chef_gem

Use the chef_gem resource to install a gem only for the instance of Ruby that is dedicated to the chef-client. When a package is installed from a local file, it must be added to the node using the remote_file or cookbook_file resources.

The chef_gem resource works with all of the same properties and options as the gem_package resource, but does not accept the gem_binary property because it always uses the CurrentGemEnvironment under which the chef-client is running. In addition to performing actions similar to the gem_package resource, the chef_gem resource does the following:

• Runs its actions immediately, before convergence, allowing a gem to be used in a recipe immediately after it is installed
• Runs Gem.clear_paths after the action, ensuring that gem is aware of changes so that it can be required immediately after it is installed

Syntax

A chef_gem resource block manages a package on a node, typically by installing it. The simplest use of the chef_gem resource is:

chef_gem 'package_name'

which will install the named package using all of the default options and the default action (:install).

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

chef_gem 'name' do
  clear_sources              TrueClass, FalseClass
  compile_time               TrueClass, FalseClass
  notifies                   # see description
  options                    String
  package_name               String, Array # defaults to 'name' if not specified
  provider                   Chef::Provider::Package::Rubygems
  source                     String
  subscribes                 # see description
  timeout                    String, Integer
  version                    String, Array
  action                     Symbol # defaults to :install if not specified
end

where

• chef_gem tells the chef-client to manage a package
• 'name' is the name of the package
• :action identifies which steps the chef-client will take to bring the node into the desired state
• clear_sources, compile_time, options, package_name, provider, source, timeout, and version are properties of this resource, with the Ruby type shown. See “Properties” section below for more information about all of the properties that may be used with this resource.

Actions

This resource has the following actions:

:install

Default. Install a package. If a version is specified, install the specified version of the package.

:nothing

Define this resource block to do nothing until notified by another resource to take action. When this resource is notified, this resource block is either run immediately or it is queued up to be run at the end of the chef-client run.

:purge

Purge a package. This action typically removes the configuration files as well as the package.

:reconfig

Reconfigure a package. This action requires a response file.

:remove

Remove a package.

:upgrade

Install a package and/or ensure that a package is the latest version.

Properties

This resource has the following attributes:

ignore_failure

Ruby Types: TrueClass, FalseClass

Continue running a recipe if a resource fails for any reason. Default value: false.

notifies

Ruby Type: Symbol, ‘Chef::Resource[String]’

A resource may notify another resource to take action when its state changes. Specify a 'resource[name]', the :action that resource should take, and then the :timer for that action. A resource may notifiy more than one resource; use a notifies statement for each resource to be notified.

A timer specifies the point during the chef-client run at which a notification is run. The following timers are available:

:delayed

Default. Specifies that a notification should be queued up, and then executed at the very end of the chef-client run.

:immediate, :immediately

Specifies that a notification should be run immediately, per resource notified.

The syntax for notifies is:

notifies :action, 'resource[name]', :timer

options

Ruby Type: String

One (or more) additional options that are passed to the command.

package_name

Ruby Types: String, Array

The name of the package. Default value: the name of the resource block See “Syntax” section above for more information.

provider

Ruby Type: Chef Class

Optional. Explicitly specifies a provider. See “Providers” section below for more information.

retries

Ruby Type: Integer

The number of times to catch exceptions and retry the resource. Default value: 0.

retry_delay

Ruby Type: Integer

The retry delay (in seconds). Default value: 2.

source

Ruby Type: String

Optional. The path to a package in the local file system.

subscribes

Ruby Type: Symbol, ‘Chef::Resource[String]’

A resource may listen to another resource, and then take action if the state of the resource being listened to changes. Specify a 'resource[name]', the :action to be taken, and then the :timer for that action.

A timer specifies the point during the chef-client run at which a notification is run. The following timers are available:

:delayed

Default. Specifies that a notification should be queued up, and then executed at the very end of the chef-client run.

:immediate, :immediately

Specifies that a notification should be run immediately, per resource notified.

The syntax for subscribes is:

subscribes :action, 'resource[name]', :timer

timeout

Ruby Types: String, Integer

The amount of time (in seconds) to wait before timing out.

version

Ruby Types: String, Array

The version of a package to be installed or upgraded.

Providers

Where a resource represents a piece of the system (and its desired state), a provider defines the steps that are needed to bring that piece of the system from its current state into the desired state.

The chef-client will determine the correct provider based on configuration data collected by Ohai at the start of the chef-client run. This configuration data is then mapped to a platform and an associated list of providers.

Generally, it’s best to let the chef-client choose the provider, and this is (by far) the most common approach. However, in some cases, specifying a provider may be desirable. There are two approaches:

• Use a more specific short name—yum_package "foo" do instead of package "foo" do, script "foo" do instead of bash "foo" do, and so on—when available
• Use the provider property within the resource block to specify the long name of the provider as a property of a resource. For example: provider Chef::Provider::Long::Name

This resource has the following providers:

Chef::Provider::Package, package

When this short name is used, the chef-client will attempt to determine the correct provider during the chef-client run.

Chef::Provider::Package::Rubygems, chef_gem

Can be used with the options attribute.

Examples

The following examples demonstrate various approaches for using resources in recipes. If you want to see examples of how Chef uses resources in recipes, take a closer look at the cookbooks that Chef authors and maintains: https://github.com/chef-cookbooks.

Install a gems file for use in recipes

chef_gem 'right_aws' do
  action :install
end

require 'right_aws'

Install MySQL for Chef

execute 'apt-get update' do
  ignore_failure true
  action :nothing
end.run_action(:run) if node['platform_family'] == 'debian'

node.set['build_essential']['compiletime'] = true
include_recipe 'build-essential'
include_recipe 'mysql::client'

node['mysql']['client']['packages'].each do |mysql_pack|
  resources("package[#{mysql_pack}]").run_action(:install)
end

chef_gem 'mysql'