Elasticsearch ：单机安装

ElasticSearch是一个基于Lucene的搜索服务器。它提供了一个分布式多用户能力的全文搜索引擎，基于RESTful web接口。Elasticsearch是用Java开发的，并作为Apache许可条款下的开放源码发布，是当前流行的企业级搜索引擎。设计用于云计算中，能够达到实时搜索，稳定，可靠，快速，安装使用方便。

1、安装环境

操作系统：centos6.9 x86_64

JDK: 1.8

Elasticsearch版本：Elasticsearch6.4.0

2、安装elasticsearch 

官网地址：https://www.elastic.co/products/elasticsearch

##下载

curl -L -O https://artifacts.elastic.co/downloads/elasticsearch/elasticsearch-6.4.0.tar.gz

##解压

tar -xvf elasticsearch-6.4.0.tar.gz

3、配置文件

cd elasticsearch

vi config/elasticsearch.yml

## 加入或修改下面的配置

## 设置自己的ip  不配置此ip默认只能在本机访问

network.host: 测试用0.0.0.0 

## 用于head插件跨域访问用

http.cors.enabled: true

http.cors.allow-origin: "*"

由于elasticsearch2.0以后禁止root启动（原因：ElasticSearch可以接收用户输入的脚本并且执行,出于系统安全考虑所以设置非root用户权限），因此建立一个es的用户

##增加es用户组

groupadd es

##增加es用户

useradd es -g es

##把elasticsearch-5.6.11文件夹权限赋予给es

chown -R es:es elasticsearch

4、切换es用户 登录

elasticsearch-6.4.0/bin/elasticsearch

5、错误解决（切换root权限）

1、提示可分配es启动的内存不足，默认分配 2g启动内存
[es@VM_0_15_centos local]$ Java HotSpot(TM) 64-Bit Server VM warning: INFO: os::commit_memory(0x0000000085330000, 2060255232, 0) failed; error='Cannot allocate memory' (errno=12)
#
# There is insufficient memory for the Java Runtime Environment to continue.
# Native memory allocation (mmap) failed to map 2060255232 bytes for committing reserved memory.
# An error report file with more information is saved as:
# /tmp/hs_err_pid27137.log
解决方法：vim elasticsearch-5.6.11/config/jvm.options
更改参数为：-Xmx512M 

2、提示给es用户分配的线程资源不足 
ERROR: bootstrap checks failed
max file descriptors [10240] for elasticsearch process likely too low, increase to at least [65536]
max number of threads [1024] for user [elsearch] likely too low, increase to at least [2048]
max virtual memory areas vm.max_map_count [65530] likely too low, increase to at least [262144]
解决方法：
1）vim /etc/security/limits.conf 添加

* soft nofile 65536

* hard nofile 131072

* soft nproc 2048

* hard nproc 4096
2）vi /etc/security/limits.d/90-nproc.conf 修改参数为

* soft nproc 2048
3）vi /etc/sysctl.conf 添加

vm.max_map_count=655360

并执行命令：sysctl -p

3、生产模式改为单节点模式

ERROR: [2] bootstrap checks failed
[1]: initial heap size [31457280] not equal to maximum heap size [536870912]; this can cause resize pauses and prevents mlockall from locking the entire heap
[2]: system call filters failed to install; check the logs and fix your configuration or disable system call filters at your own risk

解决方法：

vim config/elasticsearch.yml 添加

discovery.type: single-node

4、权限不足导致错误
Exception in thread "main" org.elasticsearch.bootstrap.BootstrapException: java.nio.file.AccessDeniedException: /usr/local/es/elasticsearch6.4/config/elasticsearch.keystore
Likely root cause: java.nio.file.AccessDeniedException: /usr/local/es/elasticsearch6.4/config/elasticsearch.keystore
解决方法：
切换root用户，
chown -R es:es es