ETCD集群安装配置及简单应用

一、环境准备

• CentOS Linux release 7.3.1611 (Core) 
• etcd-v3.2.6

二、ETCD下载

https://github.com/coreos/etcd/releases/download/v3.2.6/etcd-v3.2.6-linux-amd64.tar.gz

三、ETCD安装配置

1.部署架构

• 192.168.108.128 节点1
• 192.168.108.129 节点2
• 192.168.108.130 节点3

2.解压安装：

$ tar -zxvf  etcd-v3.2.6-linux-amd64.tar.gz -C /opt/
$ cd /opt
$ mv etcd-v3.2.6-linux-amd64  etcd-v3.2.6
# 创建etcd配置文件目录
$ mkdir /etc/etcd           

3.创建etcd配置文件：

$ vi /etc/etcd/conf.yml

节点1，添加如下内容：

name: etcd-1
data-dir: /opt/etcd-v3.2.6/data
listen-client-urls: http://192.168.108.128:2379,http://127.0.0.1:2379
advertise-client-urls: http://192.168.108.128:2379,http://127.0.0.1:2379
listen-peer-urls: http://192.168.108.128:2380
initial-advertise-peer-urls: http://192.168.108.128:2380
initial-cluster: etcd-1=http://192.168.108.128:2380,etcd-2=http://192.168.108.129:2380,etcd-3=http://192.168.108.130:2380
initial-cluster-token: etcd-cluster-token
initial-cluster-state: new

节点2，添加如下内容：

name: etcd-2
data-dir: /opt/etcd-v3.2.6/data
listen-client-urls: http://192.168.108.129:2379,http://127.0.0.1:2379
advertise-client-urls: http://192.168.108.129:2379,http://127.0.0.1:2379
listen-peer-urls: http://192.168.108.129:2380
initial-advertise-peer-urls: http://192.168.108.129:2380
initial-cluster: etcd-1=http://192.168.108.128:2380,etcd-2=http://192.168.108.129:2380,etcd-3=http://192.168.108.130:2380
initial-cluster-token: etcd-cluster-token
initial-cluster-state: new

节点3，添加如下内容：

name: etcd-3
data-dir: /opt/etcd-v3.2.6/data
listen-client-urls: http://192.168.108.130:2379,http://127.0.0.1:2379
advertise-client-urls: http://192.168.108.130:2379,http://127.0.0.1:2379
listen-peer-urls: http://192.168.108.130:2380
initial-advertise-peer-urls: http://192.168.108.130:2380
initial-cluster: etcd-1=http://192.168.108.128:2380,etcd-2=http://192.168.108.129:2380,etcd-3=http://192.168.108.130:2380
initial-cluster-token: etcd-cluster-token
initial-cluster-state: new

4.更新etcd系统默认配置：

当前使用的是etcd v3版本，系统默认的是v2，通过下面命令修改配置。

$ vi /etc/profile

在文件末尾追加：

export ETCDCTL_API=3

 使文件生效：

$ source /etc/profile

四、ETCD命令

$ cd  /opt/etcd-v3.2.6

1.查看版本信息：

$ ./etcdctl versionetcdctl version: 3.2.6
API version: 3.2

2.启动命令：

$ ./etcd --config-file=/etc/etcd/conf.yml

3.查看集群成员信息：

$ ./etcdctl member list2618ce5cd761aa8e: name=etcd-3 peerURLs=http://192.168.108.130:2380 clientURLs=http://127.0.0.1:2379,http://192.168.108.130:2379 isLeader=false
9c359d48a2f34938: name=etcd-1 peerURLs=http://192.168.108.128:2380 clientURLs=http://127.0.0.1:2379,http://192.168.108.128:2379 isLeader=false
f3c45714407d68f3: name=etcd-2 peerURLs=http://192.168.108.129:2380 clientURLs=http://127.0.0.1:2379,http://192.168.108.129:2379 isLeader=true

4.查看集群状态（Leader节点）：

$ ./etcdctl cluster-healthmember 2618ce5cd761aa8e is healthy: got healthy result from http://127.0.0.1:2379
member 9c359d48a2f34938 is healthy: got healthy result from http://127.0.0.1:2379
member f3c45714407d68f3 is healthy: got healthy result from http://127.0.0.1:2379
cluster is healthy

5.HTTPS加密下使用etcdctl检查集群健康状况:

$ etcdctl --ca-file /etc/ssl/etcd/ca.pem --cert-file /etc/ssl/etcd/server1.pem --key-file /etc/ssl/etcd/server1-key.pem member list
$ etcdctl --ca-file /etc/ssl/etcd/ca.pem --cert-file /etc/ssl/etcd/server1.pem --key-file /etc/ssl/etcd/server1-key.pem cluster-health

五、ECTD读写操作

基于HTTP协议的API使用起来比较简单，这里主要通过etcdctl和curl两种方式来做简单介绍。

1.下面通过给message key设置Hello值示例：

$ ./etcdctl set /message HelloHello$ curl -X PUT http://127.0.0.1:2379/v2/keys/message -d value="Hello"
{"action":"set","node":{"key":"/message","value":"Hello","modifiedIndex":4,"createdIndex":4}}

2.读取message的值：

$ ./etcdctl  get /message
Hello$ curl http://127.0.0.1:2379/v2/keys/message
{"action":"get","node":{"key":"/message","value":"Hello","modifiedIndex":9,"createdIndex":9}}

3.删除message key：

$ ./etcdctl  rm  /message$ curl -X DELETE http://127.0.0.1:2379/v2/keys/message
{"action":"delete","node":{"key":"/message","modifiedIndex":10,"createdIndex":9},"prevNode":{"key":"/message","value":"Hello","modifiedIndex":9,"createdIndex":9}}

说明：因为是集群，所以message在其中一个节点创建后，在集群中的任何节点都可以查询到。

4.查看所有key-value：

curl -s http://127.0.0.1:2379/v2/keys/?recursive=true

六、配置ETCD为启动服务

1.编辑/usr/lib/systemd/system/etcd.service，添加下面内容：

[Unit]
Description=Etcd Server
After=network.target
After=network-online.target
Wants=network-online.target[Service]
Type=notify
WorkingDirectory=/opt/etcd-v3.2.6/
# User=etcd
ExecStart=/opt/etcd-v3.2.6/etcd --config-file=/etc/etcd/conf.yml
Restart=on-failure
LimitNOFILE=65536[Install]
WantedBy=multi-user.target

2.更新启动：

systemctl daemon-reload
systemctl enable etcd
systemctl start etcd
systemctl restart etcdsystemctl status etcd.service -l

参考资料：

https://coreos.com/etcd/docs/latest/getting-started-with-etcd.html