Class: Chef::Property

Inherits:
Object
  • Object
show all
Defined in:
lib/chef/property.rb

Overview

Type and validation information for a property on a resource.

A property named “x” manipulates the “@x” instance variable on a resource. The presence of the variable (`instance_variable_defined?(@x)`) tells whether the variable is defined; it may have any actual value, constrained only by validation.

Properties may have validation, defaults, and coercion, and have full support for lazy values.

See Also:

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(**options) ⇒ Property

Create a new property.

Parameters:

  • options (Hash<Symbol,Object>)

    Property options, including control options here, as well as validation options (see Chef::Mixin::ParamsValidate#validate for a description of validation options). @option options [Symbol] :name The name of this property. @option options [Class] :declared_in The class this property comes from. @option options [String] :description A description of the property. @option options [Symbol] :instance_variable_name The instance variable

    tied to this property. Must include a leading `@`. Defaults to `@<name>`.
    `nil` means the property is opaque and not tied to a specific instance
    variable.
    

    @option options [String] :introduced The release that introduced this property @option options [Boolean] :desired_state `true` if this property is part of desired

    state. Defaults to `true`.
    

    @option options [Boolean] :identity `true` if this property is part of object

    identity. Defaults to `false`.
    

    @option options [Boolean] :name_property `true` if this

    property defaults to the same value as `name`. Equivalent to
    `default: lazy { name }`, except that #property_is_set? will
    return `true` if the property is set *or* if `name` is set.
    

    @option options [Boolean] :nillable `true` opt-in to Chef-13 style behavior where

    attempting to set a nil value will really set a nil value instead of issuing
    a warning and operating like a getter [DEPRECATED]
    

    @option options [Object] :default The value this property

    will return if the user does not set one. If this is `lazy`, it will
    be run in the context of the instance (and able to access other
    properties) and cached. If not, the value will be frozen with Object#freeze
    to prevent users from modifying it in an instance.
    

    @option options [String] :default_description The description of the default value

    used in docs. Particularly useful when a default is computed or lazily eval'd.
    

    @option options [Boolean] :skip_docs This property should not be included in any

    documentation output
    

    @option options [Proc] :coerce A proc which will be called to

    transform the user input to canonical form. The value is passed in,
    and the transformed value returned as output. Lazy values will *not*
    be passed to this method until after they are evaluated. Called in the
    context of the resource (meaning you can access other properties).
    

    @option options [Boolean] :required `true` if this property

    must be present; `false` otherwise. This is checked after the resource
    is fully initialized.
    

    @option options [String] :deprecated If set, this property is deprecated and

    will create a deprecation warning.
    

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# File 'lib/chef/property.rb', line 122

def initialize(**options)
  options = options.inject({}) { |memo, (key, value)| memo[key.to_sym] = value; memo }
  @options = options
  options[:name] = options[:name].to_sym if options[:name]
  options[:instance_variable_name] = options[:instance_variable_name].to_sym if options[:instance_variable_name]

  # Replace name_attribute with name_property
  if options.key?(:name_attribute)
    # If we have both name_attribute and name_property and they differ, raise an error
    if options.key?(:name_property)
      raise ArgumentError, "name_attribute and name_property are functionally identical and both cannot be specified on a property at once. Use just one on property #{self}"
    end

    # replace name_property with name_attribute in place
    options = Hash[options.map { |k, v| k == :name_attribute ? [ :name_property, v ] : [ k, v ] }]
    @options = options
  end

  if options.key?(:default) && options.key?(:name_property)
    raise ArgumentError, "A property cannot be both a name_property/name_attribute and have a default value. Use one or the other on property #{self}"
  end

  if options[:name_property]
    options[:desired_state] = false unless options.key?(:desired_state)
  end

  # Recursively freeze the default if it isn't a lazy value.
  unless default.is_a?(DelayedEvaluator)
    visitor = lambda do |obj|
      case obj
      when Hash
        obj.each_value { |value| visitor.call(value) }
      when Array
        obj.each { |value| visitor.call(value) }
      end
      obj.freeze
    end
    visitor.call(default)
  end

  # Validate the default early, so the user gets a good error message, and
  # cache it so we don't do it again if so
  begin
    # If we can validate it all the way to output, do it.
    @stored_default = input_to_stored_value(nil, default, is_default: true)
  rescue Chef::Exceptions::CannotValidateStaticallyError
    # If the validation is not static (i.e. has procs), we will have to
    # coerce and validate the default each time we run
  end
end

Instance Attribute Details

#optionsObject (readonly)

The options this Property will use for get/set behavior and validation.


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# File 'lib/chef/property.rb', line 606

def options
  @options
end

Class Method Details

.derive(**options) ⇒ Object

Create a reusable property type that can be used in multiple properties in different resources.

Examples:

Property.derive(default: 'hi')

Parameters:

  • options (Hash<Symbol,Object>)

    Validation options. See Chef::Resource.property for the list of options.


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# File 'lib/chef/property.rb', line 51

def self.derive(**options)
  new(**options)
end

.emit_deprecated_alias(from, to, message, declared_in) ⇒ Object

This is to support #deprecated_property_alias, by emitting an alias and a deprecation warning when called.

Parameters:

  • from (String)

    Name of the deprecated property

  • to (String)

    Name of the correct property

  • message (String)

    Deprecation message to show to the cookbook author

  • declared_in (Class)

    Class this property comes from


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# File 'lib/chef/property.rb', line 63

def self.emit_deprecated_alias(from, to, message, declared_in)
  declared_in.class_eval <<-EOM, __FILE__, __LINE__ + 1
    def #{from}(value=NOT_PASSED)
      Chef.deprecated(:property, "#{message}")
      #{to}(value)
    end
    def #{from}=(value)
      Chef.deprecated(:property, "#{message}")
      #{to} = value
    end
  EOM
end

Instance Method Details

#call(resource, value = NOT_PASSED) ⇒ Object

Handle the property being called.

The base implementation does the property get-or-set:

“`ruby resource.myprop # get resource.myprop value # set “`

Subclasses may implement this with any arguments they want, as long as the corresponding DSL calls it correctly.

Parameters:

  • resource (Chef::Resource)

    The resource to get the property from.

  • value (defaults to: NOT_PASSED)

    The value to set (or NOT_PASSED if it is a get).

Returns:

  • The current value of the property. If it is a `set`, lazy values will be returned without running, validating or coercing. If it is a `get`, the non-lazy, coerced, validated value will always be returned.


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# File 'lib/chef/property.rb', line 367

def call(resource, value = NOT_PASSED)
  if NOT_PASSED == value # see https://github.com/chef/chef/pull/8781 before changing this
    get(resource)
  else
    set(resource, value)
  end
end

#coerce(resource, value) ⇒ Object

Coerce an input value into canonical form for the property.

After coercion, the value is suitable for storage in the resource. You must validate values after coercion, however.

Does no special handling for lazy values.

Parameters:

  • resource (Chef::Resource)

    The resource we're coercing against (to provide context for the coerce).

  • value

    The value to coerce.

Returns:

  • The coerced value.

Raises:

  • Chef::Exceptions::ValidationFailed If the value is invalid for this property.


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# File 'lib/chef/property.rb', line 510

def coerce(resource, value)
  if options.key?(:coerce)
    # nil is never coerced
    unless value.nil?
      value = exec_in_resource(resource, options[:coerce], value)
    end
  end
  value
end

#declared_inClass

The class this property was defined in.

Returns:

  • (Class)

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# File 'lib/chef/property.rb', line 191

def declared_in
  options[:declared_in]
end

#defaultObject

The raw default value for this resource.

Does not coerce or validate the default. Does not evaluate lazy values.

Defaults to `lazy { name }` if name_property is true; otherwise defaults to `nil`


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# File 'lib/chef/property.rb', line 236

def default
  return options[:default] if options.key?(:default)
  return Chef::DelayedEvaluator.new { name } if name_property?

  nil
end

#default_descriptionString

A description of the default value of this property.

Returns:


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# File 'lib/chef/property.rb', line 248

def default_description
  options[:default_description]
end

#derive(**modified_options) ⇒ Property

Derive a new Property that is just like this one, except with some added or changed options.

Parameters:

  • options (Hash<Symbol,Object>)

    List of options that would be passed to #initialize.

Returns:


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# File 'lib/chef/property.rb', line 554

def derive(**modified_options)
  # Since name_property, name_attribute and default override each other,
  # if you specify one of them in modified_options it overrides anything in
  # the original options.
  options = self.options
  if modified_options.key?(:name_property) ||
      modified_options.key?(:name_attribute) ||
      modified_options.key?(:default)
    options = options.reject { |k, v| k == :name_attribute || k == :name_property || k == :default }
  end
  self.class.new(**options.merge(modified_options))
end

#descriptionString

A description of this property.

Returns:


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# File 'lib/chef/property.rb', line 200

def description
  options[:description]
end

#desired_state?Boolean

Whether this is part of desired state or not.

Defaults to true.

Returns:

  • (Boolean)

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# File 'lib/chef/property.rb', line 277

def desired_state?
  return true unless options.key?(:desired_state)

  options[:desired_state]
end

#emit_dslObject

Emit the DSL for this property into the resource class (`declared_in`).

Creates a getter and setter for the property.


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# File 'lib/chef/property.rb', line 572

def emit_dsl
  # We don't create the getter/setter if it's a custom property; we will
  # be using the existing getter/setter to manipulate it instead.
  return unless instance_variable_name

  # Properties may override existing properties up the inheritance heirarchy, but
  # properties must not override inherited methods like Object#hash.  When the Resource is
  # placed into the resource collection the ruby Hash object will call the
  # Object#hash method on the resource, and overriding that with a property will cause
  # very confusing results.
  if property_redefines_method?
    resource_name = declared_in.respond_to?(:resource_name) ? declared_in.resource_name : declared_in
    raise ArgumentError, "Property `#{name}` of resource `#{resource_name}` overwrites an existing method. A different name should be used for this property."
  end

  # We prefer this form because the property name won't show up in the
  # stack trace if you use `define_method`.
  declared_in.class_eval <<-EOM, __FILE__, __LINE__ + 1
    def #{name}(value=NOT_PASSED)
      raise "Property `#{name}` of `\#{self}` was incorrectly passed a block. Possible property-resource collision. To call a resource named `#{name}` either rename the property or else use `declare_resource(:#{name}, ...)`" if block_given?
      self.class.properties[#{name.inspect}].call(self, value)
    end
    def #{name}=(value)
      raise "Property `#{name}` of `\#{self}` was incorrectly passed a block. Possible property-resource collision. To call a resource named `#{name}` either rename the property or else use `declare_resource(:#{name}, ...)`" if block_given?
      self.class.properties[#{name.inspect}].set(self, value)
    end
  EOM
end

#equal_toArray, NilClass

The equal_to field of this property.

Returns:

  • (Array, NilClass)

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# File 'lib/chef/property.rb', line 257

def equal_to
  options[:equal_to]
end

#explicitly_accepts_nil?(resource) ⇒ Boolean

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Find out whether this type accepts nil explicitly.

A type accepts nil explicitly if “is” allows nil, it validates as nil, and is not simply an empty type.

A type is presumed to accept nil if it does coercion (which must handle nil).

These examples accept nil explicitly: “`ruby property :a, [ String, nil ] property :a, [ String, NilClass ] property :a, [ String, proc { |v| v.nil? } ] “`

This does not (because the “is” doesn't exist or doesn't have nil):

“`ruby property :x, String “`

These do not, even though nil would validate fine (because they do not have “is”):

“`ruby property :a property :a, equal_to: [ 1, 2, 3, nil ] property :a, kind_of: [ String, NilClass ] property :a, respond_to: [ ] property :a, callbacks: { “a” => proc { |v| v.nil? } } “`

Parameters:

  • resource (Chef::Resource)

    The resource we're coercing against (to provide context for the coerce).

Returns:

  • (Boolean)

    Whether this value explicitly accepts nil.


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# File 'lib/chef/property.rb', line 646

def explicitly_accepts_nil?(resource)
  options.key?(:coerce) ||
    (options.key?(:is) && Chef::Mixin::ParamsValidate.send(:_pv_is, { name => nil }, name, options[:is]))
rescue Chef::Exceptions::ValidationFailed, Chef::Exceptions::CannotValidateStaticallyError
  false
end

#get(resource, nil_set: false) ⇒ Object

Get the property value from the resource, handling lazy values, defaults, and validation.

  • If the property's value is lazy, it is evaluated, coerced and validated.

  • If the property has no value, and is required, raises ValidationFailed.

  • If the property has no value, but has a lazy default, it is evaluated, coerced and validated. If the evaluated value is frozen, the resulting

  • If the property has no value, but has a default, the default value will be returned and frozen. If the default value is lazy, it will be evaluated, coerced and validated, and the result stored in the property.

  • If the property has no value, but is name_property, `resource.name` is retrieved, coerced, validated and stored in the property.

  • Otherwise, `nil` is returned.

Parameters:

  • resource (Chef::Resource)

    The resource to get the property from.

Returns:

  • The value of the property.

Raises:

  • Chef::Exceptions::ValidationFailed If the value is invalid for this property, or if the value is required and not set.


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# File 'lib/chef/property.rb', line 397

def get(resource, nil_set: false)
  # If it's set, return it (and evaluate any lazy values)
  value = nil

  if is_set?(resource)
    value = get_value(resource)
    value = stored_value_to_output(resource, value)
  else
    # We are getting the default value.

    if has_default?
      # If we were able to cache the stored_default, grab it.
      if defined?(@stored_default)
        value = @stored_default
      else
        # Otherwise, we have to validate it now.
        value = input_to_stored_value(resource, default, is_default: true)
      end
      value = stored_value_to_output(resource, value)

      # If the value is mutable (non-frozen), we set it on the instance
      # so that people can mutate it.  (All constant default values are
      # frozen.)
      if !value.frozen? && !value.nil?
        set_value(resource, value)
      end
    end
  end

  if value.nil? && required?
    raise Chef::Exceptions::ValidationFailed, "#{name} is a required property"
  else
    value
  end
end

#get_value(resource) ⇒ Object

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.


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# File 'lib/chef/property.rb', line 654

def get_value(resource)
  if instance_variable_name
    resource.instance_variable_get(instance_variable_name)
  else
    resource.send(name)
  end
end

#has_default?Boolean

Whether this property has a default value.

Returns:

  • (Boolean)

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# File 'lib/chef/property.rb', line 297

def has_default?
  options.key?(:default) || name_property?
end

#identity?Boolean

Whether this is part of the resource's natural identity or not.

Returns:

  • (Boolean)

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# File 'lib/chef/property.rb', line 266

def identity?
  options[:identity]
end

#instance_variable_nameSymbol

The instance variable associated with this property.

Defaults to `@<name>`

Returns:


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# File 'lib/chef/property.rb', line 220

def instance_variable_name
  if options.key?(:instance_variable_name)
    options[:instance_variable_name]
  elsif name
    :"@#{name}"
  end
end

#introducedString

When this property was introduced

Returns:


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# File 'lib/chef/property.rb', line 209

def introduced
  options[:introduced]
end

#is_set?(resource) ⇒ Boolean

Find out whether this property has been set.

This will be true if:

  • The user explicitly set the value

  • The property has a default, and the value was retrieved.

From this point of view, it is worth looking at this as “what does the user think this value should be.” In order words, if the user grabbed the value, even if it was a default, they probably based calculations on it. If they based calculations on it and the value changes, the rest of the world gets inconsistent.

Parameters:

  • resource (Chef::Resource)

    The resource to get the property from.

Returns:

  • (Boolean)

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# File 'lib/chef/property.rb', line 479

def is_set?(resource)
  value_is_set?(resource)
end

#nameString

The name of this property.

Returns:


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# File 'lib/chef/property.rb', line 182

def name
  options[:name]
end

#name_property?Boolean

Whether this is name_property or not.

Returns:

  • (Boolean)

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# File 'lib/chef/property.rb', line 288

def name_property?
  options[:name_property]
end

#required?(action = nil) ⇒ Boolean

Whether this property is required or not.

Returns:

  • (Boolean)

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# File 'lib/chef/property.rb', line 306

def required?(action = nil)
  if !action.nil? && options[:required].is_a?(Array)
    options[:required].include?(action)
  else
    !!options[:required]
  end
end

#reset(resource) ⇒ Object

Reset the value of this property so that is_set? will return false and the default will be returned in the future.

Parameters:

  • resource (Chef::Resource)

    The resource to get the property from.


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# File 'lib/chef/property.rb', line 489

def reset(resource)
  reset_value(resource)
end

#reset_value(resource) ⇒ Object

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.


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# File 'lib/chef/property.rb', line 681

def reset_value(resource)
  if instance_variable_name
    if value_is_set?(resource)
      resource.remove_instance_variable(instance_variable_name)
    end
  else
    raise ArgumentError, "Property #{name} has no instance variable defined and cannot be reset"
  end
end

#sensitive?Boolean

Whether this property is sensitive or not.

Defaults to false.

Returns:

  • (Boolean)

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# File 'lib/chef/property.rb', line 332

def sensitive?
  options.fetch(:sensitive, false)
end

#set(resource, value) ⇒ Object

Set the value of this property in the given resource.

Non-lazy values are coerced and validated before being set. Coercion and validation of lazy values is delayed until they are first retrieved.

Parameters:

  • resource (Chef::Resource)

    The resource to set this property in.

  • value

    The value to set.

Returns:

  • The value that was set, after coercion (if lazy, still returns the lazy value)

Raises:

  • Chef::Exceptions::ValidationFailed If the value is invalid for this property.


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# File 'lib/chef/property.rb', line 448

def set(resource, value)
  value = set_value(resource, input_to_stored_value(resource, value))

  if options.key?(:deprecated)
    Chef.deprecated(:property, options[:deprecated])
  end

  if value.nil? && required?
    raise Chef::Exceptions::ValidationFailed, "#{name} is a required property"
  else
    value
  end
end

#set_value(resource, value) ⇒ Object

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.


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# File 'lib/chef/property.rb', line 663

def set_value(resource, value)
  if instance_variable_name
    resource.instance_variable_set(instance_variable_name, value)
  else
    resource.send(name, value)
  end
end

#skip_docs?Boolean

Whether this property should be skipped for documentation purposes.

Defaults to false.

Returns:

  • (Boolean)

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# File 'lib/chef/property.rb', line 321

def skip_docs?
  options.fetch(:skip_docs, false)
end

#to_sObject


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# File 'lib/chef/property.rb', line 173

def to_s
  "#{name || "<property type>"}#{declared_in ? " of resource #{declared_in.resource_name}" : ""}"
end

#validate(resource, value) ⇒ Object

Validate a value.

Calls Chef::Mixin::ParamsValidate#validate with #validation_options as options.

Parameters:

  • resource (Chef::Resource)

    The resource we're validating against (to provide context for the validation).

  • value

    The value to validate.

Raises:

  • Chef::Exceptions::ValidationFailed If the value is invalid for this property.


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# File 'lib/chef/property.rb', line 533

def validate(resource, value)
  # nils are not validated unless we have an explicit default value
  if !value.nil? || has_default?
    if resource
      resource.validate({ name => value }, { name => validation_options })
    else
      name = self.name || :property_type
      Chef::Mixin::ParamsValidate.validate({ name => value }, { name => validation_options })
    end
  end
end

#validation_optionsHash<Symbol,Object>

Validation options. (See Chef::Mixin::ParamsValidate#validate.)

Returns:


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# File 'lib/chef/property.rb', line 341

def validation_options
  @validation_options ||= options.reject do |k, v|
    %i{declared_in name instance_variable_name desired_state identity default name_property coerce required nillable sensitive description introduced deprecated default_description skip_docs}.include?(k)
  end
end

#value_is_set?(resource) ⇒ Boolean

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Returns:

  • (Boolean)

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# File 'lib/chef/property.rb', line 672

def value_is_set?(resource)
  if instance_variable_name
    resource.instance_variable_defined?(instance_variable_name)
  else
    true
  end
end