Class-based PowerShell DSC Resources include hidden properties in dsc config results

[michaeltlombardi]

Prerequisites

• Write a descriptive title.
• Make sure you are able to repro it on the latest version
• Search the existing issues.

Steps to reproduce

1. Create the files for a new PowerShell module

   mkdir ./dsc-repro/psdsc.repro
   touch ./dsc-repro/psdsc.repro/psdsc.repro.psd1
   touch ./dsc-repro/psdsc.repro/psdsc.repro.psm1

2. Define the module manifest:

   @{
       RootModule           = 'psdsc.repro.psm1'
       ModuleVersion        = '0.0.1'
       GUID                 = '361fff1b-423a-423f-9e05-39f5ab94a437'
       Author               = 'Bug Reproducer'
       CompanyName          = 'Unknown'
       Copyright            = '(c) Bug Reproducer. All rights reserved.'
       FunctionsToExport    = '*'
       CmdletsToExport      = '*'
       VariablesToExport    = '*'
       AliasesToExport      = '*'
       DscResourcesToExport = @(
           'ReproResultData'
       )
       PrivateData          = @{ PSData = @{} }
   }

3. Define the root module script:

   [DscResource()] class ReproResultData {
               [DscProperty(Key)]             [string] $KeyProperty
               [DscProperty()]                [string] $NormalProperty
                                              [string] $NonDscProperty
       hidden                                 [string] $HiddenNonDscProperty
       hidden  [DscProperty()]                [string] $HiddenDscProperty
       static  [DscProperty(NotConfigurable)] [string] $StaticDscProperty = @(
           'This property could be in results data,'
           'but is an anti-pattern unless the property'
           'is read-only.'
       ) -join ' '
       static                                 [string] $StaticNonDscProperty = @(
           "This property shouldn't be in results data,"
           "because it's not a DSC property."
       ) -join ' '
   
       ReproResultData() {
           $this.NormalProperty = 'Should be in results data.'
           $this.NonDscProperty = @(
               "This property shouldn't be in results data,"
               "because it's not a DSC property."
           ) -join ' '
           $this.HiddenNonDscProperty = @(
               "This property shouldn't be in results data,"
               "because it's hidden and not a DSC property."
           ) -join ' '
           $this.HiddenDscProperty = @(
               'This property should be in results data,'
               'but is an anti-pattern.'
           ) -join ' '
       }
   
       [ReproResultData] Get() {
           $Current             = [ReproResultData]::new()
           $Current.KeyProperty = $this.KeyProperty
   
           return $Current
       }
   
       [bool] Test() { return $true }
       [void] Set()  { }
   }

4. Add the folder containing the repro module to the PSModulePath:

   $env:PSModulePath += [System.IO.Path]::PathSeparator + "$PWD/dsc-repro"

5. Confirm you can get the ReproResultData dsc resource and see its properties:

   $Resource = Get-DscResource -Module psdsc.repro

   ImplementationDetail : ClassBased
   ResourceType         : ReproResultData
   Name                 : ReproResultData
   FriendlyName         :
   Module               : psdsc.repro
   ModuleName           : psdsc.repro
   Version              : 0.0.1
   Path                 : C:\code\dsc-repro\psdsc.repro\psdsc.repro.psd1
   ParentPath           : C:\code\dsc-repro\psdsc.repro
   ImplementedAs        : PowerShell
   CompanyName          : Unknown
   Properties           : {KeyProperty, DependsOn, HiddenDscProperty, NormalProperty…}

   $Resource | Select-Object -ExpandProperty Properties | Format-Table

   Name                 PropertyType   IsMandatory Values
   ----                 ------------   ----------- ------
   KeyProperty          [string]              True {}
   DependsOn            [string[]]           False {}
   HiddenDscProperty    [string]             False {}
   NormalProperty       [string]             False {}
   PsDscRunAsCredential [PSCredential]       False {}
   

   dsc --format yaml resource list psdsc.repro/ReproResultData

   # Formatted for easier reading
   type          : psdsc.repro/ReproResultData
   version       : 0.0.1
   path          : C:\code\dsc-repro\psdsc.repro\psdsc.repro.psd1
   description   : null
   directory     : C:\code\dsc-repro\psdsc.repro
   implementedAs : ClassBased
   author        : ''
   properties    : [
                       KeyProperty,
                       DependsOn,
                       HiddenDscProperty,
                       NormalProperty,
                       PsDscRunAsCredential
                   ]
   requires      : DSC/PowerShellGroup
   manifest      : null

6. Invoke the resource with Invoke-DscResource

   $PSInvokeParams = @{
       Method   = 'Get'
       Module   = 'psdsc.repro'
       Name     = 'ReproResultData'
       Property = @{ KeyProperty = 'Repro Example (PSDSC)' }
   }
   $PSInvokeResult = Invoke-DscResource @PSInvokeParams
   $PSInvokeResult | Format-List

   KeyProperty    : Repro Example (PSDSC)
   NormalProperty : Should be in results data.
   NonDscProperty : This property shouldn't be in results data, because it's not a DSC property.

7. Invoke the resource with dsc resource:

   $V3InvokeResult = '{ "KeyProperty": "Repro Example (DSCv3)" }' |
       dsc resource get -r psdsc.repro/ReproResultData |
       ConvertFrom-Json |
       Select-Object -ExpandProperty actualState
   $V3InvokeResult | Format-List

   KeyProperty          : Repro Example (DSCv3)
   NormalProperty       : Should be in results data.
   NonDscProperty       : This property shouldn't be in results data, because it's not a DSC property.
   HiddenNonDscProperty : This property shouldn't be in results data, because it's hidden and not a DSC property.
   HiddenDscProperty    : This property should be in results data, but is an anti-pattern.

8. Compare the actual and preferred output statuses, with metadata:

   filter Test-HasAttribute($Property, $Attribute) {
       [bool]($Property.CustomAttributes.AttributeType -eq $Attribute)
   }
   filter Test-InPropertySet($Property, $InputObject) {
       $Set = if ($InputObject -is [Microsoft.PowerShell.DesiredStateConfiguration.DscResourceInfo]) {
           $InputObject.Properties
       } else {
           $InputObject.psobject.Properties
       }
       $Property.Name -in $Set.Name
   }
   filter Test-IsHidden ($p) {
       $a = [System.Management.Automation.HiddenAttribute]
       Test-HasAttribute -Property $p -Attribute $a
   }
   filter Test-IsDscProperty ($p) {
       $a = [System.Management.Automation.DscPropertyAttribute]
       Test-HasAttribute -Property $p -Attribute $a
   }
   filter Test-ShouldBeInResult ($p) {
       $IsDscProperty    = Test-IsDscProperty $_
       $IsHiddenProperty = Test-IsHidden      $_
   
       $IsDscProperty -and (-not $IsHiddenProperty)
   }
   $PSInvokeResult.GetType().GetProperties() | Format-Table -Property @(
       'Name'
       @{ Name = 'InResourceInfo'    ; Expression = { Test-InPropertySet $_ $Resource }}
       @{ Name = 'InPSDscResult'     ; Expression = { Test-InPropertySet $_ $PSInvokeResult }}
       @{ Name = 'InV3DscResult'     ; Expression = { Test-InPropertySet $_ $V3InvokeResult }}
       @{ Name = 'ShouldBeInResults' ; Expression = { Test-ShouldBeInResult $_ }}
       @{ Name = 'IsDscProperty'     ; Expression = { Test-IsDscProperty $_ }}
       @{ Name = 'IsHidden'          ; Expression = { Test-IsHidden $_ }}
       @{ Name = 'IsStatic'          ; Expression = { $_.GetGetMethod().IsStatic }}
   )

   Name                 InResourceInfo InPSDscResult InV3DscResult ShouldBeInResults IsDscProperty IsHidden IsStatic
   ----                 -------------- ------------- ------------- ----------------- ------------- -------- --------
   KeyProperty                    True          True          True             False          True    False    False
   NormalProperty                 True          True          True             False          True    False    False
   NonDscProperty                False          True          True             False         False    False    False
   HiddenNonDscProperty          False         False          True             False         False     True    False
   HiddenDscProperty              True         False          True             False          True     True    False
   StaticDscProperty             False         False         False             False          True    False     True
   StaticNonDscProperty          False         False         False             False         False    False     True
   

Expected behavior

$Invoking = @{
    Method   = 'Get'
    Module   = 'psdsc.repro'
    Name     = 'ReproResultData'
    Property = @{ KeyProperty = 'Repro Example' }
}
Invoke-DscResource @Invoking | Format-List

KeyProperty    : Repro Example
NormalProperty : Should be in results data.

$invoking.Property |
    ConvertTo-Json |
    dsc resource get -r "$($i.Module)/$($i.Name)" |
    ConvertFrom-Json |
    Select-Object -ExpandProperty actualState |
    Format-List

KeyProperty          : Repro Example
NormalProperty       : Should be in results data.

Actual behavior

$Invoking = @{
    Method   = 'Get'
    Module   = 'psdsc.repro'
    Name     = 'ReproResultData'
    Property = @{ KeyProperty = 'Repro Example' }
}
Invoke-DscResource @Invoking | Format-List

KeyProperty    : Repro Example
NormalProperty : Should be in results data.
NonDscProperty : This property shouldn't be in results data, because it's not a DSC property.

$invoking.Property |
    ConvertTo-Json |
    dsc resource get -r "$($i.Module)/$($i.Name)" |
    ConvertFrom-Json |
    Select-Object -ExpandProperty actualState |
    Format-List

KeyProperty          : Repro Example
NormalProperty       : Should be in results data.
NonDscProperty       : This property shouldn't be in results data, because it's not a DSC property.
HiddenNonDscProperty : This property shouldn't be in results data, because it's hidden and not a DSC property.
HiddenDscProperty    : This property should be in results data, but is an anti-pattern.

Error details

No response

Environment data

Name                           Value
----                           -----
PSVersion                      7.3.6
PSEdition                      Core
GitCommitId                    7.3.6
OS                             Microsoft Windows 10.0.22621
Platform                       Win32NT
PSCompatibleVersions           {1.0, 2.0, 3.0, 4.0…}
PSRemotingProtocolVersion      2.3
SerializationVersion           1.1.0.1
WSManStackVersion              3.0

Version

DSC (build from main), PSDSC v2.0.7

Visuals

No response

Notes

While both PSDSC and DSCv3 do show the NonDscProperty in the results, that seems like a bug in PSDesiredStateConfiguration. Similarly, the non-inclusion of StaticDscProperty is (arguably) a bug in PSDesiredStateConfiguration.

However, the return data handling by the DSC/PowerShellGroup resource provider is to just convert the result data to JSON:

DSC/powershellgroup/powershellgroup.resource.ps1

Line 179 in 6b286f1

$result | ConvertTo-Json

This runs into PowerShell/PowerShell#9847, where the serialization unexpectedly includes hidden properties (compared to ConvertTo-Csv and Select-Object).

Fix Proposal

Filter the returned properties to only include properties with the DscProperty attribute, so that the schema surface for the resources matches with Get-DscResource and the contract that the class definition implements.

[SteveL-MSFT]

I believe #363 will address this