Default to native transport on CRuby 4.0+

lib/datadog/tracing/configuration/settings.rb

@@ -2,6 +2,7 @@
 
 require_relative "../../tracing/configuration/ext"
 require_relative "../../core/environment/variable_helpers"
+require_relative "../../ruby_version"
 require_relative "../contrib/status_range_matcher"
 require_relative "../contrib/status_range_env_parser"
 require_relative "http"
@@ -496,11 +497,11 @@ def self.extended(base)
               #
               # This option is recommended for internal use only.
               #
-              # @default `false`
+              # @default `true` on CRuby 4.0.0 and later, otherwise `false`
               # @return [Boolean]
               option :native_transport do |o|
                 o.env Configuration::Ext::ENV_EXPERIMENTAL_NATIVE_TRANSPORT_ENABLED
-                o.default false
+                o.default { RUBY_ENGINE == "ruby" && RubyVersion.is?(">= 4.0.0") }
                 o.type :bool
               end
 

spec/datadog/core/crashtracking/component_spec.rb

@@ -382,8 +382,9 @@ def method_that_raises
             raise StandardError, "Test Ruby unhandled exception"
           end
 
-          # Errors intake sends 2 messages, telemetry sends 2 messages
-          expect(messages.length).to eq(4)
+          paths = messages.select { |message| message.request_method == "POST" }.map(&:path)
+          expect(paths.count("/evp_proxy/v4/api/v2/errorsintake")).to eq(2)
+          expect(paths.count("/telemetry/proxy/api/v2/apmtelemetry")).to eq(2)
         end
       end
 

spec/datadog/tracing/configuration/settings_spec.rb

@@ -654,17 +654,37 @@ def propagation_style_inject
     describe "#native_transport" do
       subject(:native_transport) { settings.tracing.native_transport }
 
-      it_behaves_like "a binary setting with",
-        env_variable: "DD_EXPERIMENTAL_NATIVE_TRANSPORT_ENABLED",
-        default: false
-    end
+      [
+        ["ruby", "3.4.6", false],
+        ["ruby", "4.0.0", true],
+        ["ruby", "4.0.5", true],
+        ["ruby", "4.0.10", true],
+        ["ruby", "4.1.0", true],
+        ["ruby", "5.0.0", true],
+        ["jruby", "4.0.0", false],
+        ["truffleruby", "4.1.0", false],
+      ].each do |engine, version, default|
+        context "on #{engine} #{version}" do
+          before do
+            stub_const("RUBY_ENGINE", engine)
+            stub_const("Datadog::RubyVersion::CURRENT_RUBY_VERSION", Gem::Version.new(version))
+          end
 
-    describe "#native_transport=" do
-      it "changes the #native_transport setting" do
-        expect { settings.tracing.native_transport = true }
-          .to change { settings.tracing.native_transport }
-          .from(false)
-          .to(true)
+          it_behaves_like "a binary setting with",
+            env_variable: "DD_EXPERIMENTAL_NATIVE_TRANSPORT_ENABLED",
+            default: default
+
+          [true, false].each do |value|
+            context "when explicitly configured to #{value}" do
+              let(:envs) { {"DD_EXPERIMENTAL_NATIVE_TRANSPORT_ENABLED" => (!value).to_s} }
+
+              it "overrides the environment setting" do
+                settings.tracing.native_transport = value
+                is_expected.to be value
+              end
+            end
+          end
+        end
       end
     end
 

spec/datadog/tracing/transport/native/configuration_spec.rb

@@ -54,9 +54,11 @@ def build_writer
       end
     end
 
-    context "when native_transport is not explicitly configured" do
+    context "outside the rollout version without an explicit setting" do
       let(:settings) { Datadog::Core::Configuration::Settings.new }
 
+      before { stub_const("Datadog::RubyVersion::CURRENT_RUBY_VERSION", Gem::Version.new("3.4.6")) }
+
       around do |example|
         ClimateControl.modify("DD_EXPERIMENTAL_NATIVE_TRANSPORT_ENABLED" => nil) { example.run }
       end
@@ -123,6 +125,32 @@ def build_writer
       end
     end
 
+    context "on CRuby 4.0.0 without an explicit setting" do
+      let(:settings) { Datadog::Core::Configuration::Settings.new }
+
+      around do |example|
+        ClimateControl.modify("DD_EXPERIMENTAL_NATIVE_TRANSPORT_ENABLED" => nil) { example.run }
+      end
+
+      before do
+        stub_const("RUBY_ENGINE", "ruby")
+        stub_const("Datadog::RubyVersion::CURRENT_RUBY_VERSION", Gem::Version.new("4.0.0"))
+      end
+
+      it "selects the native transport by default" do
+        expect(build_writer.transport).to be_a(Datadog::Tracing::Transport::Native::Transport)
+      end
+
+      context "when the native extension is unavailable" do
+        before { allow(Datadog::Tracing::Transport::Native).to receive(:supported?).and_return(false) }
+
+        it "falls back to the Ruby HTTP transport" do
+          expect(logger).to receive(:warn).with(/not available/)
+          expect(build_writer.transport).to be_a(Datadog::Tracing::Transport::Traces::Transport)
+        end
+      end
+    end
+
     context "when native_transport is true but native extension is unavailable" do
       let(:native_transport_enabled) { true }
 
@@ -141,7 +169,8 @@ def build_writer
   end
 
   describe "settings" do
-    it "has native_transport defaulting to false" do
+    it "defaults native_transport to false outside the rollout version" do
+      stub_const("Datadog::RubyVersion::CURRENT_RUBY_VERSION", Gem::Version.new("3.4.6"))
       settings = Datadog::Core::Configuration::Settings.new
       expect(settings.tracing.native_transport).to be false
     end

supported-configurations.json

@@ -437,6 +437,7 @@
     ],
     "DD_EXPERIMENTAL_NATIVE_TRANSPORT_ENABLED": [
       {
+        "__comment": "Default is true on CRuby 4.0.0 and later",
         "version": "A",
         "type": "boolean",
         "default": "false"

unreleased/20261005150145.json

@@ -0,0 +1,6 @@
+{
+  "type": "Changed",
+  "product": "Core",
+  "pull_request": "https://github.com/DataDog/dd-trace-rb/pull/6419",
+  "message": "Begin the progressive rollout of the native trace exporter, enabling it by default on CRuby 4.0.0 and later."
+}