Multiple VMExtensions per (type) handler not supported for OS type...

ISSUE TITLE:
Multiple VMExtensions per (type) handler not supported for OS type...

ISSUE DESCRIPTION :

An advertised benefit of DSC in Azure is the ability to Audit VM's to ensure certain actions have been performed, ie JoinDomain, BGInfo, Anti-Malware, etc. This was the main reason I went with the added effort of DSC, instead of Custom Script Extension or Remote Powershell.

In my configurations, I need to Join a Domain, Install a gMSA, add Initialize and Format Disks, Copy Service Files, install and start Services, etc... in addition to whatever the ISO wants has as fundamental requirements.

Many of these tasks need to be performed in different combinations on different machines. The volume and combinations of parameters required also add complexity. Further combining all of this into an ARM template, which presents it's own difficulties.

This led me to an approach of creating various DSC's, each with it's own set of parameters and simple ARM template. This approach allows me to see if DomainJoin succeeded, before attempting to install gMSA

Imagine my dismay, to find out I can perform "Disk Operations" OR "Join Domain", but I can only perform both actions if I create a monolithic DSC. You can only use Microsoft.Powershell.DSC extension once per VM !!!???

 _Multiple VMExtensions per handler not supported for OS type 'Windows'. VMExtension 'DSC.xxxxx' with handler 'Microsoft.Powershell.DSC' already added or specified in input._

Why not allow multiple Microsoft.Powershell.DSC extensions, provided the names are Unique ?

Details of the scenario you tried and the problem that is occurring

I have created several DSC's that work independently when deployed via ARM templates. When attempting to deploy these DSC's in sequence, I get:

 _Multiple VMExtensions per handler not supported for OS type 'Windows'. VMExtension 'DSC.xxxxx' with handler 'Microsoft.Powershell.DSC' already added or specified in input._

Suggested solution to the issue

Allow multiple deployments of Microsoft.Powershell.DSC provided the names are unique.

The DSC configuration that is used to reproduce the issue (as detailed as possible)

# insert configuration here

The operating system the target node is running

Windows 2016 image based on default Azure image.

OsName : Microsoft Windows Server 2016 Datacenter
OsOperatingSystemSKU : DatacenterServerEdition
OsArchitecture : 64-bit
OsLanguage : en-US
OsMuiLanguages : {en-US}

Version and build of PowerShell the target node is running

Name Value

---

PSVersion 5.1.14393.2969
PSEdition Desktop
PSCompatibleVersions {1.0, 2.0, 3.0, 4.0...}
BuildVersion 10.0.14393.2969
CLRVersion 4.0.30319.42000
WSManStackVersion 3.0
PSRemotingProtocolVersion 2.3
SerializationVersion 1.1.0.1

Version of the DSC module that was used ('dev' if using current dev branch)

Custom combination of current modules.

Start by reviewing the Azure VM extension deployment behavior described in the issue, especially the Microsoft.Powershell.DSC handler and the ARM template deployment sequence. Determine whether supporting multiple uniquely named DSC extensions belongs in this repository; done would require an agreed implementation or documented resolution for deploying the separate DSC configurations together.