Preface

Windows PowerShell was a transformative event for the Windows management ecosystem. It marked a shift from the GUI-based administration of "click next, next, finish" to a composable command line experience that can be scripted and automated. This methodology was not accepted immediately by the Windows community, but time has proven the approach viable and PowerShell is now an integral part of any systems administrator's toolkit.

Windows PowerShell Desired State Configuration (DSC) marks another shift in Windows administration, but this time, it is a move away from the run-once scripts that cannot detect the existing state to declarative and repeatable automation without side effects. While PowerShell enabled an automation paradigm that was previously unmatched on Windows systems, crafting truly dependable automation took many lines of boilerplate code of exception catching and state checking. DSC handles this boilerplate code and gives you a clean and readable way to declare the expected state of your systems without worrying about how those systems are configured.

Whether you manage a few servers or several thousands of them, the same problems occur repeatedly. How do you ensure that all the servers under your care are configured to the exact specifications? How do you write those specifications down so that not only you and your coworker but also the machine understands them? This seemingly conflicting set of requirements is the purpose of DSC. Using DSC, you can write the human-readable desired state of the system you expect, and DSC ensures that the state of the system is what you desired it to be.

In this book, we will introduce the configuration management concepts that DSC uses to accomplish these feats. We then cover the architecture of DSC, which allows us to specify the state of a target system without having to code the implementation details ourselves. From there, we will cover how to create files that can be read by both DSC and humans to ensure that the state of target systems is what we specify. We will then address how to customize DSC to administer our customized and unique environments, and then walk through the ways in which we can deploy these configurations to the target systems using the different deployment models of DSC. We will wrap up with a walkthrough of a typical deployment cycle of example software using real-world problems and solutions.