refactor: Switch from prepending to conditions

instrumentation/base/lib/opentelemetry/instrumentation.rb

@@ -7,7 +7,6 @@
 require 'opentelemetry'
 require 'opentelemetry-registry'
 require 'opentelemetry/instrumentation/base'
-require 'opentelemetry/instrumentation/metrics_patch' if defined?(OpenTelemetry::Metrics) # maybe also add Env var check?
 
 module OpenTelemetry
   # The instrumentation module contains functionality to register and install

instrumentation/base/lib/opentelemetry/instrumentation/base.rb

@@ -4,8 +4,6 @@
 #
 # SPDX-License-Identifier: Apache-2.0
 
-# TODO: Maybe add an env var for globally enabling metrics as second switch?
-require_relative 'metrics_patch' if defined?(OpenTelemetry::Metrics)
 
 module OpenTelemetry
   module Instrumentation
@@ -208,13 +206,11 @@ def initialize(name, version, install_blk, present_blk,
         @installed = false
         @options = options
         @tracer = OpenTelemetry::Trace::Tracer.new
-        create_meter
+        # check to see if the API is defined here because the config isn't available yet
+        @meter = OpenTelemetry::Metrics::Meter.new if defined?(OpenTelemetry::Metrics)
       end
       # rubocop:enable Metrics/ParameterLists
 
-      # no-op, overridden in metrics patch
-      def create_meter; end
-
       # Install instrumentation with the given config. The present? and compatible?
       # will be run first, and install will return false if either fail. Will
       # return true if install was completed successfully.
@@ -232,12 +228,14 @@ def install(config = {})
         @installed = true
       end
 
-      # no-op, defined in metrics patch to use if metrics installed
-      def install_meter; end
+      def install_meter
+        @meter = OpenTelemetry.meter_provider.meter(name, version: version) if metrics_enabled?
+      end
 
-      # Metrics should not be enabled if we're trying to load them directly from base
       def metrics_enabled?
-        false
+        return @metrics_enabled if defined?(@metrics_enabled)
+
+        @metrics_enabled ||= defined?(OpenTelemetry::Metrics) && @config[:send_metrics]
       end
 
       # Whether or not this instrumentation is installable in the current process. Will

instrumentation/rack/lib/opentelemetry/instrumentation/rack/instrumentation.rb

@@ -48,16 +48,11 @@ def middleware_args
           end
         end
 
-        # def metrics_enabled?
-        #   super
-        #   # other conditions unique to Rack? Like Events also being available?
-        # end
 
         private
 
         def require_dependencies
           require_relative 'middlewares/event_handler' if defined?(::Rack::Events)
-          require_relative 'middlewares/metrics_patch' if metrics_enabled?
           require_relative 'middlewares/tracer_middleware'
         end
 

instrumentation/rack/lib/opentelemetry/instrumentation/rack/middlewares/event_handler.rb

@@ -158,8 +158,6 @@ def untraced_request?(env)
             false
           end
 
-          # no-op, defined in MetricsPatch and required if metrics enabled
-          def record_http_server_request_duration_metric(span); end
 
           # https://github.com/open-telemetry/opentelemetry-specification/blob/master/specification/data-http.md#name
           #
@@ -251,12 +249,6 @@ def tracer
             OpenTelemetry::Instrumentation::Rack::Instrumentation.instance.tracer
           end
 
-          # no-op, overwritten by metrics patch if metrics is enabled
-          def meter; end
-
-          # no-op, overwritten by metrics patch if metrics is enabled
-          def http_server_request_duration_histogram; end
-
           def config
             OpenTelemetry::Instrumentation::Rack::Instrumentation.instance.config
           end
@@ -272,6 +264,41 @@ def create_span(parent_context, request)
             span.add_event('http.proxy.request.started', timestamp: request_start_time) unless request_start_time.nil?
             span
           end
+
+          # Metrics stuff
+          def metrics_enabled?
+            OpenTelemetry::Instrumentation::Rack::Instrumentation.instance.metrics_enabled?
+          end
+
+          def meter
+            return unless metrics_enabled?
+
+            OpenTelemetry::Instrumentation::Rack::Instrumentation.instance.meter
+          end
+
+          def http_server_request_duration_histogram
+            return unless metrics_enabled?
+
+            @http_server_request_duration_histogram ||= meter.create_histogram('http.server.request.duration', unit: 's', description: 'Duration of HTTP server requests.')
+          end
+
+          def record_http_server_request_duration_metric(span)
+            return unless metrics_enabled?
+            # find span duration
+            # end - start / a billion to convert nanoseconds to seconds
+            duration = (span.end_timestamp - span.start_timestamp) / Float(10**9)
+            # Create attributes
+            #
+            attrs = {}
+            attrs['http.method'] = span.attributes['http.method']
+            attrs['http.scheme'] = span.attributes['http.scheme']
+            attrs['http.route'] = span.attributes['http.route']
+            attrs['http.status_code'] = span.attributes['http.status_code']
+            attrs['http.host'] = span.attributes['http.host']
+            attrs['error.type'] = span.status.description if span.status.code == OpenTelemetry::Trace::Status::ERROR
+
+            http_server_request_duration_histogram.record(duration, attributes: attrs)
+          end
         end
       end
     end