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Microsoft Desired State Configuration v3 overview

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Microsoft's Desired State Configuration (DSC) is a declarative configuration platform. With DSC, the state of a machine is described using a format that should be clear to understand even if the reader isn't a subject matter expert. Unlike imperative tools, with DSC the definition of an application environment is separate from the script logic that implements how it's delivered.

The DSCv3 command line application abstracts the management of software components declaratively and idempotently. DSCv3 runs on Linux, macOS, and Windows without any external dependencies.

With DSCv3, you can:

  • Author DSC Resources to manage your systems in any language.
  • Invoke individual resources.
  • Create configuration documents that define the desired state of a system.

Configuration Documents

DSC Configuration Documents are declarative YAML files that define instances of resources. Typically, configuration documents define what state to enforce.

Example scenarios include requirements for an application environment or operational/security standards.

DSC Resources

DSC Resources define how to manage state for a particular system or application component. Resources describe a schema for the manageable settings of the component. Every resource can be used with the Get and Test operations to retrieve the current state of a resource instance and validate whether it's in the desired state. Most resources also support enforcing the desired state with the Set operation.

Example scenarios include how to update the contents of a file, how to run a utility that changes the state of a machine, or how to configure settings of an application.

Differences from PowerShell DSC

DSCv3 leverages the PSDesiredStateConfiguration module to support compatibility with existing PowerShell based resources.

DSCv3 differs from PowerShell Desired State Configuration (PSDSC) in a few important ways:

  • DSCv3 doesn't depend on PowerShell. You can use DSCv3 without PowerShell installed and manage resources written in bash, python, C#, Go, or any other language.
  • DSCv3 doesn't include a local configuration manager. DSCv3 is invoked as a command. It doesn't run as a service.
  • Non-PowerShell resources define their schemas with JSON files, not MOF files.
  • Configuration documents are defined in JSON or YAML files, not PowerShell script files.

Importantly, while DSCv3 represents a major change to the DSC platform, DSCv3 is able to invoke PSDSC Resources, including script-based and class-based DSC Resources, as they exist today. The configuration documents aren't compatible, but all published PSDSC Resources are. You can use PSDSC resources in DSCv3 with both Windows PowerShell and PowerShell.

Installation

To install DSCv3:

  1. Download the latest release from the PowerShell/DSC repository.
  2. Expand the release archive.
  3. Add the folder containing the expanded archive contents to the PATH.

To install the PSDesiredStateConfiguration version 3 beta from the PowerShell Gallery:

# Using PSResourceGet
Install-PSResource -Name PSDesiredStateConfiguration -Version 3.0.0-beta1 -Prerelease
# Using PowerShellGet
Install-Module -Name PSDesiredStateConfiguration -RequiredVersion 3.0.0-beta1 -AllowPrerelease

Integrating with DSCv3

DSCv3 is a platform tool that abstracts the concerns for defining and invoking resources. Higher order tools, like Azure Machine Configuration, Azure Automanaged VM, and WinGet are early partners for DSCv3 as orchestration agents.

DSCv3 uses JSON schemas to define the structure of resources, configuration documents, and the outputs that DSCv3 returns. These schemas make it easier to integrate DSCv3 with other tools, because they standardize and document how to interface with DSCv3.

See Also