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

[jlongo62]

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.

[PlagueHO]

Hi @jlongo62 - sorry I missed this one.

The issue here isn't with Azure DSC specifically. The current version of the DSC LCM (LCM v1) currently only allows a single configuration to be applied to a machine at a time. Therefore it makes sense that the Azure DSC extension would uphold this limitation.

Future versions of the DSC LCM (LCM v2) may allow multiple configurations to be applied (the LCM v2 is currently being used by Azure Policy Guest Configuration). But there is no timeline for when or if the v2 LCM will be made available.

But what would generally be recommended here is the use of Composite resources (see https://docs.microsoft.com/en-us/powershell/dsc/resources/authoringresourcecomposite). Here is a good write up of using them: https://docs.microsoft.com/en-us/powershell/dsc/resources/authoringresourcecomposite

This is also probably not the best repo to raise this question in: I'd actually suggest heading over to the PowerShell #DSC Slack channel and asking there - there is lots of people who may have other suggestions for this. This is a great location to find all the sources of help: https://dsccommunity.org/help/