Load secrets into credentials hash to maintain existing behaviour

config/initializers/secrets_to_credentials.rb

@@ -0,0 +1,8 @@
+# Rails 7 has begung to deprecate Rails.application.secrets in favour
+# of Rails.application.credentials, but that adds the burden of master key
+# adminstration without giving us any benefit (because our production
+# secrets are handled as env vars, not committed to our repo. Here we
+# loads the config/secrets.YML values into Rails.application.credentials,
+# retaining the existing behaviour while dropping deprecated references.
+
+Rails.application.credentials.merge!(Rails.application.config_for(:secrets))