elasticsearch7.4集群搭建和go查询es demo

1.   elasticsearch集群搭建

1.1 下载安装jdk1.8(es须要jre运行环境)

去oracle官网下载jdk, 上传到服务器，执行下面命令安装:

rpm -ivh jdk-8u231-linux-x64.rpm复制代码

oracle jdk1.8下载页面:  www.oracle.com/technetwork…

1.2 下载安装安装elasticsearch

wget https://artifacts.elastic.co/downloads/elasticsearch/elasticsearch-7.4.2-x86_64.rpm
rpm -ivh elasticsearch-7.4.2-x86_64.rpm
systemctl daemon-reload                    #reload配置
systemctl enable elasticsearch.service     #设置开机启动
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1.3 配置elasticsearch（以3个节点为例）

mv  /etc/elasticsearch/elasticsearch.yml /etc/elasticsearch/elasticsearch.yml.bak

vim /etc/elasticsearch/elasticsearch.yml 建立新配置文件

 除node.name 须要更改外，其余同样

cluster.name: elasticsearch
node.name: node1                    #随机器变化。node2 node3 以此推
network.host: 0.0.0.0
http.port: 9200
transport.tcp.port: 9300
transport.tcp.compress: true
path.data: /var/lib/elasticsearch
path.logs: /var/log/elasticsearch   
action.auto_create_index: true
discovery.zen.minimum_master_nodes: 1
node.max_local_storage_nodes: 3
discovery.seed_hosts: ["ip1","ip2","ip3"]
cluster.initial_master_nodes: ["node1"]复制代码

配置解释:

cluster.name:                          集群名称
node.name: node1                       节点名称
network.host: 0.0.0.0                  监控地址 
http.port: 9200                        数据端口
transport.tcp.port: 9300               java api端口
transport.tcp.compress: true
path.data: /var/lib/elasticsearch      数据目录
path.logs: /var/log/elasticsearch      日志目录
action.auto_create_index: true         自动建立索引
discovery.zen.minimum_master_nodes:    最小通讯点数，（3节点先1，避免脑裂）
node.max_local_storage_nodes:          单机多进程数
discovery.seed_hosts:                  集群节点ip
cluster.initial_master_nodes:          初始化指定的master节点复制代码

1.4 启动elasticsearch

执行启动命令:

systemctl start elasticsearch复制代码

查看日志信息:

tail -f /var/log/elasticsearch/elasticsearch.log复制代码

2. golang demo(查看某个索引内容)

2.1 输出该索引总条数，以及显示最近10条

package main

import (
	"context"
	"encoding/json"
	"fmt"
	"github.com/olivere/elastic/v7"
	"log"
)

type Subject struct {
	id            string
	name          string
	age           int
	region        string
}

func main() {

	var client, _ = elastic.NewSimpleClient(elastic.SetURL("http://127.0.0.1:9200/"))
	ctx := context.Background()
	boolQuery := elastic.NewBoolQuery()

	searchResult,err := client.Search().Index("index_name").
		Query(boolQuery).From(0).Size(10).Do(ctx)
	if err != nil {
		log.Println("err:", err)
	}

	if searchResult.TotalHits() > 0 {
		log.Printf("Found a total of %d indice\n", searchResult.TotalHits())
		for _, hit := range searchResult.Hits.Hits {
			var t Subject
			err := json.Unmarshal(hit.Source, &t)
			if err != nil {
				log.Printf("%v", err)
			}
			fmt.Printf("name: %v,age: %v, region: %v\n",t.name,t.age,t.region)
		}
	} else {
		log.Println("没有查询到数据")
	}
}
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