Module: Datadog::Tracing::Contrib::Rack::TraceProxyMiddleware

Defined in:
lib/datadog/tracing/contrib/rack/trace_proxy_middleware.rb

Overview

Module to create virtual proxy span

Class Method Summary collapse

Class Method Details

.call(env, configuration) ⇒ Object 



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# File 'lib/datadog/tracing/contrib/rack/trace_proxy_middleware.rb', line 16

def call(env, configuration)
  return yield unless configuration[:request_queuing]

  # parse the request queue time
  start_time = Contrib::Rack::QueueTime.get_request_start(env)
  return yield unless start_time

  options = {
    service: configuration[:web_service_name],
    start_time: start_time,
    type: Tracing::Metadata::Ext::HTTP::TYPE_PROXY
  }

  request_span = Tracing.trace(Ext::SPAN_HTTP_PROXY_REQUEST, **options)

  request_span.set_tag(Tracing::Metadata::Ext::TAG_COMPONENT, Ext::TAG_COMPONENT_HTTP_PROXY)
  request_span.set_tag(Tracing::Metadata::Ext::TAG_OPERATION, Ext::TAG_OPERATION_HTTP_PROXY_REQUEST)
  request_span.set_tag(Tracing::Metadata::Ext::TAG_KIND, Tracing::Metadata::Ext::SpanKind::TAG_PROXY)

  queue_span = Tracing.trace(Ext::SPAN_HTTP_PROXY_QUEUE, **options)

  queue_span.set_tag(Tracing::Metadata::Ext::TAG_COMPONENT, Ext::TAG_COMPONENT_HTTP_PROXY)
  queue_span.set_tag(Tracing::Metadata::Ext::TAG_OPERATION, Ext::TAG_OPERATION_HTTP_PROXY_QUEUE)
  queue_span.set_tag(Tracing::Metadata::Ext::TAG_KIND, Tracing::Metadata::Ext::SpanKind::TAG_PROXY)

  Contrib::Analytics.set_measured(queue_span)
  # finish the `queue` span now to record only the time spent *in queue*,
  # excluding the time spent processing the request itself
  queue_span.finish

  yield
ensure
  # Ensure that the spans are finished even if an exception is raised.
  # **This is very important** to prevent the trace from leaking between requests,
  # especially because `queue_span` is normally a root span.
  queue_span&.finish
  request_span&.finish
end