Elasticsearch add datanode to existing cluster
I have cluster with

• elasticnode1 – master-node
• elasticnode2 – datanode
• elasticnode3 – datanode
• elasticnode4 – datanode

I want add new node

• elasticnode4 – datanode

Setup same version on elasticnode5 – i setup elasticsearch.5.6.3

wget https://artifacts.elastic.co/downloads/elasticsearch/elasticsearch-5.6.3.deb

Add node to config on all nodes

nano /etc/elasticsearch/elasticsearch.yml

discovery.zen.ping.unicast.hosts: ["elasticnode1", "elasticnode2", "elasticnode3", "elasticnode4", "elasticnode5"]

Start cluster rebalancing by put query

curl -XPUT http://elasticnode1:9200/_cluster/settings -d '{
    "transient" : {
        "cluster.routing.allocation.enable" : "all"
    }
}'