Add i18n filter with trasliterate support

lib/logstash/filters/i18n.rb

@@ -0,0 +1,51 @@
+# encoding: utf-8
+require "i18n"
+require "logstash/filters/base"
+require "logstash/namespace"
+
+# The i18n filter allows you to remove special characters from
+# from a field
+class LogStash::Filters::I18n < LogStash::Filters::Base
+  config_name "i18n"
+  milestone 0
+
+  # Replaces non-ASCII characters with an ASCII approximation, or
+  # if none exists, a replacement character which defaults to “?”
+  #
+  # Example:
+  #
+  #     filter {
+  #       i18n {
+  #          transliterate => ["field1", "field2"]
+  #       }
+  #     }
+  config :transliterate, :validate => :array
+
+  public
+  def register
+  end # def register
+
+  public
+  def filter(event)
+    return unless filter?(event)
+
+    transliterate(event) if @transliterate
+
+    filter_matched(event)
+  end # def filter
+
+  private
+  def transliterate(event)
+    @transliterate.each do |field|
+      if event[field].is_a?(Array)
+        event[field].map! { |v| I18n.transliterate(v).encode('UTF-8') }
+      elsif event[field].is_a?(String)
+        event[field] = I18n.transliterate(event[field].encode('UTF-8'))
+      else
+        @logger.debug("Can't transliterate something that isn't a string",
+                      :field => field, :value => event[field])
+      end
+    end
+  end # def transliterate
+
+end # class LogStash::Filters::I18n

spec/filters/i18n.rb

@@ -0,0 +1,25 @@
+# encoding: utf-8
+require "test_utils"
+require "logstash/filters/i18n"
+
+describe LogStash::Filters::I18n do
+  extend LogStash::RSpec
+
+  describe "transliterate" do
+    config <<-CONFIG
+      filter {
+        i18n {
+          transliterate => [ "transliterateme" ]
+        }
+      }
+    CONFIG
+
+    event = {
+      "transliterateme" => [ "Ærøskøbing" ]
+    }
+
+    sample event do
+      insist { subject["transliterateme"] } == [ "AEroskobing" ]
+    end
+  end
+end