Class: ChefMetal::Driver

Inherits:
Object
  • Object
show all
Defined in:
lib/chef_metal/driver.rb

Overview

A Driver instance represents a place where machines can be created and found, and contains methods to create, delete, start, stop, and find them.

For AWS, a Driver instance corresponds to a single account. For Vagrant, it is a directory where VM files are found.

How to Make a Driver

To implement a Driver, you must implement the following methods:

  • initialize(driver_url) - create a new driver with the given URL

  • driver_url - a URL representing everything unique about your driver.

    But NOT credentials.

  • allocate_machine - ask the driver to allocate a machine to you.

  • ready_machine - get the machine “ready” - wait for it to be booted and

    accessible (for example, accessible via SSH transport).

  • stop_machine - stop the machine.

  • destroy_machine - delete the machine.

  • connect_to_machine - connect to the given machine.

Optionally, you can also implement:

  • allocate_machines - allocate an entire group of machines.

  • ready_machines - get a group of machines warm and booted.

  • stop_machines - stop a group of machines.

  • destroy_machines - delete a group of machines.

Additionally, you must create a file named ‘chef_metal/driver_init/<scheme>.rb`, where <scheme> is the name of the scheme you chose for your driver_url. This file, when required, must call ChefMetal.add_registered_driver(<scheme>, <class>). The given <class>.from_url(url, config) will be called with a driver_url and configuration.

All of these methods must be idempotent - if the work is already done, they just don’t do anything.

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(driver_url, config) ⇒ Driver

Inflate a driver from a driver URL.

Parameters

driver_url - the URL to inflate the driver config - a configuration hash. See “config” for a list of known keys.

Returns

A Driver representing the given driver_url.



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# File 'lib/chef_metal/driver.rb', line 49

def initialize(driver_url, config)
  @driver_url = driver_url
  @config = config
end

Instance Attribute Details

#config ⇒ Object (readonly)

A configuration hash. These keys may be present:

- :driver_options: a driver-defined object containing driver config.
- :private_keys: a hash of private keys, with a "name" and a "value".  Values are either strings (paths) or PrivateKey objects.
- :private_key_paths: a list of paths to directories containing private keys.
- :write_private_key_path: the path to which we write new keys by default.
- :log_level: :debug/:info/:warn/:error/:fatal
- :chef_server_url: url to chef server
- :node_name: username to talk to chef server
- :client_key: path to key used to talk to chef server



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# File 'lib/chef_metal/driver.rb', line 86

def config
  @config
end

#driver_url ⇒ Object (readonly)

A URL representing the driver and the place where machines come from. This will be stuffed in machine_spec.location so that the machine can be reinflated. URLs must have a unique scheme identifying the driver class, and enough information to identify the place where created machines can be found. For AWS, this is the account number; for lxc and vagrant, it is the directory in which VMs and containers are.

For example:

  • fog:AWS:123456789012

  • vagrant:/var/vms

  • lxc:

  • docker:



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# File 'lib/chef_metal/driver.rb', line 75

def driver_url
  @driver_url
end

Class Method Details

.from_url(driver_url, config) ⇒ Object

Override this on specific driver classes



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# File 'lib/chef_metal/driver.rb', line 57

def self.from_url(driver_url, config)
  ChefMetal.from_url(driver_url, config)
end

Instance Method Details

#allocate_machine(action_handler, machine_spec, machine_options) ⇒ Object

Allocate a machine from the PXE/cloud/VM/container driver. This method does not need to wait for the machine to boot or have an IP, but it must store enough information in machine_spec.location to find the machine later in ready_machine.

If a machine is powered off or otherwise unusable, this method may start it, but does not need to wait until it is started. The idea is to get the gears moving, but the job doesn’t need to be done :)

## Parameters action_handler - the action_handler object that is calling this method; this

is generally a driver, but could be anything that can support the
interface (i.e., in the case of the test kitchen metal driver for
acquiring and destroying VMs).

existing_machine - a MachineSpec representing the existing machine (if any).

machine_options - a set of options representing the desired provisioning

state of the machine (image name, bootstrap ssh credentials,
etc.). This will NOT be stored in the machine_spec, and is
ephemeral.

## Returns

Modifies the passed-in machine_spec. Anything in here will be saved back after allocate_machine completes.



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# File 'lib/chef_metal/driver.rb', line 123

def allocate_machine(action_handler, machine_spec, machine_options)
  raise "#{self.class} does not implement allocate_machine"
end

#allocate_machines(action_handler, specs_and_options, parallelizer) ⇒ Object

Allocate a set of machines. This should have the same effect as running allocate_machine on all machine_specs.

Drivers do not need to implement this; the default implementation calls acquire_machine in parallel.

## Parameters action_handler - the action_handler object that is calling this method; this

is generally a driver, but could be anything that can support the
interface (i.e., in the case of the test kitchen metal driver for
acquiring and destroying VMs).

specs_and_options - a hash of machine_spec -> machine_options representing the

machines to allocate.

parallelizer - an object with a parallelize() method that works like this:

parallelizer.parallelize(specs_and_options) do |machine_spec|
  allocate_machine(action_handler, machine_spec)
end.to_a
# The to_a at the end causes you to wait until the parallelization is done

This object is shared among other chef-metal actions, ensuring that you do not go over parallelization limits set by the user. Use of the parallelizer to parallelizer machines is not required.

## Block

If you pass a block to this function, each machine will be yielded to you as it completes, and then the function will return when all machines are yielded.

allocate_machines(action_handler, specs_and_options, parallelizer) do |machine_spec|
  ...
end



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# File 'lib/chef_metal/driver.rb', line 224

def allocate_machines(action_handler, specs_and_options, parallelizer)
  parallelizer.parallelize(specs_and_options) do |machine_spec, machine_options|
    allocate_machine(add_prefix(machine_spec, action_handler), machine_spec, machine_options)
    yield machine_spec if block_given?
    machine_spec
  end.to_a
end

#connect_to_machine(machine_spec, machine_options) ⇒ Object

Connect to a machine without allocating or readying it. This method will NOT make any changes to anything, or attempt to wait.

## Parameters machine_spec - MachineSpec representing this machine.

## Returns

Machine object pointing at the machine, allowing useful actions like setup, converge, execute, file and directory.



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# File 'lib/chef_metal/driver.rb', line 166

def connect_to_machine(machine_spec, machine_options)
  raise "#{self.class} does not implement connect_to_machine"
end

#destroy_machine(action_handler, machine_spec, machine_options) ⇒ Object

Delete the given machine (idempotent). Should destroy the machine, returning things to the state before allocate_machine was called.



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# File 'lib/chef_metal/driver.rb', line 174

def destroy_machine(action_handler, machine_spec, machine_options)
  raise "#{self.class} does not implement destroy_machine"
end

#destroy_machines(action_handler, specs_and_options, parallelizer) ⇒ Object

Delete machines in batch, in parallel if possible.



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# File 'lib/chef_metal/driver.rb', line 250

def destroy_machines(action_handler, specs_and_options, parallelizer)
  parallelizer.parallelize(specs_and_options) do |machine_spec, machine_options|
    destroy_machine(add_prefix(machine_spec, action_handler), machine_spec, machine_options)
    yield machine_spec if block_given?
  end.to_a
end

#driver_options ⇒ Object

Driver configuration. Equivalent to config || {}



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# File 'lib/chef_metal/driver.rb', line 91

def driver_options
  config[:driver_options] || {}
end

#ready_machine(action_handler, machine_spec, machine_options) ⇒ Object

Ready a machine, to the point where it is running and accessible via a transport. This will NOT allocate a machine, but may kick it if it is down. This method waits for the machine to be usable, returning a Machine object pointing at the machine, allowing useful actions like setup, converge, execute, file and directory.

## Parameters action_handler - the action_handler object that is calling this method; this

is generally a driver, but could be anything that can support the
interface (i.e., in the case of the test kitchen metal driver for
acquiring and destroying VMs).

machine_spec - MachineSpec representing this machine. machine_options - a set of options representing the desired provisioning

state of the machine (image name, bootstrap ssh credentials,
etc.). This will NOT be stored in the machine_spec, and is
ephemeral.

## Returns

Machine object pointing at the machine, allowing useful actions like setup, converge, execute, file and directory.



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# File 'lib/chef_metal/driver.rb', line 150

def ready_machine(action_handler, machine_spec, machine_options)
  raise "#{self.class} does not implement ready_machine"
end

#ready_machines(action_handler, specs_and_options, parallelizer) ⇒ Object

Ready machines in batch, in parallel if possible.



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# File 'lib/chef_metal/driver.rb', line 233

def ready_machines(action_handler, specs_and_options, parallelizer)
  parallelizer.parallelize(specs_and_options) do |machine_spec, machine_options|
    machine = ready_machine(add_prefix(machine_spec, action_handler), machine_spec, machine_options)
    yield machine if block_given?
    machine
  end.to_a
end

#stop_machine(action_handler, machine_spec, machine_options) ⇒ Object

Stop the given machine.



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# File 'lib/chef_metal/driver.rb', line 181

def stop_machine(action_handler, machine_spec, machine_options)
  raise "#{self.class} does not implement stop_machine"
end

#stop_machines(action_handler, specs_and_options, parallelizer) ⇒ Object

Stop machines in batch, in parallel if possible.



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# File 'lib/chef_metal/driver.rb', line 242

def stop_machines(action_handler, specs_and_options, parallelizer)
  parallelizer.parallelize(specs_and_options) do |machine_spec, machine_options|
    stop_machine(add_prefix(machine_spec, action_handler), machine_spec, machine_options)
    yield machine_spec if block_given?
  end.to_a
end