PowerShell DSC Journey – Day 23

No intro. Going right back into trying to add a Network Adapter and a VMNetwork to that adapter. I look first at the hardware profile, and lo and behold I have 9 legacy network adapters, which is interesting because yesterday I had none. So, I remove them all first.

Ok, first things first, let’s make sure I can get the network I want, which I can do using this command:

The next thing I can do is try to create a new network adapter on the Hardware Profile, which I can do using this command.

However, this creates a Legacy network adapter. After reading the help file I determine that I need the -Synthetic parameter in order to make it a non-legacy network adapter.

So, that’s all working now. Next step is to see if I can actually set the Virtual Network on the adapter itself, which is where I failed so hard yesterday. This works.

So, let’s try this next. And it works. I swear I did this a billion times but I am not even to go back and look because it might make me angry or depressed. Or both.

So, let’s run my Configuration and see what happens again. And it works. Of course it does.

I then add most of the same code to the section of Set-TargetResource for when a Hardware Profile doesn’t exist. Now let me delete my profile and try it. And of course I get some errors because I am using the $ResourceHWProfile variable in this section of code instead of just $Name. So, I change it to this.

And that works as well. One interesting thing to note. There is a lot of Write-Verbose commands I have that aren’t being written after this section of code. And I have no idea why either.

Well, that’s working now so I am happy. Now that I have a functioning Resource that does what I wanted it to do, this will be the last post in the series 🙂

PowerShell DSC Journey – Day 22

Alright, after my little fiasco yesterday I need to do a little re-configuring of my Configuration because of course DSC will not allow a Plain text password.

Here is the new version of the Configuration.

Now, let’s try to run this and see what breaks. And. Nothing breaks. I am literally speechless. Seriously.

Well. Here goes nothing. And I forgot to change something back in .psm1 file when I was messing around with it yesterday that caused this entire thing to blow up. I will spare you all the red text but here is the error.

With that fixed I try to run it, and I don’t get any errors, but clearly I have something to fix with my Test-TargetResource function because it just skipped running Set-TargetResource.

So, let’s see if we can figure out what’s going on. I am pretty sure this section is the problem.

I set the $result to $false, then tested for the $VMMServer, and returned $True, so DSC was like “oh hey, everything is gravy.” Fail on my part. Let’s fix this. I already know if the Credential or VMMServer is invalid that it will fail, so I just need to check to make sure $ResourceVMMServer exists and then do the rest of my checks. I am pretty sure this is going to fail for a couple of reasons, but I am going to test this anyways in the interest of full disclosure :).

I run several of my tests that I expect to return both $True and $False. I made a few changes and added one line, so here is the new and improved section of my code.

So, let’s try this again! HOLY BUCKETS IT WORKED! Minus, one small issue.


Now, the one issue there is that no VMNetwork was set. Probably because there is no network adapter, which I am guessing I forgot to include in my Set-TargetResource. Let’s take a look.

Yeah, that’s not going to work. I need to create the adapter first. Turns out it’s easier than I thought it would be. Just kidding, I can’t use the parameter for $VMNetwork, it needs to be a different type.

Which opens a whole new can of worms because I need to check to make sure that is a valid VM Network somewhere. For the purposes of this, I am going to assume that if it should be present, it is a valid name. Actually I lied. We aren’t going to do that, because that opens up a giant mess when it comes to creating a new Virtual Network.

After banging away on this for about the last 30 minutes I am going to stop here for the day and pick it up again tomorrow. I am currently stuck on getting the right object type from Get-SCVMNetwork to pass to……..oh hell…wait a minute. Just kidding! Kidding again. I have a moment of genius! And this is also where I hate Virtual Machine Manager anymore. Only thing good to say is that I learned a hell of a lot more than I ever wanted to know about VMM cmdlets this afternoon.

So, let me delete the Hardware Profile and run my Configuration again. The network adapter didn’t get created. My brain is exhausted. I’m done for today. For real this time.

Tecumseh Poem from Act of Valor

So live your life that the fear of death can never enter your heart.
Trouble no one about their religion; respect others in their view, and
demand that they respect yours. Love your life, perfect your life,
beautify all things in your life. Seek to make your life long and its purpose in the service of your people.
Prepare a noble death song for the day when you go over the great divide.

Always give a word or a sign of salute when meeting or passing a
friend, even a stranger, when in a lonely place. Show respect to all
people and grovel to none.

When you arise in the morning give thanks for the food and for the joy
of living. If you see no reason for giving thanks, the fault lies only
in yourself. Abuse no one and no thing, for abuse turns the wise ones
to fools and robs the spirit of its vision.

When it comes your time to die, be not like those whose hearts are
filled with the fear of death, so that when their time comes they weep
and pray for a little more time to live their lives over again in a different way.
Sing your death song and die like a hero going home.

Chief Tecumseh (Poem from Act of Valor)

PowerShell DSC Journey – Day 21

Alright, when I left off I had added in some testing for the $Credential Property of the Resource in the Get-TargetResource and Test-TargetResource functions. Today I am going to do the same with Set-TargetResource, and then test my Configuration to see what I did wrong. If I survive that I will try to create a Hardware Profile with my Resource.

First things first, I add this same section to Set-TargetResource.

I think that is all I need to do here because Get-SCHardwareProfile and Set-SCHardwareProfile don’t require a credential.

I run my first test, and everything works great except the test removed the DVD Drive. Which it wasn’t supposed to do. And there is all some verbage for the CPU Count that is incorrect, and it looks like I need to add a case for when CPUCount is not specified.

Ok, let’s tackle the DVD Drive issue first. I didn’t specify an option for it, it was already present, and the profile was set to Ensure = Present, so it should not have been removed. Here is the code block.

What is happening is I am not specifying a value for the DVDDrive Property. So as far as it is concerned, the last Else statement gets executed. I am going to need to add a case for not specifying the DVDDrive Property. I reconfigured this code to look like this instead.

And that works exactly like it should. Now I need to do the same thing for CPUCount. This also works just fine. And it’s also at this point that I realize that I already have the VMNetwork parameter setup that way. Apparently it never occurred to me I would need to do the same thing for the others. Oh well. Moving along! I run a few more test and make a few more minor changes and tweaks but I am not going to bore you with those details. I just needed to update the part of the function that creates a new Hardware Profile with the same If checks as above.

And now. Let’s see how badly I have failed here. Let’s test this bad boy.

Pretty good. So far. I don’t expect this to continue.

Well. That was unexpected. I guess on to the next thing. Let’s try my Configuration again. Here is my current Configuration.



Alright. So….I declared my credential variable to be of the type [pscredential]. Maybe it needs to be [MSFT_Credential]? Let’s try it. But wait, I have the bright idea that I should check to see how the ADDomain resource handles it, and I find my answer in the .psm1 file for the resource.

Looks like I need to update my Resource.

Hmmm. How else would you get the schema.mof to show that Type? Then I look at the schema.mof for my resource and get my answer.

So the type Credential, automatically changes to that in the schema. Good to know. Now I try my Resource using [MSFT_Credential]$Credential and that fails.

This has me stumped. Nothing of use in the DSC Event Logs. Comparing my .psm1 file to the ADDomain.psm1 file, I notice that all of their credentials are of the type [PSCredential] while mine is of the type [System.Management.Automation.PSCredential]. Which is weird (I think?). I try to change the parameter in my Configuration to the type [System.Management.Automation.PSCredential] but I get the same error. So I am going to change the .psm1 type to just [pscredential] and see what happens. I reloaded everything and change the type for Credential back to [PSCredential] and the same thing still happens.

I am stumped. Going to call it a day on that front.

Edit: Thanks to Jason Hofferle for helping figure out what I was doing wrong (and it was something dumb). I was so wrapped up in the thought that I did something wrong in my Resource that I didn’t bother to specify the Credential property in my actual Configuration.

PowerShell DSC Journey – Day 20

When I left off yesterday I was trying to actually run a Configuration to create a Hardware Profile, and quickly realized that I was going to need a Credential parameter in order to do this, because not just anyone can connect to a Virtual Machine Manager server. So today’s post is going to be about adding a Credential property to my Configuration.

I am going to be referencing the Active Directory resource for this because I know that uses a credential parameter to authenticate to Active Directory. First thing first, let’s create a new DSC Resource Property.

Then I will need to update my resource with this new Property.

And here is what my schema.mof file looks like:

And this is a snippet of the Get-TargetResource function show the additional property as well.

Now, that’s all well and good, but how do I go about testing this in Get-TargetResource? Let’s take a look at what the Active Directory resource does. It looks like it is using the Credential property when testing other properties, so I will do the same. I believe I only need to add this where other commands need to authenticate to the VMMServer, and I should probably test to make sure the credential is valid. Get-SCHardwareProfile doesn’t require a credential, only the VMMServer name, so I don’t think I need to do anything there. I did add this to the Get-TargetResource function.

And I suppose I should test this now to see what breaks. This test prompted me for the credential and completed successfully.

Just to be safe I tried the same test but added a -Credential (Get-Credential) command and everything worked fine.

Here is a test where I submitted a completely bogus credential that has no permissions to anything.

Here is what I added to my Test-TargetResource Function.

So let’s test this out. I am astounded this is actually working properly. With valid credential:

With non valid Credential:

I am running out of time today and feel like this is a great place to stop. I will move on to the Set-TargetResource function tomorrow!

PowerShell DSC Journey – Day 19

Alright, so in my last post I was able to resolve the issue with my Custom Resource not showing up under Get-DSCResource (because as usual I was doing something dumb).


Now, let’s try and write a Configuration! Look ma, no errors!

Let’s build this out for a test.

I run this Configuration and the .MOF gets created.

When I run this configuration I immediately encounter two errors.

The first issue crossed my mind literally as I was hitting enter to start the Configuration. That is, am I going to need a credential variable to pull this off because not just anyone can connect to a VMM Server. This error came from running PowerShell as Administrator. When I run PowerShell as my elevated account (which has access) this is what happens.

I am going to try this (although if it works this not a valid solution as far as I am concerned), and this shouldn’t work but I am going to try it anyways.

And it did exactly what I thought it should do (which is nice for a change).

So, I am going to need a $Credential parameter. That sounds like a good place to start tomorrow 🙂

PowerShell DSC Journey – Day 18

Yesterday I finished up modifying the Set-TargetResource function and doing all the tests and it seems to be working exactly the way that I want. The next step today is to turn this into a module, import it, write a DSC Configuration and see if it actually works.

I already have my SCVMM_Hardware.psm1 file, so I just need to add a module manifest file.

Looking at the other DSC Resources, none of them specify a root module, so I guess we will see if this breaks it or not. They also have multiple resources associated with each module, so that could be part of the reason as well.

This article on TechNet says to “Finally, use the New-ModuleManifest cmdlet to define a .psd1 file for your custom resource module. When you invoke this cmdlet, reference the script module (.psm1) file”, but the module manifest they show has the root module as ”, which doesn’t match up with what they are saying. I am just going to try it this way and see what happens. Because that’s what I do. Actually, I am going to change something up here to prepare for my other SCVMM Resource.

  • Rename the root folder to cSCVMM
  • Create a DSCResources folder underneath
  • Create a cSCVMM_Hardware folder, move my .psm1 and schema.mof files into this folder
  • Create the module manifest and place it in the root cSCVMM folder

Round 2.

So far so good! (No errors anyways). I am going to restart ISE and see if it loads the module or what happens. This is where I had so much trouble in my previous post. And I ran into the same issue. If I say Get-Module -Name cSCVMM nothing happens. If I do Get-Module -ListAvailable it shows up in the list. So first thing, I am going to get rid of the root module path and see what happens.

Same thing. Move it out of the DSCResources folder, same thing.

Looking at the other resources, they have a CLR version and a description, so let’s just try that (although I am sure that has nothing to do with it).

Long story short, turns out (once again) that I just don’t know what I am doing. Once you import it by name, you can then get the information on it. Duh.

So, now that I wasted a bunch of time on that, let’s see if I can remember how to build a Configuration :).

First issue I run into is, when I do Import-DSCResource -Module cSCVMM it acts like it has no idea what the hell that is. So, uh, what do I do about that?

So, yeah. My .psm1 file is exporting the commands, so that shouldn’t be a problem. I guess first thing first, let’s run Get-DSCResource and see what happens.

I get that error, but then all of the DSCResources are listed (except for mine).

Further investigation reveals this.

Alright, so that’s fun. I am going to backup here and try something referencing the steps in this article.

I create a “new” DSCResource using my properties. And guess what? Even then it doesn’t show up as a DSC Resource. So, that’s good right? I don’t think so. That article makes it seem like it should be pretty simple, so I don’t know what’s going on.

Next step, I am going to test this on WMF 4.0 (I am using WMF 5.0 Preview). And the same thing happens there. So that’s good I guess. I really have no idea what is going on here. Completely. Puzzled.

Time to stop for the day. Hopefully I think of something before tomorrow as of what to try next.

Edit: I was able to resolve this issue with the help of Don Jones on the PowerShell.org forums.

When I first created the Resource what I did was this:

What I should have done was this:
New-xDscResource -Name cSCVMM_Hardware -Property $DVDDrive, $VMNetwork, $CPUCount, $Ensure, $Name, $VMMServer -FriendlyName “SCVMM_Hardware” -ClassVersion 1.0 -Path ‘C:\Program Files\WindowsPowerShell\Modules\cSCVMM’

Since I didn’t specify the Module name it just created the DSC Resources folder and that messed up everything. Lesson learned!