Class: Lono::Template

Inherits:
Object
  • Object
show all
Includes:
ERB::Util
Defined in:
lib/lono/template.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(name, block, options = {}) ⇒ Template

Returns a new instance of Template.



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# File 'lib/lono/template.rb', line 10

def initialize(name, block, options={})
  @name = name
  @block = block
  @options = options
end

Instance Attribute Details

#name ⇒ Object (readonly)

Returns the value of attribute name.



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# File 'lib/lono/template.rb', line 9

def name
  @name
end

Instance Method Details

#base64(value) ⇒ Object 



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# File 'lib/lono/template.rb', line 101

def base64(value)
  %Q|{"Fn::Base64"=>"#{value}"}|
end

#bracket_positions(line) ⇒ Object

Input:

String

Output:

Array of parse positions

The positions of tokens taking into account when brackets start and close, handles nested brackets.



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# File 'lib/lono/template.rb', line 143

def bracket_positions(line)
  positions,pair,count = [],[],0

  line.split('').each_with_index do |char,i|
    pair << i if pair.empty?

    first_pair_char = line[pair[0]]
    if first_pair_char == '{' # object logic
      if char == '{'
        count += 1
      end

      if char == '}'
        count -= 1
        if count == 0
          pair << i
          positions << pair
          pair = []
        end
      end
    else # string logic
      lookahead = line[i+1]
      if lookahead == '{'
        pair << i
        positions << pair
        pair = []
      end
    end
  end # end of loop

  # for string logic when lookahead does not contain a object token
  # need to clear out what's left to match the final pair
  if !pair.empty?
    pair << line.size - 1
    positions << pair
  end

  positions
end

#build ⇒ Object 



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# File 'lib/lono/template.rb', line 16

def build
  instance_eval(&@block)
  template = IO.read(@source)
  erb_result(@source, template)
end

#cfn_object?(s) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/lono/template.rb', line 230

def cfn_object?(s)
  exact = %w[Ref]
  pattern = %w[Fn::]
  exact_match = !!exact.detect {|word| s.include?(word)}
  pattern_match = !!pattern.detect {|p| s =~ Regexp.new(p)}
  (exact_match || pattern_match) && s =~ /^{/ && s =~ /=>/
end

#decompose(line) ⇒ Object

Input

String line of code to decompose into chunks, some can be transformed into objects

Output

Array of strings, some can be transformed into objects

Example: line = ‘abcd{dd}e’ # nested brackets template.decompose(line).should == [‘a’,‘b’,‘c’,‘d{dd}’,‘e’]



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# File 'lib/lono/template.rb', line 200

def decompose(line)
  positions = parse_positions(line)
  return [line] if positions.empty?

  result = []
  str = ''
  until positions.empty?
    left = positions.shift
    right = positions.shift
    token = line[left..right]
    # if cfn object, add to the result set but after clearing out
    # the temp str that is being built up when the token is just a string
    if cfn_object?(token)
      unless str.empty? # first token might be a object
        result << str
        str = ''
      end
      result << token
    else
      str << token # keeps building up the string
    end
  end

  # at the of the loop there's a leftover string, unless the last token
  # is an object
  result << str unless str.empty?

  result
end

#encode_base64(text) ⇒ Object

For simple just parameters files that can also be generated with lono, the CFN Fn::Base64 function is not available and as lono is not being used in the context of CloudFormation. So this can be used in it’s place.



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# File 'lib/lono/template.rb', line 249

def encode_base64(text)
  Base64.strict_encode64(text).strip
end

#erb_result(path, template) ⇒ Object 



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# File 'lib/lono/template.rb', line 48

def erb_result(path, template)
  begin
    ERB.new(template, nil, "-").result(binding)
  rescue Exception => e
    puts e

    # how to know where ERB stopped? - https://www.ruby-forum.com/topic/182051
    # syntax errors have the (erb):xxx info in e.message
    # undefined variables have (erb):xxx info in e.backtrac
    error_info = e.message.split("\n").grep(/\(erb\)/)[0]
    error_info ||= e.backtrace.grep(/\(erb\)/)[0]
    raise unless error_info # unable to find the (erb):xxx: error line
    line = error_info.split(':')[1].to_i
    puts "Error evaluating ERB template on line #{line.to_s.colorize(:red)} of: #{path.sub(/^\.\//, '')}"

    template_lines = template.split("\n")
    context = 5 # lines of context
    top, bottom = [line-context, 0].max, line+context
    spacing = template_lines.size.to_s.size
    template_lines[top..bottom].each_with_index do |line_content, index|
      line_number = top+index+1
      if line_number == line
        printf("%#{spacing}d %s\n".colorize(:red), line_number, line_content)
      else
        printf("%#{spacing}d %s\n", line_number, line_content)
      end
    end
    exit 1 unless ENV['TEST']
  end
end

#evaluate(line) ⇒ Object 



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# File 'lib/lono/template.rb', line 242

def evaluate(line)
  recompose(decompose(line))
end

#find_in_map(*args) ⇒ Object 



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# File 'lib/lono/template.rb', line 97

def find_in_map(*args)
  %Q|{"Fn::FindInMap" => [ #{transform_array(args)} ]}|
end

#get_att(*args) ⇒ Object 



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# File 'lib/lono/template.rb', line 105

def get_att(*args)
  %Q|{"Fn::GetAtt" => [ #{transform_array(args)} ]}|
end

#get_azs(region = "AWS::Region") ⇒ Object 



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# File 'lib/lono/template.rb', line 109

def get_azs(region="AWS::Region")
  %Q|{"Fn::GetAZs"=>"#{region}"}|
end

#indent(result, indentation_amount) ⇒ Object

add indentation



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# File 'lib/lono/template.rb', line 42

def indent(result, indentation_amount)
  result.split("\n").map do |line|
    " " * indentation_amount + line
  end.join("\n")
end

#join(delimiter, values) ⇒ Object 



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# File 'lib/lono/template.rb', line 113

def join(delimiter, values)
  %Q|{"Fn::Join" => ["#{delimiter}", [ #{transform_array(values)} ]]}|
end

#parse_positions(line) ⇒ Object

Input:

Array - bracket_positions

Ouput:

Array - positions that can be use to determine what to parse



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# File 'lib/lono/template.rb', line 187

def parse_positions(line)
  positions = bracket_positions(line)
  positions.flatten
end

#partial(path, vars = {}, options = {}) ⇒ Object 



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# File 'lib/lono/template.rb', line 32

def partial(path,vars={}, options={})
  path = "#{@options[:project_root]}/templates/partial/#{path}"
  template = IO.read(path)
  variables(vars)
  result = erb_result(path, template)
  result = indent(result, options[:indent]) if options[:indent]
  result
end

#recompose(decomposition) ⇒ Object 



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# File 'lib/lono/template.rb', line 238

def recompose(decomposition)
  decomposition.map { |s| cfn_object?(s) ? eval(s) : s }
end

#ref(name) ⇒ Object 



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# File 'lib/lono/template.rb', line 93

def ref(name)
  %Q|{"Ref"=>"#{name}"}|
end

#select(index, list) ⇒ Object 



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# File 'lib/lono/template.rb', line 117

def select(index, list)
  %Q|{"Fn::Select" => ["#{index}", [ #{transform_array(list)} ]]}|
end

#source(path) ⇒ Object 



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# File 'lib/lono/template.rb', line 22

def source(path)
  @source = path[0..0] == '/' ? path : "#{@options[:project_root]}/templates/#{path}"
end

#transform(data) ⇒ Object

transform each line of bash script to array with cloudformation template objects



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# File 'lib/lono/template.rb', line 127

def transform(data)
  data = evaluate(data)
  if data[-1].is_a?(String)
    data[0..-2] + ["#{data[-1]}\n"]
  else
    data + ["\n"]
  end
end

#transform_array(arr) ⇒ Object 



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# File 'lib/lono/template.rb', line 121

def transform_array(arr)
  arr.map! {|x| x =~ /=>/ ? x : x.inspect }
  arr.join(',')
end

#user_data(path, vars = {}) ⇒ Object 



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# File 'lib/lono/template.rb', line 79

def user_data(path, vars={})
  path = "#{@options[:project_root]}/templates/user_data/#{path}"
  template = IO.read(path)
  variables(vars)
  result = erb_result(path, template)
  output = []
  result.split("\n").each do |line|
    output += transform(line)
  end
  json = output.to_json
  json[0] = '' # remove first char: [
  json.chop!   # remove last char:  ]
end

#variables(vars = {}) ⇒ Object 



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# File 'lib/lono/template.rb', line 26

def variables(vars={})
  vars.each do |var,value|
    instance_variable_set("@#{var}", value)
  end
end