PowerShell Desired State Configuration

• In PowerShell Scripts
  • How to the work (Which cmdlet has to be used)
• In PowerShell DSC
  • What has be done to complete this work
• PowerShell DSC can be installed on the older versions of Windows (8,8.1, 2012) by installing Windows Management Framework 5.1.
• In Windows 10, Windows Server 2016+ DSC is already enabled.

 $PSVersionTable.PSVersion

• For Lab-Setup, Create a windows server 2016 core edition in AWS or Azure with t2.micro or B1s in Azure

PowerShell DSC Setup on Local Dev Machine

• Ensure PSDesiredStateConfiguration Module is installed on the Machine

Get-Command -Module PSDesiredStateConfiguration

• Enable PowerShell Remoting on Windows

 Enable-PSRemoting -SkipNetworkProfileCheck -Force -Verbose

• Lets try to login in the same machine

PowerShell DSC Workflow for beginners

• Create Configuration (Creating a PowerShell file with Specific Syntax)
• Use Resources in Configuration to tell what has to be done
• Execute Configuration to Create MOF file
• Start the DSC Configuration by using MOF File as input

PowerShell DSC Visual Studio Code Setup

• Install PowerShell Extension into VSCode.

Terms

• Configuration:
  • Will define on which nodes the configuration has to be execute
  • It will also define what has to be done
• Resource:
  • Smallest unit of PowerShell DSC which can perform actions
• Node:
  • Is the machine where the configuration has to be applied
• LCM (Local Configuration Manger):
  • Which is responsible for executing mof files.

Executing Sample PowerShell DSC

• Create a new directory

mkdir helloworld

• In this directory create a new ps1 file

New-Item helloworld.ps1
notepad helloworld.ps1

• Write DSC Configuration in this file

Configuration MyDscConfiguration {

    Import-DscResource -ModuleName PSDesiredStateConfiguration

    Node "localhost" {
        File myfile
        {
            Ensure = "Present" # Ensure the directory is Present on the target node.
            Type = "Directory" # The default is File.
            DestinationPath = "C:\Testing"
        }

    }
}
MyDscConfiguration

• Execute PS1 to create mof file

.\helloworld.ps1
ls

• Now Execute DSC Configuration

Start-DscConfiguration -Path .\MyDscConfiguration -Wait -Verbose

Lets try to understand Configuration

Built-in DSC Resources

• Refer Here

Exercise-1: Write PowerShell DSC Resource to Ensure Print Spooler Service is running

• We have got the Service Dsc Resource
• Now lets write the configuration

Configuration PrintSpoolerConfiguration {

    Import-DscResource -ModuleName PSDesiredStateConfiguration

    Node 'localhost' {
        Service Spooler {
            Name = 'Print Spooler'
            State = 'Running'
        }
    }
}

PrintSpoolerConfiguration

• Now Execute this on localhost

Exercise-2: Install IIS Server on Windows Server

• Follow the steps above to create a new ps1 file in a folder and write the configuration as shown below

Configuration WebServerConfiguration {

    Import-DscResource -ModuleName PSDesiredStateConfiguration

    Node 'localhost' {

        WindowsFeature 'iisinstall'{
            Name = 'web-server'
            Ensure = 'present'
        }
    }
}

WebServerConfiguration

• Execute as mentioned above

Powershell Gallery

• Along with built in resources, there are lot of Community DSC Modules which give DSC Resources. Refer Here
• Sample Module Installations

Install-Module -Name cChoco

Exercise

• Write a DSC Configuration to
  • Ensure a file is present in C:\temp\test.txt with content ‘Iam learning PowershellDSC’
  • Ensure a directory is present in c:\temp\dsc
  • copy c:\temp\dsc to c:\temp\dsccopy
  • Ensure Hyper-V is enabled as a windows feature (Windows 10 Professional)
  • Ensure Print Spooler is Running