[WIP] initial implementation of skipping prefix hash

lib/logstash/outputs/graphite.rb

@@ -79,6 +79,11 @@ class LogStash::Outputs::Graphite < LogStash::Outputs::Base
   # This config setting changes the separator from the '.' default.
   config :nested_object_separator, :validate => :string, :default => "."
 
+  # TODO
+  # In the special case of using a hash field as metrics, one could want to skip the "metrics container" name by setting this config to `true`
+  # For example an event containing a field "mymetrics" => {a => 1, b => { c => 2 }} is normally converted into `mymetrics.a` ..., with this config it would simply write `a`...
+  config :skip_prefix_for_metrics_hash, :validate => :boolean, :default => false
+
   def register
     @include_metrics.collect!{|regexp| Regexp.new(regexp)}
     @exclude_metrics.collect!{|regexp| Regexp.new(regexp)}
@@ -175,7 +180,7 @@ def event_timestamp(event)
 
   def metrics_lines_for_event(event, metric, value, timestamp)
     if event[metric].is_a?(Hash)
-      dotify(event[metric], metric).map do |k, v|
+      dotify(event[metric], @skip_prefix_for_metrics_hash ? nil: metric).map do |k, v|
         metrics_line(event, k, v, timestamp)
       end
     else

spec/outputs/graphite_spec.rb

@@ -12,6 +12,32 @@
     subject.receive(event)
   end
 
+  context "with a field hash" do
+
+    subject { LogStash::Outputs::Graphite.new("host" => "localhost", "port" => port, "metrics" => {"metrics" => "whatever"}) }
+    let(:event) { LogStash::Event.new("@meta" => {"metrics_field" => "metrics"}, "foo" => "fancy", "metrics" => { 'foo.bar' => 1.0,
+    'bar.foo'=> 2.0}, "bar" => 42) }
+
+    it "include all metrics" do
+      expect(server.size).to eq(2)
+      expect(server.pop).to match(/^metrics.bar.foo 2.0 \d{10,}\n$/)
+      expect(server.pop).to match(/^metrics.foo.bar 1.0 \d{10,}\n$/)
+    end
+  end
+
+  context "with a field hash" do
+
+    subject { LogStash::Outputs::Graphite.new("host" => "localhost", "port" => port, "metrics" => {"metrics" => "whatever"}, "skip_prefix_for_metrics_hash" => true) }
+    let(:event) { LogStash::Event.new("@meta" => {"metrics_field" => "metrics"}, "foo" => "fancy", "metrics" => { 'foo.bar' => 1.0,
+    'bar.foo'=> 2.0}, "bar" => 42) }
+
+    it "include all metrics" do
+      expect(server.size).to eq(2)
+      expect(server.pop).to match(/^bar.foo 2.0 \d{10,}\n$/)
+      expect(server.pop).to match(/^foo.bar 1.0 \d{10,}\n$/)
+    end
+  end
+
   context "with a default run" do
 
     subject { LogStash::Outputs::Graphite.new("host" => "localhost", "port" => port, "metrics" => [ "hurray.%{foo}", "%{bar}" ]) }