machine¶

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Use the machine resource to define one (or more) machines, and then converge entire clusters of machines. This allows clusters to be maintained in a version control system and to be defined using multi-machine orchestration scenarios. For example, spinning up small test clusters and using them for continuous integration and local testing, building clusters that auto-scale, moving a set of machines in one cluster to another, building images, and so on.

Each machine is declared as a separate application topology, defined using operating system- and provisioner-independent files. Recipes (defined in cookbooks) are used to manage them. The chef-client is used to converge the individual nodes (machines) within the cluster.

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 resource in a recipe is as follows:

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

where

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

:allocate: Use to create a machine, return its machine identifier, and then (depending on the provider) boot the machine to an image. This reserves the machine with the provider and subsequent :allocate actions against this machine no longer need to create the machine, just update it.
:converge: Default. Use to create a machine, return its machine identifier, boot the machine to an image with the specified parameters and transport, install the chef-client, and then converge the machine.
:converge_only: Use to converge a machine, but only if the machine is in a ready state.
:destroy: Use to destroy a machine.
: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.
:ready: Use to create a machine, return its machine identifier, and then boot the machine to an image with the specified parameters and transport. This machine is in a ready state and may be connected to (via SSH or other transport).
:setup: Use to create a machine, return its machine identifier, boot the machine to an image with the specified parameters and transport, and then install the chef-client. This machine is in a ready state, has the chef-client installed, and all of the configuration data required to apply the run-list to the machine.
:stop: Use to stop a machine.

In-Parallel Processing¶

In certain situations Chef provisioning will run multiple machine processes in-parallel, as long as each of the individual machine resources have the same declared action. The machine_batch resource is used to run in-parallel processes.

Chef provisioning will processes resources in-parallel automatically, unless:

The recipe contains complex scripts, such as when a file resource sits in-between two machine resources in a single recipe. In this situation, the resources will be run sequentially
The actions specified for each individual machine resource are not identical; for example, if resource A is set to :converge and resource B is set to :destroy, then they may not be processed in-parallel

To disable in-parallel processing, add the auto_machine_batch setting to the client.rb file, and then set it to false.

For example, a recipe that looks like:

machine 'a'
machine 'b'
machine 'c'

will show output similar to:

$ CHEF_DRIVER=fog:AWS chef-apply cluster.rb
...
Converging 1 resources
Recipe: @recipe_files::/Users/jkeiser/oc/environments/metal-test-local/cluster.rb
  * machine_batch[default] action converge
    - [a] creating machine a on fog:AWS:862552916454
    - [a]   key_name: "metal_default"
    - [a]   tags: {"Name"=>"a", ...}
    - [a]   name: "a"
    - [b] creating machine b on fog:AWS:862552916454
    - [b]   key_name: "metal_default"
    - [b]   tags: {"Name"=>"b", ...}
    - [b]   name: "b"
    - [c] creating machine c on fog:AWS:862552916454
    - [c]   key_name: "metal_default"
    - [c]   tags: {"Name"=>"c", ...}
    - [c]   name: "c"
    - [b] machine b created as i-eb778fb9 on fog:AWS:862552916454
    - create node b at http://localhost:8889
    -   add normal.tags = nil
    -   add normal.metal = {"location"=>{"driver_url"=>"fog:AWS:862552916454", ...}}
    - [a] machine a created as i-e9778fbb on fog:AWS:862552916454
    - create node a at http://localhost:8889
    -   add normal.tags = nil
    -   add normal.metal = {"location"=>{"driver_url"=>"fog:AWS:862552916454", ...}}
    - [c] machine c created as i-816d95d3 on fog:AWS:862552916454
    - create node c at http://localhost:8889
    -   add normal.tags = nil
    -   add normal.metal = {"location"=>{"driver_url"=>"fog:AWS:862552916454", ...}}
    - [b] waiting for b (i-eb778fb9 on fog:AWS:862552916454) to be ready ...
    - [c] waiting for c (i-816d95d3 on fog:AWS:862552916454) to be ready ...
    - [a] waiting for a (i-e9778fbb on fog:AWS:862552916454) to be ready ...
...
        Running handlers:
        Running handlers complete

        Chef Client finished, 0/0 resources updated in 4.053363945 seconds
    - [c] run 'chef-client -l auto' on c

Running handlers:
Running handlers complete
Chef Client finished, 1/1 resources updated in 59.64014 seconds

At the end, it shows 1/1 resources updated. The three machine resources are replaced with a single machine_batch resource, which then runs each of the individual machine processes in-parallel.

Properties¶

This resource has the following properties:

admin

Ruby Type: true, false

Use to specify whether the chef-client is an API client.

allow_overwrite_keys

Ruby Type: true, false

Use to overwrite the key on a machine when it is different from the key specified by source_key.

attribute

Use to specify an attribute, and then modify that attribute with the specified value. The following patterns may be used to specify the value.

attribute <name>, <value>

attribute [<path>], <value>

The following example will set attribute a to b:

attribute 'a', 'b'

The following example will set attribute node['a']['b']['c'] to d and will ignore attributes a.b.x, a.b.y, etc.:

attribute %w[a b c], 'd'

The following example is similar to %w[a b c], 'd':

attribute 'a', { 'b' => { 'c' => 'd' } }

Each modified attribute should be specified individually. This attribute should not be used in the same recipe as attributes.

attributes

Use to specify a Hash that contains all of the normal attributes to be applied to a machine. This attribute should not be used in the same recipe as attribute.

chef_config

Ruby Type: String

Use to specify a string that contains extra configuration settings for a machine.

chef_environment

The name of the environment.

chef_server

Ruby Type: Hash

The URL for the Chef server.

complete

Use to specify if all of the normal attributes specified by this resource represent a complete specification of normal attributes for a machine. When true, any attributes not specified will be reset to their default values. For example, if a machine resource is empty and sets complete to true, all existing attributes will be reset:

machine "foo" do
  complete "true"
end

converge

Ruby Type: true, false

Use to manage convergence when used with the :create action. Set to false to prevent convergence. Set to true to force convergence. When nil, the machine will converge only if something changes.

driver

Ruby Type: Chef::Provisioning::Driver

Use to specify the URL for the driver to be used for provisioning.

files

Ruby Type: Hash

A list of files to upload. Syntax: REMOTE_PATH => LOCAL_PATH_OR_HASH.

For example:

files '/remote/path.txt' => '/local/path.txt'

or:

files '/remote/path.txt' => {
  :local_path => '/local/path.txt'
}

or:

files '/remote/path.txt' => { :content => 'foo' }

from_image

Ruby Type: String

Use to specify an image created by the machine_image resource.

ignore_failure

Ruby Type: true, false | Default Value: false

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

machine_options

Ruby Type: Hash

A Hash that is specifies driver options.

name

Ruby Type: String

The name of the machine.

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

ohai_hints

Ruby Type: Hash

An Ohai hint to be set on the target node. For example: 'ec2' => { 'a' => 'b' } creates file ec2.json with json contents { 'a': 'b' }.

private_key_options

Ruby Type: Hash

Use to generate a private key of the desired size, type, and so on.

public_key_format

Ruby Type: String | Default Value: pem

Use to specify the format of a public key. Possible values: pem and der.

public_key_path

Ruby Type: String

The path to a public key.

raw_json

The machine as JSON data. For example:

{
  "name": "node1",
  "chef_environment": "_default",
  "json_class": "Chef::Node",
  "automatic": {
    "languages": {
      "ruby": {
        ...
      },
    ...
  ...
}

recipe

Use to add a recipe to the run-list for a machine. Use this property multiple times to add multiple recipes to a run-list. Use this property along with role to define a run-list. The order in which the recipe and role properties are specified will determine the order in which they are added to the run-list. This property should not be used in the same recipe as run_list. For example:

recipe 'foo'
role 'bar'
recipe 'baz'

remove_recipe

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

remove_role

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

remove_tag

Use to remove a tag.

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. Use this property multiple times to add multiple roles to a run-list. Use this property along with recipe to define a run-list. The order in which the recipe and role properties are specified will determine the order in which they are added to the run-list. This property should not be used in the same recipe as run_list. For example:

recipe 'foo'
role 'bar'
recipe 'baz'

run_list

An array of strings that specifies the run-list to apply to a machine. This property should not be used in the same recipe as recipe and role. For example:

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

source_key

Use to copy a private key, but apply a different format and password. Use in conjunction with source_key_pass_phrase` and source_key_path.

source_key_pass_phrase

Ruby Type: String

The pass phrase for the private key. Use in conjunction with source_key` and source_key_path.

source_key_path

Ruby Type: String

The path to the private key. Use in conjunction with source_key` and source_key_pass_phrase.

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

tag

Use to add a tag.

tags

Use to add one (or more) tags. This will remove any tag currently associated with the machine. For example: tags :a, :b, :c.

validator

Ruby Type: true, false

Use to specify if the chef-client is a chef-validator.

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 machines dynamically

machine 'mario' do
  recipe 'postgresql'
  recipe 'mydb'
  tag 'mydb_master'
end

num_webservers = 1

1.upto(num_webservers) do |i|
  machine "luigi#{i}" do
    recipe 'apache'
    recipe 'mywebapp'
  end
end

Get a remote file onto a new machine

A deployment process requires more than just setting up machines. For example, files may need to be copied to machines from remote locations. The following example shows how to use the remote_file resource to grab a tarball from a URL, create a machine, copy that tarball to the machine, and then get that machine running by using a recipe that installs and configures that tarball on the machine:

remote_file 'mytarball.tgz' do
  url 'https://myserver.com/mytarball.tgz'
end

machine 'x'
  action :allocate
end

machine_file '/tmp/mytarball.tgz' do
  machine 'x'
  local_path 'mytarball.tgz'
  action :upload
end

machine 'x' do
  recipe 'untarthatthing'
  action :converge
end

Build machines that depend on each other

The following example shows how to create two identical machines, both of which cannot exist without the other. The first machine resource block creates the first machine by omitting the recipe that requires the other machine to be defined. The second resource block creates the second machine; because the first machine exists, both recipes can be run. The third resource block applies the second recipe to the first machine:

machine 'server_a' do
  recipe 'base_recipes'
end

machine 'server_b' do
  recipe 'base_recipes'
  recipe 'theserver'
end

machine 'server_a' do
  recipe 'theserver'
end

Use a loop to build many machines

1.upto(10) do |i|
  machine "hadoop#{i}" do
    recipe 'hadoop'
  end
end

Converge multiple machine types, in-parallel

The machine_batch resource can be used to converge multiple machine types, in-parallel, even if each machine type has different drivers. For example:

machine_batch do
  machine 'db' do
    recipe 'mysql'
  end
  1.upto(50) do |i|
    machine "#{web}#{i}" do
      recipe 'apache'
    end
  end
end

Define machine_options for a driver

require 'chef/provisioning_driver'

machine 'wario' do
  recipe 'apache'

  machine_options :driver_options => {
   :base_image => {
     :name => 'ubuntu',
     :repository => 'ubuntu',
     :tag => '14.04'
     },

   :command => '/usr/sbin/httpd'
  }

end

where provisioning_driver and :driver_options specify the actual driver that is being used to build the machine.

Build a machine from a machine image

machine_image 'web_image' do
  recipe 'apache2'
end

machine 'web_machine' do
 from_image 'web_image'
end

Set up a VPC, route table, key pair, and machine for Amazon AWS

require 'chef/provisioning/aws_driver'

with_driver 'aws::eu-west-1'

aws_vpc 'test-vpc' do
  cidr_block '10.0.0.0/24'
  internet_gateway true
end

aws_route_table 'ref-public1' do
  vpc 'test-vpc'
  routes '0.0.0.0/0' => :internet_gateway
end

aws_key_pair 'ref-key-pair'

m = machine 'test' do
  machine_options bootstrap_options: { key_name: 'ref-key-pair' }
end