Powershell command. If something exists then change to something else

Question

I have a powershell script that I use in Azure so that I can update multiple NSG's at the same time. Something I run into on occasion is the priority in my script is already being used on the NSG. I am wondering if there is a way to do this so that if the priority is already being used then change it to something else.

Basically it would be if -Priority 200 is already configured then use -Priority 210

Thanks

Here's an example of my script

$RGname="RG-Name"
$port= "*"
$rulename="Rule-Name"
$nsgname="NSGName-nsg"

# Get the NSG resource
$nsg = Get-AzNetworkSecurityGroup -Name $nsgname -ResourceGroupName $RGname

# Add the inbound security rule.
$nsg | Add-AzNetworkSecurityRuleConfig -Name $rulename -Description "Rule-Description" -Access Deny `
    -Protocol * -Direction Outbound -Priority 200 -SourceAddressPrefix * -SourcePortRange * `
    -DestinationAddressPrefix "1.2.3.4" -DestinationPortRange $port

# Update the NSG.
$nsg | Set-AzNetworkSecurityGroup

Answer 1

Hi Jeff

Thanks for asking you questions!

You can achieve by fetching the priorities first and check-in if the priority exists.

$resourceGroup = "yourResourceGroup"
$nsgName = "yourNsgName"
$newRuleName = "newRuleName"
$newPriority = 200

$nsg = Get-AzNetworkSecurityGroup -ResourceGroupName $resourceGroup -Name $nsgName

# Get the priorities of existing rules
$priorities = $nsg.SecurityRules | ForEach-Object { $_.Priority }

# Check if the priority is already used
if ($priorities -contains $newPriority) {
    Write-Host "Priority $newPriority is already in use. Finding the next available priority."
    # Find the next available priority
    $newPriority = $newPriority + 10
    while ($priorities -contains $newPriority) {
        $newPriority = $newPriority + 10
    }
    Write-Host "New priority set to $newPriority."
}