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.
Chapter 1, Introduction to PowerShell DSC, introduces you to PowerShell DSC and configuration management concepts. It covers the features included in DSC and briefly introduces the different DSC versions.
Chapter 2, DSC Architecture, covers all three phases of DSC in depth, the two different DSC deployment models, and the considerations to be made when deploying a Pull Server or using a push deployment.
Chapter 3, DSC Configuration Files, covers authoring the DSC configuration scripts and configuration data files from end to end. It also covers how to use them together effectively.
Chapter 4, DSC Resources, covers the DSC Resource syntax and file structure in both PowerShell v4 and v5. It shows how to find DSC Resources on the local system as well as using community and Microsoft-provided online resources.
Chapter 5, Pushing DSC Configurations, gives step-by-step instructions on how to push DSC configurations to remote target nodes. It also covers the extra steps the user must take to make push deployments work and discusses the pros and cons of using push deployments.
Chapter 6, Pulling DSC Configurations, gives step-by-step instructions on how to set up a DSC Pull Server and your environment to best utilize a pull-based deployment. It covers the pros and cons of using pull deployments in comparison to push deployments.
Chapter 7, Example Scenarios, covers the use of DSC in the real world and how to integrate DSC into not only new environments but also with legacy-style deployments. This chapter walks us through the thought processes of handling the changing requests and the requirements of different software deployments using DSC.
You will need the following operating systems:
Windows 8.1
Windows 2012 R2
You will also need PowerShell v4 or v5 as the software.
This book is intended for system administrators, developers, or DevOps engineers who are responsible for configuration management and automation and wish to learn PowerShell Desired State Configuration for efficient management, configuration, and deployment of systems and applications.
You are expected to have some basic knowledge of Windows PowerShell and should have experience in installing and configuring operating systems and Windows servers. You also need to understand the basics and principles of configuration management and to apply both to deploying and managing systems and applications using PowerShell DSC.
In this book, you will find a number of text styles that distinguish between different kinds of information. Here are some examples of these styles and an explanation of their meaning.
Code words in text, database table names, folder names, filenames, file extensions, pathnames, dummy URLs, user input, and Twitter handles are shown as follows: "DSC operates in a push scenario when configurations are manually pushed to target nodes using the Start-DscConfiguration Cmdlet."
Any command-line input or output is written as follows:
PS C:\Examples> .\TestExample.ps1 Directory: C:\Examples\TestExample Mode LastWriteTime Length Name ---- ------------- ------ ---- -a--- 5/20/2015 7:28 PM 1136 localhost.mof
Important words are shown in bold and appear in the text like this: "These will typically fail with a generic Access Denied, which will most likely lead you down the wrong path when troubleshooting."
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