Support custom headers

lib/logstash/outputs/email.rb

@@ -96,6 +96,9 @@ class LogStash::Outputs::Email < LogStash::Outputs::Base
   # NOTE: this may not be functional (KH)
   config :contenttype, :validate => :string, :default => "text/html; charset=UTF-8"
 
+  # Custom headers to attach to the email
+  config :custom_headers, :validate => :hash, :default => {}
+
   public
   def register
     require "mail"
@@ -133,7 +136,7 @@ def register
   def receive(event)
 
 
-      @logger.debug? and @logger.debug("Creating mail with these settings : ", :via => @via, :options => @options, :from => @from, :to => @to, :cc => @cc, :bcc => @bcc, :subject => @subject, :body => @body, :content_type => @contenttype, :htmlbody => @htmlbody, :attachments => @attachments)
+      @logger.debug? and @logger.debug("Creating mail with these settings : ", :via => @via, :options => @options, :from => @from, :to => @to, :cc => @cc, :bcc => @bcc, :subject => @subject, :body => @body, :content_type => @contenttype, :htmlbody => @htmlbody, :attachments => @attachments, :custom_headers => @custom_headers)
       formatedSubject = event.sprintf(@subject)
       formattedBody = event.sprintf(@body)
       formattedHtmlBody = event.sprintf(@htmlbody)
@@ -148,6 +151,10 @@ def receive(event)
       mail.bcc = event.sprintf(@bcc)
       mail.subject = formatedSubject
 
+      @custom_headers.each do |key, value|
+        mail.header[event.sprintf(key)] = event.sprintf(value)
+      end
+
       if @htmlbody.empty? and @template_file.nil?
         formattedBody.gsub!(/\\n/, "\n") # Take new line in the email
         mail.body = formattedBody

spec/outputs/email_spec.rb

@@ -104,5 +104,22 @@
         expect(message_observer.messages[0].body.decoded).to eq(craft_multi_part_email('', '<h1>hello</h1>', message_observer.messages[0].content_type))
       end
     end
+
+    context  "custom headers for email" do
+      it "adds custom headers" do
+        headers = { "header_1" => "header_1_value", "header_2" => "header_2_value" } 
+        subject = plugin.new("to" => "me@host",
+                     "subject" => "Hello World",
+                     "body" => "Line1\\nLine2\\nLine3",
+                     "port" => port,
+                     "custom_headers" => headers )
+        subject.register
+        subject.receive(LogStash::Event.new("message" => "hello"))
+        expect(message_observer.messages.size).to eq(1)
+        headers.each do |key, value|
+          expect(message_observer.messages[0].header[key].value).to eq(value)
+        end
+      end
+    end
   end
 end