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diff --git a/docs/opentracing.rst b/docs/opentracing.rst deleted file mode 100644 index 6e98ab56ba..0000000000 --- a/docs/opentracing.rst +++ /dev/null @@ -1,123 +0,0 @@ -=========== -OpenTracing -=========== - -Background ----------- - -OpenTracing is a semi-standard being adopted by a number of distributed tracing -platforms. It is a common api for facilitating vendor-agnostic tracing -instrumentation. That is, we can use the OpenTracing api and select one of a -number of tracer implementations to do the heavy lifting in the background. -Our current selected implementation is Jaeger. - -OpenTracing is a tool which gives an insight into the causal relationship of -work done in and between servers. The servers each track events and report them -to a centralised server - in Synapse's case: Jaeger. The basic unit used to -represent events is the span. The span roughly represents a single piece of work -that was done and the time at which it occurred. A span can have child spans, -meaning that the work of the child had to be completed for the parent span to -complete, or it can have follow-on spans which represent work that is undertaken -as a result of the parent but is not depended on by the parent to in order to -finish. - -Since this is undertaken in a distributed environment a request to another -server, such as an RPC or a simple GET, can be considered a span (a unit or -work) for the local server. This causal link is what OpenTracing aims to -capture and visualise. In order to do this metadata about the local server's -span, i.e the 'span context', needs to be included with the request to the -remote. - -It is up to the remote server to decide what it does with the spans -it creates. This is called the sampling policy and it can be configured -through Jaeger's settings. - -For OpenTracing concepts see -https://opentracing.io/docs/overview/what-is-tracing/. - -For more information about Jaeger's implementation see -https://www.jaegertracing.io/docs/ - -===================== -Seting up OpenTracing -===================== - -To receive OpenTracing spans, start up a Jaeger server. This can be done -using docker like so: - -.. code-block:: bash - - docker run -d --name jaeger - -p 6831:6831/udp \ - -p 6832:6832/udp \ - -p 5778:5778 \ - -p 16686:16686 \ - -p 14268:14268 \ - jaegertracing/all-in-one:1.13 - -Latest documentation is probably at -https://www.jaegertracing.io/docs/1.13/getting-started/ - - -Enable OpenTracing in Synapse ------------------------------ - -OpenTracing is not enabled by default. It must be enabled in the homeserver -config by uncommenting the config options under ``opentracing`` as shown in -the `sample config <./sample_config.yaml>`_. For example: - -.. code-block:: yaml - - opentracing: - tracer_enabled: true - homeserver_whitelist: - - "mytrustedhomeserver.org" - - "*.myotherhomeservers.com" - -Homeserver whitelisting ------------------------ - -The homeserver whitelist is configured using regular expressions. A list of regular -expressions can be given and their union will be compared when propagating any -spans contexts to another homeserver. - -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 different sampling policies - could incur higher sampling counts than intended. -- Sending servers can attach arbitrary data to spans, known as 'baggage'. For safety this has been disabled in Synapse - but that doesn't prevent another server sending you baggage which will be logged - to OpenTracing's logs. - -========== -EDU FORMAT -========== - -EDUs can contain tracing data in their content. This is not specced but -it could be of interest for other homeservers. - -EDU format (if you're using jaeger): - -.. code-block:: json - - { - "edu_type": "type", - "content": { - "org.matrix.opentracing_context": { - "uber-trace-id": "fe57cf3e65083289" - } - } - } - -Though you don't have to use jaeger you must inject the span context into -`org.matrix.opentracing_context` using the opentracing `Format.TEXT_MAP` inject method. - -================== -Configuring Jaeger -================== - -Sampling strategies can be set as in this document: -https://www.jaegertracing.io/docs/1.13/sampling/ |