aws lambda instrumentation - http headers propagation fix (#2222)

* aws lambda instrumentation - http headers propagation fix

* documented lambda propagation behaviour

* spotless apply

instrumentation/aws-lambda-1.0/library/README.md

@@ -87,36 +87,12 @@ public class MyBatchHandler extends TracingSQSEventHandler {
 
 ## Trace propagation
 
-### X-Ray propagation
-This instrumentation supports propagating traces using the `X-Amzn-Trace-Id` format for both normal
-requests and SQS requests. To enable this propagation, in your code as early as possible,
-configure the `AwsXrayPropagator` along with any other propagators you use. If in doubt, you can
-configure X-Ray along with the default W3C propagator like this in a static block of your handler.
-
-```java
-class MyRequestHandler extends TracingRequestHandler<String, String> {
-
- static {
- OpenTelemetry.setGlobalPropagators(
- DefaultContextPropagators.builder()
- .addTextMapPropagator(HttpTraceContext.getInstance())
- .addTextMapPropagator(AwsXrayPropagator.getInstance())
- .build());
- }
+Context propagation for this instrumentation can be done either with X-Ray propagation or regular HTTP propagation. If X-Ray is enabled for instrumented lambda, it will be preferred. If X-Ray is disabled, HTTP propagation will be tried (that is HTTP headers will be read to check for a valid trace context).
 
- @Override
- protected String doHandleRequest(String input, Context context) {
- // logic
- }
-}
-```
-
-If you are using this instrumentation with SQS, you should always enable the `AwsXrayPropagator` to
-allow linking between messages in a backend-agnostic way.
 
-Otherwise, only enable the above if you are using AWS X-Ray as your tracing backend. You should not
-enable the X-Ray propagator if you are not using X-Ray as it will cause the spans in Lambda to not
-have the correct parent/child connection between client and server spans.
+### X-Ray propagation
+This instrumentation supports propagating traces using the `X-Amzn-Trace-Id` format for both normal
+requests and SQS requests. X-Ray propagation is always enabled, there is no need to configure it explicitely.
 
 ### HTTP headers based propagation
 For API Gateway (HTTP) requests instrumented by using one of following methods:

instrumentation/aws-lambda-1.0/library/src/main/java/io/opentelemetry/instrumentation/awslambda/v1_0/ParentContextExtractor.java

@@ -24,25 +24,25 @@ static Context extract(Map<String, String> headers) {
  Context parentContext = null;
  String parentTraceHeader = System.getenv(AWS_TRACE_HEADER_ENV_KEY);
  if (parentTraceHeader != null) {
- parentContext = ParentContextExtractor.fromXRayHeader(parentTraceHeader);
+ parentContext = fromXRayHeader(parentTraceHeader);
  }
- if (!isValid(parentContext)) {
+ if (!isValidAndSampled(parentContext)) {
  // try http
- parentContext = ParentContextExtractor.fromHttpHeaders(headers);
+ parentContext = fromHttpHeaders(headers);
  }
  return parentContext;
  }
 
- private static boolean isValid(Context context) {
+ private static boolean isValidAndSampled(Context context) {
  if (context == null) {
  return false;
  }
  Span parentSpan = Span.fromContext(context);
  SpanContext parentSpanContext = parentSpan.getSpanContext();
- return parentSpanContext.isValid();
+ return (parentSpanContext.isValid() && parentSpanContext.isSampled());
  }
 
- static Context fromHttpHeaders(Map<String, String> headers) {
+ private static Context fromHttpHeaders(Map<String, String> headers) {
  return BaseTracer.extractWithGlobalPropagators(lowercaseMap(headers), MapGetter.INSTANCE);
  }
 

instrumentation/aws-lambda-1.0/library/src/test/java/io/opentelemetry/instrumentation/awslambda/v1_0/ParentContextExtractorTest.java

@@ -16,14 +16,75 @@
 import io.opentelemetry.context.propagation.ContextPropagators;
 import io.opentelemetry.extension.trace.propagation.B3Propagator;
 import java.util.Map;
-import org.junit.jupiter.api.AfterEach;
-import org.junit.jupiter.api.Test;
+import org.junit.BeforeClass;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.contrib.java.lang.system.EnvironmentVariables;
+import org.junit.contrib.java.lang.system.RestoreSystemProperties;
 
-class ParentContextExtractorTest {
+public class ParentContextExtractorTest {
 
- @AfterEach
- void resetOpenTelemetry() {
- GlobalOpenTelemetry.resetForTest();
+ @Rule
+ public final RestoreSystemProperties restoreSystemProperties = new RestoreSystemProperties();
+
+ @Rule public final EnvironmentVariables environmentVariables = new EnvironmentVariables();
+
+ @BeforeClass
+ public static void setUp() {
+ GlobalOpenTelemetry.set(
+ OpenTelemetry.getPropagating(ContextPropagators.create(B3Propagator.getInstance())));
+ }
+
+ @Test
+ public void shouldUseHttpIfAwsParentNotSampled() {
+ // given
+ Map<String, String> headers =
+ ImmutableMap.of(
+ "X-b3-traceId",
+ "4fd0b6131f19f39af59518d127b0cafe",
+ "x-b3-spanid",
+ "0000000000000123",
+ "X-B3-Sampled",
+ "true");
+ environmentVariables.set(
+ "_X_AMZN_TRACE_ID",
+ "Root=1-8a3c60f7-d188f8fa79d48a391a778fa6;Parent=0000000000000456;Sampled=0");
+
+ // when
+ Context context = ParentContextExtractor.extract(headers);
+ // then
+ Span span = Span.fromContext(context);
+ SpanContext spanContext = span.getSpanContext();
+ assertThat(spanContext.isValid()).isTrue();
+ assertThat(spanContext.isValid()).isTrue();
+ assertThat(spanContext.getSpanId()).isEqualTo("0000000000000123");
+ assertThat(spanContext.getTraceId()).isEqualTo("4fd0b6131f19f39af59518d127b0cafe");
+ }
+
+ @Test
+ public void shouldPreferAwsParentHeaderIfValidAndSampled() {
+ // given
+ Map<String, String> headers =
+ ImmutableMap.of(
+ "X-b3-traceId",
+ "4fd0b6131f19f39af59518d127b0cafe",
+ "x-b3-spanid",
+ "0000000000000456",
+ "X-B3-Sampled",
+ "true");
+ environmentVariables.set(
+ "_X_AMZN_TRACE_ID",
+ "Root=1-8a3c60f7-d188f8fa79d48a391a778fa6;Parent=0000000000000456;Sampled=1");
+
+ // when
+ Context context = ParentContextExtractor.extract(headers);
+ // then
+ Span span = Span.fromContext(context);
+ SpanContext spanContext = span.getSpanContext();
+ assertThat(spanContext.isValid()).isTrue();
+ assertThat(spanContext.isValid()).isTrue();
+ assertThat(spanContext.getSpanId()).isEqualTo("0000000000000456");
+ assertThat(spanContext.getTraceId()).isEqualTo("8a3c60f7d188f8fa79d48a391a778fa6");
  }
 
  @Test
@@ -37,11 +98,9 @@ public void shouldExtractCaseInsensitiveHeaders() {
  "0000000000000456",
  "X-B3-Sampled",
  "true");
- GlobalOpenTelemetry.set(
- OpenTelemetry.getPropagating(ContextPropagators.create(B3Propagator.getInstance())));
 
  // when
- Context context = ParentContextExtractor.fromHttpHeaders(headers);
+ Context context = ParentContextExtractor.extract(headers);
  // then
  Span span = Span.fromContext(context);
  SpanContext spanContext = span.getSpanContext();