查看ES集群状态:

GET /_cluster/health?pretty=true

当一个节点加入集群的时候,ES会自动地尝试将分片在所有节点上进行均匀分配.
如果更多的节点加入集群,ES将试图在所有节点上均匀分配分片数量.这样每一个新加入的节点都能通过部分数据来分担负载
第二个节点发现第一个节点,并且加入集群的方式: 广播或单播.ES可同时使用两者,不过默认的配置时仅使用广播,因为单播需要已知节点列表来进行链接

获取集群节点状态信息

GET /_cluster/state/master_node,nodes?pretty
#响应:
{"cluster_name": "elasticsearch","cluster_uuid": "TmUQBp_9TsSG93CKys-WNg","master_node": "I-O0ckoiRwOqqsU2Y_4bAw","nodes": {"I-O0ckoiRwOqqsU2Y_4bAw": {"name": "hecs-21906","ephemeral_id": "J0VupwLZQVGQkKWsD4BknQ","transport_address": "127.0.0.1:9300","external_id": "hecs-21906","attributes": {"ml.allocated_processors": "2","ml.max_jvm_size": "1790967808","ml.allocated_processors_double": "2.0","xpack.installed": "true","ml.machine_memory": "3576066048"},"roles": ["data","data_cold","data_content","data_frozen","data_hot","data_warm","ingest","master","ml","remote_cluster_client","transform"],"version": "8.8.2"}},"transport_versions": [{"node_id": "I-O0ckoiRwOqqsU2Y_4bAw","transport_version": "8080299"}]
}