Centos 7 下安装elasticsearch 7.4.2

简单记录一下安装过程，说一下其中的坑。
我这里是四台kvm的虚拟机 安装centos7
192.168.122.30 node01
192.168.122.31 node02
192.168.122.32 node03
192.168.122.33 kibana

1. 首先找个yum源

导入密钥
rpm --import  https://artifacts.elastic.co/GPG-KEY-elasticsearch123123

添加 elasticsearch.repo
[elasticsearch-7.x]
name=Elasticsearch repository for 7.x packages
baseurl=https://artifacts.elastic.co/packages/7.x/yum
gpgcheck=1
gpgkey=https://artifacts.elastic.co/GPG-KEY-elasticsearch
enabled=1
autorefresh=1
type=rpm-md

yum install elasticsearch

2. elasticsearch 配置

目前elasticsearch最新版本为7.4.2 ，elasticsearch7.X之后的版本配置跟之前的有区别.这里直接贴一个配置出来
/etc/elasticsearch/elasticsearch.yml

cluster.name: myes
#
# ------------------------------------ Node ------------------------------------
#
# Use a descriptive name for the node:
#
node.name: node01
#
# Add custom attributes to the node:
#
#node.attr.rack: r1
#
# ----------------------------------- Paths ------------------------------------
#
# Path to directory where to store the data (separate multiple locations by comma):
#
path.data: /var/lib/elasticsearch
path.logs: /var/log/elasticsearch
#
# ----------------------------------- Memory -----------------------------------
#
# Lock the memory on startup:
#
bootstrap.memory_lock: true
# Set the bind address to a specific IP (IPv4 or IPv6):
#
network.host: 192.168.122.30
#
# Set a custom port for HTTP:
#
http.port: 9200
#
# For more information, consult the network module documentation.
#
# --------------------------------- Discovery ----------------------------------
#
# Pass an initial list of hosts to perform discovery when this node is started:
# The default list of hosts is ["127.0.0.1", "[::1]"]
#
discovery.seed_hosts: ["192.168.122.30", "192.168.122.31", "192.168.122.32"]
cluster.initial_master_nodes: ["192.168.122.30", "192.168.122.31", "192.168.122.32"]
http.cors.enabled: true
# “*” 表示支持所有域名
http.cors.allow-origin: "*"
action.destructive_requires_name: true
action.auto_create_index: .security,.monitoring*,.watches,.triggered_watches,.watcher-history*
xpack.security.enabled: false
xpack.monitoring.enabled: true
xpack.graph.enabled: false
xpack.watcher.enabled: false
xpack.ml.enabled: false

discovery.zen.minimum_master_nodes: 2
discovery.zen.fd.ping_timeout: 1m
discovery.zen.fd.ping_retries: 5

3. es 安装相关问题

1，如果打开了bootstrap.memory_lock: true，启动失败会在日志里看到

These can be adjusted by modifying /etc/security/limits.conf, for example:
# allow user 'baoshan' mlockall
elasticsearch soft memlock unlimited
elasticsearch hard memlock unlimited

elasticsearch官网建议生产环境需要设置bootstrap.memory_lock: true。因为发生系统swapping的时候ES节点的性能会非常差，也会影响节点的稳定性。所以要不惜一切代价来避免swapping。swapping会导致Java GC的周期延迟从毫秒级恶化到分钟，更严重的是会引起节点响应延迟甚至脱离集群

关于这个提示你修改了/etc/security/limits.conf也可能不够！
1， centos7下/etc/security/limits.d下的文件会覆盖limits.conf,所以可以将其注释，
2，修改/etc/sysctl.conf,

vm.max_map_count = 262144
vm.swappiness = 0

sysctl -p 生效
3，可是有文章提到

在Centos7系统中，使用Systemd替代了之前的SysV。/etc/security/limits.conf文件的配置作用域缩小了。/etc/security/limits.conf的配置，只适用于通过PAM认证登录用户的资源限制，它对systemd的service的资源限制不生效。因此登录用户的限制，通过/etc/security/limits.conf与/etc/security/limits.d下的文件设置即可,对于systemd service的资源设置，则需修改全局配置，全局配置文件放在/etc/systemd/system.conf
所以加个全局设置

vim /etc/systemd/system.conf
...
DefaultLimitNOFILE=65536
DefaultLimitNPROC=32000
DefaultLimitMEMLOCK=infinity

以上centos7下安装elasticsearch-7.4.2-x86_64 亲测有效。

4.kibana7.4.2 安装
可能是我虚拟机资源有限的问题，我发现在elasticsearch节点上安装kibana会导致本机节点死机 ， 所以，我准备了另外一台来安装kibana.

yum install kibana

配置/etc/kibana/kibana.yml

server.port: 5601

server.host: "192.168.122.33"
    
server.name: "mykb"
 
elasticsearch.hosts: ["http://192.168.122.30:9200", "http://192.168.122.31:9200", "http://192.168.122.32:9200"]
              
i18n.locale: "zh-CN"
xpack.reporting.encryptionKey: "a_random_string"

5 .其他

刚开始也尝试了docker部署， 单节点很快速，多节点出了点问题， 网上很多单机部署多个容器的，但实际情况是多台机器部署集群， 匆忙之下直接在系统安装， 下次还是考虑一步到位在k8s下部署es更好一点。