一、环境介绍
etcd主要功能是分布式的存储键值，优点不多说了，分布是集群，自动选举等等，自行百度，主要说下配置方法，折腾了几天，终于优点眉目了，记录下操作方法，本文参考了如下链接
https://www.cnblogs.com/breg/p/5728237.html
http://www.361way.com/etcd-cluster/5468.html
https://n40lab.wordpress.com/2016/08/01/installing-coreos-etcd-server-on-centos-7/
创建了4个虚拟机，虚拟机中系统为centos7（虚拟机使用的docker）
for((i=1,i<5,i++))
do
docker run -d --name etcd$i --hostname=etcd$i --privileged=true centos7 /usr/sbin/init
docker exec -it etcd$i bash -c “yum update -y&& yum install net-tools -y”
done
hostname ip
etcd1 192.168.0.5
etcd2 192.168.0.6
etcd3 192.168.0.7
etcd4 192.168.0.8
将上述ip表添加到/etc/hosts中
二、etcd安装与配置
2.1 yum安装etcd
yum install etcd -y
验证etcd是否可用
# systemctl enable etcd&&systemctl start etcd # etcdctl set hello world world # etcdctl get hello world
这里的集群模式是指完全集群模式，当然也可以在单机上通过不同的端口，部署伪集群模式，只是那样做只适合测试环境，生产环境考虑到可用性的话需要将etcd实例分布到不同的主机上，这里集群搭建有三种方式，分布是静态配置，etcd发现，dns发现。默认配置运行etcd，监听本地的2379端口，用于与client端交互，监听2380用于etcd内部交互。etcd启动时，集群模式下会用到的参数如下：
- –name
- etcd集群中的节点名，这里可以随意，可区分且不重复就行
- –listen-peer-urls
- 监听的用于节点之间通信的url，可监听多个，集群内部将通过这些url进行数据交互(如选举，数据同步等)
- –initial-advertise-peer-urls
- 建议用于节点之间通信的url，节点间将以该值进行通信。
- –listen-client-urls
- 监听的用于客户端通信的url,同样可以监听多个。
- –advertise-client-urls
- 建议使用的客户端通信url,该值用于etcd代理或etcd成员与etcd节点通信。
- –initial-cluster-token etcd-cluster-1
- 节点的token值，设置该值后集群将生成唯一id,并为每个节点也生成唯一id,当使用相同配置文件再启动一个集群时，只要该token值不一样，etcd集群就不会相互影响。
- –initial-cluster
- 也就是集群中所有的initial-advertise-peer-urls 的合集
- –initial-cluster-state new
- 新建集群的标志，初始化状态使用 new，建立之后改此值为 existing
yum安装etcd需要修改两个配置文件
# vim /lib/systemd/system/etcd.service [Unit] Description=Etcd Server After=network.target After=network-online.target Wants=network-online.target [Service] Type=notify WorkingDirectory=/var/lib/etcd/ EnvironmentFile=-/etc/etcd/etcd.conf User=etcd # set GOMAXPROCS to number of processors ExecStart=/bin/bash -c "GOMAXPROCS=$(nproc) /usr/bin/etcd --name="${ETCD_NAME}" --data-dir="${ETCD_DATA_DIR}" --listen-peer-urls="${ETCD_LISTEN_PEER_URLS}" --advertise-client-urls="${ETCD_ADVERTISE_CLIENT_URLS}" --initial-cluster-token="${ETCD_INITIAL_CLUSTER_TOKEN}" --initial-cluster="${ETCD_INITIAL_CLUSTER}" --initial-cluster-state="${ETCD_INITIAL_CLUSTER_STATE}" --listen-client-urls="${ETCD_LISTEN_CLIENT_URLS}"" Restart=on-failure LimitNOFILE=65536 [Install] WantedBy=multi-user.target
# vim /etc/etcd/etcd.conf
ETCD_NAME=etcd1
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"
ETCD_INITIAL_ADVERTISE_PEER_URLS="http://etcd1:2380"
ETCD_INITIAL_CLUSTER="etcd01=http://etcd1:2380,etcd02=http://etcd2:2380,etcd03=http://etcd3:2380"
ETCD_INITIAL_CLUSTER_STATE="new"
ETCD_INITIAL_CLUSTER_TOKEN="etcd-cluster"
ETCD_ADVERTISE_CLIENT_URLS="http://etcd1:2379"
配置好3台虚拟机之后同时启动etcd服务# systemctl start etcd
正常情况可以查看到成员列表etcdctl member list
# etcdctl member list 3b05c2e4e4c104b4: name=etcd1 peerURLs=http://etcd1:2380 clientURLs=http://etcd1:2379 isLeader=false bd388e7810915853: name=etcd2 peerURLs=http://etcd2:2380 clientURLs=http://etcd3:2379 isLeader=true d282ac2ce600c1ce: name=etcd3 peerURLs=http://etcd3:2380 clientURLs=http://etcd2:2379 isLeader=false
2.2 二进制包安装etcd
yum虽然也能用，还是二进制包的方法操作简单些。
下载稳定版本的etcd二进制包
mkdir /var/lib/etcd;mkdir /etc/etcd; groupadd -r etcd; useradd -r -g etcd -d /var/lib/etcd -s /sbin/nologin -c "etcd user" etcd;chown -R etcd:etcd /var/lib/etcd
ETCD_VERSION=`curl -s -L https://github.com/coreos/etcd/releases/latest | grep linux-amd64.tar.gz | grep href | cut -f 6 -d '/' | sort -u`; ETCD_DIR=/opt/etcd-$ETCD_VERSION; mkdir $ETCD_DIR;curl -L https://github.com/coreos/etcd/releases/download/$ETCD_VERSION/etcd-$ETCD_VERSION-linux-amd64.tar.gz | tar xz --strip-components=1 -C $ETCD_DIR; ln -sf $ETCD_DIR/etcd /usr/bin/etcd && ln -sf $ETCD_DIR/etcdctl /usr/bin/etcdctl; etcd --version
四台虚拟机新建etcd服务启动脚本
[root@etcd1 /]# vim /lib/systemd/system/etcd.service
[Unit]
Description=etcd service
After=network.target
[Service]
Type=notify
WorkingDirectory=/var/lib/etcd/
EnvironmentFile=-/etc/etcd/etcd.conf
User=etcd
ExecStart=/usr/bin/etcd
LimitNOFILE=65536
[Install]
WantedBy=multi-user.target
etcd静态模式集群配置（即知道需要哪几台虚拟机需要建立集群）etcd1，etcd2与etcd3建立集群后etcd4加入集群。
修改etcd1配置文件
[root@etcd1 /]# cat /etc/etcd/etcd.conf ETCD_NAME=etcd1 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" ETCD_INITIAL_ADVERTISE_PEER_URLS="http://etcd1:2380" ETCD_INITIAL_CLUSTER="etcd01=http://etcd1:2380,etcd02=http://etcd2:2380,etcd03=http://etcd3:2380" ETCD_INITIAL_CLUSTER_STATE="new" ETCD_INITIAL_CLUSTER_TOKEN="etcd-cluster" ETCD_ADVERTISE_CLIENT_URLS="http://etcd1:2379"
修改etcd2配置文件
[root@etcd2 /]# cat /etc/etcd/etcd.conf ETCD_NAME=etcd2 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" ETCD_INITIAL_ADVERTISE_PEER_URLS="http://etcd2:2380" ETCD_INITIAL_CLUSTER="etcd01=http://etcd1:2380,etcd02=http://etcd2:2380,etcd03=http://etcd3:2380" ETCD_INITIAL_CLUSTER_STATE="new" ETCD_INITIAL_CLUSTER_TOKEN="etcd-cluster" ETCD_ADVERTISE_CLIENT_URLS="http://etcd2:2379"
修改etcd3配置文件
[root@etcd3 /]# cat /etc/etcd/etcd.conf ETCD_NAME=etcd3 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" ETCD_INITIAL_ADVERTISE_PEER_URLS="http://etcd3:2380" ETCD_INITIAL_CLUSTER="etcd01=http://etcd1:2380,etcd02=http://etcd2:2380,etcd03=http://etcd3:2380" ETCD_INITIAL_CLUSTER_STATE="new" ETCD_INITIAL_CLUSTER_TOKEN="etcd-cluster" ETCD_ADVERTISE_CLIENT_URLS="http://etcd3:2379"
配置好3台虚拟机之后同时启动etcd服务# systemctl start etcd
正常情况可以查看到成员列表etcdctl member list
[root@etcd1 /]# etcdctl member list 3b05c2e4e4c104b4: name=etcd01 peerURLs=http://etcd1:2380 clientURLs=http://etcd1:2379 isLeader=false bd388e7810915853: name=etcd03 peerURLs=http://etcd3:2380 clientURLs=http://etcd3:2379 isLeader=true d282ac2ce600c1ce: name=etcd02 peerURLs=http://etcd2:2380 clientURLs=http://etcd2:2379 isLeader=false
etcd配置过程中遇到的问题，添加节点，删除节点，备份数据
### 本地连接报错
[root@etcd2 /]# etcdctl member list Error: client: etcd cluster is unavailable or misconfigured; error #0: dial tcp 127.0.0.1:2379: getsockopt: connection refused ; error #1: dial tcp 127.0.0.1:4001: getsockopt: connection refused error #0: dial tcp 127.0.0.1:2379: getsockopt: connection refused error #1: dial tcp 127.0.0.1:4001: getsockopt: connection refused
如果出现如上的错误，是因为ETCD_LISTEN_CLIENT_URLS参数没有配置http://127.0.0.1:2379而导致的，所以这里我使用了0.0.0.0代表了监控所有地址。
除此之外仍上述报错，当配置的很混乱的时候可以删掉/var/lib/etcd/中的default.etcd文件,前提是数据不重要哈。还要注意default.etcd文件夹权限改为etcd：etcdchown -R etcd:etcd default.etcd此步很重要，另外还需要细心检查/etc/etcd/etcd.conf和/lib/systemd/system/etcd.service是否有错误。改完之后再重启etcd服务（systemctl start etcd）就ok了。
etcd集群中添加一节点etcd04
在现有集群etcd三台虚拟机中任何一台操作添加新节点etcd04
[root@etcd1 /]# etcdctl member list 3b05c2e4e4c104b4: name=etcd01 peerURLs=http://etcd1:2380 clientURLs=http://etcd1:2379 isLeader=false bd388e7810915853: name=etcd03 peerURLs=http://etcd3:2380 clientURLs=http://etcd3:2379 isLeader=true d282ac2ce600c1ce: name=etcd02 peerURLs=http://etcd2:2380 clientURLs=http://etcd2:2379 isLeader=false [root@etcd1 /]# etcdctl member add etcd04 http://etcd4:2380 Added member named etcd04 with ID ec8c708bb5b2fdc6 to cluster ETCD_NAME="etcd04" ETCD_INITIAL_CLUSTER="etcd01=http://etcd1:2380,etcd03=http://etcd3:2380,etcd02=http://etcd2:2380,etcd04=http://etcd4:2380" ETCD_INITIAL_CLUSTER_STATE="existing" 注意此处三条必须要与etcd04配置文件（/etc/etcd/etcd.conf）相符合 [root@etcd1 /]# etcdctl member list 3b05c2e4e4c104b4: name=etcd01 peerURLs=http://etcd1:2380 clientURLs=http://etcd1:2379 isLeader=false bd388e7810915853: name=etcd03 peerURLs=http://etcd3:2380 clientURLs=http://etcd3:2379 isLeader=true d282ac2ce600c1ce: name=etcd02 peerURLs=http://etcd2:2380 clientURLs=http://etcd2:2379 isLeader=false ec8c708bb5b2fdc6[unstarted]: peerURLs=http://etcd4:2380
启动etcd服务之前修改etcd04配置文件
[root@etcd4 /]# vim /etc/etcd/etcd.conf ETCD_NAME=etcd04 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" ETCD_INITIAL_ADVERTISE_PEER_URLS="http://etcd4:2380" ETCD_INITIAL_CLUSTER="etcd01=http://etcd1:2380,etcd02=http://etcd2:2380,etcd03=http://etcd3:2380,etcd04=http://etcd4:2380" ETCD_INITIAL_CLUSTER_STATE="existing" ETCD_INITIAL_CLUSTER_TOKEN="etcd-cluster" ETCD_ADVERTISE_CLIENT_URLS="http://etcd4:2379"
如果/var/lib/etcd/中存在default.etcd一定要删除，否侧etcd服务启动失败（因为集群中给etcd04分配的物理id与现有库中的id不相同）
[root@etcd4 /]# rm -rf /var/lib/etcd/default.etcd/
[root@etcd4 /]# systemctl start etcd
[root@etcd4 /]# etcdctl member list #启动服务后再查询etcd04已加入集群中
3b05c2e4e4c104b4: name=etcd01 peerURLs=http://etcd1:2380 clientURLs=http://etcd1:2379 isLeader=false
bd388e7810915853: name=etcd03 peerURLs=http://etcd3:2380 clientURLs=http://etcd3:2379 isLeader=true
d282ac2ce600c1ce: name=etcd02 peerURLs=http://etcd2:2380 clientURLs=http://etcd2:2379 isLeader=false
ec8c708bb5b2fdc6: name=etcd04 peerURLs=http://etcd4:2380 clientURLs=http://etcd4:2379 isLeader=false
etcd集群中删除etcd04节点
现有集群节点是4个
[root@etcd1 /]# etcdctl member list
3b05c2e4e4c104b4: name=etcd01 peerURLs=http://etcd1:2380 clientURLs=http://etcd1:2379 isLeader=false
b28ea7a9615a2c72: name=etcd04 peerURLs=http://etcd4:2380 clientURLs=http://etcd4:2379 isLeader=false
bd388e7810915853: name=etcd03 peerURLs=http://etcd3:2380 clientURLs=http://etcd3:2379 isLeader=true
d282ac2ce600c1ce: name=etcd02 peerURLs=http://etcd2:2380 clientURLs=http://etcd2:2379 isLeader=false
在除etcd04节点外的任意一台中操作删除etcd04节点
[root@etcd1 /]# etcdctl member remove b28ea7a9615a2c72
Removed member b28ea7a9615a2c72 from cluster
[root@etcd1 /]# etcdctl member list
3b05c2e4e4c104b4: name=etcd01 peerURLs=http://etcd1:2380 clientURLs=http://etcd1:2379 isLeader=false
bd388e7810915853: name=etcd03 peerURLs=http://etcd3:2380 clientURLs=http://etcd3:2379 isLeader=true
d282ac2ce600c1ce: name=etcd02 peerURLs=http://etcd2:2380 clientURLs=http://etcd2:2379 isLeader=false
etcd集群中备份数据
etcd的数据应该算是很安全的，即便出现单点故障，数据也不会丢失，前提是节点不在同一台服务器中
etcd的数据备份比较。。。网上的方法etcdctl backup --data-dir /var/lib/etcd/default.etcd/ --backup-dir /home/etcd_backup
备份完之后，发现没有db文件，好尴尬啊，所有我直接cp了，cp -r /var/lib/etcd/default.etcd/ /home/etcd_backupchown -R etcd:etcd default.etcd嗯，就可以了。