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powershell_script Resource

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To suggest a change, edit the powershell_script.rb file and submit a pull request to the Chef Infra Client repository.

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Use the powershell_script resource to execute a script using the Windows PowerShell interpreter, much like how the script and script-based resources bash, csh, perl, python, and ruby are used. The powershell_script is specific to the Microsoft Windows platform, but may use both the the Windows PowerShell interpreter or the PowerShell Core (pwsh) interpreter as of Chef Infra Client 16.6 and later.

The powershell_script resource creates and executes a temporary file rather than running the command inline. Commands that are executed with this resource are (by their nature) not idempotent, as they are typically unique to the environment in which they are run. Use not_if and only_if conditionals to guard this resource for idempotence.

Syntax

A powershell_script resource block executes a batch script using the Windows PowerShell interpreter. For example, writing to an interpolated path:

powershell_script 'write-to-interpolated-path' do
  code <<-EOH
  $stream = [System.IO.StreamWriter] "#{Chef::Config[:file_cache_path]}/powershell-test.txt"
  $stream.WriteLine("In #{Chef::Config[:file_cache_path]}...word.")
  $stream.close()
  EOH
end

The full syntax for all of the properties that are available to the powershell_script resource is:

powershell_script 'name' do
  code                        String
  command                     String, Array # default value: 'name' unless specified
  convert_boolean_return      true, false # default value: false
  creates                     String
  cwd                         String
  domain                      String
  elevated                    true, false # default value: false
  environment                 Hash
  flags                       String
  group                       String, Integer
  input                       String
  interpreter                 String # default value: "powershell"
  live_stream                 true, false # default value: false
  password                    String
  returns                     Integer, Array # default value: 0
  timeout                     Integer, String, Float # default value: 3600
  user                        String, Integer
  action                      Symbol # defaults to :run if not specified
end

where:

  • powershell_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.
  • code, command, convert_boolean_return, creates, cwd, domain, elevated, environment, flags, group, input, interpreter, live_stream, password, returns, timeout, and user are the properties available to this resource.

Actions

The powershell_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. Run the script.

Properties

The powershell_script resource has the following properties:

architecture
Ruby Type: Symbol

The architecture of the process under which a script is executed. If a value is not provided, Chef Infra Client defaults to the correct value for the architecture, as determined by Ohai. An exception is raised when anything other than :i386 is specified for a 32-bit process. Possible values: :i386 (for 32-bit processes) and :x86_64 (for 64-bit processes).

code
Ruby Type: String | REQUIRED

A quoted string of code to be executed.

command
Ruby Type: String, Array | Default Value: The resource block's name

An optional property to set the command to be executed if it differs from the resource block’s name.

convert_boolean_return
Ruby Type: true, false | Default Value: false

Return 0 if the last line of a command is evaluated to be true or to return 1 if the last line is evaluated to be false.

When the guard_interpreter common attribute is set to :powershell_script, a string command will be evaluated as if this value were set to true. This is because the behavior of this attribute is similar to the value of the "$?" expression common in UNIX interpreters. For example, this:

powershell_script 'make_safe_backup' do
  guard_interpreter :powershell_script
  code 'cp ~/data/nodes.json ~/data/nodes.bak'
  not_if 'test-path ~/data/nodes.bak'
end

is similar to:

bash 'make_safe_backup' do
  code 'cp ~/data/nodes.json ~/data/nodes.bak'
  not_if 'test -e ~/data/nodes.bak'
end

creates
Ruby Type: String

Prevent a command from creating a file when that file already exists.

cwd
Ruby Type: String

The current working directory from which the command will be run.

domain
Ruby Type: String

The domain of the username specified by the user property. If not specified, the username and password specified by the user and password properties will be used to resolve that user against the domain in which the system running Chef Infra Client is joined, or if that system is not joined to a domain it will resolve the user as a local account on that system. An alternative way to specify the domain is to leave this property unspecified and specify the domain as part of the user property.

New in Chef Client 12.21

elevated
Ruby Type: true, false | Default Value: false

Determines whether the script will run with elevated permissions to circumvent User Access Control (UAC) from interactively blocking the process. This will cause the process to be run under a batch login instead of an interactive login. The user running chef-client needs the ‘Replace a process level token’ and ‘Adjust Memory Quotas for a process’ permissions. The user that is running the command needs the ‘Log on as a batch job’ permission. Because this requires a login, the user and password properties are required.

New in Chef Client 13.3

environment
Ruby Type: Hash

A Hash of environment variables in the form of ({'ENV_VARIABLE' => 'VALUE'}). Note: These variables must exist for a command to be run successfully.

flags
Ruby Type: String

A string that is passed to the Windows PowerShell command. Default value (Windows PowerShell 3.0+): -NoLogo, -NonInteractive, -NoProfile, -ExecutionPolicy Bypass, -InputFormat None.

group
Ruby Type: String, Integer

The group name or group ID that must be changed before running a command.

guard_interpreter
Ruby Type: Symbol | Default Value: :powershell_script

When this property is set to :powershell_script, the 64-bit version of the Windows PowerShell shell will be used to evaluate strings values for the not_if and only_if properties. Set this value to :default to use the 32-bit version of the cmd.exe shell.

input
Ruby Type: String

An optional property to set the input sent to the command as STDIN.

New in Chef Infra Client 16.2

interpreter
Ruby Type: String | Default Value: powershell
Allowed Values: "powershell", "pwsh"

The interpreter type, powershell or pwsh (PowerShell Core)

live_stream
Ruby Type: true, false | Default Value: false

Send the output of the command run by this execute resource block to the Chef Infra Client event stream.

password
Ruby Type: String

The password of the user specified by the user property. This property is mandatory if user is specified on Windows and may only be specified if user is specified. The sensitive property for this resource will automatically be set to true if password is specified.

New in Chef Client 12.21

returns
Ruby Type: Integer, Array | Default Value: 0

The return value for a command. This may be an array of accepted values. An exception is raised when the return value(s) do not match.

timeout
Ruby Type: Integer, String, Float | Default Value: 3600

The amount of time (in seconds) a command is to wait before timing out.

user
Ruby Type: String, Integer

The user name of the user identity with which to launch the new process. The user name may optionally be specified with a domain, i.e. domain\user or user@my.dns.domain.com via Universal Principal Name (UPN)format. It can also be specified without a domain simply as user if the domain is instead specified using the domain property. On Windows only, if this property is specified, the password property must be specified.


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 (the converge 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 a notifies 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 return true in addition to 0.
  • A block is executed as Ruby code that must return either true or false. If the block returns true, the guard property is applied. If the block returns false, 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.

Properties

The 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 powershell_script resource in recipes:

Write to an interpolated path

powershell_script 'write-to-interpolated-path' do
  code <<-EOH
  $stream = [System.IO.StreamWriter] "#{Chef::Config[:file_cache_path]}/powershell-test.txt"
  $stream.WriteLine("In #{Chef::Config[:file_cache_path]}...word.")
  $stream.close()
  EOH
end

Change the working directory

powershell_script 'cwd-then-write' do
  cwd Chef::Config[:file_cache_path]
  code <<-EOH
  $stream = [System.IO.StreamWriter] "C:/powershell-test2.txt"
  $pwd = pwd
  $stream.WriteLine("This is the contents of: $pwd")
  $dirs = dir
  foreach ($dir in $dirs) {
    $stream.WriteLine($dir.fullname)
  }
  $stream.close()
  EOH
end

Change the working directory in Microsoft Windows

powershell_script 'cwd-to-win-env-var' do
  cwd '%TEMP%'
  code <<-EOH
  $stream = [System.IO.StreamWriter] "./temp-write-from-chef.txt"
  $stream.WriteLine("chef on windows rox yo!")
  $stream.close()
  EOH
end

Pass an environment variable to a script

powershell_script 'read-env-var' do
  cwd Chef::Config[:file_cache_path]
  environment ({'foo' => 'BAZ'})
  code <<-EOH
  $stream = [System.IO.StreamWriter] "./test-read-env-var.txt"
  $stream.WriteLine("FOO is $env:foo")
  $stream.close()
  EOH
end

Evaluate for true and/or false

Use the convert_boolean_return attribute to raise an exception when certain conditions are met. For example, the following fragments will run successfully without error:

powershell_script 'false' do
  code '$false'
end

and:

powershell_script 'true' do
  code '$true'
end

whereas the following will raise an exception:

powershell_script 'false' do
  convert_boolean_return true
  code '$false'
end

Use the flags attribute

powershell_script 'Install IIS' do
  code <<-EOH
  Import-Module ServerManager
  Add-WindowsFeature Web-Server
  EOH
  flags '-NoLogo, -NonInteractive, -NoProfile, -ExecutionPolicy Unrestricted, -InputFormat None, -File'
  guard_interpreter :powershell_script
  not_if '(Get-WindowsFeature -Name Web-Server).Installed'
end

Rename computer, join domain, reboot

The following example shows how to rename a computer, join a domain, and then reboot the computer:

reboot 'Restart Computer' do
  action :nothing
end

powershell_script 'Rename and Join Domain' do
  code <<-EOH
    ...your rename and domain join logic here...
  EOH
  not_if <<-EOH
    $ComputerSystem = gwmi win32_computersystem
    ($ComputerSystem.Name -like '#{node['some_attribute_that_has_the_new_name']}') -and
      $ComputerSystem.partofdomain)
  EOH
  notifies :reboot_now, 'reboot[Restart Computer]', :immediately
end

where:

  • The powershell_script resource block renames a computer, and then joins a domain
  • The reboot resource restarts the computer
  • The not_if guard prevents the Windows PowerShell script from running when the settings in the not_if guard match the desired state
  • The notifies statement tells the reboot resource block to run if the powershell_script block was executed during a Chef Infra Client run

Run a command as an alternate user

Note: When Chef is running as a service, this feature requires that the user that Chef runs as has ‘SeAssignPrimaryTokenPrivilege’ (aka ‘SE_ASSIGNPRIMARYTOKEN_NAME’) user right. By default only LocalSystem and NetworkService have this right when running as a service. This is necessary even if the user is an Administrator.

This right can be added and checked in a recipe using this example:

# Add 'SeAssignPrimaryTokenPrivilege' for the user
Chef::ReservedNames::Win32::Security.add_account_right('<user>', 'SeAssignPrimaryTokenPrivilege')

# Check if the user has 'SeAssignPrimaryTokenPrivilege' rights
Chef::ReservedNames::Win32::Security.get_account_right('<user>').include?('SeAssignPrimaryTokenPrivilege')

The following example shows how to run mkdir test_dir from a Chef Infra Client run as an alternate user.

# Passing only username and password
powershell_script 'mkdir test_dir' do
 code "mkdir test_dir"
 cwd Chef::Config[:file_cache_path]
 user "username"
 password "password"
end

# Passing username and domain
powershell_script 'mkdir test_dir' do
 code "mkdir test_dir"
 cwd Chef::Config[:file_cache_path]
 domain "domain"
 user "username"
 password "password"
end

# Passing username = 'domain-name\\username'. No domain is passed
powershell_script 'mkdir test_dir' do
 code "mkdir test_dir"
 cwd Chef::Config[:file_cache_path]
 user "domain-name\\username"
 password "password"
end

# Passing username = 'username@domain-name'. No domain is passed
powershell_script 'mkdir test_dir' do
 code "mkdir test_dir"
 cwd Chef::Config[:file_cache_path]
 user "username@domain-name"
 password "password"
end

# Work around User Access Control (UAC)
powershell_script 'mkdir test_dir' do
 code "mkdir test_dir"
 cwd Chef::Config[:file_cache_path]
 user "username"
 password "password"
 elevated true
end

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