DSC Unpredictable Imported Modules

Question

There seems to be something buggy with DSC and PowerShell Modules.

Resources that use the RemoteDesktop module randomly fail with the following error logged in DSC Operational event log

If I run the same configuration ten times on ten different machines it will fail about half the time. If I rerun it after it fails...it might fail again or it might succeed (meaning it won't run again)

The term 'Get-RDRemoteApp' is not recognized as the name of a cmdlet, function, script file, or operable program. Check the spelling of the name, or if a path was included, verify that the path is correct and try again.

Sometimes instead of Get-RDRemoteApp, it logs Get-RDServer...even though I don't call Get-RDServer anywhere in my script. It seems like there is something messed up with how DSC uses PowerShell sessions to invoke resources. If I change the class below to actually launch the required commands by starting a new powershell.exe process, it always works...

[DSCResource()]
class zRemoteApp {
    $ErrorActionPreference = "Stop"

    [DscProperty(Key)]
    [string]$Name = "MyApp"

    [DscProperty()]
    [string]$Path

    [bool]$RemoteAppExists

    [zRemoteApp]Get() {
        Import-Module RemoteDesktop

        $this.RemoteAppExists = [boolean](Get-RDRemoteApp -Alias $this.Name)

        Return $this
    }

    [void]Set() {
        Import-Module RemoteDesktop
        $this.Get()

        Get-RDSessionCollection |% {
            New-RDRemoteApp -CollectionName $_.CollectionName -Alias $this.Name -DisplayName $this.Name -FilePath $Path
        }
    }

    [bool]Test() {    
        $this.Get()
        Return $this.RemoteAppExists
    }
}

Edit - If I use a ScriptBlock it consistently works:

    $job = Start-Job -ScriptBlock {
        param($Name)
        Import-Module RemoteDesktop
        [boolean](Get-RDRemoteApp -Alias $Name)
    } -ArgumentList $this.Name

    $this.RemoteAppExists = $job | Wait-Job | Receive-Job

    Remove-Job $job

    Return $this

I cannot seem to reproduce the problem, but I moved the import-module into a constructor ([example](https://gist.github.com/TravisEz13/9e1a6307c334b0fef615048c933fb254)) to reduce the output. What OS are you using? — TravisEz13, May 05 '16 at 05:28
Server 2012 R2 - If I change to use Start-Job with a ScriptBlock it consistently works. — Jeff, May 05 '16 at 13:21
Can you call "Get-SessionCollection" instead of "Get-RDSessionCollection" , "New-RemoteApp" instead of "New-RDRemoteApp" and "Get-RemoteApp" instead of "Get-RDRemoteApp" and try? — N.Gupta, May 05 '16 at 17:23

DSC Unpredictable Imported Modules

0 Answers0