diff --git a/synapse/config/tracer.py b/synapse/config/tracer.py
index 63a637984a..a2ce9ab3f6 100644
--- a/synapse/config/tracer.py
+++ b/synapse/config/tracer.py
@@ -18,33 +18,52 @@ from ._base import Config, ConfigError
class TracerConfig(Config):
def read_config(self, config, **kwargs):
- self.tracer_config = config.get("opentracing")
+ opentracing_config = config.get("opentracing")
+ if opentracing_config is None:
+ opentracing_config = {}
- self.tracer_config = config.get("opentracing", {"tracer_enabled": False})
+ self.opentracer_enabled = opentracing_config.get("enabled", False)
+ if not self.opentracer_enabled:
+ return
- if self.tracer_config.get("tracer_enabled", False):
- # The tracer is enabled so sanitize the config
- # If no whitelists are given
- self.tracer_config.setdefault("homeserver_whitelist", [])
+ # The tracer is enabled so sanitize the config
- if not isinstance(self.tracer_config.get("homeserver_whitelist"), list):
- raise ConfigError("Tracer homesererver_whitelist config is malformed")
+ self.opentracer_whitelist = opentracing_config.get("homeserver_whitelist", [])
+ if not isinstance(self.opentracer_whitelist, list):
+ raise ConfigError("Tracer homeserver_whitelist config is malformed")
def generate_config_section(cls, **kwargs):
return """\
## Opentracing ##
- # These settings enable opentracing which implements distributed tracing
- # This allows you to observe the causal chain of events across servers
- # including requests, key lookups etc. across any server running
- # synapse or any other other services which supports opentracing.
- # (specifically those implemented with jaeger)
-
- #opentracing:
- # # Enable / disable tracer
- # tracer_enabled: false
- # # The list of homeservers we wish to expose our current traces to.
- # # The list is a list of regexes which are matched against the
- # # servername of the homeserver
- # homeserver_whitelist:
- # - ".*"
+
+ # These settings enable opentracing, which implements distributed tracing.
+ # This allows you to observe the causal chains of events across servers
+ # including requests, key lookups etc., across any server running
+ # synapse or any other other services which supports opentracing
+ # (specifically those implemented with Jaeger).
+ #
+ opentracing:
+ # tracing is disabled by default. Uncomment the following line to enable it.
+ #
+ #enabled: true
+
+ # The list of homeservers we wish to send and receive span contexts and span baggage.
+ #
+ # Though it's mostly safe to send and receive span contexts to and from
+ # untrusted users since span contexts are usually opaque ids it can lead to
+ # two problems, namely:
+ # - If the span context is marked as sampled by the sending homeserver the receiver will
+ # sample it. Therefore two homeservers with wildly disparaging sampling policies
+ # could incur higher sampling counts than intended.
+ # - Span baggage can be arbitrary data. For safety this has been disabled in synapse
+ # but that doesn't prevent another server sending you baggage which will be logged
+ # to opentracing logs.
+ #
+ # This a list of regexes which are matched against the server_name of the
+ # homeserver.
+ #
+ # By defult, it is empty, so no servers are matched.
+ #
+ #homeserver_whitelist:
+ # - ".*"
"""
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