I've got several regional logstash'es (beats, syslog, snmptrap, netflow inputs, persistent queue) which transfer data to a central logstash for processing.
What is the best protocol for transferring structured data between logstash'es?
json_lines over TCP doesn't look like reliable since it doesn't ACK. Lumberjack does ACK, but doesn't support JSON. Beats is the best, but there is no logstash beats output.
So what is the best logstash-to-logstash protocol?