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About Recipes

A recipe is the most fundamental configuration element within the organization. A recipe:

  • Is authored using Ruby, which is a programming language designed to read and behave in a predictable manner
  • Is mostly a collection of resources, defined using patterns (resource names, attribute-value pairs, and actions); helper code is added around this using Ruby, when needed
  • Must define everything that is required to configure part of a system
  • Must be stored in a cookbook
  • May be included in another recipe
  • May use the results of a search query and read the contents of a data bag (including an encrypted data bag)
  • May have a dependency on one (or more) recipes
  • Must be added to a run-list before it can be used by Chef Infra Client
  • Is always executed in the same order as listed in a run-list

Recipe Attributes

An attribute can be defined in a cookbook (or a recipe) and then used to override the default settings on a node. When a cookbook is loaded during a Chef Infra Client run, these attributes are compared to the attributes that are already present on the node. Attributes that are defined in attribute files are first loaded according to cookbook order. For each cookbook, attributes in the default.rb file are loaded first, and then additional attribute files (if present) are loaded in lexical sort order. When the cookbook attributes take precedence over the default attributes, Chef Infra Client applies those new settings and values during a Chef Infra Client run on the node.


Attributes can be configured in cookbooks (attribute files and recipes), roles, and environments. In addition, Ohai collects attribute data about each node at the start of a Chef Infra Client run. See Attributes for more information about how all of these attributes fit together.

Environment Variables

In UNIX, a process environment is a set of key-value pairs made available to a process. Programs expect their environment to contain information required for the program to run. The details of how these key-value pairs are accessed depends on the API of the language being used.

If processes is started by using the execute or script resources (or any of the resources based on those two resources, such as bash), use the environment attribute to alter the environment that will be passed to the process.

bash 'env_test' do
  code <<-EOF
  echo $FOO
  environment ({ 'FOO' => 'bar' })

The only environment being altered is the one being passed to the child process that is started by the bash resource. This will not affect the Chef Infra Client environment or any child processes.

Work with Recipes

The following sections show approaches to working with recipes.

Use Data Bags

Data bags store global variables as JSON data. Data bags are indexed for searching and can be loaded by a cookbook or accessed during a search.

The contents of a data bag can be loaded into a recipe. For example, a data bag named apps and a data bag item named my_app:

  "id": "my_app",
  "repository": "git://"

can be accessed in a recipe, like this:

my_bag = data_bag_item('apps', 'my_app')

The data bag item’s keys and values can be accessed with a Hash:

my_bag['repository'] #=> 'git://'

Secret Keys

Encrypting a data bag item requires a secret key. A secret key can be created in any number of ways. For example, OpenSSL can be used to generate a random number, which can then be used as the secret key:

openssl rand -base64 512 | tr -d '\r\n' > encrypted_data_bag_secret

where encrypted_data_bag_secret is the name of the file which will contain the secret key. For example, to create a secret key named “my_secret_key”:

openssl rand -base64 512 | tr -d '\r\n' > my_secret_key

The tr command eliminates any trailing line feeds. Doing so avoids key corruption when transferring the file between platforms with different line endings.

Store Keys on Nodes

An encryption key can also be stored in an alternate file on the nodes that need it and specify the path location to the file inside an attribute; however, EncryptedDataBagItem.load expects to see the actual secret as the third argument, rather than a path to the secret file. In this case, you can use EncryptedDataBagItem.load_secret to slurp the secret file contents and then pass them:

# inside your attribute file:
# default[:mysql][:secretpath] = 'C:\\chef\\any_secret_filename'
# inside your recipe:
# look for secret in file pointed to by mysql attribute :secretpath
mysql_secret = Chef::EncryptedDataBagItem.load_secret('#{node['mysql']['secretpath']}')
mysql_creds = Chef::EncryptedDataBagItem.load('passwords', 'mysql', mysql_secret)
mysql_creds['pass'] # will be decrypted

Assign Dependencies

If a cookbook has a dependency on a recipe that is located in another cookbook, that dependency must be declared in the metadata.rb file for that cookbook using the depends keyword.


Declaring cookbook dependencies is not required with chef-solo.

For example, if the following recipe is included in a cookbook named my_app:

include_recipe 'apache2::mod_ssl'

Then the metadata.rb file for that cookbook would have:

depends 'apache2'

Include Recipes

A recipe can include one (or more) recipes from cookbooks by using the include_recipe method. When a recipe is included, the resources found in that recipe will be inserted (in the same exact order) at the point where the include_recipe keyword is located.

The syntax for including a recipe is like this:

include_recipe 'recipe'

For example:

include_recipe 'apache2::mod_ssl'

Multiple recipes can be included within a recipe. For example:

include_recipe 'cookbook::setup'
include_recipe 'cookbook::install'
include_recipe 'cookbook::configure'

If a specific recipe is included more than once with the include_recipe method or elsewhere in the run_list directly, only the first instance is processed and subsequent inclusions are ignored.

Reload Attributes

Attributes sometimes depend on actions taken from within recipes, so it may be necessary to reload a given attribute from within a recipe. For example:

ruby_block 'some_code' do
  block do
    node.from_file(run_context.resolve_attribute('COOKBOOK_NAME', 'ATTR_FILE'))
  action :nothing

Use Ruby

Anything that can be done with Ruby can be used within a recipe, such as expressions (if, unless, etc.), case statements, loop statements, arrays, hashes, and variables. In Ruby, the conditionals nil and false are false; every other conditional is true.

Assign a value

A variable uses an equals sign (=) to assign a value.

To assign a value to a variable:

package_name = 'apache2'

Use Case Statement

A case statement can be used to compare an expression, and then execute the code that matches.

To select a package name based on platform:

package 'apache2' do
  case node['platform']
  when 'centos', 'redhat', 'fedora', 'suse'
    package_name 'httpd'
  when 'debian', 'ubuntu'
    package_name 'apache2'
  when 'arch'
    package_name 'apache'
  action :install

Check Conditions

An if expression can be used to check for conditions (true or false).

To check for condition only for Debian and Ubuntu platforms:

if platform?('debian', 'ubuntu')
  # do something if node['platform'] is debian or ubuntu
  # do other stuff

Execute Conditions

An unless expression can be used to execute code when a condition returns a false value (effectively, an unless expression is the opposite of an if statement).

To use an expression to execute when a condition returns a false value:

unless node['platform_version'] == '5.0'
  # do stuff on everything but 5.0

Loop over Array

A loop statement is used to execute a block of code one (or more) times. A loop statement is created when .each is added to an expression that defines an array or a hash. An array is an integer-indexed collection of objects. Each element in an array can be associated with and referred to by an index.

To loop over an array of package names by platform:

['apache2', 'apache2-mpm'].each do |p|
  package p

Loop over Hash

A hash is a collection of key-value pairs. Indexing for a hash is done using arbitrary keys of any object (as opposed to the indexing done by an array). The syntax for a hash is: key => "value".

To loop over a hash of gem package names:

{ 'fog' => '0.6.0', 'highline' => '1.6.0' }.each do |g, v|
  gem_package g do
    version v

Apply to Run-lists

A recipe must be assigned to a run-list using the appropriate name, as defined by the cookbook directory and namespace. For example, a cookbook directory has the following structure:


There are two recipes: a default recipe (that has the same name as the cookbook) and a recipe named mod_ssl. The syntax that applies a recipe to a run-list is similar to:

  'run_list': [

where ::default_recipe is implied (and does not need to be specified). On a node, these recipes can be assigned to a node’s run-list similar to:

  'run_list': [

Chef Infra Server

Use knife to add a recipe to the run-list for a node. For example:

knife node run list add NODENAME "recipe[apache2]"

More than one recipe can be added:

% knife node run list add NODENAME "recipe[apache2],recipe[mysql],role[ssh]"

which creates a run-list similar to:



Use a JSON file to pass run-list details to chef-solo as long as the cookbook in which the recipe is located is available to the system on which chef-solo is running. For example, a file named dna.json contains the following details:

  "run_list": ["recipe[apache2]"]

To add the run-list to the node, enter the following:

sudo chef-solo -j /etc/chef/dna.json

Use Search Results

Search indexes allow queries to be made for any type of data that is indexed by the Chef Infra Server, including data bags (and data bag items), environments, nodes, and roles. A defined query syntax is used to support search patterns like exact, wildcard, range, and fuzzy. A search is a full-text query that can be done from several locations, including from within a recipe, by using the search subcommand in knife, the search method in the Chef Infra Language, the search box in the Chef management console, and by using the /search or /search/INDEX endpoints in the Chef Infra Server API. The search engine is based on Elasticsearch and is run from the Chef Infra Server.

The results of a search query can be loaded into a recipe. For example, a simple search query (in a recipe) might look like this:

search(:node, 'attribute:value')

A search query can be assigned to variables and then used elsewhere in a recipe. For example, to search for all nodes that have a role assignment named webserver, and then render a template which includes those role assignments:

webservers = search(:node, 'role:webserver')

template '/tmp/list_of_webservers' do
  source 'list_of_webservers.erb'
  variables(webservers: webservers)

Use Tags

A tag is a custom description that’s applied to a node. A tag, once applied, can be helpful when managing nodes using knife or when building recipes by providing alternate methods of grouping similar types of information.

You can add tags, remove tags, and check if nodes have a specific tag.

To add a tag in your recipe, use tag with the tag name you want to apply to a node.


To test if a machine is tagged with a specific tag, use tagged? with the tag name.


This will return true or false.

tagged? also accepts an array as an argument.

Remove a tag using untag.


For example:


if tagged?('test_node')"Hey I'm #{node['tags']}")


unless tagged?('test_node')'I am not tagged')

Will return something like this:

[Thu, 22 Jul 2010 18:01:45 +0000] INFO: Hey I'm test_node
[Thu, 22 Jul 2010 18:01:45 +0000] INFO: I am not tagged

End Chef Infra Client Run

Sometimes it may be necessary to stop processing a recipe and/or stop processing the entire Chef Infra Client run. There are a few ways to do this:

  • Use the return keyword to stop processing a recipe based on a condition, but continue processing a Chef Infra Client run
  • Use the raise keyword to stop a Chef Infra Client run by triggering an unhandled exception
  • Use a rescue block in Ruby code
  • Use an exception handler

The following sections show various approaches to ending a Chef Infra Client run.

return Keyword

The return keyword can be used to stop processing a recipe based on a condition, but continue processing a Chef Infra Client run. For example:

file '/tmp/name_of_file' do
  action :create

return if platform?('windows')

package 'name_of_package' do
  action :install

where platform?('windows') is the condition set on the return keyword. When the condition is met, stop processing the recipe. This approach is useful when there is no need to continue processing, such as when a package cannot be installed. In this situation, it is OK for a recipe to stop processing.

raise Keyword

In certain situations it may be useful to stop a Chef Infra Client run entirely by using an unhandled exception. The raise keyword can be used to stop a Chef Infra Client run in both the compile and execute phases.


You may also see code that uses the fail keyword, which behaves the same but is discouraged and will result in Cookstyle warnings.

Use these keywords in a recipe—but outside of any resource blocks—to trigger an unhandled exception during the compile phase. For example:

file '/tmp/name_of_file' do
  action :create

raise "message" if platform?('windows')

package 'name_of_package' do
  action :install

where platform?('windows') is the condition that will trigger the unhandled exception.

Use these keywords in the ruby_block resource to trigger an unhandled exception during the execute phase. For example:

ruby_block "name" do
  block do
    # Ruby code with a condition, for example if ::File.exist?(::File.join(path, "/tmp"))
    raise "message"  # for example "Ordering issue with file path, expected foo"

Use these keywords in a class. For example:

class CustomError < StandardError; end

and then later on:

def custom_error
  raise CustomError, "error message"


def custom_error
  raise CustomError, "error message"

Rescue Blocks

Since recipes are written in Ruby, they can be written to attempt to handle error conditions using the rescue block.

For example:

  dater = data_bag_item(:basket, 'flowers')
rescue Net::HTTPClientException
  # maybe some retry code here?
  raise 'message_to_be_raised'

where data_bag_item makes an HTTP request to the Chef Infra Server to get a data bag item named flowers. If there is a problem, the request will return a Net::HTTPClientException. The rescue block can be used to try to retry or otherwise handle the situation. If the rescue block is unable to handle the situation, then the raise keyword is used to specify the message to be raised.


Use node.run_state to stash transient data during a Chef Infra Client run. This data may be passed between resources, and then evaluated during the execution phase. run_state is an empty Hash that is always discarded at the end of a Chef Infra Client run.

For example, the following recipe will install the Apache web server, randomly choose PHP or Perl as the scripting language, and then install that scripting language:

package 'httpd' do
  action :install

ruby_block 'randomly_choose_language' do
  block do
    if Random.rand > 0.5
      node.run_state['scripting_language'] = 'php'
      node.run_state['scripting_language'] = 'perl'

package 'scripting_language' do
  package_name lazy { node.run_state['scripting_language'] }
  action :install


  • The ruby_block resource declares a block of Ruby code that is run during the execution phase of a Chef Infra Client run
  • The if statement randomly chooses PHP or Perl, saving the choice to node.run_state['scripting_language']
  • When the package resource has to install the package for the scripting language, it looks up the scripting language and uses the one defined in node.run_state['scripting_language']
  • lazy {} ensures that the package resource evaluates this during the execution phase of a Chef Infra Client run (as opposed to during the compile phase)

When this recipe runs, Chef Infra Client will print something like the following:

* ruby_block[randomly_choose_language] action run
 - execute the ruby block randomly_choose_language

* package[scripting_language] action install
 - install version 5.3.3-27.el6_5 of package php
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