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ETCD 是一个高可用的分布式键值数据库,可用于服务发现。ETCD 采用 raft 一致性算法,基于 Go 语言实现,随着CoreOS和Kubernetes等项目在开源社区日益火热,它们项目中都用到的etcd组件作为一个高可用强一致性的服务发现存储仓库,渐渐为开发人员所关注。在云计算时代,如何让服务快速透明地接入到计算集群中,如何让共享配置信息快速被集群中的所有机器发现,更为重要的是,如何构建这样一套高可用、安全、易于部署以及响应快速的服务集群,已经成为了迫切需要解决的问题。etcd为解决这类问题带来了福音,本文将从etcd的应用场景开始,深入解读etcd的实现方式,以供开发者们更为充分地享用etcd所带来的便利。
特点
简单:安装配置使用简单,提供 HTTP API
安全:支持 SSL 证书
可靠:采用 raft 算法,实现分布式系统数据的可用性和一致性
下载安装包:
[root@master ~]# wget https://github.com/coreos/etcd/releases/download/v3.3.2/etcd-v3.3.2-linux-amd64.tar.gz
复制安装包到各接点:
[root@master ~]# ansible k8s -m copy -a'src=/root/etcd-v3.3.2-linux-amd64.tar.gz dest=/root/'
部署环境三台机子:IP--主机名--集群结点名
192.168.27.211 client1 (etcd1)
192.168.27.212 client2 (etcd2)
192.168.27.213 client3 (etcd3)
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[Service]
Type=notify
WorkingDirectory=/etc/etcd-v3.3.2
#User=etcd
ExecStart=/etc/etcd-v3.3.2/etcd --config-file /etc/etcd-v3.3.2/etcd.conf
Restart=on-failure
LimitNOFILE=65536
[Install]
WantedBy=multi-user.target
注意:192.168.27.212,192.168.27.213部署如同上面步骤,只需要将步骤4里面接点名字、ip改为自己ip即可。
name: etcd2
data-dir: /etc/etcd-v3.3.2/data
listen-client-urls: http://0.0.0.0:2379
advertise-client-urls: http://192.168.27.212:2379
listen-peer-urls: http://0.0.0.0:2380
initial-advertise-peer-urls: http://192.168.27.212:2380
initial-cluster: etcd1=http://192.168.27.211:2380,etcd2=http://192.168.27.212:2380,etcd3=http://192.168.27.213:2380
initial-cluster-token: etcd-cluster-my
initial-cluster-state: new
name: etcd3
data-dir: /etc/etcd-v3.3.2/data
listen-client-urls: http://0.0.0.0:2379
advertise-client-urls: http://192.168.27.213:2379
listen-peer-urls: http://0.0.0.0:2380
initial-advertise-peer-urls: http://192.168.27.213:2380
initial-cluster: etcd1=http://192.168.27.211:2380,etcd2=http://192.168.27.212:2380,etcd3=http://192.168.27.213:2380
initial-cluster-token: etcd-cluster-my
initial-cluster-state: new
6、启动成功后查看集群成员及状态:
[root@client3 etcd-v3.3.2]# etcdctl member list
etcdctl endpoint health --endpoints=192.168.27.211:2379,192.168.27.212:2379,192.168.27.213:2379
[root@client3 etcd-v3.3.2]# etcdctl endpoint status --endpoints=192.168.27.211:2379,192.168.27.212:2379,192.168.27.213:2379
[root@client3 etcd-v3.3.2]# etcdctl endpoint status --endpoints=192.168.27.211:2379
通过非ETCD集群成员访问测试:
[root@master etcd-v3.3.2]# etcdctl endpoint status --endpoints=192.168.27.211:2379
192.168.27.211:2379, f4e909b85dbd820b, 3.3.2, 25 kB, false, 69, 71
[root@master etcd-v3.3.2]# etcdctl endpoint status --endpoints=192.168.27.211:2379
192.168.27.211:2379, f4e909b85dbd820b, 3.3.2, 25 kB, false, 69, 71
[root@master etcd-v3.3.2]# etcdctl endpoint status --endpoints=192.168.27.211:2379,192.168.27.212:2379,192.168.27.213:2379
192.168.27.211:2379, f4e909b85dbd820b, 3.3.2, 25 kB, false, 69, 71
192.168.27.212:2379, 265ebeb3298fa51f, 3.3.2, 25 kB, false, 69, 71
192.168.27.213:2379, 510ff85ed64c7436, 3.3.2, 25 kB, true, 69, 71
[root@master etcd-v3.3.2]# etcdctl put name jerry --endpoints=192.168.27.211:2379,192.168.27.212:2379,192.168.27.213:2379
OK
[root@master etcd-v3.3.2]# etcdctl put topic "this is a etcd client test" --endpoints=192.168.27.211:2379,192.168.27.212:2379,192.168.27.213:2379
OK
[root@master etcd-v3.3.2]# etcdctl get topic --endpoints=192.168.27.211:2379,192.168.27.212:2379,192.168.27.213:2379
topic
this is a etcd client test
[root@master etcd-v3.3.2]# etcdctl get topic --endpoints=192.168.27.211:2379
topic
this is a etcd client test
Etcd使用:
读写键值:
[root@client1 etcd-v3.3.2]# etcdctl put key1 value1
OK
[root@client1 etcd-v3.3.2]# etcdctl get key1
key1
value1
前缀读(将所有前缀是key的键值对都读出来)
键值删除:
[root@client1 etcd-v3.3.2]# etcdctl del key
0
[root@client1 etcd-v3.3.2]# etcdctl get key
[root@client1 etcd-v3.3.2]# etcdctl get key1
key1
value1
[root@client1 etcd-v3.3.2]# etcdctl del key1
1
[root@client1 etcd-v3.3.2]# etcdctl get key1
观察已无KEY1键及值的存在。
按前缀全部删除
观察已无键值及数据
重新创建三个键值:
其它ETCD集群成员上访问键值测试:
监听某个键,每次键值有变化
[root@client1 etcd-v3.3.2]# etcdctl watch key --prefix
PUT
key1
value
PUT
key2
jerry
设置过期时间TTL
[root@client2 etcd-v3.3.2]# etcdctl lease grant 30
lease 251f6cf538287411 granted with TTL(30s)
[root@client2 etcd-v3.3.2]# etcdctl put key5 value5 --lease=251f6cf538287411
Error: etcdserver: requested lease not found
[root@client2 etcd-v3.3.2]# etcdctl lease grant 30
lease 251f6cf538287414 granted with TTL(30s)
[root@client2 etcd-v3.3.2]# etcdctl put key5 value5 --lease=251f6cf538287414
OK
[root@client2 etcd-v3.3.2]# etcdctl lease keep-alive 251f6cf538287414
lease 251f6cf538287414 expired or revoked.
[root@client2 etcd-v3.3.2]# etcdctl get key5
[root@client2 etcd-v3.3.2]# etcdctl get key5