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Bring on the Scripts!

  • Artigo

Okay! Now that initial documentation of the Hyper-V WMI API is available I thought I would respond with a "Week of Hyper-V Scripts".

Starting with a simple one - here is a script that will list the name, identifier and state for each virtual machine on the physical computer:

VBScript:

 Option Explicit

  

 Dim WMIService

 Dim VMList

 Dim VM

  

 'Get instance of 'virtualization' WMI service on the local computer

 Set WMIService = GetObject("winmgmts:\\.\root\virtualization")

  

 'Get all the MSVM_ComputerSystem object

 Set VMList = WMIService.ExecQuery("SELECT * FROM Msvm_ComputerSystem")

     

 For Each VM In VMList

    if VM.Caption = "Microsoft Virtual Computer System" then

        WScript.Echo "========================================"

        WScript.Echo "VM Name: " & VM.ElementName

        WScript.Echo "VM GUID: " & VM.Name

        WScript.Echo "VM State: " & VM.EnabledState

     end if

 Next

PowerShell:

 # Get all VM objects on the local computer

 $VMs = gwmi -class "MSVM_ComputerSystem" -namespace "root\virtualization" -computername "."

  

 foreach ($VM in $VMs){

    if ($VM.Caption -match "Microsoft Virtual Computer System"){

       write-host "=================================="

       write-host "VM Name:  " $VM.ElementName

       write-host "VM GUID:  " $VM.Name

       write-host "VM State: " $VM.EnabledState

    }

 }

Now to pull these scripts apart a bit:

  • The flow of these scripts is:

    • Get WMI Service object for virtualization namespace
    • Execute WMI query to get all VM objects
    • Iterate over the VM objects

  • For each virtual machine object we display the "ElementName" - which is the friendly name that you give the virtual machine ("Windows Server Foo") - the "Name" - which is a GUID that is used to internally uniquely identify the virtual machine and the "EnabledState" (you can find what the different EnabledState values mean here: https://msdn2.microsoft.com/en-us/library/cc136822(VS.85).aspx).

  • "gwmi" is PowerShell shorthand for "Get-WMIObject"

  • Amusingly enough this script would also return information about the parent partition (which is technically a virtual machine) which is why I check the caption of the virtual machine and only display information about entries that are actually virtual machines.

Cheers,

Ben

Comments

  • Anonymous
    January 28, 2008
    > Amusingly enough this script would also return information about the parent partition (which is technically a virtual machine). This is a very questionable design decision - even if all partitions run under the same hypervisor, for the user the host ("parent partition") is a very different thing from a guest ("child partition").

  • Anonymous
    January 28, 2008
    > Amusingly enough this script would also return information about the parent partition (which is technically a virtual machine). This is a very questionable design decision - even if all partitions run under the same hypervisor, for the user the host ("parent partition") is a very different thing from a guest ("child partition"). Well, at least with WMI you don't have to do the funny security stuff to write a simple Powershell script.

  • Anonymous
    January 29, 2008
    Why you write PowerShell the VBS way?! :( gwmi MSVM_ComputerSystem -namespace "rootvirtualization" -computername "." | where {$_.Caption -eq "Microsoft Virtual Computer System"} | Format-List ElementName, Name, EnabledState

  • Anonymous
    January 29, 2008
    Thanks - this is great stuff. What do you need to run these scripts from a desktop? I'd like to be able to query multiple Hyper-V machines from my desktop.

  • Anonymous
    January 29, 2008
    Ben, How would I do this WMI via C#? Which Interop DLL would I need to use to get the Hyper-V WMI? Thanks

  • Anonymous
    January 30, 2008
    Jonathan - The fact that we report the parent is actually to maintain compatibility with the DMTF management standard. Xaegr - Sorry, I just find it easier to read this way. Jason - You can run this from a remote system without needing to install any thing.  Just change the '.' to the computer name. Nehru - You do not need an interop DLL, I will post on this later. Cheers, Ben

  • Anonymous
    January 30, 2008
    Nehru, You can do this is managed code like this: //Connection credentials to the remote computer - not needed if the logged in account has access            ConnectionOptions conn = new ConnectionOptions();            ManagementScope ms = new ManagementScope(@".rootvirtualization", conn);            //get the computers            ObjectQuery query = new ObjectQuery("SELECT * FROM Msvm_ComputerSystem");            //Execute the query              ManagementObjectSearcher searcher = new ManagementObjectSearcher(ms, query);            //Get the results            ManagementObjectCollection computers = searcher.Get();            //loop through found computers            listBox1.Items.Clear();            foreach (ManagementObject computer in computers)            {                Console.WriteLine(computer["ElementName"].ToString());            }

  • Anonymous
    February 04, 2008
    Ben, we have some custom code written to control VMs on Virtual Server 2005. Is there a back words compatibility layer? Or does all this code need to be re-written for WMI? thanks!