Add setting to disable shared spans (joins) in tracer

README.md

@@ -28,6 +28,7 @@ use ZipkinTracer::RackHandler, config
 * `:async` - By default senders will flush traces asynchronously. Set to `false` to make that process synchronous. Only supported by the HTTP, RabbitMQ, and SQS senders.
 * `:logger` - The default logger for Rails apps is `Rails.logger`, else it is `STDOUT`. Use this option to pass a custom logger.
 * `:write_b3_single_format` - When set to true, only writes a single b3 header for outbound propagation.
+* `:supports_join` - When set to false, it will force client and server spans to have different spanId's. This may be needed because zipkin traces may be reported to non-zipkin backends that might not support the concept of joining spans.
 
 #### Sender specific
 * `:json_api_host` - Hostname with protocol of a zipkin api instance (e.g. `https://zipkin.example.com`) to use the HTTP sender

lib/zipkin-tracer/config.rb

@@ -8,7 +8,7 @@ class Config
     attr_reader :service_name, :sample_rate, :sampled_as_boolean, :check_routes, :trace_id_128bit, :async, :logger,
       :json_api_host, :zookeeper, :kafka_producer, :kafka_topic, :sqs_queue_name, :sqs_region, :log_tracing,
       :annotate_plugin, :filter_plugin, :whitelist_plugin, :rabbit_mq_connection, :rabbit_mq_exchange,
-      :rabbit_mq_routing_key, :write_b3_single_format
+      :rabbit_mq_routing_key, :write_b3_single_format, :supports_join
 
     def initialize(app, config_hash)
       config = config_hash || Application.config(app)
@@ -58,6 +58,10 @@ def initialize(app, config_hash)
       # When set to true, only writes a single b3 header for outbound propagation.
       @write_b3_single_format =
         config[:write_b3_single_format].nil? ? DEFAULTS[:write_b3_single_format] : config[:write_b3_single_format]
+      # When set to false, the it will force client and server spans to have different spanId's. This is important
+      # because zipkin traces may be reported to non-zipkin backends that might not support the concept of
+      # joining spans.
+      @supports_join = config[:supports_join].nil? ? DEFAULTS[:supports_join] : config[:supports_join]
 
       Trace.sample_rate = @sample_rate
       Trace.trace_id_128bit = @trace_id_128bit
@@ -99,7 +103,8 @@ def domain_service_name(default_name)
       sampled_as_boolean: true,
       check_routes: false,
       trace_id_128bit: false,
-      write_b3_single_format: false
+      write_b3_single_format: false,
+      supports_join: true
     }
 
     def present?(str)

lib/zipkin-tracer/rack/zipkin_env.rb

@@ -30,6 +30,10 @@ def called_with_zipkin_headers?
     B3_REQUIRED_HEADERS = %w[HTTP_X_B3_TRACEID HTTP_X_B3_SPANID].freeze
     B3_OPT_HEADERS = %w[HTTP_X_B3_PARENTSPANID HTTP_X_B3_SAMPLED HTTP_X_B3_FLAGS].freeze
 
+    def supports_join?
+      @config.supports_join
+    end
+
     def retrieve_or_generate_ids
       if called_with_zipkin_b3_single_header?
         trace_id, span_id, parent_span_id, sampled, flags =
@@ -40,6 +44,12 @@ def retrieve_or_generate_ids
         shared = true
       end
 
+      unless supports_join?
+        parent_span_id = span_id
+        span_id = TraceGenerator.new.generate_id
+        shared = false
+      end
+
       unless trace_id
         span_id = TraceGenerator.new.generate_id
         trace_id = TraceGenerator.new.generate_id_from_span_id(span_id)

spec/lib/config_spec.rb

@@ -8,7 +8,7 @@ module ZipkinTracer
 
     [:service_name, :json_api_host,
       :zookeeper, :log_tracing,
-      :annotate_plugin, :filter_plugin, :whitelist_plugin].each do |method|
+      :annotate_plugin, :filter_plugin, :whitelist_plugin, :supports_join].each do |method|
       it "can set and read configuration values for #{method}" do
         value = rand(100)
         config = Config.new(nil, { method => value })
@@ -22,7 +22,7 @@ module ZipkinTracer
 
     it 'sets defaults' do
       config = Config.new(nil, {})
-      [:sample_rate, :sampled_as_boolean, :check_routes, :trace_id_128bit, :write_b3_single_format].each do |key|
+      [:sample_rate, :sampled_as_boolean, :check_routes, :trace_id_128bit, :write_b3_single_format, :supports_join].each do |key|
         expect(config.send(key)).to_not eq(nil)
       end
     end

spec/lib/rack/zipkin_env_spec.rb

@@ -19,11 +19,13 @@ def mock_env(params = {}, path = '/')
       whitelist_plugin: whitelist_plugin,
       sample_rate: sample_rate,
       sampled_as_boolean: sampled_as_boolean,
-      check_routes: check_routes
+      check_routes: check_routes,
+      supports_join: supports_join
     )
   end
   let(:env) { mock_env }
   let(:zipkin_env) { described_class.new(env, config) }
+  let(:supports_join) { true }
 
   it 'allows access to the original environment' do
     expect(zipkin_env.env).to eq(env)
@@ -188,6 +190,21 @@ def mock_env(params = {}, path = '/')
       it 'uses the flags' do
         expect(zipkin_env.trace_id.flags.to_i).to eq(0)
       end
+
+      context 'supports joins is false' do
+        let(:supports_join) { false }
+
+        it 'generates a new span id' do
+          trace_id = zipkin_env.trace_id
+          expect(trace_id.trace_id.to_i).to eq(id)
+          expect(trace_id.span_id.to_i).not_to eq(id)
+          expect(trace_id.parent_id.to_i).to eq(id)
+        end
+
+        it 'shared is false' do
+          expect(zipkin_env.trace_id.shared).to eq(false)
+        end
+      end
     end
 
     context 'Sampled admits using 1 as well as true' do