retrieve the Hostname from an Azure VM

Question

For monitor reasons I need to retrieve the hostname of each virtual machine.

I used the nice resource "Resource graph" in Azure Dashboard with following query.

project VMnaam = name,
location,
resourceGroup,
subscriptionId,
vmsize = properties.hardwareProfile.vmSize,
VMtype = properties.storageProfile.imageReference.offer,
diskSizeInGB = properties.storageProfile.osDisk.diskSizeGB,
OStype = properties.storageProfile.osDisk.osType,
adminUsername = properties.osProfile.adminUsername,
hostname = properties.osProfile.computerName,
type
 | where type == "microsoft.compute/virtualmachines"

which gives me a nice overview of every virtual machine. But something got my attention in the results. the hostname (properties.osProfile.computerName) is the same name as the VMname. Inside the VM I have checked this and controlled that this is indeed correct so I wanted to check what happens if I change the hostname in my VM.

In my linux VM I changed the hostname rebooted the machine and the new hostname is available in the terminal.

Through Azure Resourc Graph however The change is not visible; If I manually retrieve the computername with powershell with following powershell code:

Login-AzAccount -Subscription "mysub"
$vm = get-azvm -ResourceGroupName "myrg"  -Name "myvm"

$vm.OSProfile.ComputerName

I also see the first value of my hostname that was initially setup by Azure but not the new hostname that I changed.

Is it not possible to retrieve a changed hostname from Azure? Does it take a while? Is there any other way to retrieve the hostname from Azure?

Answer 1

no, it is not possible, azure is not aware of the actual hostname in the vm.

Also the fact that vmname and hostname match is just a coincidence (or rather a default from Azure). If you provision a vm through API you have the ability to set hostname when provisioning and it doesn't have to match vm name (although, it usually makes sense if it does).

edit: according to woter324 recent update seem to have fixed this and now Azure is aware of the actual vm hostname (confirmed for windows)

Answer 2

(az vm list | ConvertFrom-Json).osProfile.computerName