ruby¶
Use the ruby resource to execute scripts using the Ruby interpreter. This resource may also use any of the actions and properties that are available to the execute resource. Commands that are executed with this resource are (by their nature) not idempotent, as they are typically unique to the environment in which they are run. Use not_if and only_if to guard this resource for idempotence.
Note
The ruby script resource (which is based on the script resource) is different from the ruby_block resource because Ruby code that is run with this resource is created as a temporary file and executed like other script resources, rather than run inline.
Syntax¶
A ruby resource block executes scripts using Ruby:
ruby 'extract_module' do
cwd ::File.dirname(src_filepath)
code <<-EOH
mkdir -p #{extract_path}
tar xzf #{src_filename} -C #{extract_path}
mv #{extract_path}/*/* #{extract_path}/
EOH
not_if { ::File.exist?(extract_path) }
end
where
- cwd specifies the directory from which the command is run
- code specifies the command to run
The full syntax for all of the properties that are available to the ruby resource is:
ruby 'name' do
code String
creates String
cwd String
environment Hash
flags String
group String, Integer
notifies # see description
path Array
provider Chef::Provider::Script::Ruby
returns Integer, Array
subscribes # see description
timeout Integer, Float
user String, Integer
umask String, Integer
action Symbol # defaults to :run if not specified
end
where
- ruby is the resource
- name is the name of the resource block
- cwd is the location from which the command is run
- :action identifies the steps the chef-client will take to bring the node into the desired state
- code, creates, cwd, environment, flags, group, path, provider, returns, timeout, user, and umask 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:
- :nothing
- Prevent a command from running. This action is used to specify that a command is run only when another resource notifies it.
- :run
- Default. Run a script.
Properties¶
This resource has the following properties:
- code
Ruby Type: String
A quoted (” ”) string of code to be executed.
- creates
Ruby Type: String
Prevent a command from creating a file when that file already exists.
- cwd
Ruby Type: String
The current working directory.
- environment
Ruby Type: Hash
A Hash of environment variables in the form of ({"ENV_VARIABLE" => "VALUE"}). (These variables must exist for a command to be run successfully.)
- flags
Ruby Type: String
One or more command line flags that are passed to the interpreter when a command is invoked.
- group
Ruby Types: String, Integer
The group name or group ID that must be changed before running a command.
- 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
- path
Ruby Type: Array
An array of paths to use when searching for a command. These paths are not added to the command’s environment $PATH. The default value uses the system path.
Warning
For example:
ruby 'mycommand' do environment 'PATH' => "/my/path/to/bin:#{ENV['PATH']}" end
- 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.
- returns
Ruby Types: Integer, Array
The return value for a command. This may be an array of accepted values. An exception is raised when the return value(s) do not match. Default value: 0.
- 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: Integer, Float
The amount of time (in seconds) a command is to wait before timing out. Default value: 3600.
- user
Ruby Types: String, Integer
The user name or user ID that should be changed before running a command.
- umask
Ruby Types: String, Integer
The file mode creation mask, or umask.
Guards¶
A guard property can be used to evaluate the state of a node during the execution phase of the chef-client run. Based on the results of this evaluation, a guard property is then used to tell the chef-client if it should continue executing a resource. A guard property accepts either a string value or a Ruby block value:
- A string is executed as a shell command. If the command returns 0, the guard is applied. If the command returns any other value, then the guard property is not applied. String guards in a powershell_script run Windows PowerShell commands and may return true in addition to 0.
- A block is executed as Ruby code that must return either true or false. If the block returns true, the guard property is applied. If the block returns false, the guard property is not applied.
A guard property is useful for ensuring that a resource is idempotent by allowing that resource to test for the desired state as it is being executed, and then if the desired state is present, for the chef-client to do nothing.
Attributes
The following properties can be used to define a guard that is evaluated during the execution phase of the chef-client run:
- not_if
- Prevent a resource from executing when the condition returns true.
- only_if
- Allow a resource to execute only if the condition returns true.
Arguments
The following arguments can be used with the not_if or only_if guard properties:
- :user
Specify the user that a command will run as. For example:
not_if 'grep adam /etc/passwd', :user => 'adam'
- :group
Specify the group that a command will run as. For example:
not_if 'grep adam /etc/passwd', :group => 'adam'
- :environment
Specify a Hash of environment variables to be set. For example:
not_if 'grep adam /etc/passwd', :environment => { 'HOME' => '/home/adam' }
- :cwd
Set the current working directory before running a command. For example:
not_if 'grep adam passwd', :cwd => '/etc'
- :timeout
Set a timeout for a command. For example:
not_if 'sleep 10000', :timeout => 10
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::Script, script
- When this short name is used, the chef-client will determine the correct provider during the chef-client run.
- Chef::Provider::Script::Ruby, ruby
- The provider for the Ruby command interpreter.
Examples¶
None.