python Resource

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Use the python resource to execute scripts using the Python interpreter. This resource may also use any of the actions and properties that are available to the execute resource. 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 to guard this resource for idempotence.

Syntax

The python resource has the following syntax:

python 'hello world' do
  code <<-EOH
    print "Hello world! From Chef and Python."
  EOH
end

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

python 'name' do
  cgroup           String
  code             String
  command          String, Array # default value: 'name' unless specified
  creates          String
  cwd              String
  default_env      true, false # default value: false
  domain           String
  elevated         true, false # default value: false
  environment      Hash
  flags            String
  group            String, Integer
  input            String
  interpreter      String
  live_stream      true, false # default value: false
  login            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:

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

Actions

The python resource has the following actions:

:nothing

This resource block doesn’t 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

Run a command. (default)

Properties

The python resource has the following properties:

cgroup

Ruby Type: String

Linux only: Run the command within a specific cgroup, creating it if it doesn’t exist.

New in Chef Infra Client 19.0

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.

Note

Use the execute resource to run a single command. Use multiple execute resource blocks to run multiple commands.

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.

default_env

Ruby Type: true, false | Default Value: false

When true this enables ENV magic to add path_sanity to the PATH and force the locale to English+UTF-8 for parsing output

New in Chef Client 14.2

domain

Ruby Type: String

Windows only: The domain of the user 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

One or more command line flags that are passed to the interpreter when a command is invoked.

group

Ruby Type: String, Integer

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

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

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.

login

Ruby Type: true, false | Default Value: false

Use a login shell to run the commands instead of inheriting the existing execution environment.

New in Chef Infra Client 17.0

password

Ruby Type: String

Windows only: 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.

Agentless Mode

The python resource has full support for Agentless Mode.

Supported platforms:

• aix
• bsd
• linux
• solaris

Support was initially added in Chef Infra Client 19.0.

Common Resource Functionality

Chef resources include common properties, notifications, and resource guards.

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 isn’t 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 isn’t 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’s being executed, and then if the desired state is present, for Chef Infra Client to do nothing.

The following properties can be used to define a guard that’s 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

This resource does not have any examples.