fluentd/label/default_output/elasticsearch.yml

classes:
- service.fluentd.agent.output.elasticsearch
parameters:
  _params:
    fluentd_elasticsearch_host: 127.0.0.1
    elasticsearch_port: 9200
  fluentd:
    agent:
      config:
        label:
          default_output:
            match:
              elasticsearch_output:
                host: ${_param:fluentd_elasticsearch_host}
                port: ${_param:elasticsearch_port}