Add preview to ActiveStorage::LogSubscriber

a `preview` event is being instrumented in `ActiveStorage::Previewer`. However it is not added inside ActiveStorage's `LogSubscriber` class.

activestorage/CHANGELOG.md

@@ -1,3 +1,14 @@
+*   Add missing preview event to `ActiveStorage::LogSubscriber`
+
+    A `preview` event is being instrumented in `ActiveStorage::Previewer`.
+    However it was not added inside ActiveStorage's LogSubscriber class.
+
+    This will allow to have logs for when a preview happens
+    in the same fashion as all other ActiveStorage events such as
+    `upload` and `download` inside `Rails.logger`.
+
+    *Chedli Bourguiba*
+
 *   Fix retrieving rotation value from FFmpeg on version 5.0+.
 
     In FFmpeg version 5.0+ the rotation value has been removed from tags.

activestorage/lib/active_storage/log_subscriber.rb

@@ -18,6 +18,11 @@ def service_download(event)
 
     alias_method :service_streaming_download, :service_download
 
+    def preview(event)
+      info event, color("Previewed file from key: #{key_in(event)}", BLUE)
+    end
+    subscribe_log_level :preview, :info
+
     def service_delete(event)
       info event, color("Deleted file from key: #{key_in(event)}", RED)
     end

activestorage/lib/active_storage/previewer.rb

@@ -65,7 +65,12 @@ def open_tempfile
       end
 
       def instrument(operation, payload = {}, &block)
-        ActiveSupport::Notifications.instrument "#{operation}.active_storage", payload, &block
+        ActiveSupport::Notifications.instrument "#{operation}.active_storage", payload.merge(service: service_name), &block
+      end
+
+      def service_name
+        # ActiveStorage::Service::DiskService => Disk
+        blob.service.class.to_s.split("::").third.remove("Service")
       end
 
       def capture(*argv, to:)