Parallel function by Cookie.Monster. I developed the Set-AzureRMVmPowerState PowerShell function to utilize Invoke-Parallel as a module in the shutdown and startup of all 60 VMs in about 30 minutes. 

The Invoke-Parallel works by creating multiple runspaces to execute my Set-AzureRmVMPowerState function and  concurrently shutdown or startup all the Virtual Machines in the shortest possible time. My Set-AzureRmVMPowerState function accepts four parameters : State (Start/Stop), SubscriptionName, ResourceGroupName parameter set  or a FilePath for the csv file list of VMs.  An email notification is sent to the subscription admin with a list of Azure VMs processed and their current power state.
The function is also available at my github repository.

<#
.SYNOPSIS
The Set-AzureRMVmPowerState Function stops/starts multiple VMs concurrently.
.DESCRIPTION
This Azure Automation function uses the awesome Invoke-Parallel Powershell Function from Cookie.Monster to automate simultaneous VMs shutdown/start.
https://github.com/RamblingCookieMonster/Invoke-Parallel
The Invoke-Parallel function is imported as a module. The VM(s) array is passed to the Invoke-Parallel module which then execute my function in a script block.
Multiple runspaces/threads are created based on the number of VMs to be set to Start or Stop. Based on my tests, using the Invoke-Parallel function is faster than using Foreach -Parallel in a workflow.
The function can be deployed as Runbook and triggered by a set schedule or a webhook. It can take a Resource Group name or csv file of Virtual Machines as parameters.
An email notification is sent to the Subscription Admin after execution.
.PARAMETER SubscriptionName
Subscription to be processed.
.PARAMETER Path
The path parameter takes the path to a csv files that contains the list of VMs and ResourceGroupNames to be shutdown. It cannot be used with the ResourceGroupName parameter.
.PARAMETER ResourceGroupName
ResourceGroupName of the VMs to be shutdown. It cannot be used with the Path parameter.
.PARAMETER State
Power State that determines if VM(s) are to be shutdown or started. Valid values are Stop and Start.
.EXAMPLE
Set-VMPowerState -FilePath "C:\MeterRates\VSProtestvms.csv" -State Stop -SubscriptionName "Trial"

Runs against a csv file specified with the FilePath parameter
.EXAMPLE
Set-VMPowerState -ResourceGroupName RGXavier -State Stop -SubscriptionName "Trial"

Runs against a ResourceGroupName specified with the ResourceGroupName parameter
.FUNCTIONALITY
PowerShell Language
#>

[CmdletBinding()]

param(
[parameter(Mandatory = $false)]
[string]$SubscriptionName = "Trial",
[parameter(Mandatory = $false)]
[string]$FilePath,
[parameter(Mandatory = $false)]
[string]$ResourceGroupName = "RGXavier",
[parameter(Mandatory = $false)]
[ValidateSet("Start", "Stop")]
[ValidateNotNullOrEmpty()]
[string]$State = "Stop"

)

Write-Host "Started at" (Get-Date)
$WarningPreference = "SilentlyContinue"

#region Azure Logon
try {
# Get the connection "AzureRunAsConnection "
$connectionName = "AzureRunAsConnection"
$servicePrincipalConnection = Get-AutomationConnection -Name $connectionName

"Logging in to Azure..."
Add-AzureRmAccount `
-ServicePrincipal `
-TenantId $servicePrincipalConnection.TenantId `
-ApplicationId $servicePrincipalConnection.ApplicationId `
-CertificateThumbprint $servicePrincipalConnection.CertificateThumbprint
}
catch {
if (!$servicePrincipalConnection) {
$ErrorMessage = "Connection $connectionName not found."
throw $ErrorMessage
}
else {
Write-Error -Message $_.Exception
throw $_.Exception
}
}
Select-AzureRmSubscription -SubscriptionName $SubscriptionName

#endregion

#region create email creds
$Smtpserver = "smtp.sendgrid.net"
$From = "john.doe@democonsults.com"
$To = "jack.reacher@democonsults.com"
$VaultName = "vaultdemo"
$SecretName = "SendgridPassword"
$Port = "587"
$sendgridusername = "azure_eb0fc2179dd8f386d4f4e1f60dc2aff1@azure.com"
$sendgridPassword = (Get-AzureKeyVaultSecret -VaultName $VaultName -Name $SecretName).SecretValueText
$emailpassword = ConvertTo-SecureString -String $sendgridPassword -AsPlainText -Force
$emailcred = New-Object System.Management.Automation.PSCredential($sendgridusername, $emailpassword)
#endregion

#region
$currentWeekDay = (Get-Date).ToUniversalTime().ToString("dddd")
if ($FilePath) {
if ($State -eq "Stop") {
$vms = Import-Csv -Path $FilePath | Get-AzureRmVM -Status | ? {$_.Statuses[1].DisplayStatus -eq "vm running"}
Write-Host "Shutting down VM(s) today .." $currentWeekDay

$results = $vms | Invoke-Parallel -NoCloseOnTimeout -ScriptBlock {
$stopStatus = Stop-AzureRmVM -Name $_.Name -ResourceGroupName $_.ResourceGroupName -Force -Verbose
if ($stopStatus.Status -eq "Succeeded") {
$vmstatus = Get-AzureRmVM -Status -ResourceGroupName $_.ResourceGroupName -Name $_.Name -WarningAction SilentlyContinue
$vmstatus
}
}
}
else {
$vms = Import-Csv -Path $FilePath | Get-AzureRmVM -Status | ? {$_.Statuses[1].DisplayStatus -ne "vm running"}
Write-Host "Starting up VM(s) today .." $currentWeekDay
$results = $vms | Invoke-Parallel -NoCloseOnTimeout -ScriptBlock {
$startStatus = Start-AzureRmVM -Name $_.Name -ResourceGroupName $_.ResourceGroupName -Verbose
if ($startStatus.Status -eq "Succeeded") {
$vmstatus = Get-AzureRmVM -Status -ResourceGroupName $_.ResourceGroupName -Name $_.Name -WarningAction SilentlyContinue
$vmstatus
}
}
}
}
elseif ($resourceGroupName) {
if ($State -eq "Stop") {
$vms = Get-AzureRmVM -Status -ResourceGroupName $ResourceGroupName | ? {$_.PowerState -eq "vm running"}
Write-Host "Shutting down VM(s) today .." $currentWeekDay
$results = $vms | Invoke-Parallel -NoCloseOnTimeout -ScriptBlock {
$stopStatus = Stop-AzureRmVM -Name $_.Name -ResourceGroupName $_.ResourceGroupName -Force -Verbose
if ($stopStatus.Status -eq "Succeeded") {
$vmstatus = $_.ToPSVirtualMachine() | Get-AzureRmVM -Status
$vmstatus
}
}
}
else {
$vms = Get-AzureRmVM -Status -ResourceGroupName $ResourceGroupName | ? {$_.PowerState -ne "vm running"}
Write-Host "Starting up VM(s) today .." $currentWeekDay

$results = $vms | Invoke-Parallel -NoCloseOnTimeout -ScriptBlock {
$startStatus = Start-AzureRmVM -Name $_.Name -ResourceGroupName $_.ResourceGroupName -Verbose
if ($startStatus.Status -eq "Succeeded") {
$vmstatus = $_.ToPSVirtualMachine() | Get-AzureRmVM -Status
$vmstatus
}
}
}
}
else {
"Please enter a value for FilePath or ResourceGroupName"
}

$results | ft @{"Label" = "Status"; e = {$_.Statuses[1].DisplayStatus}}, Name, ResourceGroupName

#endregion

#region process email

$a = "<style>"
$a = $a + "BODY{background-color:white;}"
$a = $a + "TABLE{border-width: 1px;border-style: solid;border-color: black;border-collapse: collapse;}"
$a = $a + "TH{border-width: 1px;padding: 10px;border-style: solid;border-color: black;}"
$a = $a + "TD{border-width: 1px;padding: 10px;border-style: solid;border-color: black;}"
$a = $a + "</style>"
$body = ""
$body += "<BR>"
$body += "These" + " " + ($results.count) + " " + "Azure VM(s) were just shutdown successfully. Thank you."
$body += "<BR>"
$body += $results | Select-Object -Property @{"Label" = "Status"; e = {$_.Statuses[1].DisplayStatus}}, Name, ResourceGroupName | ConvertTo-Html -Head $a
$body = $body |Out-String
$subject = "These Azure VMs have been successfully shutdown."
if ($results -ne $null) {
Send-MailMessage -Body $body `
-BodyAsHtml `
-SmtpServer $smtpserver `
-From $from `
-Subject $subject `
-To $to `
-Port $port `
-Credential $emailcred `
-UseSsl
}
#endregion
Write-Host "Completed at " (Get-Date)
#Get-Variable | Remove-Variable -ErrorAction SilentlyContinue