Centos7环境下etcd集群的搭建

2021-07-22 00:12:03
Centos7环境下etcd集群的搭建

一、简介

"A highly-available key value store for shared configuration and service discovery."

Etcd是coreos开发的分布式服务系统，内部采用raft协议作为一致性算法。作为一个高可用的配置共享、服务发现的键值存储系统，Etcd有以下的特点：

简单：安装配置简单，而且提供了 HTTP API 进行交互，使用也很简单

安全：支持 SSL 证书验证

快速：根据官方提供的数据，单实例支持每秒2k+读操作、1k写操作

可靠：采用raft算法，实现分布式系统数据的可用性和一致性

Etcd构建自身高可用集群主要有三种形式:

静态发现: 预先已知 Etcd 集群中有哪些节点，在启动时直接指定好Etcd的各个node节点地址

Etcd动态发现: 通过已有的Etcd集群作为数据交互点，然后在扩展新的集群时实现通过已有集群进行服务发现的机制

DNS动态发现: 通过DNS查询方式获取其他节点地址信息

本文主要介绍第一种方式，后续会陆续介绍剩下的两种方式。(直接docker安装请移步：quay.io/coreos/etcd 基于Docker镜像的集群搭建)

二、环境介绍

三台虚拟机，系统环境均为Centos7，对应节点名称及IP地址如下，将这个信息添加到三台主机的hosts文件中，编辑/etc/hosts

[root@node1 ~]# cat /etc/hosts

192.168.3.198 node1

192.168.3.199 node2

192.168.3.200 node3

三、安装、配置Etcd

在3个节点上都安装etcd服务

# yum install etcd -y

yum安装的etcd默认配置文件在/etc/etcd/etcd.conf，以下将三个节点上的配置贴出来，请注意不同点（未贴出的，则表明不需要更改）

node1

[root@node1 etcd]# cat etcd.conf

#[Member]

#ETCD_CORS=""

# 数据存放位置

ETCD_DATA_DIR="/var/lib/etcd/default.etcd"

#ETCD_WAL_DIR=""

# 监听其他 Etcd 实例的地址

ETCD_LISTEN_PEER_URLS="http://0.0.0.0:2380"

# 监听客户端地址

ETCD_LISTEN_CLIENT_URLS="http://0.0.0.0:2379,http://0.0.0.0:4001"

#ETCD_MAX_SNAPSHOTS=""

#ETCD_MAX_WALS=""

# 节点名称

ETCD_NAME="node1"

#ETCD_SNAPSHOT_COUNT=""

#ETCD_HEARTBEAT_INTERVAL=""

#ETCD_ELECTION_TIMEOUT=""

#ETCD_QUOTA_BACKEND_BYTES=""

#

#[Clustering]

# 通知其他 Etcd 实例地址

ETCD_INITIAL_ADVERTISE_PEER_URLS="http://node1:2380"

# 通知客户端地址

ETCD_ADVERTISE_CLIENT_URLS="http://node1:2379,http://node1:4001"

#ETCD_DISCOVERY=""

#ETCD_DISCOVERY_FALLBACK="proxy"

#ETCD_DISCOVERY_PROXY=""

#ETCD_DISCOVERY_SRV=""

# 初始化集群内节点地址

ETCD_INITIAL_CLUSTER="node1=http://node1:2380,node2=http://node2:2380,node3=http://node3:2380"

# 初始化集群 token

ETCD_INITIAL_CLUSTER_TOKEN="chinasoft-etcd-cluster"

# 初始化集群状态，new 表示新建

ETCD_INITIAL_CLUSTER_STATE="new"

#ETCD_STRICT_RECONFIG_CHECK="true"

#ETCD_ENABLE_V2="true"

[root@node1 etcd]# egrep '^[a-Z]' etcd.conf

ETCD_DATA_DIR="/var/lib/etcd/default.etcd"

ETCD_LISTEN_PEER_URLS="http://0.0.0.0:2380"

ETCD_LISTEN_CLIENT_URLS="http://0.0.0.0:2379,http://0.0.0.0:4001"

ETCD_NAME="node1"

ETCD_INITIAL_ADVERTISE_PEER_URLS="http://node1:2380"

ETCD_ADVERTISE_CLIENT_URLS="http://node1:2379,http://node1:4001"

ETCD_INITIAL_CLUSTER="node1=http://node1:2380,node2=http://node2:2380,node3=http://node3:2380"

ETCD_INITIAL_CLUSTER_TOKEN="chinasoft-etcd-cluster"

ETCD_INITIAL_CLUSTER_STATE="new"

node2

#[Member]

#ETCD_CORS=""

ETCD_DATA_DIR="/var/lib/etcd/default.etcd"

#ETCD_WAL_DIR=""

ETCD_LISTEN_PEER_URLS="http://0.0.0.0:2380"

ETCD_LISTEN_CLIENT_URLS="http://0.0.0.0:2379,http://0.0.0.0:4001"

#ETCD_MAX_SNAPSHOTS=""

#ETCD_MAX_WALS=""

ETCD_NAME="node2"

#ETCD_SNAPSHOT_COUNT=""

#ETCD_HEARTBEAT_INTERVAL=""

#ETCD_ELECTION_TIMEOUT=""

#ETCD_QUOTA_BACKEND_BYTES=""

#

#[Clustering]

ETCD_INITIAL_ADVERTISE_PEER_URLS="http://node2:2380"

ETCD_ADVERTISE_CLIENT_URLS="http://node2:2379,http://node2:4001"

#ETCD_DISCOVERY=""

#ETCD_DISCOVERY_FALLBACK="proxy"

#ETCD_DISCOVERY_PROXY=""

#ETCD_DISCOVERY_SRV=""

ETCD_INITIAL_CLUSTER="node1=http://node1:2380,node2=http://node2:2380,node3=http://node3:2380"

ETCD_INITIAL_CLUSTER_TOKEN="chinasoft-etcd-cluster"

ETCD_INITIAL_CLUSTER_STATE="new"

#ETCD_STRICT_RECONFIG_CHECK="true"

#ETCD_ENABLE_V2="true"

node3

#[Member]

#ETCD_CORS=""

ETCD_DATA_DIR="/var/lib/etcd/default.etcd"

#ETCD_WAL_DIR=""

ETCD_LISTEN_PEER_URLS="http://0.0.0.0:2380"

ETCD_LISTEN_CLIENT_URLS="http://0.0.0.0:2379,http://0.0.0.0:4001"

#ETCD_MAX_SNAPSHOTS=""

#ETCD_MAX_WALS=""

ETCD_NAME="node3"

#ETCD_SNAPSHOT_COUNT=""

#ETCD_HEARTBEAT_INTERVAL=""

#ETCD_ELECTION_TIMEOUT=""

#ETCD_QUOTA_BACKEND_BYTES=""

#

#[Clustering]

ETCD_INITIAL_ADVERTISE_PEER_URLS="http://node3:2380"

ETCD_ADVERTISE_CLIENT_URLS="http://node3:2379,http://node3:4001"

#ETCD_DISCOVERY=""

#ETCD_DISCOVERY_FALLBACK="proxy"

#ETCD_DISCOVERY_PROXY=""

#ETCD_DISCOVERY_SRV=""

ETCD_INITIAL_CLUSTER="node1=http://node1:2380,node2=http://node2:2380,node3=http://node3:2380"

ETCD_INITIAL_CLUSTER_TOKEN="chinasoft-etcd-cluster"

ETCD_INITIAL_CLUSTER_STATE="new"

#ETCD_STRICT_RECONFIG_CHECK="true"

#ETCD_ENABLE_V2="true"

改好配置之后，在各个节点上开启etcd服务：

[root@node1 etcd]# systemctl restart etcd

[root@node1 etcd]# systemctl enable etcd

Created symlink from /etc/systemd/system/multi-user.target.wants/etcd.service to /usr/lib/systemd/system/etcd.service.

[root@node1 etcd]# systemctl status etcd

● etcd.service - Etcd Server

   Loaded: loaded (/usr/lib/systemd/system/etcd.service; enabled; vendor preset: disabled)

   Active: active (running) since Wed -- :: CST; 10s ago

 Main PID:  (etcd)

   CGroup: /system.slice/etcd.service

           └─ /usr/bin/etcd --name=node1 --data-dir=/var/lib/etcd/default.etcd --listen-client-urls=http://0.0.0.0:2379,http://0.0.0.0:4001

Jan  :: node1 etcd[]: request cluster ID mismatch (got c304f47342ea490a want cdf818194e3a8c32)

Jan  :: node1 etcd[]: request cluster ID mismatch (got c304f47342ea490a want cdf818194e3a8c32)

Jan  :: node1 etcd[]: request cluster ID mismatch (got c304f47342ea490a want cdf818194e3a8c32)

Jan  :: node1 etcd[]: request cluster ID mismatch (got c304f47342ea490a want cdf818194e3a8c32)

Jan  :: node1 etcd[]: request cluster ID mismatch (got c304f47342ea490a want cdf818194e3a8c32)

Jan  :: node1 etcd[]: request cluster ID mismatch (got c304f47342ea490a want cdf818194e3a8c32)

Jan  :: node1 etcd[]: request cluster ID mismatch (got c304f47342ea490a want cdf818194e3a8c32)

Jan  :: node1 etcd[]: request cluster ID mismatch (got c304f47342ea490a want cdf818194e3a8c32)

Jan  :: node1 etcd[]: request cluster ID mismatch (got c304f47342ea490a want cdf818194e3a8c32)

Jan  :: node1 etcd[]: request cluster ID mismatch (got c304f47342ea490a want cdf818194e3a8c32)

四、测试验证

[root@node2 etcd]# etcdctl set testdir/testkey0 

[root@node2 etcd]# etcdctl set testdir/testkey1 

[root@node2 etcd]# etcdctl set testdir/testkey2 

[root@node2 etcd]# etcdctl ls

/testdir

[root@node2 etcd]# etcdctl ls testdir

/testdir/testkey0

/testdir/testkey1

/testdir/testkey2

[root@node2 etcd]# etcdctl get testdir/testkey2

[root@node2 etcd]# etcdctl member list

3914cfb876a6deeb: name=node2 peerURLs=http://node2:2380 clientURLs=http://node2:2379,http://node2:4001 isLeader=true

4d3a7c30064f762d: name=node1 peerURLs=http://node1:2380 clientURLs= isLeader=false

a68deb812f62fac3: name=node3 peerURLs=http://node3:2380 clientURLs=http://node3:2379,http://node3:4001 isLeader=false

在其他节点也能看到创建的节点，说明集群搭建成功

[root@node3 ~]# etcdctl ls testdir

/testdir/test0

/testdir/test1

/testdir/test88
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