We have a project that's configured with both Rails/Lograge. According to the documentation it seems that you simply include the gem. I'm wondering if it's possible to send additional information as a jsonPayload. All of our logging is being parsed only as textPayload.
https://github.com/googleapis/google-cloud-ruby/tree/master/stackdriver
https://cloud.google.com/logging/docs/reference/v2/rest/v2/LogEntry
We're also using AppEngine Flex so we have less control over the Fluentd implementation.