Class: Datadog::Contrib::Sinatra::TracerMiddleware

Inherits:
Object
  • Object
show all
Defined in:
lib/ddtrace/contrib/sinatra/tracer_middleware.rb

Overview

Middleware used for automatically tagging configured headers and handle request span

Instance Method Summary collapse

Constructor Details

#initialize(app, opt = {}) ⇒ TracerMiddleware

Returns a new instance of TracerMiddleware.



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# File 'lib/ddtrace/contrib/sinatra/tracer_middleware.rb', line 12

def initialize(app, opt = {})
  @app = app
  @app_instance = opt[:app_instance]
end

Instance Method Details

#call(env) ⇒ Object

rubocop:disable Metrics/AbcSize rubocop:disable Metrics/MethodLength rubocop:disable Metrics/CyclomaticComplexity rubocop:disable Metrics/PerceivedComplexity



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# File 'lib/ddtrace/contrib/sinatra/tracer_middleware.rb', line 21

def call(env)
  # Set the trace context (e.g. distributed tracing)
  if configuration[:distributed_tracing] && tracer.provider.context.trace_id.nil?
    context = HTTPPropagator.extract(env)
    tracer.provider.context = context if context.trace_id
  end

  tracer.trace(
    Ext::SPAN_REQUEST,
    service: configuration[:service_name],
    span_type: Datadog::Ext::HTTP::TYPE_INBOUND,
    # this is kept nil until we set a correct one (either in the route or with a fallback in the ensure below)
    # the nil signals that there's no good one yet and is also seen by profiler, when sampling the resource
    resource: nil,
  ) do |span|
    begin
      Sinatra::Env.set_datadog_span(env, @app_instance, span)

      response = @app.call(env)
    ensure
      Sinatra::Env.request_header_tags(env, configuration[:headers][:request]).each do |name, value|
        span.set_tag(name, value) if span.get_tag(name).nil?
      end

      request = ::Sinatra::Request.new(env)
      span.set_tag(Datadog::Ext::HTTP::URL, request.path)
      span.set_tag(Datadog::Ext::HTTP::METHOD, request.request_method)
      span.set_tag(Ext::TAG_SCRIPT_NAME, request.script_name) if request.script_name && !request.script_name.empty?

      span.set_tag(Ext::TAG_APP_NAME, @app_instance.settings.name)

      # If this app handled the request, then Contrib::Sinatra::Tracer OR Contrib::Sinatra::Base set the
      # resource; if no resource was set, let's use a fallback
      span.resource = env['REQUEST_METHOD'] if span.resource.nil?

      # TODO: This backfills the non-matching Sinatra app with a "#{method} #{path}"
      # TODO: resource name. This shouldn't be the case, as that app has never handled
      # TODO: the response with that resource.
      # TODO: We should replace this backfill code with a clear `resource` that signals
      # TODO: that this Sinatra span was *not* responsible for processing the current request.
      rack_request_span = env[Datadog::Contrib::Rack::TraceMiddleware::RACK_REQUEST_SPAN]
      span.resource = rack_request_span.resource if rack_request_span && rack_request_span.resource

      if response
        if (status = response[0])
          sinatra_response = ::Sinatra::Response.new([], status) # Build object to use status code helpers

          span.set_tag(Datadog::Ext::HTTP::STATUS_CODE, sinatra_response.status)
          span.set_error(env['sinatra.error']) if sinatra_response.server_error?
        end

        if (headers = response[1])
          Sinatra::Headers.response_header_tags(headers, configuration[:headers][:response]).each do |name, value|
            span.set_tag(name, value) if span.get_tag(name).nil?
          end
        end
      end

      # Set analytics sample rate
      Contrib::Analytics.set_sample_rate(span, analytics_sample_rate) if analytics_enabled?

      # Measure service stats
      Contrib::Analytics.set_measured(span)
    end
  end
end