Module: NewRelic::Agent::DistributedTracing

Extended by:
DistributedTracing, SupportabilityHelper
Included in:
DistributedTracing
Defined in:
lib/new_relic/agent/distributed_tracing.rb

Overview

This module contains helper methods related to Distributed Tracing, an APM feature that ties together traces from multiple apps in one view. Use it to add distributed tracing to protocols not already supported by the agent.

Instance Method Summary collapse

Instance Method Details

#accept_distributed_trace_headers(headers, transport_type = NewRelic::HTTP) ⇒ Transaction

Accepts distributed tracing headers from any source that has been packaged as a Ruby Hash, thereby allowing the user to manually inject distributed tracing headers. It is optimized to process HTTP_TRACEPARENT, HTTP_TRACESTATE, and HTTP_NEWRELIC as the given Hash keys. which is the most common scenario from Rack middleware in most Ruby applications. However, the Hash keys are case-insensitive and the “HTTP_” prefixes may also be omitted.

Calling this method is not necessary in a typical HTTP trace as distributed tracing is already handled by the agent.

When used, invoke this method as early as possible in a transaction’s life-cycle as calling after the headers are already created will have no effect.

This method accepts both W3C trace context and New Relic distributed tracing headers. When both are present, only the W3C headers are utilized. When W3C trace context headers are present, New Relic headers are ignored regardless if W3C trace context headers are valid and parsable.

Parameters:

  • headers (Hash) —

    Incoming distributed trace headers as a Ruby Hash object. Hash keys are expected to be one of TRACEPARENT, TRACESTATE, NEWRELIC and are case-insensitive, with or without “HTTP_” prefixes.

    either as a JSON string or as a header-friendly string returned from DistributedTracePayload#http_safe

  • transport_type (String) (defaults to: NewRelic::HTTP) —

    May be one of: HTTP, HTTPS, Kafka, JMS, IronMQ, AMQP, Queue, Other. Values are case sensitive. All other values result in Unknown

Returns:



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# File 'lib/new_relic/agent/distributed_tracing.rb', line 98

def accept_distributed_trace_headers(headers, transport_type = NewRelic::HTTP)
  record_api_supportability_metric(:accept_distributed_trace_headers)

  unless Agent.config[:'distributed_tracing.enabled']
    NewRelic::Agent.logger.warn('Not configured to accept distributed trace headers')
    return nil
  end

  return unless valid_api_argument_class?(headers, 'headers', Hash)
  return unless valid_api_argument_class?(transport_type, 'transport_type', String)

  return unless transaction = Transaction.tl_current

  # assume we have Rack conforming keys when transport_type is HTTP(S)
  # otherwise, fish for key/value pairs regardless of prefix and case-sensitivity.
  hdr = if transport_type.start_with?(NewRelic::HTTP)
    headers
  else
    # start with the most common case first
    hdr = {
      NewRelic::HTTP_TRACEPARENT_KEY => headers[NewRelic::TRACEPARENT_KEY],
      NewRelic::HTTP_TRACESTATE_KEY => headers[NewRelic::TRACESTATE_KEY],
      NewRelic::HTTP_NEWRELIC_KEY => headers[NewRelic::NEWRELIC_KEY]
    }

    # when not found, search for any casing for trace context headers, ignoring potential prefixes
    hdr[NewRelic::HTTP_TRACEPARENT_KEY] ||= variant_key_value(headers, NewRelic::TRACEPARENT_KEY)
    hdr[NewRelic::HTTP_TRACESTATE_KEY] ||= variant_key_value(headers, NewRelic::TRACESTATE_KEY)
    hdr[NewRelic::HTTP_NEWRELIC_KEY] ||= variant_key_value(headers, NewRelic::CANDIDATE_NEWRELIC_KEYS)
    hdr
  end

  transaction.distributed_tracer.accept_incoming_request(hdr, transport_type)
  transaction
rescue => e
  NewRelic::Agent.logger.error('error during accept_distributed_trace_headers', e)
  nil
end

#insert_distributed_trace_headers(headers = {}) ⇒ Transaction

Adds the Distributed Trace headers so that the downstream service can participate in a distributed trace. This method should be called every time an outbound call is made since the header payload contains a timestamp.

Distributed Tracing must be enabled to use this method.

insert_distributed_trace_headers always inserts W3C trace context headers and inserts New Relic distributed tracing header by default. New Relic headers may be suppressed by setting exclude_new_relic_header to true in your configuration file.

Parameters:

  • headers (Hash) (defaults to: {}) —

    Is a Hash to which the distributed trace headers will be inserted.

Returns:

  • (Transaction) —

    The transaction the headers were inserted from, or nil if headers were not inserted.



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# File 'lib/new_relic/agent/distributed_tracing.rb', line 44

def insert_distributed_trace_headers(headers = {})
  record_api_supportability_metric(:insert_distributed_trace_headers)

  unless Agent.config[:'distributed_tracing.enabled']
    NewRelic::Agent.logger.warn('Not configured to insert distributed trace headers')
    return nil
  end

  return unless valid_api_argument_class?(headers, 'headers', Hash)

  return unless transaction = Transaction.tl_current

  transaction.distributed_tracer.insert_headers(headers)
  transaction
rescue => e
  NewRelic::Agent.logger.error('error during insert_distributed_trace_headers', e)
  nil
end