一、節點相關命令

1、檢視節點基本資訊

GET /_nodes/<node_id>

該命令能夠一次性返回節點全部的資訊，如process、jvm、plugins以及節點角色roles、屬性 attributes 和 settings 等相關資訊。如果我們想要返回特定的資訊，如process，則可以使用如下API：

GET /_nodes/<node_id>/process

返回 Response：

{  "_nodes" : {    "total" : 1,    "successful" : 1,    "failed" : 0  },  "cluster_name" : "es-xxxx",
 
  "nodes" : {    "fdaOV16OQPq6-AUVihmq4A" : {      "name" : "162680s31430001456s32",      "transport_address" : "xx.0.96.22:9300",      "host" : "xx.0.96.22",      "ip" : "xx.0.96.22",      "version" : "7.10.1",      "build_flavor" : "default",      "build_type" : "tar",      "build_hash" : "119c2106d7bd8d206aa3b65dc43c87b8aa590b2b",
 
      "roles" : [        "master",        "ml",        "remote_cluster_client"      ],      "attributes" : {        "ml.machine_memory" : "16478932992",        "rack" : "cvm_4_200003",        "xpack.installed" : "true",        "set" : "200003",        "transform.node" : "false",        "ip" : "xx.20.58.221",
 
        "temperature" : "hot",        "ml.max_open_jobs" : "20",        "region" : "4"      },      "process" : {        "refresh_interval_in_millis" : 1000,        "id" : 24918,        "mlockall" : false      }    }  }}

2、檢視節點統計資訊

GET /_nodes/statsGET /_nodes/<node_id>/statsGET/_nodes/stats/<metric>

該API能夠獲取節點各項指標的統計資訊，如 JVM、CPU、記憶體、磁碟等使用率情況、該節點上有多少個索引，get請求、search請求、merge 操作、refresh 和 flush 的相關統計資訊，以及快取相關的如 fielddata、query_cache、request_cache 的統計資訊，還包括了 segment 和 translog 的相關統計資訊。

總之，通過該 API，我們能夠全方位獲取到節點維度相關的各種指標資訊。對於我們排查叢集問題非常有幫助，我們還了解到騰訊雲 ES 的部分大客戶，通過定期去請求該API，將返回資訊輸出到對應的監控系統，來自己做更加細粒度的叢集監控。

該API預設是返回節點所有的統計指標資訊，如果我們需要檢視部分指標或者特定指標統計資訊，也可以在 API 中進行指定，如我們想檢視特定節點的 JVM 使用情況：

GET /_nodes/1626803143000145632/stats/jvm

返回 Response 如下：

{  "_nodes" : {    "total" : 1,    "successful" : 1,    "failed" : 0  },  "cluster_name" : "es-xxx",  "nodes" : {    "fdaOV16OQPq6-AUVihmq4A" : {      "timestamp" : 1639878427713,      "name" : "1626803143000145632",      "transport_address" : "xx.0.96.22:9300",      "host" : "xx.0.96.22",      "ip" : "xx.0.96.22:9300",      "roles" : [        "master",        "ml",        "remote_cluster_client"      ],      "attributes" : {        "ml.machine_memory" : "16478932992",        "rack" : "cvm_4_200003",        "xpack.installed" : "true",        "set" : "200003",        "transform.node" : "false",        "ip" : "xx.20.58.221",        "temperature" : "hot",        "ml.max_open_jobs" : "20",        "region" : "4"      },      "jvm" : {        "timestamp" : 1639878427713,        "uptime_in_millis" : 13037976328,        "mem" : {          "heap_used_in_bytes" : 214161760,          "heap_used_percent" : 2,          "heap_committed_in_bytes" : 8555069440,          "heap_max_in_bytes" : 8555069440,          "non_heap_used_in_bytes" : 178981224,          "non_heap_committed_in_bytes" : 195989504,          "pools" : {            "young" : {              "used_in_bytes" : 104047328,              "max_in_bytes" : 279183360,              "peak_used_in_bytes" : 279183360,              "peak_max_in_bytes" : 279183360            },            "survivor" : {              "used_in_bytes" : 545616,              "max_in_bytes" : 34865152,              "peak_used_in_bytes" : 34865144,              "peak_max_in_bytes" : 34865152            },            "old" : {              "used_in_bytes" : 109568816,              "max_in_bytes" : 8241020928,              "peak_used_in_bytes" : 127845408,              "peak_max_in_bytes" : 8241020928            }          }        },        "threads" : {          "count" : 41,          "peak_count" : 43        },        "gc" : {          "collectors" : {            "young" : {              "collection_count" : 4718,              "collection_time_in_millis" : 162825            },            "old" : {              "collection_count" : 3,              "collection_time_in_millis" : 359            }          }        },        "buffer_pools" : {          "direct" : {            "count" : 16,            "used_in_bytes" : 4300808,            "total_capacity_in_bytes" : 4300807          },          "mapped" : {            "count" : 0,            "used_in_bytes" : 0,            "total_capacity_in_bytes" : 0          }        },        "classes" : {          "current_loaded_count" : 21255,          "total_loaded_count" : 21361,          "total_unloaded_count" : 106        }      }    }  }}

或者我們想看該節點上索引的 merge 統計資訊：

GET /_nodes/1626803143000145632/stats/indices/merge

返回 Response 如下：

{  "_nodes" : {    "total" : 1,    "successful" : 1,    "failed" : 0  },  "cluster_name" : "es-xxx",  "nodes" : {    "fdaOV16OQPq6-AUVihmq4A" : {      "timestamp" : 1639878633590,      "name" : "1626803143000145632",      "transport_address" : "xx.0.96.22:9300",      "host" : "xx.0.96.22",      "ip" : "xx.0.96.22:9300",      "roles" : [        "master",        "ml",        "remote_cluster_client"      ],      "attributes" : {        "ml.machine_memory" : "16478932992",        "rack" : "cvm_4_200003",        "xpack.installed" : "true",        "set" : "200003",        "transform.node" : "false",        "ip" : "xx.20.58.221",        "temperature" : "hot",        "ml.max_open_jobs" : "20",        "region" : "4"      },      "indices" : {        "merges" : {          "current" : 0,          "current_docs" : 0,          "current_size_in_bytes" : 0,          "total" : 0,          "total_time_in_millis" : 0,          "total_docs" : 0,          "total_size_in_bytes" : 0,          "total_stopped_time_in_millis" : 0,          "total_throttled_time_in_millis" : 0,          "total_auto_throttle_in_bytes" : 0        }      }    }  }}

以及檢視節點索引 segment 和 translog 統計資訊：

GET /_nodes/1626803143000145632/stats/indices/segments,translog

{  "_nodes" : {    "total" : 1,    "successful" : 1,    "failed" : 0  },  "cluster_name" : "es-xxxx",  "nodes" : {    "fdaOV16OQPq6-AUVihmq4A" : {      "timestamp" : 1639878746911,      "name" : "1626803143000145632",      "transport_address" : "xx.0.96.22:9300",      "host" : "xx.0.96.22",      "ip" : "xx.0.96.22:9300",      "roles" : [        "master",        "ml",        "remote_cluster_client"      ],      "attributes" : {        "ml.machine_memory" : "16478932992",        "rack" : "cvm_4_200003",        "xpack.installed" : "true",        "set" : "200003",        "transform.node" : "false",        "ip" : "xx.20.58.221",        "temperature" : "hot",        "ml.max_open_jobs" : "20",        "region" : "4"      },      "indices" : {        "segments" : {          "count" : 0,          "memory_in_bytes" : 0,          "terms_memory_in_bytes" : 0,          "stored_fields_memory_in_bytes" : 0,          "term_vectors_memory_in_bytes" : 0,          "norms_memory_in_bytes" : 0,          "points_memory_in_bytes" : 0,          "doc_values_memory_in_bytes" : 0,          "index_writer_memory_in_bytes" : 0,          "version_map_memory_in_bytes" : 0,          "fixed_bit_set_memory_in_bytes" : 0,          "max_unsafe_auto_id_timestamp" : -9223372036854775808,          "file_sizes" : { }        },        "translog" : {          "operations" : 0,          "size_in_bytes" : 0,          "uncommitted_operations" : 0,          "uncommitted_size_in_bytes" : 0,          "earliest_last_modified_age" : 0        }      }    }  }}

也可以通過該API來檢視每個節點上所分配的索引儲存資訊：

GET /_nodes/stats/indices/store

更多靈活用法請參考【杏耀註冊】官方文件。