Docker Swarm cluster

I wasn’t sure either, just grabbed the Swarm config from the wiki

# docker-stack.yml

  elasticsearch:
    environment:
      # Force publishing on the 'elk' overlay.
      network.publish_host: _eth0_
      # Set a predictable node name.
      node.name: elk_elasticsearch.{{.Task.Slot}}
      # Disable single-node discovery.
      discovery.type: ''
      # Use internal Docker round-robin DNS for unicast discovery.
      discovery.seed_hosts: tasks.elasticsearch
      # Define initial masters, assuming a cluster size of at least 3.
      cluster.initial_master_nodes: elk_elasticsearch.1,elk_elasticsearch.2,elk_elasticsearch.3