Correctly setting up networking is very important for your nodes and cluster.

There are a lot of different installation scenarios and networking issues. The first step for configuring the nodes to build a cluster is to correctly set the node discovery.

To change configuration files, you will need a working Elasticsearch installation and a simple text editor, as well as your current networking configuration (your IP).

To setup the networking, use the following steps:

1. Using a standard Elasticsearch configuration config/elasticsearch.yml file, your node will be configured to bind on the localhost interface (by default) so that it can't be accessed by external machines or nodes.
2. To allow another machine to connect to our node, we need to set network.host to our IP (for example, I have 192.168.1.164).
3. To be able to discover other nodes, we need to list them in the discovery.zen.ping.unicast.hosts parameter. This means that it sends signals to the machine in a unicast list and waits for a response. If a node responds to it, they can join in a cluster.

4. In general, from Elasticsearch version 6.x, the node versions are compatible. You must have the same cluster name (the cluster.name option in elasticsearch.yml) to let nodes join with each other.

5. To customize the network preferences, you need to change some parameters in the elasticsearch.yml file, as follows:

cluster.name: ESCookBook
node.name: "Node1"
network.host: 192.168.1.164
discovery.zen.ping.unicast.hosts: ["192.168.1.164","192.168.1.165[9300-9400]"]

6. This configuration sets the cluster name to Elasticsearch, the node name, the network address, and it tries to bind the node to the address given in the discovery section by performing the following tasks:

• • We can check the configuration during node loading
  • We can now start the server and check whether the networking is configured, as follows:

[2018-10-28T17:42:16,386][INFO ][o.e.c.s.MasterService ] [Node1] zen-disco-elected-as-master ([0] nodes joined)[, ], reason: new_master {Node1}{fyBySLMcR3uqKiYC32P5Sg}{IX1wpA01QSKkruZeSRPlFg}{192.168.1.164}{192.168.1.164:9300}{ml.machine_memory=17179869184, xpack.installed=true, ml.max_open_jobs=20, ml.enabled=true}
 [2018-10-28T17:42:16,390][INFO ][o.e.c.s.ClusterApplierService] [Node1] new_master {Node1}{fyBySLMcR3uqKiYC32P5Sg}{IX1wpA01QSKkruZeSRPlFg}{192.168.1.164}{192.168.1.164:9300}{ml.machine_memory=17179869184, xpack.installed=true, ml.max_open_jobs=20, ml.enabled=true}, reason: apply cluster state (from master [master {Node1}{fyBySLMcR3uqKiYC32P5Sg}{IX1wpA01QSKkruZeSRPlFg}{192.168.1.164}{192.168.1.164:9300}{ml.machine_memory=17179869184, xpack.installed=true, ml.max_open_jobs=20, ml.enabled=true} committed version [1] source [zen-disco-elected-as-master ([0] nodes joined)[, ]]])
 [2018-10-28T17:42:16,403][INFO ][o.e.x.s.t.n.SecurityNetty4HttpServerTransport] [Node1] publish_address {192.168.1.164:9200}, bound_addresses {192.168.1.164:9200}
 [2018-10-28T17:42:16,403][INFO ][o.e.n.Node ] [Node1] started
 [2018-10-28T17:42:16,600][INFO ][o.e.l.LicenseService ] [Node1] license [b2754b17-a4ec-47e4-9175-4b2e0d714a45] mode [basic] - valid

As you can see from my screen dump, the transport is bound to 192.168.1.164:9300. The REST HTTP interface is bound to 192.168.1.164:9200.

The following are the main important configuration keys for networking management:

• cluster.name: This sets up the name of the cluster. Only nodes with the same name can join together.
• node.name: If not defined, this is automatically assigned by Elasticsearch.

node.name allows defining a name for the node. If you have a lot of nodes on different machines, it is useful to set their names to something meaningful in order to easily locate them. Using a valid name is easier to remember than a generated name such as fyBySLMcR3uqKiYC32P5Sg.

network.host defines the IP of your machine to be used to bind the node. If your server is on different LANs, or you want to limit the bind on only one LAN, you must set this value with your server IP.

discovery.zen.ping.unicast.hosts allows you to define a list of hosts (with ports or a port range) to be used to discover other nodes to join the cluster. The preferred port is the transport one, usually 9300.

The addresses of the hosts list can be a mix of the following:

• Hostname, that is, myhost1
• IP address, that is, 192.168.1.12
• IP address or hostname with the port, that is, myhost1:9300, 192.168.168.1.2:9300
• IP address or hostname with a range of ports, that is, myhost1:[9300-9400], 192.168.168.1.2:[9300-9400]

The Setting up a node recipe in this chapter