Tracing

Distributed tracing tracks requests as they flow through a distributed system (in this case: a Rasa assistant), sending data about the requests to a tracing backend which collects all trace data and enables inspecting it. Trace data helps you understand the flow of requests through both the components of a single service (Rasa itself), and across different distributed services, for example, your action server.

Supported Tracing Backends/Collectors

To trace requests in Rasa Pro, you can either use Jaeger as a backend, or use the OTEL Collector (OpenTelemetry Collector) to collect traces and then send them to the backend of your choice. See Configuring a Tracing Backend or Collector for instructions.

Enabling / Disabling

Tracing is automatically enabled in Rasa Pro by configuring a supported tracing backend. No further action is required to enable tracing.

You can disable tracing by leaving the tracing: configuration key empty in your endpoints file.

Action Server

The trace context is sent along with requests to the custom action server using the W3C Trace Context Specification. You can use this trace context to continue tracing the request through your custom action code. See traced events for details on what attributes are made available as part of the trace context.

Configuring a Tracing Backend or Collector

To configure a tracing backend or collector, add a tracing entry to your endpoints i.e. in your endpoints.yml file, or in the relevant section of your Helm values in a deployment.

Jaeger

To configure a Jaeger tracing backend, specify the type as jaeger.

tracing:
  type: jaeger
  host: localhost
  port: 6831
  service_name: rasa
  sync_export: ~

OTEL Collector

Collectors are components that collect traces in a vendor-agnostic way and then forward them to various backends. For example, the OpenTelemetry Collector (OTEL) can collect traces from multiple different components and instrumentation libraries, and then export them to multiple different backends e.g. jaeger.

To configure an OTEL Collector, specify the type as otlp.

tracing:
  type: otlp
  endpoint: my-otlp-host:4318
  insecure: false
  service_name: rasa
  root_certificates: ./tests/unit/tracing/fixtures/ca.pem

Traced Events

The Rasa service areas that are traceable cover the actions required to:

• train a model (i.e., the training of each graph component)
• handle a message

Model Training

Tracing is enabled for model training by instrumenting Rasa GraphTrainer and GraphNode classes.

GraphTrainer Attributes

The following attributes can be inspected during training of GraphTrainer:

• training_type of model configuration:
  • "NLU"
  • "CORE"
  • "BOTH"
  • "END-TO-END"
• language of model configuration
• recipe_name used in the config.yml file
• output_filename: the location where the packaged model is saved
• is_finetuning: boolean argument, if True enables incremental training

GraphNode Attributes

The following attributes are captured during the training (as well as prediction during message handling) of every graph node:

• node_name
• component_class
• fn_name: method of component class that gets called

Message Handling

The following Rasa classes are instrumented to enable tracing during message handling:

• Agent
• MessageProcessor
• TrackerStore
• LockStore

Namely, these operations are now traceable:

• receiving a message
• parsing the message
• predicting the next action
• running the action
• retrieving and saving the tracker
• locking the conversation
• publishing to the event broker
• passing the trace context to the action server

Agent Attributes

Tracing the Agent instance handling a message captures the following attributes:

• input_channel: the name of the channel connector
• sender_id: the conversation id
• model_id: a unique identifier for the model
• model_name: the model name

MessageProcessor Attributes

The following MessageProcessor attributes are extracted during the tracing:

• number_of_events: number of events in tracker
• action_name: the name of the predicted and executed action
• sender_id: the conversation id of the DialogueStateTracker object
• message_id: the unique message id

The latter three attributes are also injected in the trace context that gets passed to the requests made to the custom action server.

TrackerStore & LockStore Attributes

Observable TrackerStore and LockStore attributes include:

• number_of_streamed_events: number of new events to stream
• broker_class: the EventBroker on which the new events are published
• lock_store_class: Name of lock store used to lock conversations while messages are actively processed