Reset PSModulePath after MOF compilation of each node

[stehlih]

Pull Request (PR) description

Reset PSModulePath after MOF compilation of each node to avoid duplicate CIM class definition errors on the following nodes

Task list

• [X] Added an entry to the change log under the Unreleased section of the file CHANGELOG.md. Entry should say what was changed and how that affects users (if applicable), and reference the issue being resolved (if applicable).
• [ ] Resource documentation added/updated in README.md.
• [ ] Resource parameter descriptions added/updated in README.md, schema.mof and comment-based help.
• [ ] Comment-based help added/updated.
• [ ] Localization strings added/updated in all localization files as appropriate.
• [ ] Examples appropriately added/updated.
• [ ] Unit tests added/updated. See DSC Community Testing Guidelines.
• [ ] Integration tests added/updated (where possible). See DSC Community Testing Guidelines.
• [X] New/changed code adheres to DSC Community Style Guidelines.

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This change is 

[raandree]

@stehlih, do we still need this given the new Sampler task Set_PSModulePath? In #24 I have proposed to remove the PSModulePath manipulation completely as it can be configured and controlled by means of the task Set_PSModulePath.

[stehlih]

If certificates are used to encrypt passwords the PSModulePath is changed by some DSC resources during MOF compile. This fix allows a clean start of MOF compile for each node by restoring the PSModulePath to the original value at task start. The Set_PSModulePath task doesn't solve this problem.

[gaelcolas]

@stehlih could you specify which ones --> "some DSC resources" ? Are they DSC Community resources? Thanks

[raandree]

I still have this on my list. @stehlih and I found also, that eror handling in case credential decryption does not work should be improved. I hope to be able to have a look at this over the weekend.

@stehlih, but do we have this issue in general or only with specific resources?

[stehlih]

The issue is caused by resources with configured credentials (e.g. ComputerSettings from CommonTasks if the Credential attribute is set). After first occurence of this error the MOF compilation of all following nodes fails with "duplicate CIM classes or duplicate modules found" error. With this fix the following nodes hava a chance to compile without errors.

VEUA01A01 : VEUA01A01 : MOF__ NA VEUA01A01 : Client_Local_TO_EUA-SW ::> DscTagging ..............................................OK VEUA01A01 : Client_Local_TO_EUA-SW ::> OpticalDiskDrives .......................................OK VEUA01A01 : Client_Local_TO_EUA-SW ::> PowerPlans ..............................................OK VEUA01A01 : Client_Local_TO_EUA-SW ::> CertificateImports ......................................OK VEUA01A01 : Client_Local_TO_EUA-SW ::> NetworkIpConfiguration ..................................OK VEUA01A01 : Client_Local_TO_EUA-SW ::> ComputerSettings ........................................OK VEUA01A01 : Client_Local_TO_EUA-SW ::> WindowsOptionalFeatures .................................OK VEUA01A01 : Client_Local_TO_EUA-SW ::> FilesAndFolders .........................................OK ImportCimAndScriptKeywordsFromModule : Bei der Verarbeitung der Schemadatei "C:\Program Files\WindowsPowerShell\Modules\ PackageManagement\1.4.8.1\DSCResources\MSFT_PackageManagement\MSFT_PackageManagement.Schema.mof" wurde eine zweite CIM-Klassendefinition für "MSFT_PackageManagement" gefunden. Diese Klasse wurde bereits in den D:\SBX\WSP-Core\Impl\DscR efConfig\Output\output\RequiredModules\PackageManagement\1.4.8.1\DSCResources\MSFT_PackageManagement\MSFT_PackageManagem ent.Schema.mof-Dateien definiert. Entfernen Sie die redundante Definition, und wiederholen Sie den Vorgang. In C:\windows\system32\windowspowershell\v1.0\Modules\PSDesiredStateConfiguration\PSDesiredStateConfiguration.psm1:2120

[raandree]

This PR is no longer required, we have done the necessary changes in all DSC composite resources of CommonTasks.

@stehlih, please reach out to me if there is further trouble.