feat: Make Rack install optional for sinatra

instrumentation/sinatra/lib/opentelemetry/instrumentation/sinatra/extensions/tracer_extension.rb

@@ -13,23 +13,25 @@ module Extensions
         # Sinatra extension that installs TracerMiddleware and provides
         # tracing for template rendering
         module TracerExtension
-          # Sinatra hook after extension is registered
-          def self.registered(app)
-            # Create tracing `render` method
-            ::Sinatra::Base.module_eval do
-              def render(_engine, data, *)
-                template_name = data.is_a?(Symbol) ? data : :literal
+          # Contants patches for `render` method
+          module RenderPatches
+            def render(_engine, data, *)
+              template_name = data.is_a?(Symbol) ? data : :literal
 
-                Sinatra::Instrumentation.instance.tracer.in_span(
-                  'sinatra.render_template',
-                  attributes: { 'sinatra.template_name' => template_name.to_s }
-                ) do
-                  super
-                end
+              Sinatra::Instrumentation.instance.tracer.in_span(
+                'sinatra.render_template',
+                attributes: { 'sinatra.template_name' => template_name.to_s }
+              ) do
+                super
               end
             end
-            app.use(*OpenTelemetry::Instrumentation::Rack::Instrumentation.instance.middleware_args)
-            app.use(Middlewares::TracerMiddleware)
+          end
+
+          # Sinatra hook after extension is registered
+          def self.registered(app)
+            # Create tracing `render` method
+            ::Sinatra::Base.prepend(RenderPatches)
+            Sinatra::Instrumentation.instance.install_middleware(app)
           end
         end
       end

instrumentation/sinatra/lib/opentelemetry/instrumentation/sinatra/instrumentation.rb

@@ -12,15 +12,22 @@ module Sinatra
       # The Instrumentation class contains logic to detect and install the Sinatra
       # instrumentation
       class Instrumentation < OpenTelemetry::Instrumentation::Base
-        install do |_|
-          OpenTelemetry::Instrumentation::Rack::Instrumentation.instance.install({})
+        install do |config|
+          OpenTelemetry::Instrumentation::Rack::Instrumentation.instance.install({}) if config[:install_rack]
 
           ::Sinatra::Base.register Extensions::TracerExtension
         end
 
+        option :install_rack, default: true, validate: :boolean
+
         present do
           defined?(::Sinatra)
         end
+
+        def install_middleware(app)
+          app.use(*OpenTelemetry::Instrumentation::Rack::Instrumentation.instance.middleware_args) if config[:install_rack]
+          app.use(Middlewares::TracerMiddleware)
+        end
       end
     end
   end

instrumentation/sinatra/test/opentelemetry/instrumentation/sinatra_test.rb

@@ -11,6 +11,7 @@
 
   let(:instrumentation) { OpenTelemetry::Instrumentation::Sinatra::Instrumentation.instance }
   let(:exporter) { EXPORTER }
+  let(:config) { {} }
 
   class CustomError < StandardError; end
 
@@ -66,7 +67,14 @@ class CustomError < StandardError; end
   end
 
   before do
-    instrumentation.install
+    Sinatra::Base.reset!
+
+    OpenTelemetry::Instrumentation::Rack::Instrumentation.instance.instance_variable_set(:@installed, false)
+    OpenTelemetry::Instrumentation::Rack::Instrumentation.instance.config.clear
+
+    instrumentation.instance_variable_set(:@installed, false)
+    instrumentation.config.clear
+    instrumentation.install(config)
     exporter.reset
   end
 
@@ -169,4 +177,48 @@ class CustomError < StandardError; end
       _(exporter.finished_spans.first.events[0].attributes['exception.message']).must_equal('custom message')
     end
   end
+
+  describe 'when install_rack is set to false' do
+    let(:config) { { install_rack: false } }
+
+    describe 'missing rack installation' do
+      it 'disables tracing' do
+        get '/one/endpoint'
+
+        _(exporter.finished_spans).must_be_empty
+      end
+    end
+
+    describe 'when rack is manully installed' do
+      let(:app) do
+        apps_to_build = apps
+        Rack::Builder.new do
+          use(*OpenTelemetry::Instrumentation::Rack::Instrumentation.instance.middleware_args)
+
+          apps_to_build.each do |root, app|
+            map root do
+              run app
+            end
+          end
+        end.to_app
+      end
+
+      before do
+        OpenTelemetry::Instrumentation::Rack::Instrumentation.instance.install
+      end
+
+      it 'creates a span' do
+        get '/one/endpoint'
+
+        _(exporter.finished_spans.first.attributes).must_equal(
+          'http.method' => 'GET',
+          'http.host' => 'example.org',
+          'http.scheme' => 'http',
+          'http.target' => '/one/endpoint',
+          'http.route' => '/endpoint',
+          'http.status_code' => 200
+        )
+      end
+    end
+  end
 end