Class: OpenTelemetry::Processor::Baggage::BaggageSpanProcessor

Inherits:
SDK::Trace::SpanProcessor
  • Object
show all
Defined in:
lib/opentelemetry/processor/baggage/baggage_span_processor.rb

Overview

The BaggageSpanProcessor reads key/values stored in Baggage in the starting span's parent context and adds them as attributes to the span, if a key matches a provided predicate lambda.

Keys and values added to Baggage will appear on all subsequent child spans, not the current active span, for a trace within this service and will be propagated to external services via propagation headers.

If the external services also have a Baggage span processor, the keys and values will appear in those child spans as well.

⚠️ To repeat: a consequence of adding data to Baggage is that the keys and values will appear in all outgoing HTTP headers from the application. Do not put sensitive information in Baggage. ⚠️

Examples:

Adding the BaggageSpanProcessor to the SDK, only add attributes for keys that start with 'myapp.'

OUR_BAGGAGE_KEY_PREFIX = 'myapp.'.freeze

OpenTelemetry::SDK.configure do |c|
  # Add the BaggageSpanProcessor to the collection of span processors
  c.add_span_processor(
    OpenTelemetry::Processor::Baggage::BaggageSpanProcessor.new(
      ->(key) { key.start_with?(OUR_BAGGAGE_KEY_PREFIX) } # a constant here improves performance
    )
  )

  # Because the span processor list is no longer empty, the SDK will not use the
  # values in OTEL_TRACES_EXPORTER to instantiate exporters.
  # You'll need to declare your own here in the configure block.
  #
  # These lines setup the default: a batching OTLP exporter.
  c.add_span_processor(
    # these constructors without arguments will pull config from the environment
    OpenTelemetry::SDK::Trace::Export::BatchSpanProcessor.new(
      OpenTelemetry::Exporter::OTLP::Exporter.new()
    )
  )
end

Allow all Baggage keys to be added to the span as attributes

OpenTelemetry::Processor::Baggage::BaggageSpanProcessor.new(
  # This processor provides a convenience predicate that allows all keys to be added as attributes.
  OpenTelemetry::Processor::Baggage::ALLOW_ALL_BAGGAGE_KEYS
)

Instance Method Summary collapse

Constructor Details

#initialize(baggage_key_predicate) ⇒ BaggageSpanProcessor

Create a new BaggageSpanProcessor that reads Baggage keys and values from the parent context and adds them as attributes to the span.

Examples:

Only add attributes for keys that start with a specific prefix

OUR_BAGGAGE_KEY_PREFIX = 'myapp.'.freeze
OpenTelemetry::Processor::Baggage::BaggageSpanProcessor.new(
  ->(key) { key.start_with?(OUR_BAGGAGE_KEY_PREFIX) } # a constant here improves performance
)

Parameters:

  • baggage_key_predicate (lambda) —

    A lambda that takes a baggage key [String] and returns true if the key should be added to the span as an attribute, false otherwise.

Raises:

  • (ArgumentError) 


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# File 'lib/opentelemetry/processor/baggage/baggage_span_processor.rb', line 74

def initialize(baggage_key_predicate)
  raise ArgumentError, 'baggage_key_predicate must respond to :call (lambda/Proc)' unless baggage_key_predicate.respond_to?(:call)

  @baggage_key_predicate = baggage_key_predicate
  super()
end

Instance Method Details

#force_flush(timeout: nil) ⇒ Integer

Always successful; this processor does not maintain any state to flush.

NO-OP method to satisfy the SpanProcessor duck type.

Parameters:

  • timeout (optional Numeric) (defaults to: nil) —

    An optional timeout in seconds.

Returns:

  • (Integer) —

    0 for success and there is nothing to flush so always successful.



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# File 'lib/opentelemetry/processor/baggage/baggage_span_processor.rb', line 110

def force_flush(timeout: nil)
  0
end

#on_finish(span) ⇒ Object

Called when a Span is ended, does nothing.

NO-OP method to satisfy the SpanProcessor duck type.

Parameters:

  • span (Span) —

    the Trace::Span that just ended.



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# File 'lib/opentelemetry/processor/baggage/baggage_span_processor.rb', line 102

def on_finish(span); end

#on_start(span, parent_context) ⇒ Object

Called when a Span is started, adds Baggage keys/values to the span as attributes.

Parameters:

  • span (Span) —

    the Span that just started, expected to conform to the concrete Span interface from the SDK and respond to :add_attributes.

  • parent_context (Context) —

    the parent Context of the newly started span.



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# File 'lib/opentelemetry/processor/baggage/baggage_span_processor.rb', line 87

def on_start(span, parent_context)
  return unless span.respond_to?(:add_attributes) && parent_context.is_a?(::OpenTelemetry::Context)

  span.add_attributes(
    ::OpenTelemetry::Baggage
      .values(context: parent_context)
      .select { |k, _v| @baggage_key_predicate.call(k) }
  )
end

#shutdown(timeout: nil) ⇒ Integer

Always successful; this processor does not maintain any state to clean up or processes to close on shutdown.

NO-OP method to satisfy the SpanProcessor duck type.

Parameters:

  • timeout (optional Numeric) (defaults to: nil) —

    An optional timeout in seconds.

Returns:

  • (Integer) —

    0 for success and there is nothing to stop so always successful.



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# File 'lib/opentelemetry/processor/baggage/baggage_span_processor.rb', line 120

def shutdown(timeout: nil)
  0
end