Class: Datadog::Contrib::Rack::TraceMiddleware
- Inherits:
-
Object
- Object
- Datadog::Contrib::Rack::TraceMiddleware
- Defined in:
- lib/ddtrace/contrib/rack/middlewares.rb
Overview
TraceMiddleware ensures that the Rack Request is properly traced from the beginning to the end. The middleware adds the request span in the Rack environment so that it can be retrieved by the underlying application. If request tags are not set by the app, they will be set using information available at the Rack level. rubocop:disable Metrics/ClassLength
Constant Summary collapse
- RACK_REQUEST_SPAN =
DEPRECATED: Remove in 1.0 in favor of Datadog::Contrib::Rack::Ext::RACK_ENV_REQUEST_SPAN This constant will remain here until then, for backwards compatibility.
'datadog.rack_request_span'.freeze
Instance Method Summary collapse
- #call(env) ⇒ Object
- #compute_queue_time(env, tracer) ⇒ Object
-
#initialize(app) ⇒ TraceMiddleware
constructor
A new instance of TraceMiddleware.
- #resource_name_for(env, status) ⇒ Object
-
#set_request_tags!(request_span, env, status, headers, response, original_env) ⇒ Object
rubocop:disable Metrics/AbcSize.
Constructor Details
#initialize(app) ⇒ TraceMiddleware
Returns a new instance of TraceMiddleware.
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# File 'lib/ddtrace/contrib/rack/middlewares.rb', line 24 def initialize(app) @app = app end |
Instance Method Details
#call(env) ⇒ Object
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# File 'lib/ddtrace/contrib/rack/middlewares.rb', line 43 def call(env) # retrieve integration settings tracer = configuration[:tracer] # Extract distributed tracing context before creating any spans, # so that all spans will be added to the distributed trace. if configuration[:distributed_tracing] context = HTTPPropagator.extract(env) tracer.provider.context = context if context.trace_id end # [experimental] create a root Span to keep track of frontend web servers # (i.e. Apache, nginx) if the header is properly set frontend_span = compute_queue_time(env, tracer) = { service: configuration[:service_name], resource: nil, span_type: Datadog::Ext::HTTP::TYPE_INBOUND } # start a new request span and attach it to the current Rack environment; # we must ensure that the span `resource` is set later request_span = tracer.trace(Ext::SPAN_REQUEST, ) env[RACK_REQUEST_SPAN] = request_span # TODO: Add deprecation warnings back in # DEV: Some third party Gems will loop over the rack env causing our deprecation # warnings to be shown even when the user is not accessing them directly # # add_deprecation_warnings(env) # env.without_datadog_warnings do # # TODO: For backwards compatibility; this attribute is deprecated. # env[:datadog_rack_request_span] = env[RACK_REQUEST_SPAN] # end env[:datadog_rack_request_span] = env[RACK_REQUEST_SPAN] # Copy the original env, before the rest of the stack executes. # Values may change; we want values before that happens. original_env = env.dup # call the rest of the stack status, headers, response = @app.call(env) [status, headers, response] # rubocop:disable Lint/RescueException # Here we really want to catch *any* exception, not only StandardError, # as we really have no clue of what is in the block, # and it is user code which should be executed no matter what. # It's not a problem since we re-raise it afterwards so for example a # SignalException::Interrupt would still bubble up. rescue Exception => e # catch exceptions that may be raised in the middleware chain # Note: if a middleware catches an Exception without re raising, # the Exception cannot be recorded here. request_span.set_error(e) unless request_span.nil? raise e ensure # Rack is a really low level interface and it doesn't provide any # advanced functionality like routers. Because of that, we assume that # the underlying framework or application has more knowledge about # the result for this request; `resource` and `tags` are expected to # be set in another level but if they're missing, reasonable defaults # are used. (request_span, env, status, headers, response, original_env) # ensure the request_span is finished and the context reset; # this assumes that the Rack middleware creates a root span request_span.finish frontend_span.finish unless frontend_span.nil? # TODO: Remove this once we change how context propagation works. This # ensures we clean thread-local variables on each HTTP request avoiding # memory leaks. tracer.provider.context = Datadog::Context.new end |
#compute_queue_time(env, tracer) ⇒ Object
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# File 'lib/ddtrace/contrib/rack/middlewares.rb', line 28 def compute_queue_time(env, tracer) return unless configuration[:request_queuing] # parse the request queue time request_start = Datadog::Contrib::Rack::QueueTime.get_request_start(env) return if request_start.nil? tracer.trace( Ext::SPAN_HTTP_SERVER_QUEUE, span_type: Datadog::Ext::HTTP::TYPE_PROXY, start_time: request_start, service: configuration[:web_service_name] ) end |
#resource_name_for(env, status) ⇒ Object
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# File 'lib/ddtrace/contrib/rack/middlewares.rb', line 120 def resource_name_for(env, status) if configuration[:middleware_names] && env['RESPONSE_MIDDLEWARE'] "#{env['RESPONSE_MIDDLEWARE']}##{env['REQUEST_METHOD']}" else "#{env['REQUEST_METHOD']} #{status}".strip end end |
#set_request_tags!(request_span, env, status, headers, response, original_env) ⇒ Object
rubocop:disable Metrics/AbcSize
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# File 'lib/ddtrace/contrib/rack/middlewares.rb', line 129 def (request_span, env, status, headers, response, original_env) # http://www.rubydoc.info/github/rack/rack/file/SPEC # The source of truth in Rack is the PATH_INFO key that holds the # URL for the current request; but some frameworks may override that # value, especially during exception handling. # # Because of this, we prefer to use REQUEST_URI, if available, which is the # relative path + query string, and doesn't mutate. # # REQUEST_URI is only available depending on what web server is running though. # So when its not available, we want the original, unmutated PATH_INFO, which # is just the relative path without query strings. url = env['REQUEST_URI'] || original_env['PATH_INFO'] request_headers = parse_request_headers(env) response_headers = parse_response_headers(headers || {}) request_span.resource ||= resource_name_for(env, status) # Associate with runtime metrics Datadog.runtime_metrics.associate_with_span(request_span) # Set analytics sample rate if Contrib::Analytics.enabled?(configuration[:analytics_enabled]) Contrib::Analytics.set_sample_rate(request_span, configuration[:analytics_sample_rate]) end if request_span.get_tag(Datadog::Ext::HTTP::METHOD).nil? request_span.set_tag(Datadog::Ext::HTTP::METHOD, env['REQUEST_METHOD']) end if request_span.get_tag(Datadog::Ext::HTTP::URL).nil? = configuration[:quantize] request_span.set_tag(Datadog::Ext::HTTP::URL, Datadog::Quantization::HTTP.url(url, )) end if request_span.get_tag(Datadog::Ext::HTTP::BASE_URL).nil? request_obj = ::Rack::Request.new(env) base_url = if request_obj.respond_to?(:base_url) request_obj.base_url else # Compatibility for older Rack versions request_obj.url.chomp(request_obj.fullpath) end request_span.set_tag(Datadog::Ext::HTTP::BASE_URL, base_url) end if request_span.get_tag(Datadog::Ext::HTTP::STATUS_CODE).nil? && status request_span.set_tag(Datadog::Ext::HTTP::STATUS_CODE, status) end # Request headers request_headers.each do |name, value| request_span.set_tag(name, value) if request_span.get_tag(name).nil? end # Response headers response_headers.each do |name, value| request_span.set_tag(name, value) if request_span.get_tag(name).nil? end # detect if the status code is a 5xx and flag the request span as an error # unless it has been already set by the underlying framework if status.to_s.start_with?('5') && request_span.status.zero? request_span.status = 1 end end |