Add Sentry instrumentation for JavaScript

lib/middleware/websocket_sentry_headers.rb

@@ -0,0 +1,28 @@
+# frozen_string_literal: true
+
+module Middleware
+  class WebSocketSentryHeaders
+    def initialize(app)
+      @app = app
+    end
+
+    def call(env)
+      request = Rack::Request.new(env)
+      extract_sentry_parameters(request) if websocket_upgrade?(request)
+      @app.call(env)
+    end
+
+    private
+
+    def websocket_upgrade?(request)
+      request.get_header('HTTP_CONNECTION')&.casecmp?('Upgrade') &&
+        request.get_header('HTTP_UPGRADE')&.casecmp?('websocket')
+    end
+
+    def extract_sentry_parameters(request)
+      %w[HTTP_SENTRY_TRACE HTTP_BAGGAGE].each do |param|
+        request.add_header(param, request.delete_param(param))
+      end
+    end
+  end
+end