Updating Span Link creation due to header tag propagations for invalid spans (#7799)

* adding functionality and testing for attributes in Span Links from compund extraction

* running circleci tests on updated commit for system-tests

* only allowing tracestate to be passed when propagation style is tracecontext

* spotless

* reverting default_system_tests

* updating unit test to use put instead of Map.of

* updating PR comments

* spotless

Author: mhlidd

dd-trace-core/src/main/java/datadog/trace/core/propagation/HttpCodec.java

@@ -12,6 +12,7 @@
 import datadog.trace.api.TraceConfig;
 import datadog.trace.api.TracePropagationStyle;
 import datadog.trace.bootstrap.instrumentation.api.AgentPropagation;
+import datadog.trace.bootstrap.instrumentation.api.SpanAttributes;
 import datadog.trace.bootstrap.instrumentation.api.TagContext;
 import datadog.trace.core.DDSpanContext;
 import datadog.trace.core.DDSpanLink;
@@ -240,7 +241,13 @@ public <C> TagContext extract(
               }
             } else {
               // Terminate extracted context and add it as span link
-              context.addTerminatedContextLink(DDSpanLink.from((ExtractedContext) extracted));
+              context.addTerminatedContextLink(
+                  DDSpanLink.from(
+                      (ExtractedContext) extracted,
+                      SpanAttributes.builder()
+                          .put("reason", "terminated_context")
+                          .put("context_headers", extracted.getPropagationStyle().toString())
+                          .build()));
               // TODO Note: Other vendor tracestate will be lost here
             }
           }

dd-trace-core/src/test/groovy/datadog/trace/core/propagation/HttpExtractorTest.groovy

@@ -166,4 +166,44 @@ class HttpExtractorTest extends DDSpecification {
     [DATADOG, TRACECONTEXT]          | "1"            | "2"           | null      | null     | W3C_TRACE_STATE_NO_P   | "1"             | W3C_SPAN_ID_LSTR | "0000000000000002"
     // spotless:on
   }
+
+  def "verify existence of span links when extracting compound http headers"() {
+    setup:
+    Config config = Mock(Config) {
+      getTracePropagationStylesToExtract() >> styles
+    }
+    DynamicConfig dynamicConfig = DynamicConfig.create().apply()
+    HttpCodec.Extractor extractor = HttpCodec.createExtractor(config, { dynamicConfig.captureTraceConfig() })
+
+    final Map<String, String> actual = [
+      (DatadogHttpCodec.TRACE_ID_KEY.toUpperCase()): datadogTraceId,
+      (DatadogHttpCodec.SPAN_ID_KEY.toUpperCase()) : datadogSpanId,
+      (B3HttpCodec.TRACE_ID_KEY.toUpperCase())     : b3TraceId,
+      (B3HttpCodec.SPAN_ID_KEY.toUpperCase())      : b3SpanId,
+      (W3CHttpCodec.TRACE_PARENT_KEY.toUpperCase()): w3cTraceParent,
+      (W3CHttpCodec.TRACE_STATE_KEY.toUpperCase()) : traceState
+    ]
+
+    when:
+    final TagContext context = extractor.extract(actual, ContextVisitors.stringValuesMap())
+
+    then:
+    def links = context.getTerminatedContextLinks()
+    assert links.size() == expectedSpanLinks.size()
+    for (int i = 0; i < links.size(); i++) {
+      if (expectedSpanLinks[i] == TRACECONTEXT) {
+        assert links[i].traceState() == W3C_TRACE_STATE_NO_P
+      }
+      assert links[i].attributes().asMap()["context_headers"] == expectedSpanLinks[i].toString()
+    }
+
+    where:
+    // spotless:off
+    styles                           | datadogTraceId    | datadogSpanId     | b3TraceId         | b3SpanId          | w3cTraceParent   | traceState           | expectedSpanLinks
+    [DATADOG, B3MULTI, TRACECONTEXT] | "1"               | "2"               | "1"               | "b"               | W3C_TRACE_PARENT | W3C_TRACE_STATE_NO_P | []
+    [DATADOG, B3MULTI, TRACECONTEXT] | "2"               | "2"               | "2"               | "b"               | W3C_TRACE_PARENT | W3C_TRACE_STATE_NO_P | [TRACECONTEXT]
+    [DATADOG, B3MULTI, TRACECONTEXT] | "2"               | "2"               | "1"               | "b"               | W3C_TRACE_PARENT | W3C_TRACE_STATE_NO_P | [B3MULTI, TRACECONTEXT]
+    [TRACECONTEXT, B3MULTI, DATADOG] | "2"               | "2"               | "1"               | "b"               | W3C_TRACE_PARENT | W3C_TRACE_STATE_NO_P | [DATADOG]
+    // spotless:on
+  }
 }