原文网址：ElasticSearch--查看健康状态(health)的方法(API)_IT利刃出鞘的博客-CSDN博客

简介

说明

        本文介绍ElasticSearch查看健康状态的方法（API）。

官网

https://www.elastic.co/guide/en/elasticsearch/reference/7.1/cluster-health.html

Head插件查看状态

Head插件可以查看ES的状态，例如：

Head插件可以直观看到颜色，但有如下两个缺点：

1. 生产环境中ES不会放开外网端口，无法用Head插件查看状态。
2. Head插件只能看到颜色，不能看到详细错误原因

所以，如果想要查看生产环境的ES状态或者查看详细错误原因，就要用到下边的API。

API大全

_cat/health

_cat/shards

_cluster/health

_cluster/allocation/explain

示例1：索引的健康状态

方法

http://IP:9200/_cat/health

 正常的结果

1635328870 10:01:10 kubernetes-logging green 15 10 2160 1080 2 0 0 0 - 100.0%

有问题的结果

1635313779 05:49:39 kubernetes-logging red 15 10 2128 1064 0 0 32 0 - 98.5%

示例2：分片的状态 

方法

http://IP:9200/_cat/shards?v=true&h=index,shard,prirep,state,node,unassigned.reason&s=state

• v=true, 代表显示字段含义；否则首行内容不显示。
• h=*，代表列名；
• s=state，代表基于state方式排序。等价于：s=state:asc，默认升序方式排序。
• prirep，代表分片类型。p：代表主分片；r：代表副本分片。

结果

order_info、test_data等索引包含未分配的副本分片。其集群健康状态肯定是“黄色”。 

示例3：集群的健康状态

方法

http://IP:9200/_cluster/health

结果

{
    "cluster_name": "kubernetes-logging",
    "status": "red",
    "timed_out": false,
    "number_of_nodes": 15,
    "number_of_data_nodes": 10,
    "active_primary_shards": 1064,
    "active_shards": 2128,
    "relocating_shards": 0,
    "initializing_shards": 0,
    "unassigned_shards": 32,
    "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": 98.51851851851852
}

"unassigned_shards" ：未分配的分片数

示例4：所有索引的健康状态

方法

http://IP:9200/_cluster/health?level=indices

结果

{
    // 其他数据
    
    "bj-task-hdfs-rpc-2021.11.24" : {
      "status" : "red",             // 分片状态为红色
      "number_of_shards" : 5,       // 主分片数
      "number_of_replicas" : 1,     // 每个分片的副本数
      "active_primary_shards" : 4,  // 活动的主分片数，说明 1 个故障
      "active_shards" : 7,          // 活动的总分片数，说明 3 个故障
      "relocating_shards" : 0,
      "initializing_shards" : 0,
      "unassigned_shards" : 3       // 未分配的分片有3个（1主分片 + 2副本分片）
    }
}

示例5：单个索引的健康状态

方法

http://IP:9200/_cluster/health/dev-tool-deployment-service

结果

{
    "cluster_name": "kubernetes-logging",
    "status": "red",
    "timed_out": false,
    "number_of_nodes": 15,
    "number_of_data_nodes": 10,
    "active_primary_shards": 2,
    "active_shards": 4,
    "relocating_shards": 0,
    "initializing_shards": 0,
    "unassigned_shards": 6,
    "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": 98.52534562211981
}

示例6：查看故障原因

GET /_cluster/allocation/explain

结果

{
  "index" : "idx",
  "shard" : 0,
  "primary" : true,
  "current_state" : "unassigned",                 
  "unassigned_info" : {
    "reason" : "INDEX_CREATED",                   
    "at" : "2017-01-04T18:08:16.600Z",
    "last_allocation_status" : "no"
  },
  "can_allocate" : "no",                          
  "allocate_explanation" : "cannot allocate because allocation is not permitted to any of the nodes",
  "node_allocation_decisions" : [
    {
      "node_id" : "8qt2rY-pT6KNZB3-hGfLnw",
      "node_name" : "node-0",
      "transport_address" : "127.0.0.1:9401",
      "node_attributes" : {},
      "node_decision" : "no",                     
      "weight_ranking" : 1,
      "deciders" : [
        {
          "decider" : "filter",                   
          "decision" : "NO",
          "explanation" : "node does not match index setting [index.routing.allocation.include] filters [_name:\"non_existent_node\"]"  
        }
      ]
    }
  ]
}