Linux环境部署Elasticsearch 6.x和常见问题

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介绍

Elasticsearch（ES）是一个基于Lucene构建的开源、分布式、RESTful接口的全文搜索引擎。 Elasticsearch还是一个分布式文档数据库，其中每个字段均可被索引，而且每个字段的数据均可被搜索，ES能够横向扩展至数以百计的服务器存储以及处理PB级的数据。

本文内容基于Elastic 技术栈6.x版本；

准备工作

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# lasticsearch-6-3-2

wget https://www.elastic.co/cn/downloads/past-releases/elasticsearch-6-3-2

# or
wget https://artifacts.elastic.co/downloads/elasticsearch/elasticsearch-6.3.2.tar.gz

下载到指定目录~/path/，解压

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tar -zxvf elasticsearch-6.3.2.tar.gz

由于elasticsearch 不允许使用root用户启动
创建一个用于启动elasticsearch 的用户

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useradd  elastic 
passwd  elastic

输入密码，并确认，完成特定用户创建

并为该用户授权elasticsearch相关目录

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chown -R elastic:elastic elasticsearch*

切换到用户elastic ，创建elasticsearch目录软连接指向elastic用户的根目录

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cd ~
ln -s /path/to/elasticsearch ./elasticsearch

进入该目录

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cd ./elasticsearch

执行

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./bin/elasticsearch

启动elasticsearch

后台启动 (daemonize)

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./bin/elasticsearch  -d

常见问题

启动错误提示1：

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ERROR: [4] bootstrap checks failed
[1]: max file descriptors [4096] for elasticsearch process is too low, increase to at least [65536]
[2]: max number of threads [1024] for user [elastic] is too low, increase to at least [4096]
[3]: max virtual memory areas vm.max_map_count [65530] is too low, increase to at least [262144]
[4]: system call filters failed to install; check the logs and fix your configuration or disable system call filters at your own risk


[1]: max file descriptors [4096] for elasticsearch process is too low, increase to at least [65536]

Make sure to increase the limit on the number of open files descriptors for the user running Elasticsearch to 65,536 or higher. For the .zip and .tar.gz packages, set ulimit -n 65536 as root before starting Elasticsearch, or set nofile to 65536 in /etc/security/limits.conf .

解决：切换到root用户，编辑limits.conf 添加相关配置

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vi /etc/security/limits.conf

添加如下内容:

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* soft nofile 65536
* hard nofile 131072
* soft nproc 2048
* hard nproc 4096

启动错误提示2：

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[2]: max number of threads [1024] for user [elastic] is too low, increase to at least [4096]

对于第二条错误同意需要切换到root用户，进入limits.d目录下修改配置文件。

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vi /etc/security/limits.d/90-nproc.conf

修改如下内容：

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* soft nproc 1024

#修改为

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* soft nproc 4096

错误提示3

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[3]: max virtual memory areas vm.max_map_count [65530] is too low, increase to at least [262144]

第三条错误需要切换到root用户修改配置sysctl.conf
vi /etc/sysctl.conf

添加下面配置：

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vm.max_map_count=655360

并执行命令：

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sysctl -p

错误提示4:

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[4]: system call filters failed to install; check the logs and fix your configuration or disable system call filters at your own risk

原因：
这是在因为Centos6不支持SecComp，而ES 6.x默认bootstrap.system_call_filter为true进行检测，所以导致检测失败，失败后直接导致ES不能启动。

解决：
在elasticsearch.yml中配置bootstrap.system_call_filter为false，注意要在Memory下面:

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bootstrap.memory_lock: false
bootstrap.system_call_filter: false

操作完成，现在所有的机器都能访问Linux服务器的HTTP服务了。

监控健康状况
http://[es_host]:9200/_cat/health?v
监控节点情况
http://[es_host]:9200/_cat/nodes?v
监控索引情况
http://[es_host]:9200/_cat/indices?v