machine_image¶

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Use the machine_image resource to define a machine image. This image may then be used by the machine resource when building machines.

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.

Syntax¶

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

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

where

machine_image tells the chef-client to use the Chef::Provider::MachineImage provider during the chef-client run
name is the name of the resource block and also the name of the machine image
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:

:archive: Use to archive a machine image.
:create: Default. Use to create a machine image.
:destroy: Use to destroy a machine image.
: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:

attributes

Use to specify a hash of attributes to be applied to the machine image.

chef_environment

The name of the environment.

complete

Use to specify if all of the attributes specified in attributes represent a complete specification for the machine image. When true, any attributes not specified in attributes will be reset to their default values.

ignore_failure

Ruby Type: true, false | Default Value: false

Continue running a recipe if a resource fails for any reason.

image_options

Ruby Type: Hash

Use to specify options that are used with this machine image.

name

The name of the machine image.

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 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

raw_json

The machine image as JSON data. For example:

{

}

recipe

Use to add a recipe to the run-list for the machine image. Each recipe adds a single recipe to the run-list. The order in which recipe defines the run-list is the order in which Chef will execute the run-list on the machine image.

remove_recipe

Use to remove a recipe from the run-list for the machine image.

remove_role

Use to remove a role from the run-list for the machine image.

retries

Ruby Type: Integer | Default Value: 0

The number of times to catch exceptions and retry the resource.

retry_delay

Ruby Type: Integer | Default Value: 2

The retry delay (in seconds).

role

Use to add a role to the run-list for the machine image.

run_list

Use to specify the run-list to be applied to the machine image.

A run-list defines all of the information necessary for Chef to configure a node into the desired state. A run-list is:

An ordered list of roles and/or recipes that are run in the exact order defined in the run-list; if a recipe appears more than once in the run-list, the chef-client will not run it twice
Always specific to the node on which it runs; nodes may have a run-list that is identical to the run-list used by other nodes
Stored as part of the node object on the Chef server
Maintained using knife and then uploaded from the workstation to the Chef server, or maintained using Chef Automate

A run-list must be in one of the following formats: fully qualified, cookbook, or default. Both roles and recipes must be in quotes, for example:

'role[NAME]'

or

'recipe[COOKBOOK::RECIPE]'

Use a comma to separate roles and recipes when adding more than one item the run-list:

'recipe[COOKBOOK::RECIPE],COOKBOOK::RECIPE,role[NAME]'

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 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

tags

Use to specify the list of tags to be applied to the machine image. Any tag not specified in this list will be removed.

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.

Build a machine from a machine image

machine_image 'web_image' do
  recipe 'apache2'
end

machine 'web_machine' do
 from_image 'web_image'
end