dsc_script Resource
This page is generated from the Chef Infra Client source code.To suggest a change, edit the dsc_script.rb file and submit a pull request to the Chef Infra Client repository.
Windows PowerShell is a task-based command-line shell and scripting language developed by Microsoft. Windows PowerShell uses a document-oriented approach for managing Windows-based machines, similar to the approach that is used for managing Unix and Linux-based machines. Windows PowerShell is a tool-agnostic platform that supports using Chef for configuration management.
Desired State Configuration (DSC) is a feature of Windows PowerShell that provides a set of language extensions, cmdlets, and resources that can be used to declaratively configure software. DSC is similar to Chef, in that both tools are idempotent, take similar approaches to the concept of resources, describe the configuration of a system, and then take the steps required to do that configuration. The most important difference between Chef and DSC is that Chef uses Ruby and DSC is exposed as configuration data from within Windows PowerShell.
Many DSC resources are comparable to built-in Chef Infra Client resources. For example, both DSC and Chef Infra Client
have file, package, and service resources. The dsc_script resource is most useful for those DSC resources that do not have a direct comparison to a
resource in Chef Infra Client, such as the DSC Archive resource, a custom DSC resource, an existing DSC script that performs an important
task, and so on. Use the dsc_script
resource to embed the code that defines a DSC configuration directly within a Chef Infra Client recipe.
Note
Windows PowerShell 4.0 is required for using the dsc_script resource with Chef Infra.
Note
The WinRM service must be enabled. (Use winrm quickconfig
to enable the service.)
Warning
The dsc_script resource may not be used in the same run-list with the dsc_resource. This is because the dsc_script resource requires that RefreshMode
in the Local Configuration Manager be set to Push
, whereas the dsc_resource resource requires it to be set to Disabled
.
Warning
The dsc_script resource is only available on 64-bit versions of Chef Infra Client.
Syntax
A dsc_script resource block embeds the code that defines a DSC configuration directly within a Chef recipe:
dsc_script 'get-dsc-resource-kit' do
code <<-EOH
Archive reskit
{
ensure = 'Present'
path = "#{Chef::Config[:file_cache_path]}\\DSCResourceKit620082014.zip"
destination = "#{ENV['PROGRAMW6432']}\\WindowsPowerShell\\Modules"
}
EOH
end
where
- the remote_file resource is first used to download the
DSCResourceKit620082014.zip
file.
where:
- the remote_file resource is first used to download the
DSCResourceKit620082014.zip
file.
The full syntax for all of the properties that are available to the dsc_script resource is:
dsc_script 'name' do
cwd String
environment Hash
flags Hash
timeout Integer
action Symbol # defaults to :run if not specified
end
where:
dsc_script
is the resource.name
is the name given to the resource block.action
identifies which steps Chef Infra Client will take to bring the node into the desired state.cwd
,environment
,flags
, andtimeout
are the properties available to this resource.
Actions
The dsc_script resource has the following actions:
:nothing
- This resource block does not act unless notified by another resource to take action. Once notified, this resource block either runs immediately or is queued up to run at the end of a Chef Infra Client run.
:run
- (default)
Properties
The dsc_script resource has the following properties:
code
- Ruby Type: String
The code for the DSC configuration script. This property may not be used in conjunction with the
command
property.
command
- Ruby Type: String
The path to a valid Windows PowerShell data file that contains the DSC configuration script. This data file must be capable of running independently of Chef and must generate a valid DSC configuration. This property may not be used in conjunction with the
code
property.
configuration_data
- Ruby Type: String
The configuration data for the DSC script. The configuration data must be a valid Windows PowerShell data file. This property may not be used in conjunction with the
configuration_data_script
property.
configuration_data_script
- Ruby Type: String
The path to a valid Windows PowerShell data file that also contains a node called
localhost
. This property may not be used in conjunction with theconfiguration_data
property.
configuration_name
- Ruby Type: String
The name of a valid Windows PowerShell cmdlet. The name may only contain letter (a-z, A-Z), number (0-9), and underscore (_) characters and should start with a letter. The name may not be null or empty. This property may not be used in conjunction with the
code
property.
cwd
- Ruby Type: String
The current working directory.
environment
- Ruby Type: Hash
A Hash of environment variables in the form of ({‘ENV_VARIABLE’ => ‘VALUE’}). (These variables must exist for a command to be run successfully).
flags
- Ruby Type: Hash
Pass parameters to the DSC script that is specified by the
command
property. Parameters are defined as key-value pairs, where the value of each key is the parameter to pass. This property may not be used in the same recipe as thecode
property. For example:flags ({ :EditorChoice => 'emacs', :EditorFlags => '--maximized' })
.
imports
- Ruby Type: Array
Warning
This property MUST be used with the
code
attribute.Use to import DSC resources from a module.
To import all resources from a module, specify only the module name:
imports 'module_name'
To import specific resources, specify the module name, and then specify the name for each resource in that module to import:
imports 'module_name', 'resource_name_a', 'resource_name_b', ...
For example, to import all resources from a module named
cRDPEnabled
:imports 'cRDPEnabled'
To import only the
PSHOrg_cRDPEnabled
resource:imports 'cRDPEnabled', 'PSHOrg_cRDPEnabled'
timeout
- Ruby Type: Integer
The amount of time (in seconds) a command is to wait before timing out.
ps_credential Helper
Use the ps_credential
helper to embed a PSCredential
object— a
set of security credentials, such as a user name or
password
—within a script, which allows that script to be run using security
credentials.
For example, assuming the CertificateID
is configured in the local
configuration manager, the SeaPower1@3
object is created and embedded
within the seapower-user
script:
dsc_script 'seapower-user' do
code <<-EOH
User AlbertAtom
{
UserName = 'AlbertAtom'
Password = #{ps_credential('SeaPower1@3')}
}
EOH
configuration_data <<-EOH
@{
AllNodes = @(
@{
NodeName = "localhost";
CertificateID = 'A8D1234559F349F7EF19104678908F701D4167'
}
)
}
EOH
end
Common Resource Functionality
Chef resources include common properties, notifications, and resource guards.
Common Properties
The following properties are common to every resource:
compile_time
Ruby Type: true, false | Default Value:
false
Control the phase during which the resource is run on the node. Set to true to run while the resource collection is being built (the
compile phase
). Set to false to run while Chef Infra Client is configuring the node (theconverge phase
).ignore_failure
Ruby Type: true, false, :quiet | Default Value:
false
Continue running a recipe if a resource fails for any reason.
:quiet
will not display the full stack trace and the recipe will continue to run if a resource fails.retries
Ruby Type: Integer | Default Value:
0
The number of attempts to catch exceptions and retry the resource.
retry_delay
Ruby Type: Integer | Default Value:
2
The delay in seconds between retry attempts.
sensitive
Ruby Type: true, false | Default Value:
false
Ensure that sensitive resource data is not logged by Chef Infra Client.
Notifications
notifies
Ruby Type: Symbol, 'Chef::Resource[String]'
A resource may notify another resource to take action when its state changes. Specify a
'resource[name]'
, the:action
that resource should take, and then the:timer
for that action. A resource may notify more than one resource; use anotifies
statement for each resource to be notified.If the referenced resource does not exist, an error is raised. In contrast,
subscribes
will not fail if the source resource is not found.
A timer specifies the point during a Chef Infra Client run at which a notification is run. The following timers are available:
:before
Specifies that the action on a notified resource should be run before processing the resource block in which the notification is located.
:delayed
Default. Specifies that a notification should be queued up, and then executed at the end of a Chef Infra Client run.
:immediate
,:immediately
Specifies that a notification should be run immediately, for each resource notified.
The syntax for notifies
is:
notifies :action, 'resource[name]', :timer
subscribes
Ruby Type: Symbol, 'Chef::Resource[String]'
A resource may listen to another resource, and then take action if the
state of the resource being listened to changes. Specify a
'resource[name]'
, the :action
to be taken, and then the :timer
for
that action.
Note that subscribes
does not apply the specified action to the
resource that it listens to - for example:
file '/etc/nginx/ssl/example.crt' do
mode '0600'
owner 'root'
end
service 'nginx' do
subscribes :reload, 'file[/etc/nginx/ssl/example.crt]', :immediately
end
In this case the subscribes
property reloads the nginx
service
whenever its certificate file, located under
/etc/nginx/ssl/example.crt
, is updated. subscribes
does not make any
changes to the certificate file itself, it merely listens for a change
to the file, and executes the :reload
action for its resource (in this
example nginx
) when a change is detected.
If the other resource does not exist, the subscription will not raise an
error. Contrast this with the stricter semantics of notifies
, which
will raise an error if the other resource does not exist.
A timer specifies the point during a Chef Infra Client run at which a notification is run. The following timers are available:
:before
Specifies that the action on a notified resource should be run before processing the resource block in which the notification is located.
:delayed
Default. Specifies that a notification should be queued up, and then executed at the end of a Chef Infra Client run.
:immediate
,:immediately
Specifies that a notification should be run immediately, for each resource notified.
The syntax for subscribes
is:
subscribes :action, 'resource[name]', :timer
Guards
A guard property can be used to evaluate the state of a node during the execution phase of a Chef Infra Client run. Based on the results of this evaluation, a guard property is then used to tell Chef Infra Client if it should continue executing a resource. A guard property accepts either a string value or a Ruby block value:
- A string is executed as a shell command. If the command returns
0
, the guard is applied. If the command returns any other value, then the guard property is not applied. String guards in a powershell_script run Windows PowerShell commands and may returntrue
in addition to0
. - A block is executed as Ruby code that must return either
true
orfalse
. If the block returnstrue
, the guard property is applied. If the block returnsfalse
, the guard property is not applied.
A guard property is useful for ensuring that a resource is idempotent by allowing that resource to test for the desired state as it is being executed, and then if the desired state is present, for Chef Infra Client to do nothing.
PropertiesThe following properties can be used to define a guard that is evaluated during the execution phase of a Chef Infra Client run:
not_if
Prevent a resource from executing when the condition returns
true
.only_if
Allow a resource to execute only if the condition returns
true
.
Examples
The following examples demonstrate various approaches for using the dsc_script resource in recipes:
Specify DSC code directly
DSC data can be specified directly in a recipe:
dsc_script 'emacs' do
code <<-EOH
Environment 'texteditor'
{
Name = 'EDITOR'
Value = 'c:\\emacs\\bin\\emacs.exe'
}
EOH
end
Specify DSC code using a Windows PowerShell data file
Use the command
property to specify the path to a Windows PowerShell
data file. For example, the following Windows PowerShell script defines
the DefaultEditor
:
Configuration 'DefaultEditor'
{
Environment 'texteditor'
{
Name = 'EDITOR'
Value = 'c:\emacs\bin\emacs.exe'
}
}
Use the following recipe to specify the location of that data file:
dsc_script 'DefaultEditor' do
command 'c:\dsc_scripts\emacs.ps1'
end
Pass parameters to DSC configurations
If a DSC script contains configuration data that takes parameters, those
parameters may be passed using the flags
property. For example, the
following Windows PowerShell script takes parameters for the
EditorChoice
and EditorFlags
settings:
$choices = @{'emacs' = 'c:\emacs\bin\emacs';'vi' = 'c:\vim\vim.exe';'powershell' = 'powershell_ise.exe'}
Configuration 'DefaultEditor'
{
[CmdletBinding()]
param
(
$EditorChoice,
$EditorFlags = ''
)
Environment 'TextEditor'
{
Name = 'EDITOR'
Value = "$($choices[$EditorChoice]) $EditorFlags"
}
}
Use the following recipe to set those parameters:
dsc_script 'DefaultEditor' do
flags ({ :EditorChoice => 'emacs', :EditorFlags => '--maximized' })
command 'c:\dsc_scripts\editors.ps1'
end
Use custom configuration data
Configuration data in DSC scripts may be customized from a recipe. For example, scripts are typically customized to set the behavior for Windows PowerShell credential data types. Configuration data may be specified in one of three ways:
- By using the
configuration_data
attribute - By using the
configuration_data_script
attribute - By specifying the path to a valid Windows PowerShell data file
The following example shows how to specify custom configuration data
using the configuration_data
property:
dsc_script 'BackupUser' do
configuration_data <<-EOH
@{
AllNodes = @(
@{
NodeName = "localhost";
PSDscAllowPlainTextPassword = $true
})
}
EOH
code <<-EOH
$user = 'backup'
$password = ConvertTo-SecureString -String "YourPass$(random)" -AsPlainText -Force
$cred = New-Object -TypeName System.Management.Automation.PSCredential -ArgumentList $user, $password
User $user
{
UserName = $user
Password = $cred
Description = 'Backup operator'
Ensure = "Present"
Disabled = $false
PasswordNeverExpires = $true
PasswordChangeRequired = $false
}
EOH
end
The following example shows how to specify custom configuration data
using the configuration_name
property. For example, the following
Windows PowerShell script defines the vi
configuration:
Configuration 'emacs'
{
Environment 'TextEditor'
{
Name = 'EDITOR'
Value = 'c:\emacs\bin\emacs.exe'
}
}
Configuration 'vi'
{
Environment 'TextEditor'
{
Name = 'EDITOR'
Value = 'c:\vim\bin\vim.exe'
}
}
Use the following recipe to specify that configuration:
dsc_script 'EDITOR' do
configuration_name 'vi'
command 'C:\dsc_scripts\editors.ps1'
end
Using DSC with other Chef resources
The dsc_script resource can be used with other resources. The
following example shows how to download a file using the
remote_file resource, and then uncompress it using the DSC
Archive
resource:
remote_file "#{Chef::Config[:file_cache_path]}\\DSCResourceKit620082014.zip" do
source 'http://gallery.technet.microsoft.com/DSC-Resource-Kit-All-c449312d/file/124481/1/DSC%20Resource%20Kit%20Wave%206%2008282014.zip'
end
dsc_script 'get-dsc-resource-kit' do
code <<-EOH
Archive reskit
{
ensure = 'Present'
path = "#{Chef::Config[:file_cache_path]}\\DSCResourceKit620082014.zip"
destination = "#{ENV['PROGRAMW6432']}\\WindowsPowerShell\\Modules"
}
EOH
end