Module: Datadog::Tracing::Contrib::HTTPX::Plugin::RequestTracer

Extended by:
Contrib::HttpAnnotationHelper
Defined in:
lib/httpx/adapters/datadog.rb

Constant Summary collapse

SPAN_REQUEST = 
"httpx.request"

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.call(request) ⇒ Object

initializes tracing on the request.



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# File 'lib/httpx/adapters/datadog.rb', line 41

def call(request)
  return unless configuration(request).enabled

  span = nil

  # request objects are reused, when already buffered requests get rerouted to a different
  # connection due to connection issues, or when they already got a response, but need to
  # be retried. In such situations, the original span needs to be extended for the former,
  # while a new is required for the latter.
  request.on(:idle) do
    span = nil
  end
  # the span is initialized when the request is buffered in the parser, which is the closest
  # one gets to actually sending the request.
  request.on(:headers) do
    next if span

    span = initialize_span(request, now)
  end

  request.on(:response) do |response|
    unless span
      next unless response.is_a?(::HTTPX::ErrorResponse) && response.error.respond_to?(:connection)

      # handles the case when the +error+ happened during name resolution, which means
      # that the tracing start point hasn't been triggered yet; in such cases, the approximate
      # initial resolving time is collected from the connection, and used as span start time,
      # and the tracing object in inserted before the on response callback is called.
      span = initialize_span(request, response.error.connection.init_time)

    end

    finish(response, span)
  end
end

.configuration(request) ⇒ Object 



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# File 'lib/httpx/adapters/datadog.rb', line 133

def configuration(request)
  Datadog.configuration.tracing[:httpx, request.uri.host]
end

.finish(response, span) ⇒ Object 



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# File 'lib/httpx/adapters/datadog.rb', line 77

def finish(response, span)
  if response.is_a?(::HTTPX::ErrorResponse)
    span.set_error(response.error)
  else
    span.set_tag(TAG_STATUS_CODE, response.status.to_s)

    span.set_error(::HTTPX::HTTPError.new(response)) if response.status >= 400 && response.status <= 599
  end

  span.finish
end

.initialize_span(request, start_time) ⇒ Object

return a span initialized with the @request state.



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# File 'lib/httpx/adapters/datadog.rb', line 90

def initialize_span(request, start_time)
  verb = request.verb
  uri = request.uri

  config = configuration(request)

  span = create_span(request, config, start_time)

  span.resource = verb

  # Add additional request specific tags to the span.

  span.set_tag(TAG_URL, request.path)
  span.set_tag(TAG_METHOD, verb)

  span.set_tag(TAG_TARGET_HOST, uri.host)
  span.set_tag(TAG_TARGET_PORT, uri.port)

  # Tag as an external peer service
  span.set_tag(TAG_PEER_SERVICE, span.service)

  if config[:distributed_tracing]
    propagate_trace_http(
      Datadog::Tracing.active_trace,
      request.headers
    )
  end

  # Set analytics sample rate
  if Contrib::Analytics.enabled?(config[:analytics_enabled])
    Contrib::Analytics.set_sample_rate(span, config[:analytics_sample_rate])
  end

  span
rescue StandardError => e
  Datadog.logger.error("error preparing span for http request: #{e}")
  Datadog.logger.error(e.backtrace)
end

.now ⇒ Object 



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# File 'lib/httpx/adapters/datadog.rb', line 129

def now
  ::Datadog::Core::Utils::Time.now.utc
end

Instance Method Details

#create_span(request, configuration, start_time) ⇒ Object 



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# File 'lib/httpx/adapters/datadog.rb', line 142

def create_span(request, configuration, start_time)
  Datadog::Tracing.trace(
    SPAN_REQUEST,
    service: service_name(request.uri.host, configuration),
    type: TYPE_OUTBOUND,
    start_time: start_time
  )
end

#propagate_trace_http(trace, headers) ⇒ Object 



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# File 'lib/httpx/adapters/datadog.rb', line 138

def propagate_trace_http(trace, headers)
  Datadog::Tracing::Contrib::HTTP.inject(trace, headers)
end