[root@k8s-master01 deploy]# kubectl exec -ti es-0 -n wiseco -- /bin/bash
[elasticsearch@es-0 /]$ curl http://es-svc.wiseco.svc.cluster.local:9200
{
  "name" : "es-0.es-svc.wiseco.svc.cluster.local",
  "cluster_name" : "es-cluster",
  "cluster_uuid" : "K-AFavs-RaKjq60rMQG1WQ",
  "version" : {
    "number" : "7.6.2",
    "build_flavor" : "default",
    "build_type" : "tar",
    "build_hash" : "ef48eb35cf30adf4db14086e8aabd07ef6fb113f",
    "build_date" : "2020-03-26T06:34:37.794943Z",
    "build_snapshot" : false,
    "lucene_version" : "8.4.0",
    "minimum_wire_compatibility_version" : "6.8.0",
    "minimum_index_compatibility_version" : "6.0.0-beta1"
  },
  "tagline" : "You Know, for Search"
}

[elasticsearch@es-0 /]$ curl -XGET "http://es-svc.wiseco.svc.cluster.local:9200/_cat/nodes"
172.30.135.154 11 54 2 0.13 0.31 0.25 dilm - es-2.es-svc.wiseco.svc.cluster.local
172.30.85.230  10 66 2 0.11 0.29 0.46 dilm * es-0.es-svc.wiseco.svc.cluster.local
172.30.217.85   6 65 1 0.22 0.21 0.21 dilm - es-1.es-svc.wiseco.svc.cluster.local

查看集群详细信息，后面添加"?v"
注意：带*符号的表示是当前的master主节点
[elasticsearch@es-0 /]$ curl -XGET 'http://es-svc.wiseco.svc.cluster.local:9200/_cat/nodes?v'
ip             heap.percent ram.percent cpu load_1m load_5m load_15m node.role master name
172.30.135.154           12          54   2    0.09    0.29     0.25 dilm      -      es-2.es-svc.wiseco.svc.cluster.local
172.30.85.230            12          66   1    0.07    0.27     0.45 dilm      *      es-0.es-svc.wiseco.svc.cluster.local
172.30.217.85             8          65   3    0.22    0.21     0.21 dilm      -      es-1.es-svc.wiseco.svc.cluster.local

查询集群状态方法
[elasticsearch@es-0 /]$ curl -XGET 'http://es-svc.wiseco.svc.cluster.local:9200/_cluster/state/nodes?pretty'
{
  "cluster_name" : "es-cluster",
  "cluster_uuid" : "K-AFavs-RaKjq60rMQG1WQ",
  "nodes" : {
    "HTD4h0xZRcO3uypCzmxfpQ" : {
      "name" : "es-2.es-svc.wiseco.svc.cluster.local",
      "ephemeral_id" : "OyTHKFt9Ska6-XGp1ucRsQ",
      "transport_address" : "172.30.135.154:9300",
      "attributes" : {
        "ml.machine_memory" : "8370167808",
        "ml.max_open_jobs" : "20",
        "xpack.installed" : "true"
      }
    },
    "ZyL8_6pHTjOwLXCzJDRyVw" : {
      "name" : "es-0.es-svc.wiseco.svc.cluster.local",
      "ephemeral_id" : "JATRby-lTzicDZb9oBoqUQ",
      "transport_address" : "172.30.85.230:9300",
      "attributes" : {
        "ml.machine_memory" : "8366628864",
        "xpack.installed" : "true",
        "ml.max_open_jobs" : "20"
      }
    },
    "KGQQtVrqR0CeajjARZY4LQ" : {
      "name" : "es-1.es-svc.wiseco.svc.cluster.local",
      "ephemeral_id" : "5NKITiKTTMWUI0QAXXX6qg",
      "transport_address" : "172.30.217.85:9300",
      "attributes" : {
        "ml.machine_memory" : "8370184192",
        "ml.max_open_jobs" : "20",
        "xpack.installed" : "true"
      }
    }
  }
}

查询集群中的master（下面两个命令都可以）
[elasticsearch@es-0 /]$ curl -XGET 'http://es-svc.wiseco.svc.cluster.local:9200/_cluster/state/master_node?pretty'
{
  "cluster_name" : "es-cluster",
  "cluster_uuid" : "K-AFavs-RaKjq60rMQG1WQ",
  "master_node" : "ZyL8_6pHTjOwLXCzJDRyVw"
}

[elasticsearch@es-0 /]$ curl -XGET 'http://es-svc.wiseco.svc.cluster.local:9200/_cat/master?v'
id                     host          ip            node
ZyL8_6pHTjOwLXCzJDRyVw 172.30.85.230 172.30.85.230 es-0.es-svc.wiseco.svc.cluster.local


查询集群的健康状态（一共三种状态：green、yellow，red；其中green表示健康）
下面两个命令都可以
[elasticsearch@es-0 /]$ curl -XGET 'http://es-svc.wiseco.svc.cluster.local:9200/_cat/health?v'
epoch      timestamp cluster    status node.total node.data shards pri relo init unassign pending_tasks max_task_wait_time active_shards_percent
1613915456 13:50:56  es-cluster green           3         3      0   0    0    0        0             0                  -                100.0%

[elasticsearch@es-0 /]$ curl -XGET 'http://es-svc.wiseco.svc.cluster.local:9200/_cluster/health?pretty'
{
  "cluster_name" : "es-cluster",
  "status" : "green",
  "timed_out" : false,
  "number_of_nodes" : 3,
  "number_of_data_nodes" : 3,
  "active_primary_shards" : 0,
  "active_shards" : 0,
  "relocating_shards" : 0,
  "initializing_shards" : 0,
  "unassigned_shards" : 0,
  "delayed_unassigned_shards" : 0,
  "number_of_pending_tasks" : 0,
  "number_of_in_flight_fetch" : 0,
  "task_max_waiting_in_queue_millis" : 0,
  "active_shards_percent_as_number" : 100.0
}