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dsc_lite

PowerShell Desired State Configuration (DSC) Lite
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Version information

  • 4.0.1 (latest)
  • 4.0.0
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  • 3.0.1
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  • 0.6.0
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  • 0.4.0
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released Jun 7th 2018
This version is compatible with:
  • Puppet Enterprise 2018.1.x, 2017.3.x, 2017.2.x, 2017.1.x, 2016.5.x, 2016.4.x
  • Puppet >= 4.7.0 < 6.0.0

Start using this module

  • r10k or Code Manager
  • Bolt
  • Manual installation
  • Direct download

Add this module to your Puppetfile:

mod 'puppetlabs-dsc_lite', '0.4.0'
Learn more about managing modules with a Puppetfile

Add this module to your Bolt project:

bolt module add puppetlabs-dsc_lite
Learn more about using this module with an existing project

Manually install this module globally with Puppet module tool:

puppet module install puppetlabs-dsc_lite --version 0.4.0

Direct download is not typically how you would use a Puppet module to manage your infrastructure, but you may want to download the module in order to inspect the code.

Download
Tags: powershell, dsc, desired-state-configuration

Documentation

puppetlabs/dsc_lite — version 0.4.0 Jun 7th 2018

dsc_lite

Table of Contents

  1. Description - What is the dsc module and what does it do
  2. Prerequisites
  3. Setup
  4. Usage
  1. Reference
  1. Limitations
  1. Development - Guide for contributing to the module
  2. Learn More About DSC
  3. License

Description

The Puppet dsc_lite module allows you to manage target nodes using Windows PowerShell DSC (Desired State Configuration) Resources.

Windows System Prerequisites

Setup

puppet module install puppetlabs-dsc_lite

See known issues for troubleshooting setup.

Usage

The generic dsc type is a streamlined and minimal representation of a DSC Resource declaration in Puppet syntax. You can use a DSC Resource by supplying the same properties you would set in a DSC Configuration script inside the dsc_resource_properties parameter. For most use cases the dsc_resource_properties parameter accepts the same structure as the PowerShell syntax, with the substitution of Puppet syntax for arrays, hashes and other data structures.

So a DSC resource specified in PowerShell...

WindowsFeature IIS {
  Ensure => 'present'
  Name   => 'Web-Server'
}

...would look like this in Puppet:

dsc {'iis':
  dsc_resource_name        => 'WindowsFeature',
  dsc_resource_module      => 'PSDesiredStateConfiguration',
  dsc_resource_properties  => {
    ensure => 'present',
    name   => 'Web-Server',
  }
}

For the simplest cases, the above example is enough. However there are more advanced use cases in DSC that require more custom syntax in the dsc Puppet type. Since the dsc Puppet type has no prior knowledge of the type for each property in a DSC Resource, it can't format the hash correctly without some hints.

The dsc_resource_properties parameter will recognize any key with a hash value that contains two keys: dsc_type and dsc_properties, as a indication of how to format the data supplied. The dsc_type contains the CimInstance name to use, and the dsc_properties contains a hash or an array of hashes representing the data for the CimInstances.

A contrived, but simple example follows:

dsc {'foo':
  dsc_resource_name        => 'xFoo',
  dsc_resource_module      => 'xFooBar',
  dsc_resource_properties  => {
    ensure  => 'present',
    fooinfo => {
      'dsc_type'       => 'FooBarBaz',
      'dsc_properties' => {
        "wakka"      => "woot",
        "number"     => 8090
      }
    }
  }
}

Specifying a DSC Resource version

When there is more than one version installed for a given DSC Resource module, you must specify the version in your declaration. You can specify the version with similar syntax to a DSC Configuration script by using a hash containing the name and version of the DSC Resource module to use.

dsc {'iis_server':
  dsc_resource_name   => 'WindowsFeature',
  dsc_resource_module => {
    name    => 'PSDesiredStateConfiguration',
    version => '1.1'
  },
  dsc_resource_properties  => {
    ensure => 'present',
    name   => 'Web-Server',
  }
}

Distributing DSC Resources

There are several methods to distribute DSC Resources to the target nodes for the dsc_lite module to use.

PowerShell Gallery

You can choose to install DSC Resources yourself using a mechanism that calls the builtin PowerShell package management system called PackageManagement, which uses the PowerShellGet module and pulls from the PowerShell Gallery. You would be responsible for orchestrating this before Puppet is run on the host, or you could do so using exec in your Puppet manifest. This gives you control of the process, but requires you to manage the complexity yourself.

The following example shows how to install the xPSDesiredStateConfiguration DSC Resource, and could be extended to support different DSC Resource names. This example assumes a package repository was configured already.

exec { 'xPSDesiredStateConfiguration-Install':
  command   => 'Install-Module -Name xPSDesiredStateConfiguration -Force',
  provider  => 'powershell',
}

Puppet hbuckle/powershellmodule module

A community created module hbuckle/powershellmodule handles using PackageMangement and PowerShellGet to download and install DSC Resources on target nodes. It is another Puppet package provider, so it looks and feels like how you install packages with Puppet for any other use case.

Installing a DSC Resource can be as simple as the following declaration:

package { 'xPSDesiredStateConfiguration':
  ensure   => latest,
  provider => 'windowspowershell',
  source   => 'PSGallery',
}

The module supports configuring repository sources and other PackageManagement options like configuring trusted package repositories and private or on-premise package sources. For more information please refer to the forge page.

Chocolatey

Puppet already works well with chocolatey, so you can create chocolatey packages that wrap the DSC Resources you need. 

package { 'xPSDesiredStateConfiguration':
  ensure   => latest,
  provider => 'chocolatey',
}

This works well for users that already have a chocolatey source feed setup internally, as all that's needed is to push the DSC Resource chocolatey packages to the internal feed. If you use the community feed, you will have to check that the DSC Resource you use is present there.

Using PSCredential or MSFT_Credential

Specifying credentials in DSC Resources requires using a PSCredential object. The dsc type will automatically create a PSCredential if the dsc_type has MSFT_Credential as a value.

dsc {'foouser':
  dsc_resource_name       => 'User',
  dsc_resource_module     => 'PSDesiredStateConfiguration',
  dsc_resource_properties => {
    'username'    => 'jane-doe',
    'description' => 'Jane Doe user',
    'ensure'      => 'present',
    'password'    => {
      'dsc_type'       => 'MSFT_Credential',
      'dsc_properties' => {
        'user'     => 'jane-doe',
        'password' => 'StartFooo123&^!'
      }
    },
    'passwordneverexpires' => false,
    'disabled'             => true,
  }
}

Some DSC Resources require a password or passphrase for a setting, but do not need a user name. All credentials in DSC must be a PSCredential, so these passwords still have to be specified in a PSCredential format, even if there is no user to specify. How you specify the PSCredential will depend on how the DSC Resource implemented the password requirement. Some DSC Resources will accept an empty or null string for user, others do not. If it does not accept an empty or null string, then specify a dummy value. Do not use undef as it will error out.

You can also use the Puppet Sensitive type to ensure logs and reports redact the password.

dsc {'foouser':
  dsc_resource_name       => 'User',
  dsc_resource_module     => 'PSDesiredStateConfiguration',
  dsc_resource_properties => {
    'username'    => 'jane-doe',
    'description' => 'Jane Doe user',
    'ensure'      => 'present',
    'password'    => {
      'dsc_type'       => 'MSFT_Credential',
      'dsc_properties' => {
        'user'     => 'jane-doe',
        'password' => Sensitive('StartFooo123&^!')
      }
    },
    'passwordneverexpires' => false,
    'disabled'             => true,
  }
}

Using CimInstance

A DSC Resource may need a more complex type than a simple key value pair, so an EmbeddedInstance is used. An EmbeddedInstance is serialized as CimInstance over the wire. In order to represent a CimInstance in the dsc type, we will use the dsc_type key to specify which CimInstance to use. If the CimInstance is an array, we append a [] to the end of the name.

For example, we'll create a new IIS website using the xWebSite DSC Resource, bound to port 80. We use dsc_type to specify a MSFT_xWebBindingInformation CimInstance, and append [] to indicate that it is an array. Note that we do this even if we are only putting a single value in dsc_properties.

dsc {'NewWebsite':
  dsc_resource_name        => 'xWebsite',
  dsc_resource_module      => 'xWebAdministration',
  dsc_resource_properties  => {
    ensure       => 'Present',
    state        => 'Started',
    name         => 'TestSite',
    physicalpath => 'C:\testsite',
    bindinginfo  => {
      'dsc_type'       => 'MSFT_xWebBindingInformation[]',
      'dsc_properties' => {
        "protocol" => "HTTP",
        "port"     => 80
      }
    }
  }
}

To show using more than one value in dsc_properties, let's create the same site but now bound to both port 80 and 443.

dsc {'NewWebsite':
  dsc_resource_name        => 'xWebsite',
  dsc_resource_module      => 'xWebAdministration',
  dsc_resource_properties  => {
    ensure       => 'Present',
    state        => 'Started',
    name         => 'TestSite',
    physicalpath => 'C:\testsite',
    bindinginfo  => {
      'dsc_type'       => 'MSFT_xWebBindingInformation[]',
      'dsc_properties' => [
        {
          "protocol" => "HTTP",
          "port"     => 80
        },
        {
          'protocol'              => 'HTTPS',
          'port'                  => 443,
          'certificatethumbprint' => 'F94B4CC4C445703388E418F82D1BBAA6F3E9E512',
          'certificatestorename'  => 'My',
          'ipaddress'             => '*'
        }
      ]
    }
  }
}

Handling Reboots with DSC

Add the following reboot resource to your manifest. It must have the name dsc_reboot for the dsc module to find and use it.

reboot { 'dsc_reboot' :
  message => 'DSC has requested a reboot',
  when    => 'pending'
}

Reference

Types and Providers

dsc

The dsc type allows specifying any DSC Resource declaration as a minimal Puppet declaration.

Properties/Parameters

name

The name of the declaration. This has no affect on the DSC Resource declaration and is not used by the DSC Resource.

dsc_resource_name

The name of the DSC Resource to use. For example, the xRemoteFile DSC Resource.

dsc_resource_module

The name of the DSC Resource module to use. For example, the xPSDesiredStateConfiguration DSC Resource module contains the xRemoteFile DSC Resource.

dsc_resource_properties

The hash of properties to pass to the DSC Resource.

To express EmbeddedInstances, the dsc_resource_properties parameter will recognize any key with a hash value that contains two keys: dsc_type and dsc_properties, as a indication of how to format the data supplied. The dsc_type contains the CimInstance name to use, and the dsc_properties contains a hash or an array of hashes representing the data for the CimInstances. If the CimInstance is an array, we append a [] to the end of the name.

Limitations

  • For a list of tradeoffs and improvements in the dsc_lite module compared to the dsc module, see README_Tradeoffs.md

  • DSC Composite Resources are not supported.

  • DSC requires PowerShell Execution Policy for the LocalMachine scope to be set to a less restrictive setting than Restricted. If you see the error below, see MODULES-2500 for more information.

    Error: /Stage[main]/Main/Dsc_xgroup[testgroup]: Could not evaluate: Importing module MSFT_xGroupResource failed with
error - File C:\Program
Files\WindowsPowerShell\Modules\PuppetVendoredModules\xPSDesiredStateConfiguration\DscResources\MSFT_xGroupR
esource\MSFT_xGroupResource.psm1 cannot be loaded because running scripts is disabled on this system. For more
information, see about_Execution_Policies at http://go.microsoft.com/fwlink/?LinkID=135170.

  • You cannot use forward slashes for the MSI Path property for the Package DSC Resource. The underlying implementation does not accept forward slashes instead of backward slashes in paths, and it throws a misleading error that it could not find a Package with the Name and ProductId provided. MODULES-2486 has more examples and information on this subject.

  • Use of this module with the 3.8.x x86 version of Puppet is highly discouraged, though supported. Normally, this module employs a technique to dramatically improve performance by reusing a PowerShell process to execute DSC related commands. However, due to the Ruby 1.9.3 runtime used with the 3.8.x x86 version of Puppet, this technique must be disabled, resulting in at least a 2x slowdown.

Known Issues

  • --noop mode, puppet resource and property change notifications are currently not implemented - see MODULES-2270 for details.

Running Puppet and DSC without Administrative Privileges

While there are avenues for using Puppet with a non-administrative account, DSC is limited to only accounts with administrative privileges. The underlying CIM implementation DSC uses for DSC Resource invocation requires administrative credentials to function.

  • Using the Invoke-DscResource cmdlet requires administrative credentials

The Puppet agent on a Windows node can run DSC with a normal default install. If the Puppet agent was configured to use an alternate user account, that account must have administrative privileges on the system in order to run DSC.

Troubleshooting

When Puppet runs, the dsc_lite module takes the code supplied in your puppet manifest and converts that into PowerShell code that is sent to the DSC engine directly using Invoke-DscResource. You can see both the commands sent and the result of this by running puppet interactively, e.g. puppet apply --debug. It will output the PowerShell code that is sent to DSC to execute and the return data from DSC. For example:

Notice: Compiled catalog for win2012r2 in environment production in 0.82 seconds
Debug: Creating default schedules
Debug: Loaded state in 0.03 seconds
Debug: Loaded state in 0.05 seconds
Info: Applying configuration version '1475264065'
Debug: Reloading posix reboot provider
Debug: Facter: value for uses_win32console is still nil
Debug: PowerShell Version: 5.0.10586.117
$invokeParams = @{
Name          = 'ExampleDSCResource'
Method        = 'test'
Property      = @{
property1 = 'value1'
property2 = 'value2'
}
ModuleName = 'ExampleDscResourceModule'
}
############### SNIP ################
Debug: Waited 50 milliseconds...
############### SNIP ################
Debug: Waited 500 total milliseconds.
Debug: Dsc Resource returned: {"rebootrequired":false,"indesiredstate":false,"errormessage":""}
Debug: Dsc Resource Exists?: false
Debug: ensure: present
############### SNIP ################
$invokeParams = @{
Name          = 'ExampleDSCResource'
Method        = 'set'
Property      = @{
property1 = 'value1'
property2 = 'value2'
}
ModuleName = 'ExampleDscResourceModule'
}
############### SNIP ################\
Debug: Waited 100 total milliseconds.
Debug: Create Dsc Resource returned: {"rebootrequired":false,"indesiredstate":true,"errormessage":""}
Notice: /Stage[main]/Main/Dsc_exampledscresource[foober]/ensure: created
Debug: /Stage[main]/Main/Dsc_exampledscresource[foober]: The container Class[Main] will propagate my refresh event
Debug: Class[Main]: The container Stage[main] will propagate my refresh event
Debug: Finishing transaction 56434520
Debug: Storing state
Debug: Stored state in 0.10 seconds
############### SNIP ################

This shows us that there wasn't any problem parsing your manifest and turning it into a command to send to DSC. It also shows that there are two commands/operations for every DSC Resource executed, a SET and a test. DSC operates in two stages, it first tests if a system is in the desired state, then it sets the state of the system to the desired state. You can see the result of each operation in the debug log.

By using the debug logging of a puppet run, you can troubleshoot the application of DSC Resources during the development of your puppet manifests.

Development

Puppet Inc modules on the Puppet Forge are open projects, and community contributions are essential for keeping them great. We can’t access the huge number of platforms and myriad of hardware, software, and deployment configurations that Puppet is intended to serve.

We want to keep it as easy as possible to contribute changes so that our modules work in your environment. There are a few guidelines that we need contributors to follow so that we can have a chance of keeping on top of things.

For more information, see our module contribution guide.

Contributors

To see who's already involved, see the list of contributors.

Learn More About DSC

You can learn more about PowerShell DSC from the following online resources:

There are several books available as well. Here are some selected books for reference:

License