[net/http] Allow overriding service name.

Rakefile

@@ -230,12 +230,14 @@ task :ci do
     sh 'rvm $MRI_VERSIONS --verbose do appraisal contrib rake spec:dalli'
     sh 'rvm $MRI_VERSIONS --verbose do appraisal contrib rake spec:faraday'
     sh 'rvm $MRI_VERSIONS --verbose do appraisal contrib rake spec:graphql'
+    sh 'rvm $MRI_VERSIONS --verbose do appraisal contrib rake spec:http'
     sh 'rvm $MRI_VERSIONS --verbose do appraisal contrib rake spec:racecar'
     sh 'rvm $MRI_VERSIONS --verbose do appraisal contrib rake spec:redis'
     sh 'rvm $MRI_OLD_VERSIONS --verbose do appraisal contrib-old rake spec:active_record'
     sh 'rvm $MRI_OLD_VERSIONS --verbose do appraisal contrib-old rake spec:active_support'
     sh 'rvm $MRI_OLD_VERSIONS --verbose do appraisal contrib-old rake spec:dalli'
     sh 'rvm $MRI_OLD_VERSIONS --verbose do appraisal contrib-old rake spec:faraday'
+    sh 'rvm $MRI_OLD_VERSIONS --verbose do appraisal contrib-old rake spec:http'
     sh 'rvm $MRI_OLD_VERSIONS --verbose do appraisal contrib-old rake spec:redis'
   when 2
     sh 'rvm $MRI_VERSIONS --verbose do appraisal contrib rake test:sidekiq'

docs/GettingStarted.md

@@ -514,8 +514,10 @@ Where `options` is an optional `Hash` that accepts the following parameters:
 
 | Key | Description | Default |
 | --- | --- | --- |
-| ``service_name`` | Service name used for `http` instrumentation | http |
+| ``service_name`` | Service name used for `http` instrumentation | net/http |
 | ``distributed_tracing`` | Enables distributed tracing | ``false`` |
+| ``tracer`` | A ``Datadog::Tracer`` instance used to instrument the application. Usually you don't need to set that. | ``Datadog.tracer`` |
+
 
 If you wish to configure each connection object individually, you may use the ``Datadog.configure`` as it follows:
 

lib/ddtrace/contrib/http/patcher.rb

@@ -48,6 +48,8 @@ module Patcher
         include Base
         register_as :http, auto_patch: true
         option :distributed_tracing, default: false
+        option :service_name, default: SERVICE
+        option :tracer, default: Datadog.tracer
 
         @patched = false
 
@@ -64,7 +66,7 @@ def patch
               require 'ddtrace/ext/net'
               require 'ddtrace/ext/distributed'
 
-              patch_http()
+              patch_http
 
               @patched = true
             rescue StandardError => e
@@ -74,7 +76,7 @@ def patch
           @patched
         end
 
-        # patched? tells wether patch has been successfully applied
+        # patched? tells whether patch has been successfully applied
         def patched?
           @patched
         end
@@ -84,27 +86,27 @@ def patched?
         # rubocop:disable Metrics/AbcSize
         def patch_http
           ::Net::HTTP.class_eval do
-            alias_method :initialize_without_datadog, :initialize
-            Datadog::Patcher.without_warnings do
-              remove_method :initialize
-            end
-
-            def initialize(*args)
-              pin = Datadog::Pin.new(SERVICE, app: APP, app_type: Datadog::Ext::AppTypes::WEB)
-              pin.onto(self)
-              initialize_without_datadog(*args)
-            end
-
             alias_method :request_without_datadog, :request
             remove_method :request
 
+            def datadog_pin
+              @datadog_pindatadog_pin ||= begin
+                service = Datadog.configuration[:http][:service_name]
+                tracer = Datadog.configuration[:http][:tracer]
+
+                Datadog::Pin.new(service, app: APP, app_type: Datadog::Ext::AppTypes::WEB, tracer: tracer)
+              end
+            end
+
             def request(req, body = nil, &block) # :yield: +response+
-              pin = Datadog::Pin.get_from(self)
+              pin = datadog_pin
               return request_without_datadog(req, body, &block) unless pin && pin.tracer
 
               transport = pin.tracer.writer.transport
-              return request_without_datadog(req, body, &block) if
-                Datadog::Contrib::HTTP.should_skip_tracing?(req, @address, @port, transport, pin)
+
+              if Datadog::Contrib::HTTP.should_skip_tracing?(req, @address, @port, transport, pin)
+                return request_without_datadog(req, body, &block)
+              end
 
               pin.tracer.trace(NAME) do |span|
                 begin

spec/ddtrace/contrib/http/patcher_spec.rb

@@ -0,0 +1,48 @@
+require 'spec_helper'
+require 'ddtrace'
+require 'net/http'
+
+RSpec.describe 'net/http patcher' do
+  let(:tracer) { ::Datadog::Tracer.new(writer: FauxWriter.new) }
+  let(:host) { 'example.com' }
+
+  before do
+    WebMock.disable_net_connect!(allow_localhost: true)
+    WebMock.enable!
+
+    stub_request(:any, host)
+
+    Datadog.registry[:http].reset_options!
+    Datadog.configure do |c|
+      c.use :http, tracer: tracer
+    end
+  end
+
+  let(:request_span) do
+    tracer.writer.spans(:keep).find { |span| span.name == Datadog::Contrib::HTTP::NAME }
+  end
+
+  describe 'with default configuration' do
+    it 'uses default service name' do
+      Net::HTTP.get(host, '/')
+
+      expect(request_span.service).to eq('net/http')
+    end
+  end
+
+  describe 'with changed service name' do
+    let(:new_service_name) { 'new_service_name' }
+
+    before do
+      Datadog.configure do |c|
+        c.use :http, tracer: tracer, service_name: new_service_name
+      end
+    end
+
+    it 'uses new service name' do
+      Net::HTTP.get(host, '/')
+
+      expect(request_span.service).to eq(new_service_name)
+    end
+  end
+end