From 12befb7eaf9407ba3af878d5221a9d1720ad1a49 Mon Sep 17 00:00:00 2001
From: Neel Shah <neelshah.sa@gmail.com>
Date: Thu, 27 Jul 2023 14:32:31 +0200
Subject: [PATCH] Add new trace_propagation_targets configuration to set
 outgoing targets for trace header propagation

---
 CHANGELOG.md                            |  7 +++++++
 sentry-ruby/lib/sentry/configuration.rb |  8 ++++++++
 sentry-ruby/lib/sentry/net/http.rb      | 18 +++++++++++-------
 3 files changed, 26 insertions(+), 7 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 5ec6fd7db..fc9fa589b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,6 +3,13 @@
 ### Features
 
 - Make `:value` in `SingleExceptionInterface` writable, so that it can be modified in `before_send` under `event.exception.values[n].value` [#2072](https://github.com/getsentry/sentry-ruby/pull/2072)
+- Add new `config.trace_propagation_targets` option to set targets for which headers are propagated in outgoing HTTP requests [#2079](https://github.com/getsentry/sentry-ruby/pull/2079)
+
+  ```rb
+  # takes an array of strings or regexps
+  config.trace_propagation_targets = [/.*/]  # default is to all targets
+  config.trace_propagation_targets = [/example.com/, 'foobar.org']
+  ```
 
 ## 5.10.0
 
diff --git a/sentry-ruby/lib/sentry/configuration.rb b/sentry-ruby/lib/sentry/configuration.rb
index fb619adcb..11c2ce3bd 100644
--- a/sentry-ruby/lib/sentry/configuration.rb
+++ b/sentry-ruby/lib/sentry/configuration.rb
@@ -243,6 +243,11 @@ def capture_exception_frame_locals=(value)
     # @return [Boolean]
     attr_accessor :auto_session_tracking
 
+    # Allowlist of outgoing request targets to which sentry-trace and baggage headers are attached.
+    # Default is all (/.*/)
+    # @return [Array<String, Regexp>]
+    attr_accessor :trace_propagation_targets
+
     # The instrumenter to use, :sentry or :otel
     # @return [Symbol]
     attr_reader :instrumenter
@@ -290,6 +295,8 @@ def capture_exception_frame_locals=(value)
 
     INSTRUMENTERS = [:sentry, :otel]
 
+    PROPAGATION_TARGETS_MATCH_ALL = /.*/.freeze
+
     class << self
       # Post initialization callbacks are called at the end of initialization process
       # allowing extending the configuration of sentry-ruby by multiple extensions
@@ -332,6 +339,7 @@ def initialize
       self.dsn = ENV['SENTRY_DSN']
       self.server_name = server_name_from_env
       self.instrumenter = :sentry
+      self.trace_propagation_targets = [PROPAGATION_TARGETS_MATCH_ALL]
 
       self.before_send = nil
       self.before_send_transaction = nil
diff --git a/sentry-ruby/lib/sentry/net/http.rb b/sentry-ruby/lib/sentry/net/http.rb
index 470d1a796..e1170dc23 100644
--- a/sentry-ruby/lib/sentry/net/http.rb
+++ b/sentry-ruby/lib/sentry/net/http.rb
@@ -30,13 +30,13 @@ def request(req, body = nil, &block)
         return super if from_sentry_sdk?
 
         Sentry.with_child_span(op: OP_NAME, start_timestamp: Sentry.utc_now.to_f) do |sentry_span|
-          set_sentry_trace_header(req, sentry_span)
+          request_info = extract_request_info(req)
+          set_sentry_trace_header(req, sentry_span, request_info)
 
           super.tap do |res|
-            record_sentry_breadcrumb(req, res)
+            record_sentry_breadcrumb(req, res, request_info)
 
             if sentry_span
-              request_info = extract_request_info(req)
               sentry_span.set_description("#{request_info[:method]} #{request_info[:url]}")
               sentry_span.set_data('url', request_info[:url])
               sentry_span.set_data('http.method', request_info[:method])
@@ -49,10 +49,12 @@ def request(req, body = nil, &block)
 
       private
 
-      def set_sentry_trace_header(req, sentry_span)
+      def set_sentry_trace_header(req, sentry_span, request_info)
         return unless sentry_span
 
         client = Sentry.get_current_client
+        return unless client
+        return unless propagate_trace?(request_info[:url], client.configuration.trace_propagation_targets)
 
         trace = client.generate_sentry_trace(sentry_span)
         req[SENTRY_TRACE_HEADER_NAME] = trace if trace
@@ -61,11 +63,9 @@ def set_sentry_trace_header(req, sentry_span)
         req[BAGGAGE_HEADER_NAME] = baggage if baggage && !baggage.empty?
       end
 
-      def record_sentry_breadcrumb(req, res)
+      def record_sentry_breadcrumb(req, res, request_info)
         return unless Sentry.initialized? && Sentry.configuration.breadcrumbs_logger.include?(:http_logger)
 
-        request_info = extract_request_info(req)
-
         crumb = Sentry::Breadcrumb.new(
           level: :info,
           category: BREADCRUMB_CATEGORY,
@@ -96,6 +96,10 @@ def extract_request_info(req)
 
         result
       end
+
+      def propagate_trace?(url, trace_propagation_targets)
+        url && trace_propagation_targets.any? { |target| url.match?(target) }
+      end
     end
   end
 end