Class: AWS::CloudFormation

Inherits:
Object
  • Object
show all
Includes:
AWS::Core::ServiceInterface
Defined in:
lib/aws/cloud_formation.rb,
lib/aws/cloud_formation/stack.rb,
lib/aws/cloud_formation/client.rb,
lib/aws/cloud_formation/errors.rb,
lib/aws/cloud_formation/request.rb,
lib/aws/cloud_formation/stack_event.rb,
lib/aws/cloud_formation/stack_output.rb,
lib/aws/cloud_formation/stack_options.rb,
lib/aws/cloud_formation/stack_resource.rb,
lib/aws/cloud_formation/stack_collection.rb,
lib/aws/cloud_formation/stack_event_collection.rb,
lib/aws/cloud_formation/stack_summary_collection.rb,
lib/aws/cloud_formation/stack_resource_collection.rb,
lib/aws/cloud_formation/stack_resource_summary_collection.rb

Overview

AWS::CloudFormation

Provides an expressive, object-oriented interface to AWS CloudFormation.

Credentials

You can setup default credentials for all AWS services via AWS.config:

AWS.config(
  :access_key_id => 'YOUR_ACCESS_KEY_ID',
  :secret_access_key => 'YOUR_SECRET_ACCESS_KEY')

Or you can set them directly on the CloudFormation interface:

cf = AWS::CloudFormation.new(
  :access_key_id => 'YOUR_ACCESS_KEY_ID',
  :secret_access_key => 'YOUR_SECRET_ACCESS_KEY')

Stacks

This is the starting point for working with CloudFormation.

Creating a Stack

You can create a CloudFormation stack with a name and a template.

template = <<-TEMPLATE
{
  "AWSTemplateFormatVersion" : "2010-09-09",
  "Description": "A simple template",
  "Resources": {
    "web": {
      "Type": "AWS::EC2::Instance",
      "Properties": {
        "ImageId": "ami-41814f28"
      }
    }
  }
}
TEMPLATE

cfm = AWS::CloudFormation.new
stack = cfm.stacks.create('stack-name', template)

See StackCollection#create for more information on creating templates with capabilities and parameters.

Getting a Stack

Given a name, you can fetch a Stack.

stack = cfm.stacks['stack-name']

Enumerating Stacks

You can enumerate stacks in two ways. You can enumerate Stack objects or stack summaries (simple hashes). You can filter the stack summary collection by a status.

# enumerating all stack objects
cfm.stacks.each do |stack|
  # ...
end

# enumerating stack summaries (hashes)
cfm.stack_summaries.each do |stack_summary|
  # ...
end

# filtering stack summaries by status
cfm.stack_summaries.with_status(:create_failed).each do |summary|
  puts summary.to_yaml
end

Template

You can fetch the template body for a stack as a JSON string.

cfm.stacks['stack-name'].template
#=> "{...}"

You can update the template for a Stack with the Stack#update method:

cfm.stacks['stack-name'].update(:template => new_template)

Stack Events

You can enumerate events for a stack.

stack.events.each do |event|
  puts "#{event.physical_resource_id}: #{event.resource_status}"
end

See StackEvent for a complete list of event attributes.

Stack Resources

You can enumerate stack resources or request a stack resource by its logical resource id.

# enumerating stack resources
stack.resources.each do |resource|
  # ...
end

# getting a resource by its logical id
res = stack.resources['logical-resource-id']
puts res.physical_resource_id

If you need a stack resource, but only have its physical resource id, then you can call #stack_resource.

stack_resource = cfm.stack_resource('physical-resource-id')

Stack Resource Summaries

As an alternative to stack resources, you can enumerate stack resource summaries (hashes).

# enumerate all resources, this collection can not be filtered
stack.resource_summaries.each do |summary|
  # ...
end

Defined Under Namespace

Modules: Errors Classes: Client, Stack, StackCollection, StackEvent, StackEventCollection, StackOutput, StackResource, StackResourceCollection, StackResourceSummaryCollection, StackSummaryCollection

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods included from AWS::Core::ServiceInterface

included, #initialize, #inspect

Instance Attribute Details

#client ⇒ Client (readonly)

Returns the low-level CloudFormation client object.

Returns:

  • (Client) —

    the low-level CloudFormation client object



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# File 'lib/aws/cloud_formation.rb', line 146

class CloudFormation

  autoload :Client, 'aws/cloud_formation/client'
  autoload :Errors, 'aws/cloud_formation/errors'
  autoload :Request, 'aws/cloud_formation/request'
  autoload :Stack, 'aws/cloud_formation/stack'
  autoload :StackCollection, 'aws/cloud_formation/stack_collection'
  autoload :StackEvent, 'aws/cloud_formation/stack_event'
  autoload :StackEventCollection, 'aws/cloud_formation/stack_event_collection'
  autoload :StackOptions, 'aws/cloud_formation/stack_options'
  autoload :StackOutput, 'aws/cloud_formation/stack_output'
  autoload :StackSummaryCollection, 'aws/cloud_formation/stack_summary_collection'
  autoload :StackResource, 'aws/cloud_formation/stack_resource'
  autoload :StackResourceCollection, 'aws/cloud_formation/stack_resource_collection'
  autoload :StackResourceSummaryCollection, 'aws/cloud_formation/stack_resource_summary_collection'

  include Core::ServiceInterface
  include StackOptions

  endpoint_prefix 'cloudformation'

  # @return [StackCollection]
  def stacks
    StackCollection.new(:config => config)
  end

  # @return [StackSummaryCollection]
  def stack_summaries
    StackSummaryCollection.new(:config => config)
  end

  # Returns a stack resource with the given physical resource
  # id.
  #
  #     resource = cfm.stack_resource('i-123456789')
  #
  # Alternatively, you may pass a stack name and logical resource id:
  #
  #     resource = cfm.stack_resource('stack-name', 'logical-resource-id')
  #
  # @overload stack_resource(physical_resource_id)
  #   @param [String] physical_resource_id The physical resource id
  #     of the stack resource you want returned.
  #
  # @overload stack_resource(stack_name, logical_resource_id)
  #   @param [String] stack_name
  #   @param [String] logical_resource_id
  #
  # @return [StackResource] Returns the stack resource with the
  #   given physical resource id.
  #
  def stack_resource *args

    client_opts = {}

    if args.size == 1
      client_opts[:physical_resource_id] = args.first
    else
      client_opts[:stack_name] = args[0]
      client_opts[:logical_resource_id] = args[1]
    end

    response = client.describe_stack_resources(client_opts)

    details = response.stack_resources.first

    StackResource.new_from(
      :describe_stack_resource, details,
      Stack.new(details.stack_name, :config => config),
      details.logical_resource_id)

  end

  # Validates the template and returns a hash.  If the template is valid,
  # the returned hash may/will contain the following keys (actual
  # key list depends on the template).
  #
  #   * `:description`
  #   * `:capabilities`
  #   * `:capabilities_reason`
  #   * `:parameters`
  #
  # If the template is not parseable, then a hash will the following
  # keys will be returned:
  #
  #   * `:code`
  #   * `:message`
  #
  # @return [Hash]
  #
  def validate_template template
    begin

      client_opts = {}
      client_opts[:template] = template
      apply_template(client_opts)
      client.validate_template(client_opts).data

    rescue CloudFormation::Errors::ValidationError => e

      results = {}
      results[:code] = e.code
      results[:message] = e.message
      results

    end
  end

  # @param (see Stack#template=)
  #
  # @param [Hash] parameters A hash that specifies the input
  #   parameters for the template.
  #
  # @return [String] Returns a URL to the AWS Simple Monthly Calculator
  #   with a query string that describes the resources required to run
  #   the template.
  #
  def estimate_template_cost template, parameters = {}
    client_opts = {}
    client_opts[:template] = template
    client_opts[:parameters] = parameters
    apply_template(client_opts)
    apply_parameters(client_opts)
    client.estimate_template_cost(client_opts).url
  end

end

Instance Method Details

#estimate_template_cost(template, parameters = {}) ⇒ String

Returns a URL to the AWS Simple Monthly Calculator with a query string that describes the resources required to run the template.

Parameters:

  • parameters (Hash) (defaults to: {}) —

    A hash that specifies the input parameters for the template.

Returns:

  • (String) —

    Returns a URL to the AWS Simple Monthly Calculator with a query string that describes the resources required to run the template.



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# File 'lib/aws/cloud_formation.rb', line 263

def estimate_template_cost template, parameters = {}
  client_opts = {}
  client_opts[:template] = template
  client_opts[:parameters] = parameters
  apply_template(client_opts)
  apply_parameters(client_opts)
  client.estimate_template_cost(client_opts).url
end

#stack_resource(physical_resource_id) ⇒ StackResource #stack_resource(stack_name, logical_resource_id) ⇒ StackResource

Returns a stack resource with the given physical resource id.

resource = cfm.stack_resource('i-123456789')

Alternatively, you may pass a stack name and logical resource id:

resource = cfm.stack_resource('stack-name', 'logical-resource-id')

Overloads:

  • #stack_resource(physical_resource_id) ⇒ StackResource

    Parameters:

    • physical_resource_id (String) —

      The physical resource id of the stack resource you want returned.

  • #stack_resource(stack_name, logical_resource_id) ⇒ StackResource

    Parameters:

    • stack_name (String)
    • logical_resource_id (String)

Returns:

  • (StackResource) —

    Returns the stack resource with the given physical resource id.



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# File 'lib/aws/cloud_formation.rb', line 197

def stack_resource *args

  client_opts = {}

  if args.size == 1
    client_opts[:physical_resource_id] = args.first
  else
    client_opts[:stack_name] = args[0]
    client_opts[:logical_resource_id] = args[1]
  end

  response = client.describe_stack_resources(client_opts)

  details = response.stack_resources.first

  StackResource.new_from(
    :describe_stack_resource, details,
    Stack.new(details.stack_name, :config => config),
    details.logical_resource_id)

end

#stack_summaries ⇒ StackSummaryCollection

Returns:



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# File 'lib/aws/cloud_formation.rb', line 173

def stack_summaries
  StackSummaryCollection.new(:config => config)
end

#stacks ⇒ StackCollection

Returns:



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# File 'lib/aws/cloud_formation.rb', line 168

def stacks
  StackCollection.new(:config => config)
end

#validate_template(template) ⇒ Hash

Validates the template and returns a hash. If the template is valid, the returned hash may/will contain the following keys (actual key list depends on the template).

  • :description
  • :capabilities
  • :capabilities_reason
  • :parameters

If the template is not parseable, then a hash will the following keys will be returned:

  • :code
  • :message

Returns:

  • (Hash) 


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# File 'lib/aws/cloud_formation.rb', line 236

def validate_template template
  begin

    client_opts = {}
    client_opts[:template] = template
    apply_template(client_opts)
    client.validate_template(client_opts).data

  rescue CloudFormation::Errors::ValidationError => e

    results = {}
    results[:code] = e.code
    results[:message] = e.message
    results

  end
end