diff --git a/synapse/logging/opentracing.py b/synapse/logging/opentracing.py
index 4f18792c99..140ed711e3 100644
--- a/synapse/logging/opentracing.py
+++ b/synapse/logging/opentracing.py
@@ -173,6 +173,7 @@ from typing import TYPE_CHECKING, Collection, Dict, List, Optional, Pattern, Typ
import attr
from twisted.internet import defer
+from twisted.web.http_headers import Headers
from synapse.config import ConfigError
from synapse.util import json_decoder, json_encoder
@@ -668,6 +669,25 @@ def inject_header_dict(
headers[key.encode()] = [value.encode()]
+def inject_response_headers(response_headers: Headers) -> None:
+ """Inject the current trace id into the HTTP response headers"""
+ if not opentracing:
+ return
+ span = opentracing.tracer.active_span
+ if not span:
+ return
+
+ # This is a bit implementation-specific.
+ #
+ # Jaeger's Spans have a trace_id property; other implementations (including the
+ # dummy opentracing.span.Span which we use if init_tracer is not called) do not
+ # expose it
+ trace_id = getattr(span, "trace_id", None)
+
+ if trace_id is not None:
+ response_headers.addRawHeader("Synapse-Trace-Id", f"{trace_id:x}")
+
+
@ensure_active_span("get the active span context as a dict", ret={})
def get_active_span_text_map(destination=None):
"""
@@ -843,6 +863,7 @@ def trace_servlet(request: "SynapseRequest", extract_context: bool = False):
scope = start_active_span(request_name)
with scope:
+ inject_response_headers(request.responseHeaders)
try:
yield
finally:
|
