Module: References

Defined in:
lib/cfn-model/model/references.rb

Overview

this is a placeholder for anything related to resolving references

not sure if we are going to be able to have a useful generic set of code for references yet… in the meantime pile things up here and hope a pattern becomes clear

Class Method Summary collapse

Class Method Details

.is_security_group_id_external(group_id) ⇒ Object 



62
63
64
 
# File 'lib/cfn-model/model/references.rb', line 62

def self.is_security_group_id_external(group_id)
  resolve_security_group_id(group_id).nil?
end

.resolve_map(cfn_model, find_in_map) ⇒ Object

Try to compute the FindInMap against a real Mapping

If anything doesn’t match up - either a syntax error, a missing Mapping, or some other kind Cfn evaluation we don’t understand, just return the call to FindInMap



76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
 
# File 'lib/cfn-model/model/references.rb', line 76

def self.resolve_map(cfn_model, find_in_map)
  map_name = find_in_map['Fn::FindInMap'][0]
  top_level_key = find_in_map['Fn::FindInMap'][1]
  second_level_key = find_in_map['Fn::FindInMap'][2]

  map = cfn_model.mappings[map_name]

  return find_in_map if map.nil?

  top_level_resolved = resolve_value(cfn_model, top_level_key)

  return find_in_map if !map.has_key?(top_level_resolved)

  top_level = map[top_level_resolved]
  second_level = top_level[resolve_value(cfn_model, second_level_key)]

  return find_in_map if second_level.nil?

  second_level
end

.resolve_reference(cfn_model, value) ⇒ Object

For a !Ref to another resource.… just returns the !REf For a !Ref to a Parameter, then try to synthesize the value



30
31
32
33
34
35
36
37
38
39
40
41
42
 
# File 'lib/cfn-model/model/references.rb', line 30

def self.resolve_reference(cfn_model, value)
  ref_id = value['Ref']
  if ref_id.is_a? String
    if cfn_model.parameters.has_key?(ref_id)
      return value if cfn_model.parameters[ref_id].synthesized_value.nil?
      return cfn_model.parameters[ref_id].synthesized_value
    else
      return value
    end
  else
    value
  end
end

.resolve_resource_id(reference, attr = nil) ⇒ Object 



44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
 
# File 'lib/cfn-model/model/references.rb', line 44

def self.resolve_resource_id(reference, attr = nil)
  return nil if reference.is_a? String

  # an imported value can only yield a literal to an external resource vs. referencing something local
  if !reference['Ref'].nil?
    reference['Ref']
  elsif !reference['Fn::GetAtt'].nil?
    logical_resource_id_from_get_att reference['Fn::GetAtt'], attr
  else
    # anything else will be string manipulation functions
    # which again leads us back to a string which must be an external resource known out of band
    # so don't/can't link it up
    return nil
  end
rescue NoMethodError => e
  raise ParserError, e.inspect
end

.resolve_security_group_id(group_id) ⇒ Object 



66
67
68
 
# File 'lib/cfn-model/model/references.rb', line 66

def self.resolve_security_group_id(group_id)
  resolve_resource_id group_id, 'GroupId'
end

.resolve_value(cfn_model, value) ⇒ Object 



12
13
14
15
16
17
18
19
20
21
22
23
24
25
 
# File 'lib/cfn-model/model/references.rb', line 12

def self.resolve_value(cfn_model, value)

  if value.is_a? Hash
    if value.has_key?('Ref')
      resolve_reference(cfn_model, value)
    elsif value.has_key?('Fn::FindInMap')
      resolve_map(cfn_model, value)
    else
      value
    end
  else
    value
  end
end