xray tracer: correctly annotate child spans as xray subsegments

docs/root/version_history/current.rst

@@ -38,6 +38,7 @@ Bug Fixes
 * tls: fix a bug while matching a certificate SAN with an exact value in ``match_typed_subject_alt_names`` of a listener where wildcard ``*`` character is not the only character of the dns label. Example, ``baz*.example.net`` and ``*baz.example.net`` and ``b*z.example.net`` will match ``baz1.example.net`` and ``foobaz.example.net`` and ``buzz.example.net``, respectively.
 * upstream: fix stack overflow when a cluster with large number of idle connections is removed.
 * xray: fix the AWS X-Ray tracer extension to not sample the trace if ``sampled=`` keyword is not present in the header ``x-amzn-trace-id``.
+* xray: fix the AWS X-Ray tracer extension to annotate a child span with ``type=subsegment`` to correctly relate subsegments to a parent segment. Previously a subsegment would be treated as an independent segment.
 
 Removed Config or Runtime
 -------------------------

source/extensions/tracers/xray/daemon.proto

@@ -43,6 +43,9 @@ message Segment {
   }
   // Object containing one or more fields that X-Ray indexes for use with filter expressions.
   map<string, string> annotations = 8;
+  // Set type to "subsegment" when sending a child span so X-Ray treats it as a subsegment.
+  // https://docs.aws.amazon.com/xray/latest/devguide/xray-api-segmentdocuments.html#api-segmentdocuments-subsegments
+  string type = 14;
 }
 
 message Header {

source/extensions/tracers/xray/tracer.cc

@@ -71,7 +71,9 @@ void Span::finishSpan() {
   s.set_error(clientError());
   s.set_fault(serverError());
   s.set_throttle(isThrottled());
-
+  if (type() == Subsegment) {
+    s.set_type(std::string(Subsegment));
+  }
   auto* aws = s.mutable_aws()->mutable_fields();
   for (const auto& field : aws_metadata_) {
     aws->insert({field.first, field.second});
@@ -108,13 +110,14 @@ void Span::injectContext(Tracing::TraceContext& trace_context) {
 Tracing::SpanPtr Span::spawnChild(const Tracing::Config& config, const std::string& operation_name,
                                   Envoy::SystemTime start_time) {
   auto child_span = std::make_unique<XRay::Span>(time_source_, random_, broker_);
-  child_span->setName(name());
+  child_span->setName(operation_name);
   child_span->setOperation(operation_name);
   child_span->setDirection(Tracing::HttpTracerUtility::toString(config.operationName()));
   child_span->setStartTime(start_time);
   child_span->setParentId(id());
   child_span->setTraceId(traceId());
   child_span->setSampled(sampled());
+  child_span->setType(Subsegment);
   return child_span;
 }
 

source/extensions/tracers/xray/tracer.h

@@ -26,6 +26,7 @@ namespace Tracers {
 namespace XRay {
 
 constexpr auto XRayTraceHeader = "x-amzn-trace-id";
+constexpr absl::string_view Subsegment = "subsegment";
 
 class Span : public Tracing::Span, Logger::Loggable<Logger::Id::config> {
 public:
@@ -101,6 +102,12 @@ class Span : public Tracing::Span, Logger::Loggable<Logger::Id::config> {
     parent_segment_id_ = std::string(parent_segment_id);
   }
 
+  /**
+   * Sets the type of the Span. In X-Ray, an independent subsegment has a type of "subsegment".
+   * https://docs.aws.amazon.com/xray/latest/devguide/xray-api-segmentdocuments.html#api-segmentdocuments-subsegments
+   */
+  void setType(absl::string_view type) { type_ = std::string(type); }
+
   /**
    * Sets the aws metadata field of the Span.
    */
@@ -156,6 +163,11 @@ class Span : public Tracing::Span, Logger::Loggable<Logger::Id::config> {
    */
   const std::string& direction() const { return direction_; }
 
+  /**
+   * Gets this Span's type.
+   */
+  const std::string& type() const { return type_; }
+
   /**
    * Gets this Span's name.
    */
@@ -216,6 +228,7 @@ class Span : public Tracing::Span, Logger::Loggable<Logger::Id::config> {
   std::string parent_segment_id_;
   std::string name_;
   std::string origin_;
+  std::string type_;
   absl::flat_hash_map<std::string, ProtobufWkt::Value> aws_metadata_;
   absl::flat_hash_map<std::string, ProtobufWkt::Value> http_request_annotations_;
   absl::flat_hash_map<std::string, ProtobufWkt::Value> http_response_annotations_;

test/extensions/tracers/xray/tracer_test.cc

@@ -97,6 +97,7 @@ TEST_F(XRayTracerTest, SerializeSpanTest) {
     EXPECT_FALSE(s.id().empty());
     EXPECT_EQ(2, s.annotations().size());
     EXPECT_TRUE(s.parent_id().empty());
+    EXPECT_TRUE(s.type().empty());
     EXPECT_FALSE(s.fault());    /*server error*/
     EXPECT_FALSE(s.error());    /*client error*/
     EXPECT_FALSE(s.throttle()); /*request throttled*/
@@ -142,6 +143,7 @@ TEST_F(XRayTracerTest, SerializeSpanTestServerError) {
     EXPECT_FALSE(s.trace_id().empty());
     EXPECT_FALSE(s.id().empty());
     EXPECT_TRUE(s.parent_id().empty());
+    EXPECT_TRUE(s.type().empty());
     EXPECT_TRUE(s.fault());  /*server error*/
     EXPECT_FALSE(s.error()); /*client error*/
     EXPECT_EQ(expected_status_code,
@@ -175,6 +177,7 @@ TEST_F(XRayTracerTest, SerializeSpanTestClientError) {
     EXPECT_FALSE(s.trace_id().empty());
     EXPECT_FALSE(s.id().empty());
     EXPECT_TRUE(s.parent_id().empty());
+    EXPECT_TRUE(s.type().empty());
     EXPECT_FALSE(s.fault());    /*server error*/
     EXPECT_TRUE(s.error());     /*client error*/
     EXPECT_FALSE(s.throttle()); /*request throttled*/
@@ -208,6 +211,7 @@ TEST_F(XRayTracerTest, SerializeSpanTestClientErrorWithThrottle) {
     EXPECT_FALSE(s.trace_id().empty());
     EXPECT_FALSE(s.id().empty());
     EXPECT_TRUE(s.parent_id().empty());
+    EXPECT_TRUE(s.type().empty());
     EXPECT_FALSE(s.fault());   /*server error*/
     EXPECT_TRUE(s.error());    /*client error*/
     EXPECT_TRUE(s.throttle()); /*request throttled*/
@@ -239,6 +243,7 @@ TEST_F(XRayTracerTest, SerializeSpanTestWithEmptyValue) {
     EXPECT_FALSE(s.trace_id().empty());
     EXPECT_FALSE(s.id().empty());
     EXPECT_TRUE(s.parent_id().empty());
+    EXPECT_TRUE(s.type().empty());
     EXPECT_FALSE(s.http().request().fields().contains(Tracing::Tags::get().Status));
   };
 
@@ -270,6 +275,7 @@ TEST_F(XRayTracerTest, SerializeSpanTestWithStatusCodeNotANumber) {
     EXPECT_FALSE(s.trace_id().empty());
     EXPECT_FALSE(s.id().empty());
     EXPECT_TRUE(s.parent_id().empty());
+    EXPECT_TRUE(s.type().empty());
     EXPECT_FALSE(s.http().request().fields().contains(Tracing::Tags::get().Status));
     EXPECT_FALSE(s.http().request().fields().contains("content_length"));
   };
@@ -346,7 +352,9 @@ TEST_F(XRayTracerTest, ChildSpanHasParentInfo) {
     TestUtility::validate(s);
     // Hex encoded 64 bit identifier
     EXPECT_STREQ("00000000000003e7", s.parent_id().c_str());
-    EXPECT_EQ(expected_->span_name, s.name().c_str());
+    EXPECT_EQ(expected_->operation_name, s.name().c_str());
+    EXPECT_TRUE(xray_parent_span->type().empty());
+    EXPECT_EQ(Subsegment, s.type().c_str());
     EXPECT_STREQ(xray_parent_span->traceId().c_str(), s.trace_id().c_str());
     EXPECT_STREQ("0000003d25bebe62", s.id().c_str());
   };

tools/spelling/spelling_dictionary.txt

@@ -1176,6 +1176,7 @@ subnets
 suboptimal
 subsecond
 subseconds
+subsegment
 subsequence
 subsetting
 substr