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") ⇒ Template

Returns a new instance of Template.



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# File 'lib/mkstack/template.rb', line 13

def initialize(format = "json")
  @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, 100),
    "Metadata"    => Section.new("Metadata",    Hash, nil),
    "Outputs"     => Section.new("Outputs",     Hash, 60),
    "Parameters"  => Section.new("Parameters",  Hash, 60),
    "Resources"   => Section.new("Resources",   Hash, nil),
    "Transforms"  => Section.new("Transforms",  Hash, nil),
  }
  @limit = 51200

  # 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

  # See add_domain_types
  @yaml_domain = "mlfs.org,2019"
  @global_tag = "tag:#{@yaml_domain}:"
end

Instance Attribute Details

#format ⇒ Object (readonly)

Returns the value of attribute format.



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# File 'lib/mkstack/template.rb', line 11

def format
  @format
end

#limit ⇒ Object (readonly)

Returns the value of attribute limit.



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# File 'lib/mkstack/template.rb', line 11

def limit
  @limit
end

#sections ⇒ Object (readonly)

Returns the value of attribute sections.



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# File 'lib/mkstack/template.rb', line 11

def sections
  @sections
end

Instance Method Details

#[](section) ⇒ Object

Shorthand accessor for template sections



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# File 'lib/mkstack/template.rb', line 44

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 50

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 47

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 55

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

  begin
    # Try JSON
    cfn = JSON.load(contents)
  rescue Exception => e
    # Try YAML
    add_domain_types
    cfn = YAML.load(contents)
  end

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

  # 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 88

def pp
  case @format
  when "json"
    to_hash.to_json
  when "yaml"
    # Strip enclosing quotes around tags and revert tags to their short form
    # And keep Psych from splitting "long" lines
    to_hash.to_yaml({ line_width: -1 }).gsub(/"(#{@global_tag}[^"]+?)"/, '\1').gsub("#{@global_tag}", "!")
  else
    to_hash
  end
end

#validate ⇒ Object

Call ValidateTemplate



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# File 'lib/mkstack/template.rb', line 80

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