PowerShell Desired State Configuration (DSC) is a technology that allows you to define a configuration for an environment, and ensure it automatically gets configured tat way. It can also help you monitor the delta between the current state of the environment and what the defined configuration (a.k.a. Desired State) is. So as an example in the case of SharePoint, if you were to specify that you needed to register a Managed Account for user sp_services, and that someone was to delete that account, PowerShell DSC would automatically report the discrepancy in the logs or attempt to automatically recreated it based on how you configured your environment (Configuration Mode).
The SharePoint module for DSC is great to build new environments from the ground up. Simply specify what the Desired State should be (Web Applications, Site Collections, Service Applications, etc.) and let DSC do its job and automatically configure it. It acts as some kind of abstraction layer for the user, where they only need to define resources and their various settings for DSC to create and configure everything for them in the background. They don’t need to know the cmdlets to use, know what the objects’ properties are, and even less understand the object model behind it all. They only need to know what the DSC resource accepts.
In many cases however, clients who want to get into DSC already have investments in SharePoint, where they have an existing SharePoint 2013 or 2016 farm that they would like to replicate somewhere else with DSC. Writing a DSC configuration script from scratch that represents their exact environment is a complex job and often results in the customer writing tens of thousands of lines of code. This is where the ReverseDSC orchestrator for SharePoint, called SharePointDSC.Reverse comes into play. SharePointDSC.Reverse is a PowerShell script (.ps1) that you execute against an existing SharePoint 2013 or 2016 farm to extract its PowerShell Desired State Configuration. The script will scan every component of the farm, down to the SPWeb level. This means that everything that can be defined in Central Administration, with the addition of Sites can be extracted with the SharePointDSC.Reverse. The output will be another .ps1 script that will contain the DSC configuration of your farm. That script can then be executed to compile a .MOF file that can be used to replicate your SharePoint environment elsewhere.
The ReverseDSC Orchestrator for SharePoint can also be used for several scenarios other than replicating a farm. It can be used to:
- Extract a SharePoint 2013 Farm Configuration and replicate it as a SharePoint 2016 one;
- Compare deltas between two extractions to see what changed between two point in time;
- Create standalone copies of a Farm for developers;
- Move an on-premises SharePoint Farm into Azure Infrastructure-as-a-Service;
- On-board an existing farm onto PowerShell DSC to monitor it and ensure it remains in its desired state.
How to Use
The ReverseDSC Orchestrator for SharePoint is now officially available in the PowerShell Gallery. It can be installed, alongside all of its dependencies, by executing the following PowerShell one-liner from a machine that has internet connectivity:
Install-Script SharePointDSC.Reverse -Force
Note that this has to be done on only one server in the farm; you don’t need to install it on all servers. If your SharePoint server doesn’t have internet connectivity, simply run the above line of PowerShell from a machine that does have internet connectivity, and manually copy the ReverseDSC, SharePointDSC from the PowerShell modules folder (C:\Program Files\WindowsPowerShell\Modules), and the SharePointDSC.Reverse.ps1 script from the PowerShell script folder (C:\Program Files\WindowsPowerShell\Scripts) onto the destination server.
To learn more about the ReverseDSC Orchestrator for SharePoint, you can watch my Microsoft Virtual Academy session on the topic at the following URL: https://mva.microsoft.com/en-US/training-courses/sharepoint-automation-with-dsc-17843