CentOS 7 ETCD集群部署

一、前言
Etcd 是 CoreOS 基于 Raft 开发的分布式 key-value 存储，可用于服务发现、共享配置以及一致性保障（如数据库选主、分布式锁等）

Etcd 集群配置分为三种:
静态发现
Etcd 动态发现
DNS 动态发现 通过DNS的SRV解析动态发现集群

二、环境准备

主机名	ip	系统版本
etcd0	192.168.1.85	Centos 7
etcd1	192.168.1.86	Centos 7
etcd2	192.168.1.87	Centos 7

1.1、在三台机器上均执行

[[email protected] ~]# yum install etcd -y
[[email protected] ~]# rpm -qa etcd
etcd-3.3.11-2.el7.centos.x86_64

1.2、创建Etcd所需目录，在三台机器上均执行

mkdir /data/k8s/etcd/{data,wal} -p
chown -R etcd.etcd /data/k8s/etcd

三、配置集群
3.1、etcd0 配置文件

ETCD_DATA_DIR="/data/k8s/etcd/data"
ETCD_WAL_DIR="/data/k8s/etcd/wal"
ETCD_LISTEN_PEER_URLS="http://192.168.1.85:2380"
ETCD_LISTEN_CLIENT_URLS="http://192.168.1.85:2379"
ETCD_MAX_SNAPSHOTS="5"
ETCD_MAX_WALS="5"
ETCD_NAME="etcd1"
ETCD_SNAPSHOT_COUNT="100000"
ETCD_HEARTBEAT_INTERVAL="100"
ETCD_ELECTION_TIMEOUT="1000"

ETCD_INITIAL_ADVERTISE_PEER_URLS="http://192.168.1.85:2380"
ETCD_ADVERTISE_CLIENT_URLS="http://192.168.1.85:2379"

ETCD_INITIAL_CLUSTER="etcd1=http://192.168.1.85:2380,etcd2=http://192.168.1.86:2380,etcd3=http://192.168.1.87:2380"
ETCD_INITIAL_CLUSTER_TOKEN="etcd-cluster"
ETCD_INITIAL_CLUSTER_STATE="new"

3.2、etcd1 配置文件

ETCD_DATA_DIR="/data/k8s/etcd/data"
ETCD_WAL_DIR="/data/k8s/etcd/wal"
ETCD_LISTEN_PEER_URLS="http://192.168.1.86:2380"
ETCD_LISTEN_CLIENT_URLS="http://192.168.1.86:2379"
ETCD_MAX_SNAPSHOTS="5"
ETCD_MAX_WALS="5"
ETCD_NAME="etcd2"
ETCD_SNAPSHOT_COUNT="100000"
ETCD_HEARTBEAT_INTERVAL="100"
ETCD_ELECTION_TIMEOUT="1000"

ETCD_INITIAL_ADVERTISE_PEER_URLS="http://192.168.1.86:2380"
ETCD_ADVERTISE_CLIENT_URLS="http://192.168.1.86:2379"

ETCD_INITIAL_CLUSTER="etcd1=http://192.168.1.85:2380,etcd2=http://192.168.1.86:2380,etcd3=http://192.168.1.87:2380"
ETCD_INITIAL_CLUSTER_TOKEN="etcd-cluster"
ETCD_INITIAL_CLUSTER_STATE="new"

3.3、etcd2 配置文件

ETCD_DATA_DIR="/data/k8s/etcd/data"
ETCD_WAL_DIR="/data/k8s/etcd/wal"
ETCD_LISTEN_PEER_URLS="http://192.168.1.87:2380"
ETCD_LISTEN_CLIENT_URLS="http://192.168.1.87:2379"
ETCD_MAX_SNAPSHOTS="5"
ETCD_MAX_WALS="5"
ETCD_NAME="etcd3"
ETCD_SNAPSHOT_COUNT="100000"
ETCD_HEARTBEAT_INTERVAL="100"
ETCD_ELECTION_TIMEOUT="1000"

ETCD_INITIAL_ADVERTISE_PEER_URLS="http://192.168.1.87:2380"
ETCD_ADVERTISE_CLIENT_URLS="http://192.168.1.87:2379"

ETCD_INITIAL_CLUSTER="etcd1=http://192.168.1.85:2380,etcd2=http://192.168.1.86:2380,etcd3=http://192.168.1.87:2380"
ETCD_INITIAL_CLUSTER_TOKEN="etcd-cluster"
ETCD_INITIAL_CLUSTER_STATE="new"

四、启动测试（三个节点都需要操作）

[[email protected] etcd]# systemctl start etcd
[[email protected] etcd]# systemctl status etcd
● etcd.service - Etcd Server
   Loaded: loaded (/usr/lib/systemd/system/etcd.service; disabled; vendor preset: disabled)
   Active: active (running) since Thu 2019-11-07 09:28:54 CST; 5s ago
 Main PID: 1546 (etcd)
    Tasks: 8
   Memory: 41.3M
   CGroup: /system.slice/etcd.service
           └─1546 /usr/bin/etcd --name=etcd1 --data-dir=/data/k8s/etcd/data --listen-client-urls=http://192.168.1.85:2379

Nov 07 09:28:54 etcd0.k8s.com etcd[1546]: 3b8b38de05e2c497 [term: 1] received a MsgVote message with higher term from 9c64fba479c5e94 [term: 2]
Nov 07 09:28:54 etcd0.k8s.com etcd[1546]: 3b8b38de05e2c497 became follower at term 2
Nov 07 09:28:54 etcd0.k8s.com etcd[1546]: 3b8b38de05e2c497 [logterm: 1, index: 3, vote: 0] cast MsgVote for 9c64fba479c5e94 [logterm: 1, index: 3] at term 2
Nov 07 09:28:54 etcd0.k8s.com etcd[1546]: raft.node: 3b8b38de05e2c497 elected leader 9c64fba479c5e94 at term 2
Nov 07 09:28:54 etcd0.k8s.com etcd[1546]: published {Name:etcd1 ClientURLs:[http://192.168.1.85:2379]} to cluster 19456f0bfd57284e
Nov 07 09:28:54 etcd0.k8s.com etcd[1546]: ready to serve client requests
Nov 07 09:28:54 etcd0.k8s.com etcd[1546]: serving insecure client requests on 192.168.1.85:2379, this is strongly discouraged!
Nov 07 09:28:54 etcd0.k8s.com systemd[1]: Started Etcd Server.
Nov 07 09:28:54 etcd0.k8s.com etcd[1546]: set the initial cluster version to 3.3
Nov 07 09:28:54 etcd0.k8s.com etcd[1546]: enabled capabilities for version 3.3

4.1、查看 /var/log/message 日志中，会有日下体现：

Nov  7 09:28:53 etcd1 etcd: added member 9c64fba479c5e94 [http://192.168.1.86:2380] to cluster 19456f0bfd57284e
Nov  7 09:28:53 etcd1 etcd: added member 3b8b38de05e2c497 [http://192.168.1.85:2380] to cluster 19456f0bfd57284e
Nov  7 09:28:53 etcd1 etcd: added member 76ea8679db7365b3 [http://192.168.1.87:2380] to cluster 19456f0bfd57284e

五、查看集群状态

[[email protected] etcd]# ETCDCTL_API=3 etcdctl --endpoints=http://192.168.1.85:2379,http://192.168.1.86:2379,http://192.168.1.87:2379 endpoint health
http://192.168.1.86:2379 is healthy: successfully committed proposal: took = 1.103545ms
http://192.168.1.87:2379 is healthy: successfully committed proposal: took = 2.122478ms
http://192.168.1.85:2379 is healthy: successfully committed proposal: took = 2.690215ms
[[email protected] etcd]# etcdctl --endpoints=http://192.168.1.85:2379,http://192.168.1.86:2379,http://192.168.1.87:2379 cluster-health
member 9c64fba479c5e94 is healthy: got healthy result from http://192.168.1.85:2379
member 3b8b38de05e2c497 is healthy: got healthy result from http://192.168.1.86:2379
member 76ea8679db7365b3 is healthy: got healthy result from http://192.168.1.87:2379
cluster is healthy