Start-AzureVMsByTier.ps1

param (
	[String] $ResourceGroupName = ''
)

# Returns strings with status messages
[OutputType([String])]

# Connect to Azure and select the subscription to work against
$servicePrincipalConnection = Get-AutomationConnection -Name AzureRunAsConnection

Add-AzureRmAccount `
    -ServicePrincipal `
    -TenantId $servicePrincipalConnection.TenantId `
    -ApplicationId $servicePrincipalConnection.ApplicationId `
    -CertificateThumbprint $servicePrincipalConnection.CertificateThumbprint | Out-Null

if($err)
{
    throw $err
}

# If there is a specific resource group, then get all VMs in the resource group,
# otherwise get all VMs in the subscription.
$vms = Get-AzureRmVM -ResourceGroupName $ResourceGroupName

$groupedVMs = $vms | `
    Group-Object -Property { $_.Tags.tier } | `
	Sort-Object -Property Name


for($tier = 0; $tier -lt $groupedVMs.Length; $tier++)
{
	$vmGroup = $groupedVMs[$tier]
    $anyStarted = $false
    foreach($vmInfo in $vmGroup.Group)
    {
        $vm = Get-AzureRmVM `
		        -Status `
		        -ResourceGroupName $vmInfo.ResourceGroupName `
		        -Name $vmInfo.Name
        
        if(($vm.Statuses | `
		        Select-Object -ExpandProperty Code | `
		        ? { $_.StartsWith("PowerState") }).Substring(11) -ne 'running')
	    {
            Write-Output "Starting $($vm.Name)"
            Start-AzureRmVM -ResourceGroupName $vmInfo.ResourceGroupName -Name $vmInfo.Name
            $anyStarted = $true
        }
    }
	
	# If !$anystarted there is no need to pause as the machines were already running
	# If $group -gt $groupedVMs.Length then this is the last group, no need to pause
    if($anyStarted -and ($tier -lt $groupedVMs.Length))
    {
		$secondsToWait = [int]::Parse($vmGroup.Group[0].Tags.tierStartupTimeoutSeconds)
        Write-Output 'Tier $tier started. Waiting $secondsToWait seconds.'
        Start-Sleep -Seconds $secondsToWait
    }
}