Class: MkStack::Template

Inherits:
Object
  • Object
show all
Defined in:
lib/mkstack/template.rb

Overview

A CloudFormation template

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(format = 'json', argv = nil) ⇒ Template

Returns a new instance of Template.



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# File 'lib/mkstack/template.rb', line 36

def initialize(format = 'json', argv = nil)
  @format = format

  @sections = {
    'AWSTemplateFormatVersion' => Section.new('AWSTemplateFormatVersion', String, nil),
    'Description' => Section.new('Description', String, 1024),

    'Conditions' => Section.new('Conditions', Hash,  nil),
    'Mappings'   => Section.new('Mappings',   Hash,  200),
    'Metadata'   => Section.new('Metadata',   Hash,  nil),
    'Outputs'    => Section.new('Outputs',    Hash,  200),
    'Parameters' => Section.new('Parameters', Hash,  200),
    'Resources'  => Section.new('Resources',  Hash,  500),
    'Transform'  => Section.new('Transform',  Array, nil),
    'Rules'      => Section.new('Rules',      Hash,  nil),
  }
  @limit = 51_200

  # Keep track of parsed files to avoid loops
  @parsed = {}

  # Save a binding so ERB can reuse it instead of creating a new one
  # every time we load a file.  This allows ERB code in one file to
  # be referenced in another.
  @binding = binding
end

Instance Attribute Details

#format ⇒ Object (readonly)

Returns the value of attribute format.



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# File 'lib/mkstack/template.rb', line 34

def format
  @format
end

#limit ⇒ Object (readonly)

Returns the value of attribute limit.



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# File 'lib/mkstack/template.rb', line 34

def limit
  @limit
end

#sections ⇒ Object (readonly)

Returns the value of attribute sections.



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# File 'lib/mkstack/template.rb', line 34

def sections
  @sections
end

Instance Method Details

#[](section) ⇒ Object

Shorthand accessor for template sections



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# File 'lib/mkstack/template.rb', line 64

def [](section)
  @sections[section]
end

#exceeds_limit? ⇒ Boolean

Check if the template exceeds the AWS limit

Returns:

  • (Boolean) 


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# File 'lib/mkstack/template.rb', line 74

def exceeds_limit?
  limit && length > limit
end

#length ⇒ Object

Return the length of the entire template



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# File 'lib/mkstack/template.rb', line 69

def length
  to_json.to_s.length
end

#merge(file, erb) ⇒ Object

Merge contents of a file



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# File 'lib/mkstack/template.rb', line 81

def merge(file, erb)
  contents = load(file, erb)

  begin
    # Try JSON
    cfn = JSON.load(contents)
  rescue Exception => _e
    # Try YAML
    add_tags
    cfn = YAML.safe_load(contents, permitted_classes: [IntrinsicShort])
    @format = 'yaml'
  end

  # Check if there were any sections
  unless cfn
    $logger.debug { "no content in #{file}" }
    return
  end

  # Merge sections that are present in the file
  @sections.each do |name, section|
    section.merge(cfn[name]) if cfn[name]
  end

  # Look for Includes and merge them
  # Files are Included relative to the file with the Include directive
  cfn['Include'].each do |file|
    Dir.chdir(File.dirname(file)) { self.merge(File.basename(file), erb) }
  end if cfn['Include']
end

#pp ⇒ Object

Format contents



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# File 'lib/mkstack/template.rb', line 123

def pp
  case @format
  when 'json'
    to_hash.to_json
  when 'yaml'
    to_hash.to_yaml({ line_width: -1 }) # Keep Psych from splitting "long" lines
  else
    to_hash
  end
end

#validate ⇒ Object

Call ValidateTemplate



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# File 'lib/mkstack/template.rb', line 115

def validate
  require 'aws-sdk-cloudformation'
  Aws::CloudFormation::Client.new.validate_template({ template_body: pp })
end