etcd介绍
etcd是CoreOS团队于2013年6月发起的开源项目，它的目标是构建一个高可用的分布式键值(key-value)数据库。etcd内部采用raft协议作为一致性算法，etcd基于Go语言实现。
etcd的有点有以下：
- 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benchmark数据，单实例支持每秒2k+读操作
- 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 项目详见：https://github.com/coreos/etcd/
安装之前
一般不建议root安装业务中间件服务，故这里需要先进行环境初始化
| 主机IP | etcd name |
|---|---|
| 192.168.2.213 | etcd1 |
| 192.168.2.214 | etcd2 |
| 192.168.2.215 | etcd3 |
新增系统用户etcd
groupadd --system etcd
useradd -s /sbin/nologin -m /var/lib/etcd --system -g etcd etcd
新增配置文件路径
mkdir /etc/etcd
chown -R etcd:etcd /etc/etcd
修改 SELinux 为 disabled
setenforce 0
sed -i 's/^SELINUX=.*/SELINUX=disabled/g' /etc/selinux/config
安装
下载二进制安装包
curl -s https://api.github.com/repos/etcd-io/etcd/releases/latest | grep browser_download_url | grep linux-amd64 |cut -d '"' -f 4 | wget -qi -
或者百度网盘下载
链接: https://pan.baidu.com/s/1xOeIYWTAs0VMcLoCuT6BTg 提取码: 5kmf
如下进入安装
tar -zxvf etcd-v3.2.32-linux-amd64.tar.gz
cd etcd-v3.2.32-linux-amd64
cp etcd etcdctl /usr/local/bin
chown -R etcd:etcd /usr/local/bin/etcd*
验证安装
root@pts/1 $ etcd --version
etcd Version: 3.2.32
Git SHA: 7dc07f2a9
Go Version: go1.12.17
Go OS/Arch: linux/amd64
root@pts/1 $ etcdctl --version
etcdctl version: 3.2.32
API version: 2
配置和启动
1、三台主机分别配置/etc/hosts如下
# etcd
192.168.2.213 etc1
192.168.2.214 etc2
192.168.2.215 etc3
2、三台主机配置新增配置文件/etc/etcd/etcd.conf 这里注意 etcd1 配置中 ETCD_INITIAL_CLUSTER_STATE 为 new 其余两个为exist
另外参数ETCD_LISTEN_CLIENT_URLS、ETCD_ADVERTISE_CLIENT_URLS、ETCD_LISTEN_PEER_URLS 、ETCD_INITIAL_ADVERTISE_PEER_URLS 分别为当前主机的IP，ETCD_NAME 根据开始的定义配置
# member
ETCD_NAME=etcd1
ETCD_DATA_DIR=/var/lib/etcd
ETCD_LISTEN_CLIENT_URLS=http://192.168.2.213:2379,http://127.0.0.1:2379
ETCD_ADVERTISE_CLIENT_URLS=http://192.168.2.213:2379
# cluster
ETCD_LISTEN_PEER_URLS=http://192.168.2.213:2380
ETCD_INITIAL_ADVERTISE_PEER_URLS=http://192.168.2.213:2380
ETCD_INITIAL_CLUSTER=etcd1=http://192.168.2.213:2380,etcd2=http://192.168.2.214:2380,etcd3=http://192.168.2.215:2380
ETCD_INITIAL_CLUSTER_STATE=new
ETCD_INITIAL_CLUSTER_TOKEN=k8s_etcd
3、三台主机配置systemctl启动方式
/usr/lib/systemd/system/etcd.service
[Unit]
Description=etcd key-value store
Documentation=https://github.com/etcd-io/etcd
After=network.target
[Service]
User=etcd
Type=notify
WorkingDirectory=/var/lib/etcd/
EnvironmentFile=/etc/etcd/etcd.conf
ExecStart=/usr/local/bin/etcd
Restart=on-failure
RestartSec=10s
LimitNOFILE=40000
[Install]
WantedBy=multi-user.target
启动服务
systemctl enable etcd.service
systemctl start etcd.service
systemctl status etcd.service
测试和验收
1、检查各节点
root@pts/1 $ etcdctl member list
59b0ee3829e2b866: name=etcd2 peerURLs=http://192.168.2.214:2380 clientURLs=http://192.168.2.214:2379 isLeader=false
a8b07bac1693e30e: name=etcd1 peerURLs=http://192.168.2.213:2380 clientURLs=http://192.168.2.213:2379 isLeader=false
cf682ab5655702b8: name=etcd3 peerURLs=http://192.168.2.215:2380 clientURLs=http://192.168.2.215:2379 isLeader=true
2、检查集群状态
root@pts/1 $ etcdctl cluster-health
member 59b0ee3829e2b866 is healthy: got healthy result from http://192.168.2.214:2379
member a8b07bac1693e30e is healthy: got healthy result from http://192.168.2.213:2379
member cf682ab5655702b8 is healthy: got healthy result from http://192.168.2.215:2379
cluster is healthy
3、进行测试
root@pts/1 $ etcdctl set /demo 'hello etcd'
hello etcd
root@pts/1 $ etcdctl get /demo
hello etcd
故障演练
停掉Leader节点
root@pts/1 $ etcdctl member list
59b0ee3829e2b866: name=etcd2 peerURLs=http://192.168.2.214:2380 clientURLs=http://192.168.2.214:2379 isLeader=false
a8b07bac1693e30e: name=etcd1 peerURLs=http://192.168.2.213:2380 clientURLs=http://192.168.2.213:2379 isLeader=true
cf682ab5655702b8: name=etcd3 peerURLs=http://192.168.2.215:2380 clientURLs=http://192.168.2.215:2379 isLeader=false
看到Leader从etcd3转移到etcd1
查看集群状态
root@pts/1 $ etcdctl cluster-health
member 59b0ee3829e2b866 is healthy: got healthy result from http://192.168.2.214:2379
member a8b07bac1693e30e is healthy: got healthy result from http://192.168.2.213:2379
failed to check the health of member cf682ab5655702b8 on http://192.168.2.215:2379: Get http://192.168.2.215:2379/health: dial tcp 192.168.2.215:2379: connect: connection refused
member cf682ab5655702b8 is unreachable: [http://192.168.2.215:2379] are all unreachable
cluster is healthy
看到etcd3连接失败，这个时候在执行如下命令进行测试，发现请求正常
root@pts/1 $ etcdctl get /demo
hello etcd
然后启动故障节点之后检查，集群状态恢复
root@pts/1 $ etcdctl cluster-health
member 59b0ee3829e2b866 is healthy: got healthy result from http://192.168.2.214:2379
member a8b07bac1693e30e is healthy: got healthy result from http://192.168.2.213:2379
member cf682ab5655702b8 is healthy: got healthy result from http://192.168.2.215:2379
cluster is healthy
