fluent.conf

  <filter kubernetes.**>
    type record_transformer
    enable_ruby
    <record>
      hostname ${(kubernetes_host rescue nil) || File.open('/etc/docker-hostname') { |f| f.readline }.rstrip}
      message ${(message rescue nil) || log}
      project_labels ${(kubernetes_project.metadata.labels rescue nil)}
      version 1.2.0
    </record>
    remove_keys log,stream
  </filter>