added header option

lib/logstash/outputs/csv.rb

@@ -26,17 +26,28 @@ class LogStash::Outputs::CSV < LogStash::Outputs::File
   # may not make the values safe in your spreadsheet application
   config :spreadsheet_safe, :validate => :boolean, :default => true
 
+  # Optional headers to add to the CSV file once it's generated.
+  config :headers, :validate => :string
+
   public
   def register
     super
-    @csv_options = Hash[@csv_options.map{|(k, v)|[k.to_sym, v]}]
+    @csv_options = Hash[@csv_options.map{|(k, v)|[k.to_sym, v]}]   
+
+    if headers 
+      @csv_options[:headers] = headers
+    end
   end
 
   public
   def receive(event)
 
     path = event.sprintf(@path)
+
+    @csv_options[:write_headers] = !File.exist?(path) || File.zero?(path)
+
     fd = open(path)
+
     csv_values = @fields.map {|name| get_value(name, event)}
     fd.write(csv_values.to_csv(@csv_options))
 

spec/outputs/csv_spec.rb

@@ -315,4 +315,34 @@
     end
   end
 
+  describe "can turn on headers" do
+    tmpfile = Tempfile.new('logstash-spec-output-csv')
+    config <<-CONFIG
+      input {
+        generator {
+          add_field => ["foo","1+1", "baz", "=1+1"]
+          count => 2
+        }
+      }
+      output {
+        csv {
+          path => "#{tmpfile.path}"
+          spreadsheet_safe => false
+          fields => ["foo", "baz"]
+          headers => "header1,header2"
+        }
+      }
+    CONFIG
+
+    agent do
+      lines = CSV.read(tmpfile.path, :headers => true)
+      print lines
+      insist {lines.headers[0]} == "header1"
+      insist {lines.headers[1]} == "header2"
+      insist {lines.count} == 2
+      insist {lines[0][0]} == "1+1"
+      insist {lines[0][1]} == "=1+1"
+    end
+  end
+
 end