Centos7在线搭建docker的elasticsearch环境(单节点)

# 在线搭建elasticsearch环境
引用：[docker安装ES](https://blog.csdn.net/qq_44732146/article/details/120744829)

### 1. 拉取docker镜像
```
sudo docker pull elasticsearch:7.12.0
```
> 注：版本号可以获取最新

### 2. 创建宿主机映射目录
```
sudo mkdir -p /opt/elasticsearch/config
sudo mkdir -p /opt/elasticsearch/data
sudo mkdir -p /opt/elasticsearch/plugins
```

### 3. 添加elasticsearch配置文件内容
```
echo "http.host: 0.0.0.0" >> /opt/elasticsearch/config/elasticsearch.yml
```

### 4. 设置虚拟内存大小
```
sudo sysctl -w vm.max_map_count=262144
```
> 注：默认虚拟内存大小为65535

### 5. 设置目录可读写
```
sudo chmod 777 -R /opt/elasticsearch
```

### 6. 启动容器
```
sudo docker run --name elasticsearch -p 9200:9200  -p 9300:9300 \
 -e "discovery.type=single-node" \
 -e ES_JAVA_OPTS="-Xms84m -Xmx512m" \
 -v /opt/elasticsearch/config/elasticsearch.yml:/usr/share/elasticsearch/config/elasticsearch.yml \
 -v /opt/elasticsearch/data:/usr/share/elasticsearch/data \
 -v /opt/elasticsearch/plugins:/usr/share/elasticsearch/plugins \
 -d elasticsearch:7.12.0
```
> 说明：
> * -p 端口映射
> * -e discovery.type=single-node 单点模式启动
> * -e ES_JAVA_OPTS="-Xms84m -Xmx512m"：设置启动占用的内存范围
> * -v 目录挂载
> * -d 后台运行

> 关于端口说明
> * 9200：ES节点和外部通讯使用
> * 9300：ES节点之间的通讯使用

### 7. docker相关命令
```
docker ps  查看是否启动
docker logs elasticsearch  启动日志查询
docker restart elasticsearch   重启
docker exec -it elasticsearch bash 进入
```

### 8. 验证是否可用
访问 http://ip:9200 ，能够显示以下内容，表示服务可用。
```
{
  "name" : "32a6ea85392f",
  "cluster_name" : "elasticsearch",
  "cluster_uuid" : "FnNph4ecTD-TpurnqdOhcQ",
  "version" : {
    "number" : "7.12.0",
    "build_flavor" : "default",
    "build_type" : "docker",
    "build_hash" : "78722783c38caa25a70982b5b042074cde5d3b3a",
    "build_date" : "2021-03-18T06:17:15.410153305Z",
    "build_snapshot" : false,
    "lucene_version" : "8.8.0",
    "minimum_wire_compatibility_version" : "6.8.0",
    "minimum_index_compatibility_version" : "6.0.0-beta1"
  },
  "tagline" : "You Know, for Search"
}
```
> 注：注意开放防火墙的9200和9300端口