class Chef::Property
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 Chef::Resource.property @see Chef::DelayedEvaluator
Attributes
The options this Property
will use for get/set behavior and validation.
@see initialize for a list of valid options.
Public Class Methods
Create a reusable property type that can be used in multiple properties in different resources.
@param options [Hash<Symbol,Object>] Validation options. See Chef::Resource.property for
the list of options.
@example
Property.derive(default: 'hi')
# File lib/chef/property.rb, line 51 def self.derive(**options) new(**options) end
This is to support deprecated_property_alias, by emitting an alias and a deprecation warning when called.
@param from [String] Name of the deprecated property @param to [String] Name of the correct property @param message [String] Deprecation
message to show to the cookbook author @param declared_in
[Class] Class this property comes from
# 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
Create a new property.
@param 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.
# 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
Public Instance Methods
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.
@param resource [Chef::Resource] The resource to get the property from. @param value The value to set (or NOT_PASSED if it is a get).
@return 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.
# 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 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.
@param resource [Chef::Resource] The resource we're coercing against
(to provide context for the coerce).
@param value The value to coerce.
@return The coerced value.
@raise Chef::Exceptions::ValidationFailed
If the value is invalid for
this property.
# File lib/chef/property.rb, line 511 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
The class this property was defined in.
@return [Class]
# File lib/chef/property.rb, line 191 def declared_in options[:declared_in] end
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`
# 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
A description of the default value of this property.
@return [String]
# File lib/chef/property.rb, line 248 def default_description options[:default_description] end
Derive a new Property
that is just like this one, except with some added or changed options.
@param options [Hash<Symbol,Object>] List of options that would be passed
to #initialize.
@return [Property] The new property type.
# File lib/chef/property.rb, line 555 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| %i{name_attribute name_property default}.include?(k) } end self.class.new(**options.merge(modified_options)) end
A description of this property.
@return [String]
# File lib/chef/property.rb, line 200 def description options[:description] end
Whether this is part of desired state or not.
Defaults to true.
@return [Boolean]
# File lib/chef/property.rb, line 277 def desired_state? return true unless options.key?(:desired_state) options[:desired_state] end
Emit the DSL
for this property into the resource class (`declared_in`).
Creates a getter and setter for the property.
# File lib/chef/property.rb, line 573 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 hierarchy, 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
The equal_to
field of this property.
@return [Array, NilClass]
# File lib/chef/property.rb, line 257 def equal_to options[:equal_to] end
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? } } “`
@param resource [Chef::Resource] The resource we're coercing against
(to provide context for the coerce).
@return [Boolean] Whether this value explicitly accepts nil.
@api private
# File lib/chef/property.rb, line 647 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 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.
@param resource [Chef::Resource] The resource to get the property from.
@return The value of the property.
@raise Chef::Exceptions::ValidationFailed
If the value is invalid for
this property, or if the value is required and not set.
# 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 = deep_dup(value) 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
@api private
# File lib/chef/property.rb, line 655 def get_value(resource) if instance_variable_name resource.instance_variable_get(instance_variable_name) else resource.send(name) end end
Whether this property has a default value.
@return [Boolean]
# File lib/chef/property.rb, line 297 def has_default? options.key?(:default) || name_property? end
Whether this is part of the resource's natural identity or not.
@return [Boolean]
# File lib/chef/property.rb, line 266 def identity? options[:identity] end
The instance variable associated with this property.
Defaults to `@<name>`
@return [Symbol]
# 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
When this property was introduced
@return [String]
# File lib/chef/property.rb, line 209 def introduced options[:introduced] end
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.
@param resource [Chef::Resource] The resource to get the property from.
@return [Boolean]
# File lib/chef/property.rb, line 480 def is_set?(resource) value_is_set?(resource) end
The name of this property.
@return [String]
# File lib/chef/property.rb, line 182 def name options[:name] end
Whether this is name_property or not.
@return [Boolean]
# File lib/chef/property.rb, line 288 def name_property? options[:name_property] end
Whether this property is required or not.
@return [Boolean]
# 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 the value of this property so that is_set? will return false and the default will be returned in the future.
@param resource [Chef::Resource] The resource to get the property from.
# File lib/chef/property.rb, line 490 def reset(resource) reset_value(resource) end
@api private
# File lib/chef/property.rb, line 682 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
Whether this property is sensitive or not.
Defaults to false.
@return [Boolean]
# File lib/chef/property.rb, line 332 def sensitive? options.fetch(:sensitive, false) end
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.
@param resource [Chef::Resource] The resource to set this property in. @param value The value to set.
@return The value that was set, after coercion (if lazy, still returns
the lazy value)
@raise Chef::Exceptions::ValidationFailed
If the value is invalid for
this property.
# File lib/chef/property.rb, line 449 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
@api private
# File lib/chef/property.rb, line 664 def set_value(resource, value) if instance_variable_name resource.instance_variable_set(instance_variable_name, value) else resource.send(name, value) end end
Whether this property should be skipped for documentation purposes.
Defaults to false.
@return [Boolean]
# File lib/chef/property.rb, line 321 def skip_docs? options.fetch(:skip_docs, false) end
# File lib/chef/property.rb, line 173 def to_s "#{name || "<property type>"}#{declared_in ? " of resource #{declared_in.resource_name}" : ""}" end
Validate a value.
Calls Chef::Mixin::ParamsValidate#validate
with validation_options
as options.
@param resource [Chef::Resource] The resource we're validating against
(to provide context for the validation).
@param value The value to validate.
@raise Chef::Exceptions::ValidationFailed
If the value is invalid for
this property.
# File lib/chef/property.rb, line 534 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 options. (See Chef::Mixin::ParamsValidate#validate
.)
@return [Hash<Symbol,Object>]
# 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
@api private
# File lib/chef/property.rb, line 673 def value_is_set?(resource) if instance_variable_name resource.instance_variable_defined?(instance_variable_name) else true end end
Private Instance Methods
Coerces and validates the value.
# File lib/chef/property.rb, line 746 def coerce_and_validate(resource, value) result = coerce(resource, value) validate(resource, result) result end
recursively dup the value
# File lib/chef/property.rb, line 754 def deep_dup(value) return value if value.is_a?(DelayedEvaluator) visitor = lambda do |obj| obj = obj.dup rescue obj case obj when Hash obj.each { |k, v| obj[k] = visitor.call(v) } when Array obj.each_with_index { |v, i| obj[i] = visitor.call(v) } end obj end visitor.call(value) end
# File lib/chef/property.rb, line 713 def exec_in_resource(resource, proc, *args) if resource if proc.arity > args.size value = proc.call(resource, *args) else value = resource.instance_exec(*args, &proc) end else # If we don't have a resource yet, we can't exec in resource! raise Chef::Exceptions::CannotValidateStaticallyError, "Cannot validate or coerce without a resource" end end
# File lib/chef/property.rb, line 726 def input_to_stored_value(resource, value, is_default: false) if value.nil? && !is_default && !explicitly_accepts_nil?(resource) value = default end unless value.is_a?(DelayedEvaluator) value = coerce_and_validate(resource, value) end value end
# File lib/chef/property.rb, line 694 def property_redefines_method? # We only emit deprecations if this property already exists as an instance method. # Weeding out class methods avoids unnecessary deprecations such Chef::Resource # defining a `name` property when there's an already-existing `name` method # for a Module. return false unless declared_in.instance_methods.include?(name) # Only emit deprecations for some well-known classes. This will still # allow more advanced users to subclass their own custom resources and # override their own properties. return false unless [ Object, BasicObject, Kernel, Chef::Resource ].include?(declared_in.instance_method(name).owner) # Allow top-level Chef::Resource properties, such as `name`, to be overridden. # As of this writing, `name` is the only Chef::Resource property created with the # `property` definition, but this will allow for future properties to be extended # as needed. !Chef::Resource.properties.key?(name) end
# File lib/chef/property.rb, line 736 def stored_value_to_output(resource, value) # Crack open lazy values before giving the result to the user if value.is_a?(DelayedEvaluator) value = exec_in_resource(resource, value) value = coerce_and_validate(resource, value) end value end