Added: #runtime_metrics_enabled flag to configuration.

docs/GettingStarted.md

@@ -1748,8 +1748,13 @@ require 'datadog/statsd'
 require 'ddtrace'
 
 Datadog.configure do |c|
+  # To enable runtime metrics collection, set `true`. Defaults to `false`
+  # You can also set DD_RUNTIME_METRICS_ENABLED=true to configure this.
+  c.runtime_metrics_enabled = true
+
+  # Optionally, you can configure the Statsd instance used for sending runtime metrics.
   # Statsd is automatically configured with default settings if `dogstatsd-ruby` is available.
-  # Otherwise, you can configure with host and port of Datadog agent; defaults to 'localhost:8125'.
+  # You can configure with host and port of Datadog agent; defaults to 'localhost:8125'.
   c.runtime_metrics statsd: Datadog::Statsd.new
 end
 ```

lib/ddtrace/configuration/settings.rb

@@ -1,4 +1,5 @@
 require 'ddtrace/ext/analytics'
+require 'ddtrace/ext/runtime'
 require 'ddtrace/configuration/options'
 
 require 'ddtrace/environment'
@@ -16,6 +17,10 @@ class Settings
               default: -> { env_to_bool(Ext::Analytics::ENV_TRACE_ANALYTICS_ENABLED, nil) },
               lazy: true
 
+      option :runtime_metrics_enabled,
+              default: -> { env_to_bool(Ext::Runtime::Metrics::ENV_ENABLED, false) },
+              lazy: true
+
       option :tracer, default: Tracer.new
 
       def initialize(options = {})

lib/ddtrace/ext/runtime.rb

@@ -20,6 +20,8 @@ module Runtime
 
       # Metrics
       module Metrics
+        ENV_ENABLED = 'DD_RUNTIME_METRICS_ENABLED'.freeze
+
         METRIC_CLASS_COUNT = 'runtime.ruby.class_count'.freeze
         METRIC_GC_PREFIX = 'runtime.ruby.gc'.freeze
         METRIC_THREAD_COUNT = 'runtime.ruby.thread_count'.freeze

lib/ddtrace/writer.rb

@@ -95,6 +95,8 @@ def send_services(services, transport)
     end
 
     def send_runtime_metrics
+      return unless Datadog.configuration.runtime_metrics_enabled
+
       runtime_metrics.flush
     end
 

spec/ddtrace/writer_spec.rb

@@ -140,6 +140,40 @@
         end
       end
 
+      describe '#send_runtime_metrics' do
+        subject(:send_runtime_metrics) { writer.send_runtime_metrics }
+
+        context 'when runtime metrics are' do
+          context 'enabled' do
+            around do |example|
+              Datadog.configuration.runtime_metrics_enabled = Datadog.configuration.runtime_metrics_enabled.tap do
+                Datadog.configuration.runtime_metrics_enabled = true
+                example.run
+              end
+            end
+
+            it do
+              expect(writer.runtime_metrics).to receive(:flush)
+              send_runtime_metrics
+            end
+          end
+
+          context 'disabled' do
+            around do |example|
+              Datadog.configuration.runtime_metrics_enabled = Datadog.configuration.runtime_metrics_enabled.tap do
+                Datadog.configuration.runtime_metrics_enabled = false
+                example.run
+              end
+            end
+
+            it do
+              expect(writer.runtime_metrics).to_not receive(:flush)
+              send_runtime_metrics
+            end
+          end
+        end
+      end
+
       describe '#sampling_updater' do
         subject(:result) { writer.send(:sampling_updater, action, response, api) }
         let(:options) { { priority_sampler: sampler } }