add field setting with default of type

docs/index.asciidoc

@@ -21,7 +21,8 @@ include::{include_path}/plugin_header.asciidoc[]
 ==== Description
 
 The clone filter is for duplicating events.
-A clone will be created for each type in the clone list.
+A clone will be created for each value in the clone list.
+By default `clones` values overwrite the `type` field, or you can specify an optional `field`.
 The original event is left unchanged.
 Created events are inserted into the pipeline 
 as normal events and will be processed by the remaining pipeline configuration 
@@ -36,6 +37,7 @@ This plugin supports the following configuration options plus the <<plugins-{typ
 |=======================================================================
 |Setting |Input type|Required
 | <<plugins-{type}s-{plugin}-clones>> |<<array,array>>|Yes
+| <<plugins-{type}s-{plugin}-field>> |<<string,string>>|No
 |=======================================================================
 
 Also see <<plugins-{type}s-{plugin}-common-options>> for a list of options supported by all
@@ -50,10 +52,36 @@ filter plugins.
   * Value type is <<array,array>>
   * There is no default value for this setting.
 
-A new clone will be created with the given type for each type in this list.
+A new clone will be created with the given value for each field in this list.
+
+Example:
+[source,ruby]
+   filter { 
+     clone {
+       clones => [ "clone1", "clone2" ]
+     }
+   }
 
 Note: setting an empty array will not create any clones. A warning message is logged.
 
+[id="plugins-{type}s-{plugin}-fields"]
+===== `field`
+
+  * Value type is <<string,string>>
+  * Default value is `type`
+
+Specify the field into which `clones` values will be added.
+
+Example:
+[source,ruby]
+   filter { 
+     clone {
+       field => "clone"
+       clones => [ "clone1", "clone2" ]
+     }
+   }
+
 
 [id="plugins-{type}s-{plugin}-common-options"]
 include::{include_path}/{type}.asciidoc[]
+

lib/logstash/filters/clone.rb

@@ -13,6 +13,7 @@ class LogStash::Filters::Clone < LogStash::Filters::Base
   config_name "clone"
 
   # A new clone will be created with the given type for each type in this list.
+  config :field, :validate => :string, :required => false, :default => "type"
   config :clones, :validate => :array, :required => true
 
   public
@@ -22,9 +23,9 @@ def register
 
   public
   def filter(event)
-    @clones.each do |type|
+    @clones.each do |value|
       clone = event.clone
-      clone.set("type", type)
+      clone.set(field,value)
       filter_matched(clone)
       @logger.debug("Cloned event", :clone => clone, :event => event)
 

spec/filters/clone_spec.rb

@@ -62,6 +62,28 @@
     end
   end
 
+  describe "Other Field" do
+    config <<-CONFIG
+      filter {
+        clone {
+          field => "clone"
+          clones => ["clone1", "clone2"]
+        }
+      }
+    CONFIG
+
+    sample("message" => "hello world", "type" => "original") do
+      insist { subject }.is_a? Array
+      insist { subject.length } == 3
+      insist { subject[1].get("clone") } == "clone1"
+      insist { subject[2].get("clone") } == "clone2"
+      subject.each do |s|
+        insist { s.get("type") } == "original"
+        insist { s.get("message") } == "hello world"
+      end
+    end
+  end
+
   describe "Bug LOGSTASH-1225" do
     ### LOGSTASH-1225: Cannot clone events containing numbers.
     config <<-CONFIG