From 98c80144a9a17e74a4bad61a95a4a609f7d4e6d8 Mon Sep 17 00:00:00 2001
From: mackjmr <mackwolves@hotmail.fr>
Date: Tue, 10 May 2022 14:31:21 +0200
Subject: [PATCH] handle synthetics origin parent id

---
 ddtrace/tracer/textmap.go      |  2 +-
 ddtrace/tracer/textmap_test.go | 26 ++++++++++++++++++++++++++
 2 files changed, 27 insertions(+), 1 deletion(-)

diff --git a/ddtrace/tracer/textmap.go b/ddtrace/tracer/textmap.go
index 66a3047b4d..c281bce69e 100644
--- a/ddtrace/tracer/textmap.go
+++ b/ddtrace/tracer/textmap.go
@@ -310,7 +310,7 @@ func (p *propagator) extractTextMap(reader TextMapReader) (ddtrace.SpanContext,
 	if err != nil {
 		return nil, err
 	}
-	if ctx.traceID == 0 || ctx.spanID == 0 {
+	if ctx.traceID == 0 || (ctx.spanID == 0 && ctx.origin != "synthetics") {
 		return nil, ErrSpanContextNotFound
 	}
 	return &ctx, nil
diff --git a/ddtrace/tracer/textmap_test.go b/ddtrace/tracer/textmap_test.go
index dd878f14fb..0307eb031f 100644
--- a/ddtrace/tracer/textmap_test.go
+++ b/ddtrace/tracer/textmap_test.go
@@ -117,6 +117,12 @@ func TestTextMapPropagatorErrors(t *testing.T) {
 		DefaultParentIDHeader: "0",
 	}))
 	assert.Equal(ErrSpanContextNotFound, err)
+
+	_, err = propagator.Extract(TextMapCarrier(map[string]string{
+		DefaultTraceIDHeader:  "3",
+		DefaultParentIDHeader: "0",
+	}))
+	assert.Equal(ErrSpanContextNotFound, err)
 }
 
 func TestTextMapPropagatorInjectHeader(t *testing.T) {
@@ -175,6 +181,26 @@ func TestTextMapPropagatorOrigin(t *testing.T) {
 	}
 }
 
+func TestExtractOriginSynthetics(t *testing.T) {
+	src := TextMapCarrier(map[string]string{
+		originHeader:          "synthetics",
+		DefaultTraceIDHeader:  "3",
+		DefaultParentIDHeader: "0",
+	})
+	tracer := newTracer()
+	ctx, err := tracer.Extract(src)
+	if err != nil {
+		t.Fatal(err)
+	}
+	sctx, ok := ctx.(*spanContext)
+	if !ok {
+		t.Fatal("not a *spanContext")
+	}
+	assert.Equal(t, sctx.spanID, uint64(0))
+	assert.Equal(t, sctx.traceID, uint64(3))
+	assert.Equal(t, sctx.origin, "synthetics")
+}
+
 func TestTextMapPropagatorInvalidTraceTagsHeader(t *testing.T) {
 	src := TextMapCarrier(map[string]string{
 		DefaultTraceIDHeader:  "1",