Basics of Hyper-V and Desired State Configuration

I am not sure how many posts I am going to write about desired state configuration.  But lets begin with some basics with Hyper-V.  Two posts from this, I will mention the DSC module that I have built for VMHost.

If you have been following – Desired State Configuration is a new feature that comes from the PowerShell team.  It is a core feature that does what folks have been doing using agents for years.

You can do a number of nifty things from installation to configuration, putting files in a specific place, and more.

I really did not get excited about it until I wrote a Resource Provider, for my favorite Server Role – Hyper-V.

Now, you may know about the MSFT provided community modules for Hyper-V, Networking, WebAdministration, and Computer management.  These add to the in-box capabilities of managing Role and Features, files, and a number of other things.  If you have been paying attention you will also know that there is a PowerShell.org community DSC provider repository where folks are already adding to the MSFT ones.

I started looking at the Hyper-V modules and thought.. interesting.  And then I immediately thought, but I want to modify the default configuration of the Hyper-v Server and it isn’t there.

So, I built the first version of a VMHost module.

But before we go there lets start with the basics.

Here is the scenario; you have Windows Server 2012 R2 (Full or Core) and you want to add the Hyper-V Role.

Open a PowerShell prompt locally on the server and apply the following:

configuration Sample_cVMHost
{
    WindowsFeature hypervRole
    {
        Ensure = ‘Present’
        Name = 'Hyper-V'
    }
}

Sample_cVMHost

Start-DscConfiguration -Wait -Verbose -Path .\Sample_cVMHost

And watch.

What looks like a function named “Sample_VMHost” is a configuration .  Executing the command that calls this configuration generates a MOF format output file in current path.  And Start-DscConfiguration applies that configuration.

The –Wait and –Verbose let you watch the output of the Resource Providers under this all that are turning that configuration into reality.

After you reboot, you have the Hyper-V Role installed.  But only the Hyper-V Role.  That is not enough, lets add the Hyper-V PowerShell Module too.

So, open PowerShell again and apply this new configuration:

configuration Sample_cVMHost
{ 

    WindowsFeature hypervRole
    {
        Ensure = 'Present'
        Name = 'Hyper-V'
    }
    WindowsFeature hypervManagement
    {
        Ensure = 'Present'
        Name = 'Hyper-V-PowerShell'
        DependsOn = '[WindowsFeature]hypervRole'

    }

}

Sample_cVMHost

Start-DscConfiguration -Wait -Verbose -Path .\Sample_cVMHost

Apply this and you will notice that it tests for the Hyper-V Role first, then adds the PowerShell provider.

That is what the DependsOn does.  This feature, depends on that that other feature being enabled first.  Otherwise, they all get applied at the same time.  And notice how these are enforced as single things.

I just want to keep it simple for now.  Enabling Roles and Features.