I have following node configurations for 3 node cluster :
Each node has two network cards, one for private IP for internode communication and another for public IP to connect from kibana/ external users.
The private IP's can't be reachable from outside than of 3 nodes.
Node-1 :
cluster.name: cad-elastisearch
node.name: node-1-gnbsx00043
path.data: /data/esdb/data
path.logs: /data/esdb/log
network.host: 10.129.212.43 <= public IP
http.host: 10.129.212.43
transport.host: 10.129.213.43 <= private IP
http.port: 9200
discovery.zen.ping.unicast.hosts: ["10.129.212.43","10.129.212.44","10.129.212.45"] <= Public IP's
discovery.zen.minimum_master_nodes: 2
Node-2
cluster.name: cad-elastisearch
node.name: node-2-gnbsx00044
path.data: /data/esdb/data
path.logs: /data/esdb/log
network.host: 10.129.212.44
http.host: 10.129.212.44
transport.host: 10.129.213.44
http.port: 9200
discovery.zen.ping.unicast.hosts: ["10.129.212.43","10.129.212.44","10.129.212.45"]
discovery.zen.minimum_master_nodes: 2
Node-3
cluster.name: cad-elastisearch
node.name: node-2-gnbsx00044
path.data: /data/esdb/data
path.logs: /data/esdb/log
network.host: 10.129.212.44
http.host: 10.129.212.44
transport.host: 10.129.213.44
http.port: 9200
discovery.zen.ping.unicast.hosts: ["10.129.212.43","10.129.212.44","10.129.212.45"]
discovery.zen.minimum_master_nodes: 2
With this configuration the error log shows
[2019-07-30T06:58:56,639][INFO ][o.e.p.PluginsService ] [node-1-gnbsx00043] loaded module [x-pack-monitoring]
[2019-07-30T06:58:56,640][INFO ][o.e.p.PluginsService ] [node-1-gnbsx00043] loaded module [x-pack-rollup]
[2019-07-30T06:58:56,640][INFO ][o.e.p.PluginsService ] [node-1-gnbsx00043] loaded module [x-pack-security]
[2019-07-30T06:58:56,640][INFO ][o.e.p.PluginsService ] [node-1-gnbsx00043] loaded module [x-pack-sql]
[2019-07-30T06:58:56,640][INFO ][o.e.p.PluginsService ] [node-1-gnbsx00043] loaded module [x-pack-upgrade]
[2019-07-30T06:58:56,640][INFO ][o.e.p.PluginsService ] [node-1-gnbsx00043] loaded module [x-pack-watcher]
[2019-07-30T06:58:56,640][INFO ][o.e.p.PluginsService ] [node-1-gnbsx00043] no plugins loaded
[2019-07-30T06:59:00,292][INFO ][o.e.x.s.a.s.FileRolesStore] [node-1-gnbsx00043] parsed [0] roles from file [/data/essw/elasticsearch-6.6.0/config/roles.yml]
[2019-07-30T06:59:00,796][INFO ][o.e.x.m.p.l.CppLogMessageHandler] [node-1-gnbsx00043] [controller/237437] [Main.cc@109] controller (64 bit): Version 6.6.0 (Build bbb4919f4d17a5) Copyright (c) 2019 Elasticsearch BV
[2019-07-30T06:59:01,187][DEBUG][o.e.a.ActionModule ] [node-1-gnbsx00043] Using REST wrapper from plugin org.elasticsearch.xpack.security.Security
[2019-07-30T06:59:01,400][INFO ][o.e.d.DiscoveryModule ] [node-1-gnbsx00043] using discovery type [zen] and host providers [settings]
[2019-07-30T06:59:02,099][INFO ][o.e.n.Node ] [node-1-gnbsx00043] initialized
[2019-07-30T06:59:02,099][INFO ][o.e.n.Node ] [node-1-gnbsx00043] starting ...
[2019-07-30T06:59:02,237][INFO ][o.e.t.TransportService ] [node-1-gnbsx00043] publish_address {10.129.213.43:9300}, bound_addresses {10.129.213.43:9300}
[2019-07-30T06:59:02,255][INFO ][o.e.b.BootstrapChecks ] [node-1-gnbsx00043] bound or publishing to a non-loopback address, enforcing bootstrap checks
[2019-07-30T06:59:05,308][WARN ][o.e.d.z.ZenDiscovery ] [node-1-gnbsx00043] not enough master nodes discovered during pinging (found [[Candidate{node={node-1-gnbsx00043}{78KaKTlkSJefU6tt3ZRPkg}{7m9ar3gEQ1OIIq1u-pFOXQ}{10.129.213.43}{10.129.213.43:9300}{ml.machine_memory=270841049088, xpack.installed=true, ml.max_open_jobs=20, ml.enabled=true}, clusterStateVersion=-1}]], but needed [2]), pinging again
[2019-07-30T06:59:08,309][WARN ][o.e.d.z.ZenDiscovery ] [node-1-gnbsx00043] not enough master nodes discovered during pinging (found [[Candidate{node={node-1-gnbsx00043}{78KaKTlkSJefU6tt3ZRPkg}{7m9ar3gEQ1OIIq1u-pFOXQ}{10.129.213.43}{10.129.213.43:9300}{ml.machine_memory=270841049088, xpack.installed=true, ml.max_open_jobs=20, ml.enabled=true}, clusterStateVersion=-1}]], but needed [2]), pinging again
[2019-07-30T06:59:11,310][WARN ][o.e.d.z.ZenDiscovery ] [node-1-gnbsx00043] not enough master nodes discovered during pinging (found [[Candidate{node={node-1-gnbsx00043}{78KaKTlkSJefU6tt3ZRPkg}{7m9ar3gEQ1OIIq1u-pFOXQ}{10.129.213.43}{10.129.213.43:9300}{ml.machine_memory=270841049088, xpack.installed=true, ml.max_open_jobs=20, ml.enabled=true}, clusterStateVersion=-1}]], but needed [2]), pinging again
[2019-07-30T06:59:14,311][WARN ][o.e.d.z.ZenDiscovery ] [node-1-gnbsx00043] not enough master nodes discovered during pinging (found [[Candidate{node={node-1-gnbsx00043}{78KaKTlkSJefU6tt3ZRPkg}{7m9ar3gEQ1OIIq1u-pFOXQ}{10.129.213.43}{10.129.213.43:9300}{ml.machine_memory=270841049088, xpack.installed=true, ml.max_open_jobs=20, ml.enabled=true}, clusterStateVersion=-1}]], but needed [2]), pinging again