feat(tracing): add W3C traceparent header support and corresponding tests

Author: hangy

sentry_sdk/tracing.py

@@ -531,7 +531,8 @@ def continue_from_headers(
     def iter_headers(self):
         # type: () -> Iterator[Tuple[str, str]]
         """
-        Creates a generator which returns the span's ``sentry-trace`` and ``baggage`` headers.
+        Creates a generator which returns the span's ``sentry-trace`` and ``baggage`` headers,
+        as well as a ``traceparent`` header for W3C compatibility.
         If the span's containing transaction doesn't yet have a ``baggage`` value,
         this will cause one to be generated and stored.
         """
@@ -543,6 +544,7 @@ def iter_headers(self):
             return
 
         yield SENTRY_TRACE_HEADER_NAME, self.to_traceparent()
+        yield W3C_TRACE_HEADER_NAME, self.to_w3c_traceparent()
 
         baggage = self.containing_transaction.get_baggage().serialize()
         if baggage:
@@ -588,6 +590,16 @@ def to_traceparent(self):
 
         return traceparent
 
+    def to_w3c_traceparent(self):
+        # type: () -> str
+        if self.sampled is True:
+            trace_flags = "01"
+        else:
+            trace_flags = "00"
+
+        traceparent = "00-%s-%s-%s" % (self.trace_id, self.span_id, trace_flags)
+        return traceparent
+
     def to_baggage(self):
         # type: () -> Optional[Baggage]
         """Returns the :py:class:`~sentry_sdk.tracing_utils.Baggage`
@@ -1233,6 +1245,10 @@ def to_traceparent(self):
         # type: () -> str
         return ""
 
+    def to_w3c_traceparent(self):
+        # type: () -> str
+        return ""
+
     def to_baggage(self):
         # type: () -> Optional[Baggage]
         return None

tests/tracing/test_http_headers.py

@@ -62,6 +62,14 @@ def test_iter_headers(monkeypatch):
         mock.Mock(return_value="12312012123120121231201212312012-0415201309082013-0"),
     )
 
+    monkeypatch.setattr(
+        Transaction,
+        "to_w3c_traceparent",
+        mock.Mock(
+            return_value="00-12312012123120121231201212312012-0415201309082013-00"
+        ),
+    )
+
     transaction = Transaction(
         name="/interactions/other-dogs/new-dog",
         op="greeting.sniff",
@@ -71,3 +79,7 @@ def test_iter_headers(monkeypatch):
     assert (
         headers["sentry-trace"] == "12312012123120121231201212312012-0415201309082013-0"
     )
+    assert (
+        headers["traceparent"]
+        == "00-12312012123120121231201212312012-0415201309082013-00"
+    )

tests/tracing/test_integration_tests.py

@@ -147,6 +147,101 @@ def test_continue_from_headers(
     assert message_payload["message"] == "hello"
 
 
+@pytest.mark.parametrize("parent_sampled", [True, False, None])
+@pytest.mark.parametrize("sample_rate", [0.0, 1.0])
+def test_continue_from_w3c_headers(
+    sentry_init, capture_envelopes, parent_sampled, sample_rate
+):
+    """
+    Ensure data is actually passed along via headers, and that they are read
+    correctly. This test is similar to the one above, but uses W3C headers
+    instead of Sentry headers.
+    """
+    sentry_init(traces_sample_rate=sample_rate)
+    envelopes = capture_envelopes()
+
+    # make a parent transaction (normally this would be in a different service)
+    with start_transaction(name="hi", sampled=True if sample_rate == 0 else None):
+        with start_span() as old_span:
+            old_span.sampled = parent_sampled
+            headers = dict(
+                sentry_sdk.get_current_scope().iter_trace_propagation_headers(old_span)
+            )
+            headers["baggage"] = (
+                "other-vendor-value-1=foo;bar;baz, "
+                "sentry-trace_id=d055bff6ed16698222b464d97f980489, "
+                "sentry-public_key=49d0f7386ad645858ae85020e393bef3, "
+                "sentry-sample_rate=0.01337, sentry-user_id=Amelie, "
+                "other-vendor-value-2=foo;bar;"
+            )
+
+    # child transaction, to prove that we can read 'sentry-trace' header data correctly
+    child_transaction = Transaction.continue_from_headers(headers, name="WRONG")
+    assert child_transaction is not None
+    assert child_transaction.parent_sampled == parent_sampled
+    assert child_transaction.trace_id == old_span.trace_id
+    assert child_transaction.same_process_as_parent is False
+    assert child_transaction.parent_span_id == old_span.span_id
+    assert child_transaction.span_id != old_span.span_id
+
+    baggage = child_transaction._baggage
+    assert baggage
+    assert not baggage.mutable
+    assert baggage.sentry_items == {
+        "public_key": "49d0f7386ad645858ae85020e393bef3",
+        "trace_id": "d055bff6ed16698222b464d97f980489",
+        "user_id": "Amelie",
+        "sample_rate": "0.01337",
+    }
+
+    # add child transaction to the scope, to show that the captured message will
+    # be tagged with the trace id (since it happens while the transaction is
+    # open)
+    with start_transaction(child_transaction):
+        # change the transaction name from "WRONG" to make sure the change
+        # is reflected in the final data
+        sentry_sdk.get_current_scope().transaction = "ho"
+        capture_message("hello")
+
+    if parent_sampled is False or (sample_rate == 0 and parent_sampled is None):
+        # in this case the child transaction won't be captured
+        trace1, message = envelopes
+        message_payload = message.get_event()
+        trace1_payload = trace1.get_transaction_event()
+
+        assert trace1_payload["transaction"] == "hi"
+    else:
+        trace1, message, trace2 = envelopes
+        trace1_payload = trace1.get_transaction_event()
+        message_payload = message.get_event()
+        trace2_payload = trace2.get_transaction_event()
+
+        assert trace1_payload["transaction"] == "hi"
+        assert trace2_payload["transaction"] == "ho"
+
+        assert (
+            trace1_payload["contexts"]["trace"]["trace_id"]
+            == trace2_payload["contexts"]["trace"]["trace_id"]
+            == child_transaction.trace_id
+            == message_payload["contexts"]["trace"]["trace_id"]
+        )
+
+        if parent_sampled is not None:
+            expected_sample_rate = str(float(parent_sampled))
+        else:
+            expected_sample_rate = str(sample_rate)
+
+        assert trace2.headers["trace"] == baggage.dynamic_sampling_context()
+        assert trace2.headers["trace"] == {
+            "public_key": "49d0f7386ad645858ae85020e393bef3",
+            "trace_id": "d055bff6ed16698222b464d97f980489",
+            "user_id": "Amelie",
+            "sample_rate": expected_sample_rate,
+        }
+
+    assert message_payload["message"] == "hello"
+
+
 @pytest.mark.parametrize("sample_rate", [0.0, 1.0])
 def test_propagate_traces_deprecation_warning(sentry_init, sample_rate):
     sentry_init(traces_sample_rate=sample_rate, propagate_traces=False)