How to Get-AzPublicIpAddress based on ResourceId? - azure

Question

Deployment script needs to enumerate existing public IP addresses from public IP prefix. Public IP Prefix object contains an array of resource identifies of individual public IP address.
I'd like to retrieve individual public ip addresses using provided resource identifier. Something like this:
Get-AzPublicIpAddress -ResourceId $resourceId;
Unfortunately, such signature doesn't exist. Get-AzPublicIpAddress expects ip address name as input parameter.
I understand that I can do:
Call Get-AzResource and get needed information from returned object [it means extra network call]
Parse needed information out of resource identifier [would like to avoid implementing this logic in PowerShell]
Question - are these the only options? Or maybe Az provides a built-in way of parsing resource identifiers?

Answer 1

You can use Get-AzResource -resourceId xxx -ExpandProperties | fl * for such requests. its a generic cmdlet that will work for any resource.
How is calling Get-AzResource an extra network call, compared to Get-AzPublicIpAddress? Its 1 call vs 1 call.
No, Az doesnt provide any parsing capabilities, they are not needed. You have tools to use resource id as well as individual names.
getting resource name out of resource id is fairly easy:
$resourceId -split '/' | Select-Object -Last 1

Answer 2

I don't think you can pass the -ResourceId directly to the command, all the built-in parameters are here : https://learn.microsoft.com/en-us/powershell/module/az.network/get-azpublicipaddress?view=azps-1.4.0. The most close way I can find is your option 2.
Not sure why you want to use Get-AzPublicIpAddress via ResourceId, even if we use -Name and -ResourceGroupName i.e. Get-AzPublicIpAddress -Name <publicIpName> -ResourceGroupName <ResourceGroupName>, it essentially also passes them into the request url of the rest api which the command called.
GET https://management.azure.com/subscriptions/xxxxxxxxx/resourceGroups/joywebapp/providers/Microsoft.Network/publicIPAddresses/joyVM-ip?api-version=2018-10-01
Actually, you could find /subscriptions/xxxxxxxxx/resourceGroups/joywebapp/providers/Microsoft.Network/publicIPAddresses/joyVM-ip is the ResourceId.
So I think it should be not too difficult for Microsoft to add the -ResourceId as a bulit-in parameter of the Get-AzPublicIpAddress command, if you want to improve it, you could give the feedback here.
Update:
Microsoft has replied to the this issue, see : https://github.com/Azure/azure-powershell/issues/8704#issuecomment-470604852
thanks for opening this feature request -- to provide more insight as to why the issues you mentioned above were closed: all new cmdlets that we ship in Az must conform to the pattern of having parameter sets that allow the user to do the following:
Provide the components of a resource (e.g., resource group name, resource name, etc.)
Provide the resource id of a resource
Provide the object representation of the resource (some cmdlets won't use this, like Get-*)
Later this year, we will begin generating our cmdlets using AutoRest (see this blog post for more details), and the above patterns will be enforced in the generator. Our goal then is to generate cmdlets for existing Azure services and replace our existing cmdlets with the generated ones.