Add HTTP multiplexing

Rakefile

@@ -53,8 +53,21 @@ namespace :spec do
   end
 
   RSpec::Core::RakeTask.new(:contrib) do |t, args|
-    # rubocop:disable Metrics/LineLength
-    t.pattern = 'spec/**/contrib/{analytics,configurable,extensions,integration,patchable,patcher,registerable,registry,configuration/*}_spec.rb'
+    contrib_paths = [
+      'analytics',
+      'configurable',
+      'configuration/*',
+      'configuration/resolvers/*',
+      'extensions',
+      'integration',
+      'patchable',
+      'patcher',
+      'registerable',
+      'registry',
+      'registry/*'
+    ].join(',')
+
+    t.pattern = "spec/**/contrib/{#{contrib_paths}}_spec.rb"
     t.rspec_opts = args.to_a.join(' ')
   end
 

docs/GettingStarted.md

@@ -674,6 +674,12 @@ require 'ddtrace'
 
 Datadog.configure do |c|
   c.use :ethon, options
+
+  # optionally, specify a different service name for hostnames matching a regex
+  c.use :ethon, describes: /user-[^.]+\.example\.com/ do |ethon|
+    ethon.service_name = 'user.example.com'
+    ethon.split_by_domain = false # Only necessary if split_by_domain is true by default
+  end
 end
 ```
 
@@ -684,6 +690,7 @@ Where `options` is an optional `Hash` that accepts the following parameters:
 | `analytics_enabled` | Enable analytics for spans produced by this integration. `true` for on, `nil` to defer to global setting, `false` for off. | `false` |
 | `distributed_tracing` | Enables [distributed tracing](#distributed-tracing) | `true` |
 | `service_name` | Service name for `ethon` instrumentation. | `'ethon'` |
+| `split_by_domain` | Uses the request domain as the service name when set to `true`. | `false` |
 | `tracer` | `Datadog::Tracer` used to perform instrumentation. Usually you don't need to set this. | `Datadog.tracer` |
 
 ### Excon
@@ -697,6 +704,12 @@ require 'ddtrace'
 # Configure default Excon tracing behavior
 Datadog.configure do |c|
   c.use :excon, options
+
+  # optionally, specify a different service name for hostnames matching a regex
+  c.use :excon, describes: /user-[^.]+\.example\.com/ do |excon|
+    excon.service_name = 'user.example.com'
+    excon.split_by_domain = false # Only necessary if split_by_domain is true by default
+  end
 end
 
 connection = Excon.new('https://example.com')
@@ -750,6 +763,12 @@ require 'ddtrace'
 # Configure default Faraday tracing behavior
 Datadog.configure do |c|
   c.use :faraday, options
+
+  # optionally, specify a different service name for hostnames matching a regex
+  c.use :faraday, describes: /user-[^.]+\.example\.com/ do |faraday|
+    faraday.service_name = 'user.example.com'
+    faraday.split_by_domain = false # Only necessary if split_by_domain is true by default
+  end
 end
 
 # Configure Faraday tracing behavior for single connection
@@ -991,6 +1010,12 @@ require 'ddtrace'
 
 Datadog.configure do |c|
   c.use :http, options
+
+  # optionally, specify a different service name for hostnames matching a regex
+  c.use :http, describes: /user-[^.]+\.example\.com/ do |http|
+    http.service_name = 'user.example.com'
+    http.split_by_domain = false # Only necessary if split_by_domain is true by default
+  end
 end
 
 Net::HTTP.start('127.0.0.1', 8080) do |http|
@@ -1008,6 +1033,7 @@ Where `options` is an optional `Hash` that accepts the following parameters:
 | `analytics_enabled` | Enable analytics for spans produced by this integration. `true` for on, `nil` to defer to global setting, `false` for off. | `false` |
 | `distributed_tracing` | Enables [distributed tracing](#distributed-tracing) | `true` |
 | `service_name` | Service name used for `http` instrumentation | `'net/http'` |
+| `split_by_domain` | Uses the request domain as the service name when set to `true`. | `false` |
 | `tracer` | `Datadog::Tracer` used to perform instrumentation. Usually you don't need to set this. | `Datadog.tracer` |
 
 If you wish to configure each connection object individually, you may use the `Datadog.configure` as it follows:

lib/ddtrace/contrib/configuration/resolvers/pattern_resolver.rb

@@ -0,0 +1,39 @@
+require 'ddtrace/contrib/configuration/resolver'
+
+module Datadog
+  module Contrib
+    module Configuration
+      # Resolves a value to a configuration key
+      module Resolvers
+        # Matches strings against Regexps.
+        class PatternResolver < Datadog::Contrib::Configuration::Resolver
+          def resolve(name)
+            # Try to find a matching pattern
+            matching_pattern = patterns.find do |pattern|
+              # Rubocop incorrectly thinks assignment is done here...
+              # rubocop:disable Style/ConditionalAssignment
+              if pattern.is_a?(Proc)
+                pattern === name
+              else
+                pattern === name.to_s # Co-erce to string
+              end
+            end
+
+            # Return match or default
+            matching_pattern || :default
+          end
+
+          def add(pattern)
+            patterns << (pattern.is_a?(Regexp) || pattern.is_a?(Proc) ? pattern : pattern.to_s)
+          end
+
+          private
+
+          def patterns
+            @patterns ||= Set.new
+          end
+        end
+      end
+    end
+  end
+end

lib/ddtrace/contrib/ethon/configuration/settings.rb

@@ -19,6 +19,7 @@ class Settings < Contrib::Configuration::Settings
 
           option :distributed_tracing, default: true
           option :service_name, default: Ext::SERVICE_NAME
+          option :split_by_domain, default: false
         end
       end
     end

lib/ddtrace/contrib/ethon/easy_patch.rb

@@ -2,6 +2,7 @@
 require 'ddtrace/ext/distributed'
 require 'ddtrace/propagation/http_propagator'
 require 'ddtrace/contrib/ethon/ext'
+require 'ddtrace/contrib/http_annotation_helper'
 
 module Datadog
   module Contrib
@@ -14,7 +15,10 @@ def self.included(base)
 
         # InstanceMethods - implementing instrumentation
         module InstanceMethods
+          include Datadog::Contrib::HttpAnnotationHelper
+
           def http_request(url, action_name, options = {})
+            load_datadog_configuration_for(url)
             return super unless tracer_enabled?
 
             # It's tricky to get HTTP method from libcurl
@@ -23,14 +27,13 @@ def http_request(url, action_name, options = {})
           end
 
           def headers=(headers)
-            return super unless tracer_enabled?
-
             # Store headers to call this method again when span is ready
             @datadog_original_headers = headers
             super
           end
 
           def perform
+            load_datadog_configuration_for(url)
             return super unless tracer_enabled?
             datadog_before_request
             super
@@ -61,17 +64,17 @@ def complete
           def reset
             super
           ensure
-            if tracer_enabled?
-              @datadog_span = nil
-              @datadog_method = nil
-              @datadog_original_headers = nil
-            end
+            @datadog_span = nil
+            @datadog_method = nil
+            @datadog_original_headers = nil
+            @datadog_configuration = nil
           end
 
           def datadog_before_request(parent_span: nil)
+            load_datadog_configuration_for(url)
             @datadog_span = datadog_configuration[:tracer].trace(
               Ext::SPAN_REQUEST,
-              service: datadog_configuration[:service_name],
+              service: uri ? service_name(uri.host, datadog_configuration) : datadog_configuration[:service_name],
               span_type: Datadog::Ext::HTTP::TYPE_OUTBOUND
             )
             @datadog_span.parent = parent_span unless parent_span.nil?
@@ -91,9 +94,10 @@ def datadog_span_started?
 
           private
 
+          attr_reader :datadog_configuration
+
           def datadog_tag_request
             span = @datadog_span
-            uri = URI.parse(url)
             method = 'N/A'
             if instance_variable_defined?(:@datadog_method) && !@datadog_method.nil?
               method = @datadog_method.to_s
@@ -103,12 +107,11 @@ def datadog_tag_request
             # Set analytics sample rate
             Contrib::Analytics.set_sample_rate(span, analytics_sample_rate) if analytics_enabled?
 
+            return unless uri
             span.set_tag(Datadog::Ext::HTTP::URL, uri.path)
             span.set_tag(Datadog::Ext::HTTP::METHOD, method)
             span.set_tag(Datadog::Ext::NET::TARGET_HOST, uri.host)
             span.set_tag(Datadog::Ext::NET::TARGET_PORT, uri.port)
-          rescue URI::InvalidURIError
-            return
           end
 
           def set_span_error_message(message)
@@ -117,8 +120,14 @@ def set_span_error_message(message)
             @datadog_span.set_tag(Datadog::Ext::Errors::MSG, message)
           end
 
-          def datadog_configuration
-            Datadog.configuration[:ethon]
+          def uri
+            URI.parse(url)
+          # rubocop:disable Lint/HandleExceptions
+          rescue URI::InvalidURIError
+          end
+
+          def load_datadog_configuration_for(host = :default)
+            @datadog_configuration = Datadog.configuration[:ethon, host]
           end
 
           def tracer_enabled?

lib/ddtrace/contrib/ethon/integration.rb

@@ -1,5 +1,6 @@
 require 'ddtrace/contrib/integration'
 require 'ddtrace/contrib/ethon/configuration/settings'
+require 'ddtrace/contrib/configuration/resolvers/pattern_resolver'
 require 'ddtrace/contrib/ethon/patcher'
 
 module Datadog
@@ -32,6 +33,10 @@ def default_configuration
         def patcher
           Patcher
         end
+
+        def resolver
+          @resolver ||= Contrib::Configuration::Resolvers::PatternResolver.new
+        end
       end
     end
   end

lib/ddtrace/contrib/excon/integration.rb

@@ -1,5 +1,6 @@
 require 'ddtrace/contrib/integration'
 require 'ddtrace/contrib/excon/configuration/settings'
+require 'ddtrace/contrib/configuration/resolvers/pattern_resolver'
 require 'ddtrace/contrib/excon/patcher'
 
 module Datadog
@@ -32,6 +33,10 @@ def default_configuration
         def patcher
           Patcher
         end
+
+        def resolver
+          @resolver ||= Contrib::Configuration::Resolvers::PatternResolver.new
+        end
       end
     end
   end

lib/ddtrace/contrib/excon/middleware.rb

@@ -5,24 +5,28 @@
 require 'ddtrace/propagation/http_propagator'
 require 'ddtrace/contrib/analytics'
 require 'ddtrace/contrib/excon/ext'
+require 'ddtrace/contrib/http_annotation_helper'
 
 module Datadog
   module Contrib
     module Excon
       # Middleware implements an excon-middleware for ddtrace instrumentation
       class Middleware < ::Excon::Middleware::Base
+        include Datadog::Contrib::HttpAnnotationHelper
+
         DEFAULT_ERROR_HANDLER = lambda do |response|
           Datadog::Ext::HTTP::ERROR_RANGE.cover?(response[:status])
         end
 
         def initialize(stack, options = {})
           super(stack)
-          @options = Datadog.configuration[:excon].options_hash.merge(options)
+          @default_options = datadog_configuration.options_hash.merge(options)
         end
 
         def request_call(datum)
           begin
             unless datum.key?(:datadog_span)
+              @options = build_request_options!(datum)
               tracer.trace(Ext::SPAN_REQUEST).tap do |span|
                 datum[:datadog_span] = span
                 annotate!(span, datum)
@@ -99,13 +103,9 @@ def error_handler
           @options[:error_handler] || DEFAULT_ERROR_HANDLER
         end
 
-        def split_by_domain?
-          @options[:split_by_domain] == true
-        end
-
         def annotate!(span, datum)
           span.resource = datum[:method].to_s.upcase
-          span.service = service_name(datum)
+          span.service = service_name(datum[:host], @options)
           span.span_type = Datadog::Ext::HTTP::TYPE_OUTBOUND
 
           # Set analytics sample rate
@@ -144,9 +144,12 @@ def propagate!(span, datum)
           Datadog::HTTPPropagator.inject!(span.context, datum[:headers])
         end
 
-        def service_name(datum)
-          # TODO: Change this to implement more sensible multiplexing
-          split_by_domain? ? datum[:host] : @options[:service_name]
+        def build_request_options!(datum)
+          datadog_configuration(datum[:host]).options_hash.merge(@default_options)
+        end
+
+        def datadog_configuration(host = :default)
+          Datadog.configuration[:excon, host]
         end
       end
     end

lib/ddtrace/contrib/faraday/integration.rb

@@ -1,4 +1,5 @@
 require 'ddtrace/contrib/integration'
+require 'ddtrace/contrib/configuration/resolvers/pattern_resolver'
 require 'ddtrace/contrib/faraday/configuration/settings'
 require 'ddtrace/contrib/faraday/patcher'
 
@@ -32,6 +33,10 @@ def default_configuration
         def patcher
           Patcher
         end
+
+        def resolver
+          @resolver ||= Contrib::Configuration::Resolvers::PatternResolver.new
+        end
       end
     end
   end