Author Posts

November 20, 2014 at 10:59 am

Okay so suppose I have a Composite resource that I create using Steves "new-dsccompositeresource" function. (this is what shows up in the WebServersDefaultWinAuth.schema.psm1 file)

configuration WebServersDefaultWinAuth {
                 WindowsFeature IIS {
                    Ensure = 'Present'
                    Name = 'Web Server'
                }
                WindowsFeature aspnet45 {
                    Ensure = 'Present'
                    Name = 'Web-Asp-Net45'
                }
                WindowsFeature WebWindowsAuth {
                    Name = 'Web-Windows-Auth'
                    Ensure = 'Present'
    }
  
}

In my master config, when I go to reference it, I know I can reference this composite resource like so:

Configuration WebServer {
    Node $AllNodes.Where{$_.NodeRole -eq "WebServer"}.NodeGUID {
        WebServersDefaultWinAuth aspnet45 {}
    }
}

Question: In the above if I interpret it right, I'm only taking the aspnet45 feature out of WebServersDefaultWinAuth. What would the formatting look like if I want more of them? What would the formatting look like if I wanted to use all features in WebServersDefaultWinAuth?

Thanks again, as always! 🙂

November 20, 2014 at 11:07 am

You're always using the entire composite configuration. In this line:

WebServersDefaultWinAuth aspnet45 {}

The word "aspnet45" is just the name you're assigning to that composite resource. It could just as easily have been WebServersDefaultWinAuth GeorgeOfTheJungle {}

November 20, 2014 at 11:09 am

Oh okay I wasn't interpreting it correctly then! What if I wanted to pick and choose one of the things out of the composite resource then? I imagine said things would go in the braces at the end?

November 20, 2014 at 11:15 am

Another question / clarification. Steve's "new-dsccompositeresource" command has you editing RESOURCE.schema.psm1 files with you custom configs. In another powershell.org thread: https://powershell.org/forums/topic/how-are-people-managing-their-configuration/#post-20397

David Jones seems to be referencing psd1 files? It's just confusing me a little. Or is it really just the mass size of his configuration that's just a little beyond me (for now!)

November 20, 2014 at 11:26 am

That other thread is talking about configuration data, not composite resources. (At least, the portions of it that refer to psd1 files.)

As for your other question, you would have to add parameters to your composite resource, and then pass in values for those parameters in the configuration that's using it. For example:

# Composite resource

configuration MyCompositeResource
{
    param (
        [bool] $IIS = $true,
        [bool] $XPSViewer = $true
    )

    if ($IIS)
    {
        WindowsFeature MyCompositeResource_IIS
        {
            Name = 'Web-Server'
            Ensure = 'Present'
        }
    }
    
    if ($IIS)
    {
        WindowsFeature MyCompositeResource_XPSViewer
        {
            Name = 'XPS-Viewer'
            Ensure = 'Present'
        }
    }
}


#####

configuration MyConfig
{
    Import-DscResource -ModuleName MyCompositeResourceModuleName

    node localhost
    {
        MyCompositeResource George
        {
            IIS = $true
            XPSViewer = $false
        }
    }
}

Personally, I think that's a little convoluted, and would not place resources into a composite resource if they were conditional like that.

November 20, 2014 at 11:30 am

Cool, very awesome. And while I'm at it (on a roll here lol). I imagine that if I wanted to reference multiple composite resources it'd look like this (as long as said resources don't conflict):

Configuration CombinedWebServer {
    Node $AllNodes.Where{$_.NodeRole -eq "WebServer"}.NodeGUID {
        WebServersDefaultWinAuth aspnet45 {}
        SomeOtherModuleIWant    SomeFeatureINameAndConfigured {}
    }
}

November 20, 2014 at 11:31 am

Yep. You can have any number of resources inside a Node block (and those resources can be composite resources if you want; no limitations.) The only thing you have to be careful of is that there are no duplicated resource names or key properties in the entire configuration, including inside any composite resources. If that happens, you'll get errors when you try to compile the MOF.

November 20, 2014 at 11:35 am

For "big laughs" I went to a server we already have and basically used get-windowsfeature -isinstalled $true (paraphrasing this) to get me a list of all the windows features installed on that thing. I then plugged ALL of those features into a single composite resource. Thing is, (admittedly out of lazyness and lack of time) I haven't specified the "depends upon" for each feature. I kind of just assume it'll go through the list, install what it can, error out and then pick up where it left off on next attempt. I was just about to test this, but maybe you can save me the time XD :)?

Edit: clarifying it, I'll use this to apply to a new test server I put out.

November 20, 2014 at 11:40 am

I'm not sure what you're asking. If your windows features have dependencies, then you will probably need to make sure you've called those out properly in the DSC configuration.

November 20, 2014 at 11:51 am

Does dsc stop everything on error or continue I guess is the better question? If I fail to specify a dependancy for a windows feature, does it move on and try to install the next thing in the list? presuming that I have all dependancies in the list of things to install (eventually) but I'm just not telling DSC what those dependancies are, what'll happen?

November 20, 2014 at 2:13 pm

Any error causes it to stop processing.