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, &block) ⇒ Object 



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

def call(env, configuration, &block)
  if configuration[:inferred_proxy_enabled] &&
      (proxy_type = env[Ext::HEADER_X_DD_PROXY]) && !proxy_type.empty?
    return call_with_inferred_proxy(env, proxy_type, &block)
  end
  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_SVC_SRC, Ext::TAG_COMPONENT_HTTP_PROXY)
  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_SVC_SRC, Ext::TAG_COMPONENT_HTTP_PROXY)
  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

.call_with_inferred_proxy(env, proxy_type) ⇒ Object

Creates a virtual parent span representing the upstream proxy that wraps the actual request processing.

rubocop:disable Metrics/CyclomaticComplexity, Metrics/PerceivedComplexity



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# File 'lib/datadog/tracing/contrib/rack/trace_proxy_middleware.rb', line 65

def call_with_inferred_proxy(env, proxy_type)
  span_name = Ext::PROXY_SPAN_NAMES[proxy_type]
  return yield unless span_name

  request_time_ms = env[Ext::HEADER_X_DD_PROXY_REQUEST_TIME_MS].to_f
  return yield unless request_time_ms.positive?

  path = env[Ext::HEADER_X_DD_PROXY_PATH]
  stage = env[Ext::HEADER_X_DD_PROXY_STAGE]
  domain = env[Ext::HEADER_X_DD_PROXY_DOMAIN_NAME]
  http_method = env[Ext::HEADER_X_DD_PROXY_HTTPMETHOD]
  resource_path = env[Ext::HEADER_X_DD_PROXY_RESOURCE_PATH]

  # NOTE: resource_path is the parameterized route (e.g. /users/{id}) vs literal path
  resource = "#{http_method} #{resource_path || path}" if http_method

  inferred_span = Tracing.trace(
    span_name,
    service: domain,
    type: Tracing::Metadata::Ext::AppTypes::TYPE_WEB,
    start_time: Time.at(request_time_ms / 1_000),
  )
  inferred_span.resource = resource if resource
  inferred_span.set_tag(Tracing::Metadata::Ext::TAG_COMPONENT, proxy_type)
  inferred_span.set_tag(Tracing::Metadata::Ext::TAG_KIND, Tracing::Metadata::Ext::SpanKind::TAG_SERVER)
  inferred_span.set_tag("stage", stage) if stage
  inferred_span.set_tag(Tracing::Metadata::Ext::HTTP::TAG_METHOD, http_method) if http_method
  inferred_span.set_tag(Tracing::Metadata::Ext::HTTP::TAG_URL, "https://#{domain}#{path}") if domain && path
  inferred_span.set_tag(Tracing::Metadata::Ext::HTTP::TAG_ROUTE, resource_path) if resource_path
  inferred_span.set_metric(Ext::TAG_INFERRED_SPAN, 1)

  set_optional_tags(inferred_span, env: env, proxy_type: proxy_type)

  yield
# NOTE: The underlying {Rack::TraceMiddleware} rescues {Exception}
#       to tag the request span with error details.
#       We must propagate errors to the inferred proxy parent span.
rescue Exception => e # rubocop:disable Lint/RescueException
  inferred_span&.set_error(e)
  raise
ensure
  if inferred_span
    propagate_request_span_tags(inferred_span, env: env)

    if (trace = Tracing.active_trace) && resource
      trace.resource = resource
    end

    inferred_span.finish
  end
end

.propagate_request_span_tags(span, env:) ⇒ Object

Propagates response-level and security tags from the request span to the inferred parent.



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# File 'lib/datadog/tracing/contrib/rack/trace_proxy_middleware.rb', line 149

def propagate_request_span_tags(span, env:)
  rack_span = env[Ext::RACK_ENV_REQUEST_SPAN]
  return unless rack_span

  if (status_code = rack_span.get_tag(Tracing::Metadata::Ext::HTTP::TAG_STATUS_CODE))
    span.set_tag(Tracing::Metadata::Ext::HTTP::TAG_STATUS_CODE, status_code)
    span.status = rack_span.status
  end

  if (user_agent = rack_span.get_tag(Tracing::Metadata::Ext::HTTP::TAG_USER_AGENT))
    span.set_tag(Tracing::Metadata::Ext::HTTP::TAG_USER_AGENT, user_agent)
  end

  # NOTE: Tracing shouldn't know about AppSec tags.
  if (appsec_enabled = rack_span.get_metric("_dd.appsec.enabled"))
    span.set_metric("_dd.appsec.enabled", appsec_enabled)
  end

  # NOTE: Tracing shouldn't know about AppSec tags.
  if (appsec_json = rack_span.get_tag("_dd.appsec.json"))
    span.set_tag("_dd.appsec.json", appsec_json)
  end
end

.set_optional_tags(span, env:, proxy_type:) ⇒ Object

Sets cloud provider metadata and constructs the resource ARN.

rubocop:disable Metrics/CyclomaticComplexity, Metrics/PerceivedComplexity



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# File 'lib/datadog/tracing/contrib/rack/trace_proxy_middleware.rb', line 121

def set_optional_tags(span, env:, proxy_type:)
  api_id = env[Ext::HEADER_X_DD_PROXY_API_ID]
  region = env[Ext::HEADER_X_DD_PROXY_REGION]

  # API Gateway v1 sends region as a single-quoted string
  region = region.delete("'") if region

  span.set_tag("apiid", api_id) if api_id
  span.set_tag("region", region) if region

  if ( = env[Ext::HEADER_X_DD_PROXY_ACCOUNT_ID])
    span.set_tag("account_id", )
  end

  if (user = env[Ext::HEADER_X_DD_PROXY_USER])
    span.set_tag("aws_user", user)
  end

  if api_id && region
    # NOTE: Update this when adding non-AWS proxy types.
    restapi_prefix = (proxy_type == Ext::PROXY_AWS_APIGATEWAY) ? "restapis" : "apis"
    span.set_tag("dd_resource_key", "arn:aws:apigateway:#{region}::/#{restapi_prefix}/#{api_id}")
  end
end