fix: Grape Instrumentation handle status code symbol (#448)

Since grape 1.7.0 grape endpoints can return status codes as rack
status code symbols. The symbols are converted to integers by the
Grape error middleware.

This performs the same conversion with `Rack::Utils`. Rack is already
an implicit runtime dependency (and should remain implicit) of the
instrumentation, but has now been added as an explicit development
dependency for the tests.

If the status_code is not valid the status code is assumed to be 0.

Author: Dhruv Paranjape

instrumentation/grape/lib/opentelemetry/instrumentation/grape/event_handler.rb

@@ -4,6 +4,8 @@
 #
 # SPDX-License-Identifier: Apache-2.0
 
+require 'rack'
+
 module OpenTelemetry
   module Instrumentation
     module Grape
@@ -79,7 +81,7 @@ def handle_payload_exception(span, exception)
             # Only record exceptions if they were not raised (i.e. do not have a status code in Grape)
             # or do not have a 5xx status code. These exceptions are recorded by Rack.
             # See instrumentation/rack/lib/opentelemetry/instrumentation/rack/middlewares/tracer_middleware.rb#L155
-            return unless exception.respond_to?('status') && exception.status.to_i < 500
+            return unless exception.respond_to?('status') && ::Rack::Utils.status_code(exception.status) < 500
 
             span.record_exception(exception)
             span.status = OpenTelemetry::Trace::Status.error("Unhandled exception of type: #{exception.class}")

instrumentation/grape/opentelemetry-instrumentation-grape.gemspec

@@ -36,6 +36,7 @@ Gem::Specification.new do |spec|
   spec.add_development_dependency 'minitest', '~> 5.0'
   spec.add_development_dependency 'opentelemetry-sdk', '~> 1.0'
   spec.add_development_dependency 'opentelemetry-test-helpers'
+  spec.add_development_dependency 'rack'
   spec.add_development_dependency 'rack-test'
   spec.add_development_dependency 'rake', '~> 13.0'
   spec.add_development_dependency 'rspec-mocks'

instrumentation/grape/test/opentelemetry/instrumentation/grape_test.rb

@@ -376,6 +376,25 @@ class ErrorResponseAPI < Grape::API
       end
     end
 
+    describe 'when an API endpoint returns an error with the status as a symbol' do
+      class ErrorResponseAPI < Grape::API
+        get :error_response do
+          error!('Not found', :not_found)
+        end
+      end
+
+      let(:app) { build_rack_app(ErrorResponseAPI) }
+      let(:request_path) { '/error_response' }
+      let(:expected_span_name) { 'HTTP GET /error_response' }
+
+      before { app.get request_path }
+
+      it 'does not set span status to error' do
+        _(span.name).must_equal expected_span_name
+        _(span.status.code).wont_equal OpenTelemetry::Trace::Status::ERROR
+      end
+    end
+
     describe 'when an API endpoint receives a request and some events are ignored in the configs' do
       class IgnoredEventAPI < Grape::API
         get :success do