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#
# Author:: Adam Jacob (<adam@chef.io>)
# Author:: Seth Chisamore (<schisamo@chef.io>)
# Author:: Tyler Cloke (<tyler@chef.io>)
# Copyright:: Copyright (c) Chef Software Inc.
# License:: Apache License, Version 2.0
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
require_relative "file"
require_relative "../mixin/securable"
require "chef-utils/dist" unless defined?(ChefUtils::Dist)
class Chef
class Resource
# A cookbook template is an Embedded Ruby (ERB) template that is used to dynamically generate static text files.
# Templates may contain Ruby expressions and statements, and are a great way to manage configuration files. Use the
# template resource to add cookbook templates to recipes; place the corresponding Embedded Ruby (ERB) template file
# in a cookbook's /templates directory.
#
# Use the template resource to manage the contents of a file using an Embedded Ruby (ERB) template by transferring
# files from a sub-directory of COOKBOOK_NAME/templates/ to a specified path located on a host that is running the
# chef-client. This resource includes actions and properties from the file resource. Template files managed by the
# template resource follow the same file specificity rules as the remote_file and file resources.
class Template < Chef::Resource::File
unified_mode true
provides :template
include Chef::Mixin::Securable
attr_reader :inline_helper_blocks
attr_reader :inline_helper_modules
def initialize(name, run_context = nil)
super
@source = "#{::File.basename(name)}.erb"
@inline_helper_blocks = {}
@inline_helper_modules = []
@helper_modules = []
end
def source(file = nil)
set_or_return(
:source,
file,
kind_of: [ String, Array ]
)
end
property :variables, Hash,
description: "The variables property of the template resource can be used to reference a partial template file by using a Hash.",
default: lazy { {} }
property :cookbook, String,
description: "The cookbook in which a file is located (if it is not located in the current cookbook). The default value is the current cookbook.",
desired_state: false
property :local, [ TrueClass, FalseClass ],
default: false, desired_state: false,
description: "Load a template from a local path. By default, the #{ChefUtils::Dist::Infra::CLIENT} loads templates from a cookbook's /templates directory. When this property is set to true, use the source property to specify the path to a template on the local node."
# Declares a helper method to be defined in the template context when
# rendering.
#
# === Example:
#
# ==== Basic usage:
# Given the following helper:
# helper(:static_value) { "hello from helper" }
# A template with the following code:
# <%= static_value %>
# Will render as;
# hello from helper
#
# ==== Referencing Instance Variables:
# Any instance variables available to the template can be referenced in
# the method body. For example, you can simplify accessing app-specific
# node attributes like this:
# helper(:app) { @node[:my_app_attributes] }
# And use it in a template like this:
# <%= app[:listen_ports] %>
# This is equivalent to the non-helper template code:
# <%= @node[:my_app_attributes][:listen_ports] %>
#
# ==== Method Arguments:
# Helper methods can also take arguments. The syntax available for
# argument specification supports full syntax available for method
# definition.
#
# Continuing the above example of simplifying attribute access, we can
# define a helper to look up app-specific attributes like this:
# helper(:app) { |setting| @node[:my_app_attributes][setting] }
# The template can then look up attributes like this:
# <%= app(:listen_ports) %>
def helper(method_name, &block)
unless block_given?
raise Exceptions::ValidationFailed,
"`helper(:method)` requires a block argument (e.g., `helper(:method) { code }`)"
end
unless method_name.is_a?(Symbol)
raise Exceptions::ValidationFailed,
"method_name argument to `helper(method_name)` must be a symbol (e.g., `helper(:method) { code }`)"
end
@inline_helper_blocks[method_name] = block
end
# Declares a module to define helper methods in the template's context
# when rendering. There are two primary forms.
#
# === Inline Module Definition
# When a block is given, the block is used to define a module which is
# then mixed in to the template context w/ `extend`.
#
# ==== Inline Module Example
# Given the following code in the template resource:
# helpers do
# # Add "syntax sugar" for referencing app-specific attributes
# def app(attribute)
# @node[:my_app_attributes][attribute]
# end
# end
# You can use it in the template like so:
# <%= app(:listen_ports) %>
# Which is equivalent to:
# <%= @node[:my_app_attributes][:listen_ports] %>
#
# === External Module Form
# When a module name is given, the template context will be extended with
# that module. This is the recommended way to customize template contexts
# when you need to define more than an handful of helper functions (but
# also try to keep your template helpers from getting out of hand--if you
# have very complex logic in your template helpers, you should further
# extract your code into separate libraries).
#
# ==== External Module Example
# To extract the above inline module code to a library, you'd create a
# library file like this:
# module MyTemplateHelper
# # Add "syntax sugar" for referencing app-specific attributes
# def app(attribute)
# @node[:my_app_attributes][attribute]
# end
# end
# And in the template resource:
# helpers(MyTemplateHelper)
# The template code in the above example will work unmodified.
def helpers(module_name = nil, &block)
if block_given? && !module_name.nil?
raise Exceptions::ValidationFailed,
"Passing both a module and block to #helpers is not supported. Call #helpers multiple times instead"
elsif block_given?
@inline_helper_modules << block
elsif module_name.is_a?(::Module)
@helper_modules << module_name
elsif module_name.nil?
raise Exceptions::ValidationFailed,
"#helpers requires either a module name or inline module code as a block.\n" +
"e.g.: helpers do; helper_code; end;\n" +
"OR: helpers(MyHelpersModule)"
else
raise Exceptions::ValidationFailed,
"Argument to #helpers must be a module. You gave #{module_name.inspect} (#{module_name.class})"
end
end
# Compiles all helpers from inline method definitions, inline module
# definitions, and external modules into an Array of Modules. The context
# object for the template is extended with these modules to provide
# per-resource template logic.
def helper_modules
compiled_helper_methods + compiled_helper_modules + @helper_modules
end
private
# compiles helper methods into a module that can be included in template context
def compiled_helper_methods
if inline_helper_blocks.empty?
[]
else
resource_helper_blocks = inline_helper_blocks
helper_mod = Module.new do
resource_helper_blocks.each do |method_name, method_body|
define_method(method_name, &method_body)
end
end
[ helper_mod ]
end
end
def compiled_helper_modules
@inline_helper_modules.map do |module_body|
Module.new(&module_body)
end
end
end
end
end
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