1. Overview
2. Module Description - What the module does and why it is useful
3. Setup - The basics of getting started with powershell
   • Setup requirements
   • Beginning with powershell
4. Usage - Configuration options and additional functionality
   • External files and exit codes
   • Console Error Output
5. Reference - An under-the-hood peek at what the module is doing and how
6. Limitations - OS compatibility, etc.
7. Development - Guide for contributing to the module

This module adds a new exec provider capable of executing PowerShell commands.

Puppet provides a built-in exec type that is capable of executing commands. This module adds a powershell provider to the exec type, which enables exec parameters, listed below. This module is particularly helpful if you need to run PowerShell commands but don't know the details about how PowerShell is executed, since you can technically run PowerShell commands in Puppet without the module.

This module requires PowerShell to be installed and the powershell.exe to be available in the system PATH.

The powershell module adapts the Puppet exec resource to run PowerShell commands. To get started, simply install the module and declare 'powershell' in provider with the applicable command.

exec { 'RESOURCENAME':
  command   => '$(SOMECOMMAND)',
  provider  => powershell,
}

When using exec resources with the powershell provider, the command parameter must be single-quoted to prevent Puppet from interpolating $(..).

For instance, if you wanted to rename the Guest account:

exec { 'rename-guest':
  command   => '$(Get-WMIObject Win32_UserAccount -Filter "Name=\'guest\'").Rename("new-guest")',
  unless    => 'if (Get-WmiObject Win32_UserAccount -Filter "Name=\'guest\'") { exit 1 }',
  provider  => powershell,
}

Note that the example uses the unless parameter to make the resource idempotent. The command is only executed if the Guest account does not exist, as indicated by unless returning 0.

Note: PowerShell variables (e.g. $_), must be escaped in Puppet manifests either using backslashes or single quotes.

Alternatively, you can put the PowerShell code for the command, onlyif, and unless parameters into separate files and then invoke the file function in the resource. Templates and the template() function could also be used here if the PowerShell scripts need to have access to variables from Puppet.

exec { 'rename-guest':
  command   => file('guest/rename-guest.ps1'),
  onlyif    => file('guest/guest-exists.ps1'),
  provider  => powershell,
  logoutput => true,
}

Each file is a PowerShell script that should be in the module's files/ folder.

For example, here is the script at: guest/files/rename-guest.ps1

$obj = $(Get-WMIObject Win32_UserAccount -Filter "Name='Guest'")
$obj.Rename("OtherGuest")

This has the added benefit of not requiring escaping '$' in the PowerShell code. Note that the files need to have DOS linefeeds or they will not work as expected. One tool for converting UNIX linefeeds to DOS linefeeds is unix2dos.

If you are calling external files, such as other PowerShell scripts or executables, be aware that the last executed script's exitcode will be used by Puppet to determine whether the command was successful. For example:

Suppose the file C:\fail.ps1 contains the following PowerShell script

& cmd /c EXIT 5
& cmd /c EXIT 1

and we use the following Puppet manifest

exec { 'test':
  command   => '& C:\fail.ps1',
  provider  => powershell,
}

The exec['test'] resource will always fail because the last exit code from the the external file C:\fail.ps1 is 1. This behavior may have unintended consequences if you are combining multiple external files.

To stop this behavior ensure that you use explicit Exit statements in your PowerShell scripts. For example we changed the Puppet manifest from above to:

exec { 'test':
  command   => '& C:\fail.ps1; Exit 0',
  provider  => powershell,
}

It will always succeed because the Exit 0 statement overrides the exit code from the C:\fail.ps1 script.

The PowerShell module will internally capture output sent to the .NET [System.Console]::Error stream like:

exec { 'test':
  command   => '[System.Console]::Error.WriteLine("foo")',
  provider  => powershell,
}

However, to produce output from a script, prefer to use the Write- prefixed cmdlets like Write-Output, Write-Debug and Write-Error

• powershell - Adapts the Puppet exec resource to run PowerShell commands.

All parameters are optional.

Specifies the file to look for before running the command. The command will only run if the file doesn't exist. Note: This parameter will not create a file, it will simpy look for one. Valid options: A string of the path to the file. Default: Undefined.

Sets the directory from which to run the command. Valid options: A string of the directory path. Default: Undefined.

Specifies the actual PowerShell command to execute. Must either be fully qualified or a search path for the command must be provided. Valid options: String. Default: Undefined.

Sets additional environment variables to set for a command. Valid options: String, or an array of multiple options. Default: Undefined.

Defines whether to log command output in addition to logging the exit code. If you specify 'on_failure', it only logs the output when the command has an exit code that does not match any value specified by the returns attribute. Valid options: 'true', 'false', and 'on_failure'. Default: 'on_failure'.

Runs the exec only if the command returns 0. Valid options: String. Default: Undefined.

Specifies the search path used for command execution. Valid options: String of the path, an array, or a semicolon-separated list. Default: Undefined.

Refreshes the command. Valid options: String. Default: Undefined.

Refreshes the command only when a dependent object is changed. Used with subscribe and notify metaparameters. Valid options: 'true', 'false'. Default: 'false'.

Lists the expected return code(s). An error will be returned if the executed command returns something else. Valid options: An array of acceptable return codes or a single value. Default: 0.

Sets the maximum time in seconds that the command should take. Valid options: Number or string representation of a number. Default: 300.

Determines the number of times execution of the command should be attempted. Valid options: Number or a string representation of a number. Default: '1'.

Specifies the time to sleep in seconds between tries. Valid options: Number or a string representation of a number. Default: Undefined.

Runs the exec, unless the command returns 0. Valid options: String. Default: Undefined.

• Only supported on Windows Server 2008 and above, and Windows 7 and above.

• Only supported on Powershell 2.0 and above.

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 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.