Expose span context to filters

include/envoy/http/BUILD

@@ -64,6 +64,7 @@ envoy_cc_library(
         "//include/envoy/event:dispatcher_interface",
         "//include/envoy/router:router_interface",
         "//include/envoy/ssl:connection_interface",
+        "//include/envoy/tracing:http_tracer_interface",
     ],
 )
 

include/envoy/http/filter.h

@@ -11,6 +11,7 @@
 #include "envoy/http/header_map.h"
 #include "envoy/router/router.h"
 #include "envoy/ssl/connection.h"
+#include "envoy/tracing/http_tracer.h"
 
 namespace Http {
 
@@ -117,6 +118,12 @@ class StreamFilterCallbacks {
    */
   virtual AccessLog::RequestInfo& requestInfo() PURE;
 
+  /**
+   * @return span context used for tracing purposes. Individual filters may add or modify
+   *              information in the span context.
+   */
+  virtual Tracing::Span& activeSpan() PURE;
+
   /**
    * @return the trusted downstream address for the connection.
    */

source/common/http/BUILD

@@ -26,6 +26,7 @@ envoy_cc_library(
         "//source/common/common:linked_object",
         "//source/common/http/access_log:request_info_lib",
         "//source/common/router:router_lib",
+        "//source/common/tracing:http_tracer_lib",
     ],
 )
 

source/common/http/async_client_impl.h

@@ -18,12 +18,14 @@
 #include "envoy/router/router_ratelimit.h"
 #include "envoy/router/shadow_writer.h"
 #include "envoy/ssl/connection.h"
+#include "envoy/tracing/http_tracer.h"
 
 #include "common/common/empty_string.h"
 #include "common/common/linked_object.h"
 #include "common/http/access_log/request_info_impl.h"
 #include "common/http/message_impl.h"
 #include "common/router/router.h"
+#include "common/tracing/http_tracer_impl.h"
 
 namespace Http {
 
@@ -184,6 +186,7 @@ class AsyncStreamImpl : public AsyncClient::Stream,
   Router::RouteConstSharedPtr route() override { return route_; }
   uint64_t streamId() override { return stream_id_; }
   AccessLog::RequestInfo& requestInfo() override { return request_info_; }
+  Tracing::Span& activeSpan() override { return active_span_; }
   const std::string& downstreamAddress() override { return EMPTY_STRING; }
   void continueDecoding() override { NOT_IMPLEMENTED; }
   Buffer::InstancePtr& decodingBuffer() override {
@@ -198,6 +201,7 @@ class AsyncStreamImpl : public AsyncClient::Stream,
   Router::ProdFilter router_;
   std::function<void()> reset_callback_;
   AccessLog::RequestInfoImpl request_info_;
+  Tracing::NullSpan active_span_;
   std::shared_ptr<RouteImpl> route_;
   bool local_closed_{};
   bool remote_closed_{};

source/common/http/conn_manager_impl.cc

@@ -878,6 +878,10 @@ AccessLog::RequestInfo& ConnectionManagerImpl::ActiveStreamFilterBase::requestIn
   return parent_.request_info_;
 }
 
+Tracing::Span& ConnectionManagerImpl::ActiveStreamFilterBase::activeSpan() {
+  return *parent_.active_span_;
+}
+
 Router::RouteConstSharedPtr ConnectionManagerImpl::ActiveStreamFilterBase::route() {
   if (!parent_.cached_route_.valid()) {
     parent_.cached_route_.value(

source/common/http/conn_manager_impl.h

@@ -282,6 +282,7 @@ class ConnectionManagerImpl : Logger::Loggable<Logger::Id::http>,
     Router::RouteConstSharedPtr route() override;
     uint64_t streamId() override;
     AccessLog::RequestInfo& requestInfo() override;
+    Tracing::Span& activeSpan() override;
     const std::string& downstreamAddress() override;
 
     ActiveStream& parent_;

source/common/tracing/http_tracer_impl.h

@@ -82,4 +82,11 @@ class HttpTracerImpl : public HttpTracer {
   const LocalInfo::LocalInfo& local_info_;
 };
 
+class NullSpan : public Tracing::Span {
+public:
+  // Tracing::Span
+  void setTag(const std::string&, const std::string&) override {}
+  void finishSpan() override {}
+};
+
 } // Tracing

test/common/http/BUILD

@@ -82,6 +82,7 @@ envoy_cc_test(
         "//include/envoy/buffer:buffer_interface",
         "//include/envoy/event:dispatcher_interface",
         "//include/envoy/http:access_log_interface",
+        "//include/envoy/tracing:http_tracer_interface",
         "//source/common/buffer:buffer_lib",
         "//source/common/event:dispatcher_lib",
         "//source/common/http:conn_manager_lib",

test/common/http/conn_manager_impl_test.cc

@@ -7,6 +7,7 @@
 #include "envoy/buffer/buffer.h"
 #include "envoy/event/dispatcher.h"
 #include "envoy/http/access_log.h"
+#include "envoy/tracing/http_tracer.h"
 
 #include "common/buffer/buffer_impl.h"
 #include "common/http/access_log/access_log_formatter.h"
@@ -235,6 +236,8 @@ TEST_F(HttpConnectionManagerImplTest, StartAndFinishSpanNormalFlow) {
   EXPECT_CALL(*span, setTag(_, _)).Times(testing::AnyNumber());
   // Verify tag is set based on the request headers.
   EXPECT_CALL(*span, setTag(":method", "GET"));
+  // Verify if the activeSpan interface returns reference to the current span.
+  EXPECT_CALL(*span, setTag("service-cluster", "scoobydoo"));
   EXPECT_CALL(runtime_.snapshot_, featureEnabled("tracing.global_enabled", 100, _))
       .WillOnce(Return(true));
 
@@ -260,6 +263,7 @@ TEST_F(HttpConnectionManagerImplTest, StartAndFinishSpanNormalFlow) {
 
         Http::HeaderMapPtr response_headers{new TestHeaderMapImpl{{":status", "200"}}};
         filter->callbacks_->encodeHeaders(std::move(response_headers), true);
+        filter->callbacks_->activeSpan().setTag("service-cluster", "scoobydoo");
 
         data.drain(4);
       }));

test/mocks/http/BUILD

@@ -21,10 +21,12 @@ envoy_cc_mock(
         "//include/envoy/http:conn_pool_interface",
         "//include/envoy/http:filter_interface",
         "//include/envoy/ssl:connection_interface",
+        "//include/envoy/tracing:http_tracer_interface",
         "//source/common/http:conn_manager_lib",
         "//source/common/http:header_map_lib",
         "//test/mocks/event:event_mocks",
         "//test/mocks/router:router_mocks",
+        "//test/mocks/tracing:tracing_mocks",
         "//test/mocks/upstream:host_mocks",
     ],
 )

test/mocks/http/mocks.h

@@ -20,6 +20,7 @@
 #include "test/mocks/common.h"
 #include "test/mocks/event/mocks.h"
 #include "test/mocks/router/mocks.h"
+#include "test/mocks/tracing/mocks.h"
 #include "test/mocks/upstream/host.h"
 #include "test/test_common/printers.h"
 
@@ -229,6 +230,7 @@ class MockStreamDecoderFilterCallbacks : public StreamDecoderFilterCallbacks,
   MOCK_METHOD0(route, Router::RouteConstSharedPtr());
   MOCK_METHOD0(streamId, uint64_t());
   MOCK_METHOD0(requestInfo, Http::AccessLog::RequestInfo&());
+  MOCK_METHOD0(activeSpan, Tracing::Span&());
   MOCK_METHOD0(downstreamAddress, const std::string&());
 
   // Http::StreamDecoderFilterCallbacks
@@ -261,6 +263,7 @@ class MockStreamEncoderFilterCallbacks : public StreamEncoderFilterCallbacks,
   MOCK_METHOD0(route, Router::RouteConstSharedPtr());
   MOCK_METHOD0(streamId, uint64_t());
   MOCK_METHOD0(requestInfo, Http::AccessLog::RequestInfo&());
+  MOCK_METHOD0(activeSpan, Tracing::Span&());
   MOCK_METHOD0(downstreamAddress, const std::string&());
 
   // Http::StreamEncoderFilterCallbacks