tracing: add option to choice mutation policy for RequestID extension

api/envoy/extensions/request_id/uuid/v3/uuid.proto

@@ -40,4 +40,9 @@ message UuidRequestIdConfig {
   // stable sampling of traces, access logs, etc. will no longer work and only random sampling will
   // be possible.
   google.protobuf.BoolValue pack_trace_reason = 1;
+
+  // Set whether to use :ref:`x-request-id<config_http_conn_man_headers_x-request-id>` for sampling or not.
+  // This defaults to true. See the :ref:`context propagation <arch_overview_tracing_context_propagation>`
+  // overview for more information.
+  google.protobuf.BoolValue use_request_id_for_trace_sampling = 2;
 }

docs/root/intro/arch_overview/observability/tracing.rst

@@ -69,6 +69,16 @@ to be correlated.
   field can be used to disable this behavior at the expense of also disabling stable trace reason
   propagation and associated features within a deployment.
 
+.. attention::
+
+  The sampling policy for Envoy is determined by the value of :ref:`x-request-id <config_http_conn_man_headers_x-request-id>` by default.
+  However, such a sampling policy is only valid for a fleet of Envoys. If a service proxy
+  that is not Envoy is present in the fleet, sampling is performed without considering the policy of that proxy.
+  For meshes consisting of multiple service proxies such as this, it is more effective to
+  bypass Envoy's sampling policy and sample based on the trace provider's sampling policy. This can be achieved by setting
+  :ref:`use_request_id_for_trace_sampling <envoy_v3_api_field_extensions.request_id.uuid.v3.UuidRequestIdConfig.use_request_id_for_trace_sampling>`
+  to false.
+
 The tracing providers also require additional context, to enable the parent/child relationships
 between the spans (logical units of work) to be understood. This can be achieved by using the
 LightStep (via OpenTracing API) or Zipkin tracer directly within the service itself, to extract the

docs/root/version_history/current.rst

@@ -36,6 +36,7 @@ Minor Behavior Changes
 * listener: respect the :ref:`connection balance config <envoy_v3_api_field_config.listener.v3.Listener.connection_balance_config>`
   defined within the listener where the sockets are redirected to. Clear that field to restore the previous behavior.
 * tcp: switched to the new connection pool by default. Any unexpected behavioral changes can be reverted by setting runtime guard ``envoy.reloadable_features.new_tcp_connection_pool`` to false.
+* tracing: add option :ref:`use_request_id_for_trace_sampling <envoy_v3_api_field_extensions.request_id.uuid.v3.UuidRequestIdConfig.use_request_id_for_trace_sampling>` whether to use sampling policy based on :ref:`x-request-id<config_http_conn_man_headers_x-request-id>` or not.
 
 Bug Fixes
 ---------

envoy/http/request_id_extension.h

@@ -63,6 +63,12 @@ class RequestIDExtension : public RequestIdStreamInfoProvider {
    * @param status the trace reason that should be set for this request.
    */
   virtual void setTraceReason(Http::RequestHeaderMap& request_headers, Tracing::Reason reason) PURE;
+
+  /**
+   * Get whether to use request_id based sampling policy or not.
+   * @return whether to use request_id based sampling policy or not.
+   */
+  virtual bool useRequestIdForTraceSampling() const PURE;
 };
 
 using RequestIDExtensionSharedPtr = std::shared_ptr<RequestIDExtension>;

source/common/http/conn_manager_utility.cc

@@ -283,6 +283,9 @@ Tracing::Reason ConnectionManagerUtility::mutateTracingRequestHeader(
   }
 
   auto rid_extension = config.requestIDExtension();
+  if (!rid_extension->useRequestIdForTraceSampling()) {
+    return Tracing::Reason::Sampling;
+  }
   const auto rid_to_integer = rid_extension->toInteger(request_headers);
   // Skip if request-id is corrupted, or non-existent
   if (!rid_to_integer.has_value()) {

source/extensions/request_id/uuid/config.h

@@ -16,7 +16,9 @@ class UUIDRequestIDExtension : public Http::RequestIDExtension {
   UUIDRequestIDExtension(const envoy::extensions::request_id::uuid::v3::UuidRequestIdConfig& config,
                          Random::RandomGenerator& random)
       : random_(random),
-        pack_trace_reason_(PROTOBUF_GET_WRAPPED_OR_DEFAULT(config, pack_trace_reason, true)) {}
+        pack_trace_reason_(PROTOBUF_GET_WRAPPED_OR_DEFAULT(config, pack_trace_reason, true)),
+        use_request_id_for_trace_sampling_(
+            PROTOBUF_GET_WRAPPED_OR_DEFAULT(config, use_request_id_for_trace_sampling, true)) {}
 
   static Http::RequestIDExtensionSharedPtr defaultInstance(Random::RandomGenerator& random) {
     return std::make_shared<UUIDRequestIDExtension>(
@@ -32,10 +34,12 @@ class UUIDRequestIDExtension : public Http::RequestIDExtension {
   absl::optional<uint64_t> toInteger(const Http::RequestHeaderMap& request_headers) const override;
   Tracing::Reason getTraceReason(const Http::RequestHeaderMap& request_headers) override;
   void setTraceReason(Http::RequestHeaderMap& request_headers, Tracing::Reason status) override;
+  bool useRequestIdForTraceSampling() const override { return use_request_id_for_trace_sampling_; }
 
 private:
   Envoy::Random::RandomGenerator& random_;
   const bool pack_trace_reason_;
+  const bool use_request_id_for_trace_sampling_;
 
   // Byte on this position has predefined value of 4 for UUID4.
   static const int TRACE_BYTE_POSITION = 14;

test/common/http/conn_manager_utility_test.cc

@@ -63,13 +63,15 @@ class MockRequestIDExtension : public RequestIDExtension {
             [this](Http::RequestHeaderMap& request_headers, Tracing::Reason trace_status) {
               real_->setTraceReason(request_headers, trace_status);
             });
+    ON_CALL(*this, useRequestIdForTraceSampling()).WillByDefault(Return(true));
   }
 
   MOCK_METHOD(void, set, (Http::RequestHeaderMap&, bool));
   MOCK_METHOD(void, setInResponse, (Http::ResponseHeaderMap&, const Http::RequestHeaderMap&));
   MOCK_METHOD(absl::optional<uint64_t>, toInteger, (const Http::RequestHeaderMap&), (const));
   MOCK_METHOD(Tracing::Reason, getTraceReason, (const Http::RequestHeaderMap&));
   MOCK_METHOD(void, setTraceReason, (Http::RequestHeaderMap&, Tracing::Reason));
+  MOCK_METHOD(bool, useRequestIdForTraceSampling, (), (const));
 
 private:
   RequestIDExtensionSharedPtr real_;
@@ -1229,6 +1231,14 @@ TEST_F(ConnectionManagerUtilityTest, SamplingWithoutRouteOverride) {
   EXPECT_EQ(Tracing::Reason::Sampling, request_id_extension_->getTraceReason(request_headers));
 }
 
+TEST_F(ConnectionManagerUtilityTest, CheckSamplingDecisionWithBypassSamplingWithRequestId) {
+  EXPECT_CALL(*request_id_extension_, useRequestIdForTraceSampling()).WillOnce(Return(false));
+  Http::TestRequestHeaderMapImpl request_headers{
+      {"x-request-id", "125a4afb-6f55-44ba-ad80-413f09f48a28"}};
+  const auto ret = callMutateRequestHeaders(request_headers, Protocol::Http2);
+  EXPECT_EQ(Tracing::Reason::Sampling, ret.trace_reason_);
+}
+
 TEST_F(ConnectionManagerUtilityTest, SamplingWithRouteOverride) {
   EXPECT_CALL(
       runtime_.snapshot_,

test/extensions/filters/network/http_connection_manager/config_test.cc

@@ -1721,7 +1721,7 @@ class TestRequestIDExtension : public Http::RequestIDExtension {
     return Tracing::Reason::Sampling;
   }
   void setTraceReason(Http::RequestHeaderMap&, Tracing::Reason) override {}
-
+  bool useRequestIdForTraceSampling() const override { return true; }
   std::string testField() { return config_.test_field(); }
 
 private:
@@ -1836,6 +1836,7 @@ TEST_F(HttpConnectionManagerConfigTest, DefaultRequestIDExtension) {
       config.requestIDExtension().get());
   ASSERT_NE(nullptr, request_id_extension);
   EXPECT_TRUE(request_id_extension->packTraceReason());
+  EXPECT_EQ(request_id_extension->useRequestIdForTraceSampling(), true);
 }
 
 TEST_F(HttpConnectionManagerConfigTest, DefaultRequestIDExtensionWithParams) {
@@ -1847,6 +1848,7 @@ TEST_F(HttpConnectionManagerConfigTest, DefaultRequestIDExtensionWithParams) {
     typed_config:
       "@type": type.googleapis.com/envoy.extensions.request_id.uuid.v3.UuidRequestIdConfig
       pack_trace_reason: false
+      use_request_id_for_trace_sampling: false
   http_filters:
   - name: envoy.filters.http.router
   )EOF";
@@ -1859,6 +1861,7 @@ TEST_F(HttpConnectionManagerConfigTest, DefaultRequestIDExtensionWithParams) {
       config.requestIDExtension().get());
   ASSERT_NE(nullptr, request_id_extension);
   EXPECT_FALSE(request_id_extension->packTraceReason());
+  EXPECT_EQ(request_id_extension->useRequestIdForTraceSampling(), false);
 }
 
 TEST_F(HttpConnectionManagerConfigTest, UnknownOriginalIPDetectionExtension) {