chef_role

[edit on GitHub]

Warning

This functionality is available with Chef provisioning and is packaged in the Chef development kit. Chef provisioning is a framework that allows clusters to be managed by the chef-client and the Chef server in the same way nodes are managed: with recipes. Use Chef provisioning to describe, version, deploy, and manage clusters of any size and complexity using a common set of tools.

A role is a way to define certain patterns and processes that exist across nodes in an organization as belonging to a single job function. Each role consists of zero (or more) attributes and a run-list. Each node can have zero (or more) roles assigned to it. When a role is run against a node, the configuration details of that node are compared against the attributes of the role, and then the contents of that role’s run-list are applied to the node’s configuration details. When a chef-client runs, it merges its own attributes and run-lists with those contained within each assigned role.

Use the chef_role resource to manage roles.

Syntax

The syntax for using the chef_role resource in a recipe is as follows:

chef_role 'name' do
  attribute 'value' # see properties section below
  ...
  action :action # see actions section below
end

where

  • chef_role tells the chef-client to use the Chef::Provider::ChefRole provider during the chef-client run
  • name is the name of the resource block; when the name property is not specified as part of a recipe, name is also the name of the role
  • attribute is zero (or more) of the properties that are available for this resource
  • action identifies which steps the chef-client will take to bring the node into the desired state

Actions

This resource has the following actions:

:create
Default. Use to create a role.
:delete
Use to delete a role.
: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.

Properties

This resource has the following properties:

chef_server
The URL for the Chef server.
complete
Use to specify if this resource defines a role completely. When true, any property not specified by this resource will be reset to default property values.
default_attributes

A default attribute is automatically reset at the start of every chef-client run and has the lowest attribute precedence. Use default attributes as often as possible in cookbooks.

Default value: {}.

description
The description of the role. This value populates the description field for the role on the Chef server.
env_run_lists
The environment-specific run-list for a role. Default value: []. For example: ["env_run_lists[webserver]"]
ignore_failure

Ruby Types: TrueClass, FalseClass

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

name
The name of the role.
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 notify 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:

:before
Specifies that the action on a notified resource should be run before processing the resource block in which the notification is located.
: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
override_attributes

An override attribute is automatically reset at the start of every chef-client run and has a higher attribute precedence than default, force_default, and normal attributes. An override attribute is most often specified in a recipe, but can be specified in an attribute file, for a role, and/or for an environment. A cookbook should be authored so that it uses override attributes only when required.

Default value: {}.

raw_json

The role as JSON data. For example:

{
  "name": "webserver",
  "chef_type": "role",
  "json_class": "Chef::Role",
  "default_attributes": {},
  "description": "A webserver",
  "run_list": [
    "recipe[apache2]"
  ],
  "override_attributes": {}
}
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.

run_list
A comma-separated list of roles and/or recipes to be applied. Default value: []. For example: ["recipe[default]","recipe[apache2]"]
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.

Note that subscribes does not apply the specified action to the resource that it listens to - for example:

file '/etc/nginx/ssl/example.crt' do
   mode '0600'
   owner 'root'
end

service 'nginx' do
   subscribes :reload, 'file[/etc/nginx/ssl/example.crt]', :immediately
end

In this case the subscribes property reloads the nginx service whenever its certificate file, located under /etc/nginx/ssl/example.crt, is updated. subscribes does not make any changes to the certificate file itself, it merely listens for a change to the file, and executes the :reload action for its resource (in this example nginx) when a change is detected.

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

:before
Specifies that the action on a notified resource should be run before processing the resource block in which the notification is located.
: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

Examples

None.