A way to prevent accidental leaking of sensitive data

sensitive.rb

class Sensitive
  @@being_responsible = false

  def initialize(value)
    @value = value
  end

  def to_s
    @@being_responsible ? @value : '[REDACTED]'
  end

  def inspect
    @@being_responsible ? super : '[REDACTED]'
  end

  def self.responsibly
    @@being_responsible = true
    yield
  ensure
    @@being_responsible = false
  end
end

require 'json'

s = Sensitive.new('super secret')

puts s
puts s.to_json
puts s.inspect

Sensitive.responsibly do
  puts s
  puts s.to_json
  puts s.inspect
end

puts s
puts s.to_json
puts s.inspect

Sensitive data such as credit card numbers or passwords can accidentally leak into logs (e.g. through diagnostic logging) when a log filtering mechanism is not in place. By wrapping sensitive data in a class that requires a special contract to return the actual data, these accidents can be reduced, if not completely prevented.

Output:

[REDACTED]
"[REDACTED]"
[REDACTED]
super secret
"super secret"
#<Sensitive:0x00007f7f7a069dd8 @value="super secret">
[REDACTED]
"[REDACTED]"
[REDACTED]