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At this point, we have covered what PowerShell DSC is and how it relates to DevOps and configuration management, and lightly stepped through how it is structured and how it compares to other solutions out there.
We will now cover the requirements and available versions of PowerShell DSC.
To use DSC, both the computer you author the configuration files on (more on this later) and the target computers must have PowerShell 4 or higher installed. This means that at least WMF 4 is installed on all target hosts and the computer in which you are making your configuration files.
PowerShell DSC comes as part of PowerShell starting in version 4. PowerShell 4 will already be present on the following operating systems and no further action is needed to enable PowerShell V4:
PowerShell 4 will have to be installed on the following operating systems:
PowerShell 5 and 6 support the installation on all the preceding operating systems.
While it may already be installed depending on your patching process, you can check whether it is installed or not by running the following command:
[PS]> Get-HotFix -Id KB2883200
Source Description HotFixID InstalledBy InstalledOn
------ ----------- -------- ----------- -----------
HOSTNAME Update KB2883200 HOSTNAMEAdmini... 9/30/2013 12:00:00 AM
The only dependency PowerShell has is on the .NET framework. PowerShell V4 and V5 require .NET framework V4.5. If you have Windows 2008 R2, read the release notes at https://www.microsoft.com/en-US/download/details.aspx?id=40855, carefully because the WMF 4 installer will not alert you that .NET 4.5 is not already installed.
Some functions of DSC do not work on the client operating systems as either the features needed aren't present on the client OS, or due to various other reasons, such as licensing or software availability. Where applicable, we'll call out these differences as we come across them. Something to note is that some DSC resources, the ones provided by the community or the xDSCResourceDesigner project (more on that later in Chapter 4, DSC Resources), do not work on Windows 2008. You will have to check the release notes for each DSC resource to determine what operating systems it is compatible with.
In the next chapter, we will delve into the details and inner workings of the DSC architecture. Before we do that, it will help to have an overview of the cmdlets and tools at your disposal when working with DSC. Some terms and concepts may be fuzzy here but will be explained in much more detail in further chapters. We can also use this section as a reference while authoring our own DSC configurations and resources.
PowerShell DSC is released as a feature of PowerShell, so its versioning scheme follows that of PowerShell. PowerShell is distributed as part of the WMF. When referring to the installed version of DSC, we use the version of PowerShell that is installed to denote which version of DSC it is currently running.
PowerShell V6, at the time of writing this, has not been released yet and is still in the alpha status, but we will still cover V4, V5, and V6 in this book. This will make things somewhat more complex to explain, as we will have to list, compare, contrast, and cover all the similarities and differences between the two versions as we move along. However, it is important to cover these because we fully expect you to have to deal with both PowerShell V4 and V5 deployed in your environments at the same time while looking at the future with V6. The final version of PowerShell V6 does not have a release date published yet, so realistically, you will have PowerShell V4 and V5 on your production systems for quite a while before moving to V6.
