My GKE cluster is currently in default settings and is logging to stack driver. However, I would like to be able to log to elastic stack that I am deploying at elastic.co.
https://cloud.google.com/solutions/customizing-stackdriver-logs-fluentd
I see that I am able to customize filtering and parsing of default fluentd daemonset but how do I install elasticsearch output plugin so that I can stream logs to my elasticsearch endpoint instead of Stackdriver?
The tutorial you linked to answers your question. You need to create a GKE cluster without the built-in fluentd (by passing the --no-enable-cloud-logging flag when creating the cluster) and then install a custom daemon set with the fluentd configuration you want to use.