Implement traceparent/baggage/DSC for PropagationContext and apply in…

… scope

sentry-ruby/lib/sentry/propagation_context.rb

@@ -1,24 +1,78 @@
 # frozen_string_literal: true
 
 require "securerandom"
+require "sentry/baggage"
 
 module Sentry
   class PropagationContext
-    def initialize
+
+    # An uuid that can be used to identify a trace.
+    # @return [String]
+    attr_reader :trace_id
+    # An uuid that can be used to identify the span.
+    # @return [String]
+    attr_reader :span_id
+    # Span parent's span_id.
+    # @return [String]
+    attr_reader :parent_span_id
+
+    def initialize(scope)
+      @scope = scope
       @trace_id = SecureRandom.uuid.delete("-")
       @span_id = SecureRandom.uuid.delete("-").slice(0, 16)
       @parent_span_id = nil
-      @dynamic_sampling_context = nil
+      @baggage = nil
     end
 
     # Returns the trace context that can be used to embed in an Event.
     # @return [Hash]
     def get_trace_context
       {
-        trace_id: @trace_id,
-        span_id: @span_id,
-        parent_span_id: @parent_span_id
+        trace_id: trace_id,
+        span_id: span_id,
+        parent_span_id: parent_span_id
+      }
+    end
+
+    # Returns the sentry-trace header from the propagation context.
+    # @return [String]
+    def get_traceparent
+      "#{trace_id}-#{span_id}"
+    end
+
+    # Returns the W3C baggage header from the propagation context.
+    # @return [String, nil]
+    def get_baggage
+      populate_head_baggage if @baggage.nil? || @baggage.mutable
+      @baggage
+    end
+
+    # Returns the Dynamic Sampling Context from the baggage.
+    # @return [String, nil]
+    def get_dynamic_sampling_context
+      get_baggage&.dynamic_sampling_context
+    end
+
+    private
+
+    def populate_head_baggage
+      return unless Sentry.initialized?
+
+      configuration = Sentry.configuration
+
+      items = {
+        "trace_id" => trace_id,
+        "sample_rate" => configuration.traces_sample_rate,
+        "environment" => configuration.environment,
+        "release" => configuration.release,
+        "public_key" => configuration.dsn&.public_key
       }
+
+      user = @scope&.user
+      items["user_segment"] = user["segment"] if user && user["segment"]
+
+      items.compact!
+      @baggage = Baggage.new(items, mutable: false)
     end
   end
 end

sentry-ruby/lib/sentry/scope.rb

@@ -55,6 +55,7 @@ def apply_to_event(event, hint = nil)
         event.contexts[:trace] ||= span.get_trace_context
       else
         event.contexts[:trace] ||= propagation_context.get_trace_context
+        event.dynamic_sampling_context ||= propagation_context.get_dynamic_sampling_context
       end
 
       event.fingerprint = fingerprint
@@ -307,7 +308,7 @@ def set_new_breadcrumb_buffer
     end
 
     def generate_propagation_context
-      @propagation_context = PropagationContext.new
+      @propagation_context = PropagationContext.new(self)
     end
 
     class << self