diff --git a/synapse/logging/opentracing.py b/synapse/logging/opentracing.py
index dd9377340e..140ed711e3 100644
--- a/synapse/logging/opentracing.py
+++ b/synapse/logging/opentracing.py
@@ -168,11 +168,12 @@ import inspect
import logging
import re
from functools import wraps
-from typing import TYPE_CHECKING, Dict, Optional, Pattern, Type
+from typing import TYPE_CHECKING, Collection, Dict, List, Optional, Pattern, Type
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
@@ -278,6 +279,10 @@ class SynapseTags:
DB_TXN_ID = "db.txn_id"
+class SynapseBaggage:
+ FORCE_TRACING = "synapse-force-tracing"
+
+
# Block everything by default
# A regex which matches the server_names to expose traces for.
# None means 'block everything'.
@@ -285,6 +290,8 @@ _homeserver_whitelist = None # type: Optional[Pattern[str]]
# Util methods
+Sentinel = object()
+
def only_if_tracing(func):
"""Executes the function only if we're tracing. Otherwise returns None."""
@@ -447,12 +454,28 @@ def start_active_span(
)
-def start_active_span_follows_from(operation_name, contexts):
+def start_active_span_follows_from(
+ operation_name: str, contexts: Collection, inherit_force_tracing=False
+):
+ """Starts an active opentracing span, with additional references to previous spans
+
+ Args:
+ operation_name: name of the operation represented by the new span
+ contexts: the previous spans to inherit from
+ inherit_force_tracing: if set, and any of the previous contexts have had tracing
+ forced, the new span will also have tracing forced.
+ """
if opentracing is None:
return noop_context_manager()
references = [opentracing.follows_from(context) for context in contexts]
scope = start_active_span(operation_name, references=references)
+
+ if inherit_force_tracing and any(
+ is_context_forced_tracing(ctx) for ctx in contexts
+ ):
+ force_tracing(scope.span)
+
return scope
@@ -551,6 +574,10 @@ def start_active_span_from_edu(
# Opentracing setters for tags, logs, etc
+@only_if_tracing
+def active_span():
+ """Get the currently active span, if any"""
+ return opentracing.tracer.active_span
@ensure_active_span("set a tag")
@@ -571,62 +598,52 @@ def set_operation_name(operation_name):
opentracing.tracer.active_span.set_operation_name(operation_name)
-# Injection and extraction
-
+@only_if_tracing
+def force_tracing(span=Sentinel) -> None:
+ """Force sampling for the active/given span and its children.
-@ensure_active_span("inject the span into a header")
-def inject_active_span_twisted_headers(headers, destination, check_destination=True):
+ Args:
+ span: span to force tracing for. By default, the active span.
"""
- Injects a span context into twisted headers in-place
+ if span is Sentinel:
+ span = opentracing.tracer.active_span
+ if span is None:
+ logger.error("No active span in force_tracing")
+ return
- Args:
- headers (twisted.web.http_headers.Headers)
- destination (str): address of entity receiving the span context. If check_destination
- is true the context will only be injected if the destination matches the
- opentracing whitelist
- check_destination (bool): If false, destination will be ignored and the context
- will always be injected.
- span (opentracing.Span)
+ span.set_tag(opentracing.tags.SAMPLING_PRIORITY, 1)
- Returns:
- In-place modification of headers
+ # also set a bit of baggage, so that we have a way of figuring out if
+ # it is enabled later
+ span.set_baggage_item(SynapseBaggage.FORCE_TRACING, "1")
- Note:
- The headers set by the tracer are custom to the tracer implementation which
- should be unique enough that they don't interfere with any headers set by
- synapse or twisted. If we're still using jaeger these headers would be those
- here:
- https://github.com/jaegertracing/jaeger-client-python/blob/master/jaeger_client/constants.py
- """
- if check_destination and not whitelisted_homeserver(destination):
- return
+def is_context_forced_tracing(span_context) -> bool:
+ """Check if sampling has been force for the given span context."""
+ if span_context is None:
+ return False
+ return span_context.baggage.get(SynapseBaggage.FORCE_TRACING) is not None
- span = opentracing.tracer.active_span
- carrier = {} # type: Dict[str, str]
- opentracing.tracer.inject(span.context, opentracing.Format.HTTP_HEADERS, carrier)
- for key, value in carrier.items():
- headers.addRawHeaders(key, value)
+# Injection and extraction
-@ensure_active_span("inject the span into a byte dict")
-def inject_active_span_byte_dict(headers, destination, check_destination=True):
+@ensure_active_span("inject the span into a header dict")
+def inject_header_dict(
+ headers: Dict[bytes, List[bytes]],
+ destination: Optional[str] = None,
+ check_destination: bool = True,
+) -> None:
"""
- Injects a span context into a dict where the headers are encoded as byte
- strings
+ Injects a span context into a dict of HTTP headers
Args:
- headers (dict)
- destination (str): address of entity receiving the span context. If check_destination
- is true the context will only be injected if the destination matches the
- opentracing whitelist
+ headers: the dict to inject headers into
+ destination: address of entity receiving the span context. Must be given unless
+ check_destination is False. The context will only be injected if the
+ destination matches the opentracing whitelist
check_destination (bool): If false, destination will be ignored and the context
will always be injected.
- span (opentracing.Span)
-
- Returns:
- In-place modification of headers
Note:
The headers set by the tracer are custom to the tracer implementation which
@@ -635,8 +652,13 @@ def inject_active_span_byte_dict(headers, destination, check_destination=True):
here:
https://github.com/jaegertracing/jaeger-client-python/blob/master/jaeger_client/constants.py
"""
- if check_destination and not whitelisted_homeserver(destination):
- return
+ if check_destination:
+ if destination is None:
+ raise ValueError(
+ "destination must be given unless check_destination is False"
+ )
+ if not whitelisted_homeserver(destination):
+ return
span = opentracing.tracer.active_span
@@ -647,36 +669,23 @@ def inject_active_span_byte_dict(headers, destination, check_destination=True):
headers[key.encode()] = [value.encode()]
-@ensure_active_span("inject the span into a text map")
-def inject_active_span_text_map(carrier, destination, check_destination=True):
- """
- Injects a span context into a dict
-
- Args:
- carrier (dict)
- destination (str): address of entity receiving the span context. If check_destination
- is true the context will only be injected if the destination matches the
- opentracing whitelist
- check_destination (bool): If false, destination will be ignored and the context
- will always be injected.
-
- Returns:
- In-place modification of carrier
-
- Note:
- The headers set by the tracer are custom to the tracer implementation which
- should be unique enough that they don't interfere with any headers set by
- synapse or twisted. If we're still using jaeger these headers would be those
- here:
- https://github.com/jaegertracing/jaeger-client-python/blob/master/jaeger_client/constants.py
- """
-
- if check_destination and not whitelisted_homeserver(destination):
+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
- opentracing.tracer.inject(
- opentracing.tracer.active_span.context, opentracing.Format.TEXT_MAP, carrier
- )
+ # 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={})
@@ -854,6 +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:
|
