PowerShell v4

Desired State Configuration

Windows does not work that way!

•Win32 API•COM•WMI•.NET

PowerShell is …

• .NET underneath• Structured data and behaviours• Objects in, objects out• A dynamic COM client• A WMI/CIM native• … capable of text manipulation and Regular Expressions too

PowerShell Desired State Configuration is …• New language KeywordsKeywords to declaratively define ConfigurationsConfigurations• Configurations that compile to Managed Object Format (MOF)• DSC Providers DSC Providers to apply Configurations to ResourcesResources• New Cmdlets Cmdlets to test, apply, and restore Configurations on demand• Local Configuration Manager Local Configuration Manager to maintain config and PullPull updates• DSC Service DSC Service to host Configurations and Providers centrally for Pull• Available in-the-box with Windows Server 2012 R2 on October 18th

Built-in Resources include …

•Archive• Environment• File•Group• Log•Package

•WindowsProcess•Registry•WindowsFeature• Script• Service•User

Configuration DemoConfig {param (…)

Node localhost {

WindowsFeature Telnet {Ensure = 'Present' # or 'Absent'Name = 'Telnet-Client'

}}

}

instance of MSFT_RoleResource as $MSFT_RoleResource1ref{

ResourceID = "[WindowsFeature]Telnet";Ensure = "Present";SourceInfo = "::6::9::WindowsFeature";Name = "Telnet-Client";ModuleName = "MSFT_RoleResource";ModuleVersion = "1.0";

};

instance of OMI_ConfigurationDocument { … };

Local Configuration Manager

• Responsible for validating and applying configuration• Runs under the context of the SYSTEM account• Only Administrators can submit configuration• Defaults to running in Push mode on a clean OS / PSv4 install• Supports Pull mode via file share or web service• Pull mode handles custom Resource Provider deployment• A single MOF file must encompass all the configuration

PS /> Start-DscConfiguration

DSC Service

• An IIS-hosted OData web service• An optional feature in Server 2012 R2• Consists of two components:• The Pull Server• The Compliance Server

• No documentation yet

Custom DSC Providers

• Custom Resources are a formalisation of the Script Resource:• Get-TargetResource• Set-TargetResource• Test-TargetResource

• MOF Schema with a Key and properties• Existing examples:• DHCP (by @gpduck)• Hosts file (on github.com/PowerShellOrg/DSC)• Website (in the Hands-On Lab)

• Expect to develop custom resources as an early adopter

What about System Center?

• Configuration Manager is expected to be used by the Enterprise. DSC is expected to be used for Azure and for DevOps.• Virtual Machine Manager 2012 R2 can call DSC during

provisioning

With DSC, Windows becomes text files•Versionable• Indexable•Auditable• Self-documenting

Without DSC, follow the same principals• Idempotency• Separate intent from implementation• Separate environmental configuration differences• Server names• Credentials• Number machines per role

Jason Stangroome@jstangroome

blog.stangroome.com