Docker 搭建 etcd 集群

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阅读目录：

主机安装
集群搭建
API 操作
API 说明和 etcdctl 命令说明

etcd 是 CoreOS 团队发起的一个开源项目（Go 语言，其实很多这类项目都是 Go 语言实现的，只能说很强大），实现了分布式键值存储和服务发现，etcd 和 ZooKeeper/Consul 非常相似，都提供了类似的功能，以及 REST API 的访问操作，具有以下特点：

简单：安装和使用简单，提供了 REST API 进行操作交互
安全：支持 HTTPS SSL 证书
快速：支持并发 10 k/s 的读写操作
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 可以单个实例使用，也可以进行集群配置，因为很多项目都是以 etcd 作为服务发现，比如 CoreOS 和 Kubernetes，所以，下面我们使用 Docker 简单搭建一下 etcd 集群。

1. 主机安装

如果不使用 Docker 的话，etcd 在主机上安装，也非常简单。

Linux 安装命令：

$ curl -L https://github.com/coreos/etcd/releases/download/v3.3.0-rc.0/etcd-v3.3.0-rc.0-linux-amd64.tar.gz -o etcd-v3.3.0-rc.0-linux-amd64.tar.gz && sudo tar xzvf etcd-v3.3.0-rc.0-linux-amd64.tar.gz && cd etcd-v3.3.0-rc.0-linux-amd64 && sudo cp etcd* /usr/local/bin/

其实就是将编译后的二进制文件，拷贝到/usr/local/bin/目录，各个版本的二进制文件，可以从 https://github.com/coreos/etcd/releases/ 中查找下载。

Mac OS 安装命令：

$ ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)" < /dev/null 2> /dev/null $ brew install etcd

执行下面命令，查看 etcd 是否安装成功：

$ etcd --version etcd Version: 3.2.12 Git SHA: GitNotFound Go Version: go1.9.2 Go OS/Arch: darwin/amd64

2. 集群搭建

搭建 etcd 集群，需要借助下 Docker Machine 创建三个 Docker 主机，命令：

$ docker-machine create -d virtualbox manager1 && docker-machine create -d virtualbox worker1 && docker-machine create -d virtualbox worker2$ docker-machine ls NAME ACTIVE DRIVER STATE URL SWARM DOCKER ERRORS manager1 - virtualbox Running tcp://192.168.99.100:2376 v17.11.0-ce worker1 - virtualbox Running tcp://192.168.99.101:2376 v17.11.0-ce worker2 - virtualbox Running tcp://192.168.99.102:2376 v17.11.0-ce

为防止 Docker 主机中垃取官方镜像，速度慢的问题，我们还需要将 etcd 镜像打包推送到私有仓库中，命令：

$ docker tag quay.io/coreos/etcd 192.168.99.1:5000/quay.io/coreos/etcd:latest && docker push 192.168.99.1:5000/quay.io/coreos/etcd:latest && docker pull 192.168.99.1:5000/quay.io/coreos/etcd:latest

另外，还需要将私有仓库地址配置在 Docker 主机中，并重启三个 Docker 主机，具体配置参考：Docker 三剑客之 Docker Swarm

Docker 主机配置好之后，我们需要使用docker-machine ssh命令，分别进入三个 Docker 主机中，执行 Docker etcd 配置命令。

manager1 主机（node1 192.168.99.100）：

$ docker run -d --name etcd \ -p 2379:2379 \ -p 2380:2380 \ --volume=etcd-data:/etcd-data \ 192.168.99.1:5000/quay.io/coreos/etcd \ /usr/local/bin/etcd \ --data-dir=/etcd-data --name node1 \ --initial-advertise-peer-urls http://192.168.99.100:2380 --listen-peer-urls http://0.0.0.0:2380 \ --advertise-client-urls http://192.168.99.100:2379 --listen-client-urls http://0.0.0.0:2379 \ --initial-cluster-state new \ --initial-cluster-token docker-etcd \ --initial-cluster node1=http://192.168.99.100:2380,node2=http://192.168.99.101:2380,node3=http://192.168.99.102:2380

worker1 主机（node2 192.168.99.101）：

$ docker run -d --name etcd \ -p 2379:2379 \ -p 2380:2380 \ --volume=etcd-data:/etcd-data \ 192.168.99.1:5000/quay.io/coreos/etcd \ /usr/local/bin/etcd \ --data-dir=/etcd-data --name node2 \ --initial-advertise-peer-urls http://192.168.99.101:2380 --listen-peer-urls http://0.0.0.0:2380 \ --advertise-client-urls http://192.168.99.101:2379 --listen-client-urls http://0.0.0.0:2379 \ --initial-cluster-state new \ --initial-cluster-token docker-etcd \ --initial-cluster node1=http://192.168.99.100:2380,node2=http://192.168.99.101:2380,node3=http://192.168.99.102:2380

worker2 主机（node1 192.168.99.102）：

$ docker run -d --name etcd \ -p 2379:2379 \ -p 2380:2380 \ --volume=etcd-data:/etcd-data \ 192.168.99.1:5000/quay.io/coreos/etcd \ /usr/local/bin/etcd \ --data-dir=/etcd-data --name node3 \ --initial-advertise-peer-urls http://192.168.99.102:2380 --listen-peer-urls http://0.0.0.0:2380 \ --advertise-client-urls http://192.168.99.102:2379 --listen-client-urls http://0.0.0.0:2379 \ --initial-cluster-state existing \ --initial-cluster-token docker-etcd \ --initial-cluster node1=http://192.168.99.100:2380,node2=http://192.168.99.101:2380,node3=http://192.168.99.102:2380

先来说明下 etcd 各个配置参数的意思（参考自 etcd 使用入门）：

--name：节点名称，默认为 default。
--data-dir：服务运行数据保存的路径，默认为${name}.etcd。
--snapshot-count：指定有多少事务（transaction）被提交时，触发截取快照保存到磁盘。
--heartbeat-interval：leader 多久发送一次心跳到 followers。默认值是 100ms。
--eletion-timeout：重新投票的超时时间，如果 follow 在该时间间隔没有收到心跳包，会触发重新投票，默认为 1000 ms。
--listen-peer-urls：和同伴通信的地址，比如http://ip:2380，如果有多个，使用逗号分隔。需要所有节点都能够访问，所以不要使用 localhost！
--listen-client-urls：对外提供服务的地址：比如http://ip:2379,http://127.0.0.1:2379，客户端会连接到这里和 etcd 交互。
--advertise-client-urls：对外公告的该节点客户端监听地址，这个值会告诉集群中其他节点。
--initial-advertise-peer-urls：该节点同伴监听地址，这个值会告诉集群中其他节点。
--initial-cluster：集群中所有节点的信息，格式为node1=http://ip1:2380,node2=http://ip2:2380,…，注意：这里的 node1 是节点的 --name 指定的名字；后面的 ip1:2380 是 --initial-advertise-peer-urls 指定的值。
--initial-cluster-state：新建集群的时候，这个值为 new；假如已经存在的集群，这个值为 existing。
--initial-cluster-token：创建集群的 token，这个值每个集群保持唯一。这样的话，如果你要重新创建集群，即使配置和之前一样，也会再次生成新的集群和节点 uuid；否则会导致多个集群之间的冲突，造成未知的错误。

上述配置也可以设置配置文件，默认为/etc/etcd/etcd.conf。

我们可以使用docker ps，查看 Docker etcd 是否配置成功：

$ docker ps CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES 463380d23dfe 192.168.99.1:5000/quay.io/coreos/etcd "/usr/local/bin/et..." 2 hours ago Up 2 hours 0.0.0.0:2379-2380->2379-2380/tcp etcd

然后进入其中一个 Docker 主机：

$ docker exec -it etcd bin/sh

执行下面命令（查看集群成员）：

$ etcdctl member list 773d30c9fc6640b4: name=node2 peerURLs=http://192.168.99.101:2380 clientURLs=http://192.168.99.101:2379 isLeader=true b2b0bca2e0cfcc19: name=node3 peerURLs=http://192.168.99.102:2380 clientURLs=http://192.168.99.102:2379 isLeader=false c88e2cccbb287a01: name=node1 peerURLs=http://192.168.99.100:2380 clientURLs=http://192.168.99.100:2379 isLeader=false

可以看到，集群里面有三个成员，并且node2为管理员，node1和node3为普通成员。

etcdctl 是 ectd 的客户端命令工具（也是 go 语言实现），里面封装了 etcd 的 REST API 执行命令，方便我们进行操作 etcd，后面再列出 etcdctl 的命令详细说明。

上面命令的 etcd API 版本为 2.0，我们可以手动设置版本为 3.0，命令：

$ export ETCDCTL_API=3 && /usr/local/bin/etcdctl put foo bar OK

部分命令和执行结果还是和 2.0 版本，有很多不同的，比如同是查看集群成员，3.0 版本的执行结果：

$ etcdctl member list 773d30c9fc6640b4, started, node2, http://192.168.99.101:2380, http://192.168.99.101:2379 b2b0bca2e0cfcc19, started, node3, http://192.168.99.102:2380, http://192.168.99.102:2379 c88e2cccbb287a01, started, node1, http://192.168.99.100:2380, http://192.168.99.100:2379

好了，我们现在再演示一种情况，就是从集群中移除一个节点，然后再把它添加到集群中，为演示 etcd 中使用 Raft 算法，我们将node2管理节点，作为操作对象。

我们在随便一个主机 etcd 容器中（node2除外），执行成员移除集群命令（必须使用 ID，使用别名会报错）：

$ etcdctl member remove 773d30c9fc6640b4 Member 773d30c9fc6640b4 removed from cluster f84185fa5f91bdf6

我们再执行下查看集群成员命令（v2 版本）：

$ etcdctl member list b2b0bca2e0cfcc19: name=node3 peerURLs=http://192.168.99.102:2380 clientURLs=http://192.168.99.102:2379 isLeader=true c88e2cccbb287a01: name=node1 peerURLs=http://192.168.99.100:2380 clientURLs=http://192.168.99.100:2379 isLeader=false

会发现node2管理节点被移除集群了，并且通过 Raft 算法，node3被推举为管理节点。

在将node2节点重新加入集群之前，我们需要执行下面命令：

$ etcdctl member add node2 --peer-urls="http://192.168.99.101:2380" Member 22b0de6ffcd98f00 added to cluster f84185fa5f91bdf6ETCD_NAME="node2" ETCD_INITIAL_CLUSTER="node2=http://192.168.99.101:2380,node3=http://192.168.99.102:2380,node1=http://192.168.99.100:2380" ETCD_INITIAL_CLUSTER_STATE="existing"

可以看到，ETCD_INITIAL_CLUSTER_STATE 值为existing，也就是我们配置的--initial-cluster-state参数。

我们再执行下查看集群成员命令（v2 版本）：

$ etcdctl member list 22b0de6ffcd98f00[unstarted]: peerURLs=http://192.168.99.101:2380 b2b0bca2e0cfcc19: name=node3 peerURLs=http://192.168.99.102:2380 clientURLs=http://192.168.99.102:2379 isLeader=true c88e2cccbb287a01: name=node1 peerURLs=http://192.168.99.100:2380 clientURLs=http://192.168.99.100:2379 isLeader=false

会发现22b0de6ffcd98f00成员状态变为了unstarted。

我们在node2节点，执行 Docker etcd 集群配置命令：

$ docker run -d --name etcd \ -p 2379:2379 \ -p 2380:2380 \ --volume=etcd-data:/etcd-data \ 192.168.99.1:5000/quay.io/coreos/etcd \ /usr/local/bin/etcd \ --data-dir=/etcd-data --name node2 \ --initial-advertise-peer-urls http://192.168.99.101:2380 --listen-peer-urls http://0.0.0.0:2380 \ --advertise-client-urls http://192.168.99.101:2379 --listen-client-urls http://0.0.0.0:2379 \ --initial-cluster-state existing \ --initial-cluster-token docker-etcd \ --initial-cluster node1=http://192.168.99.100:2380,node2=http://192.168.99.101:2380,node3=http://192.168.99.102:2380

结果并不像我们想要的那样成功，执行查看日志：

$ docker logs etcd 2017-12-25 08:19:30.160967 I | etcdmain: etcd Version: 3.2.12 2017-12-25 08:19:30.161062 I | etcdmain: Git SHA: b19dae0 2017-12-25 08:19:30.161082 I | etcdmain: Go Version: go1.8.5 2017-12-25 08:19:30.161092 I | etcdmain: Go OS/Arch: linux/amd64 2017-12-25 08:19:30.161105 I | etcdmain: setting maximum number of CPUs to 1, total number of available CPUs is 1 2017-12-25 08:19:30.161144 N | etcdmain: the server is already initialized as member before, starting as etcd member... 2017-12-25 08:19:30.161195 I | embed: listening for peers on http://0.0.0.0:2380 2017-12-25 08:19:30.161232 I | embed: listening for client requests on 0.0.0.0:2379 2017-12-25 08:19:30.165269 I | etcdserver: name = node2 2017-12-25 08:19:30.165317 I | etcdserver: data dir = /etcd-data 2017-12-25 08:19:30.165335 I | etcdserver: member dir = /etcd-data/member 2017-12-25 08:19:30.165347 I | etcdserver: heartbeat = 100ms 2017-12-25 08:19:30.165358 I | etcdserver: election = 1000ms 2017-12-25 08:19:30.165369 I | etcdserver: snapshot count = 100000 2017-12-25 08:19:30.165385 I | etcdserver: advertise client URLs = http://192.168.99.101:2379 2017-12-25 08:19:30.165593 I | etcdserver: restarting member 773d30c9fc6640b4 in cluster f84185fa5f91bdf6 at commit index 14 2017-12-25 08:19:30.165627 I | raft: 773d30c9fc6640b4 became follower at term 11 2017-12-25 08:19:30.165647 I | raft: newRaft 773d30c9fc6640b4 [peers: [], term: 11, commit: 14, applied: 0, lastindex: 14, lastterm: 11] 2017-12-25 08:19:30.169277 W | auth: simple token is not cryptographically signed 2017-12-25 08:19:30.170424 I | etcdserver: starting server... [version: 3.2.12, cluster version: to_be_decided] 2017-12-25 08:19:30.171732 I | etcdserver/membership: added member 773d30c9fc6640b4 [http://192.168.99.101:2380] to cluster f84185fa5f91bdf6 2017-12-25 08:19:30.171845 I | etcdserver/membership: added member c88e2cccbb287a01 [http://192.168.99.100:2380] to cluster f84185fa5f91bdf6 2017-12-25 08:19:30.171877 I | rafthttp: starting peer c88e2cccbb287a01... 2017-12-25 08:19:30.171902 I | rafthttp: started HTTP pipelining with peer c88e2cccbb287a01 2017-12-25 08:19:30.175264 I | rafthttp: started peer c88e2cccbb287a01 2017-12-25 08:19:30.175339 I | rafthttp: added peer c88e2cccbb287a01 2017-12-25 08:19:30.178326 I | etcdserver/membership: added member cbd7fa8d01297113 [http://192.168.99.102:2380] to cluster f84185fa5f91bdf6 2017-12-25 08:19:30.178383 I | rafthttp: starting peer cbd7fa8d01297113... 2017-12-25 08:19:30.178410 I | rafthttp: started HTTP pipelining with peer cbd7fa8d01297113 2017-12-25 08:19:30.179794 I | rafthttp: started peer cbd7fa8d01297113 2017-12-25 08:19:30.179835 I | rafthttp: added peer cbd7fa8d01297113 2017-12-25 08:19:30.180062 N | etcdserver/membership: set the initial cluster version to 3.0 2017-12-25 08:19:30.180132 I | etcdserver/api: enabled capabilities for version 3.0 2017-12-25 08:19:30.180255 N | etcdserver/membership: updated the cluster version from 3.0 to 3.2 2017-12-25 08:19:30.180430 I | etcdserver/api: enabled capabilities for version 3.2 2017-12-25 08:19:30.183979 I | rafthttp: started streaming with peer c88e2cccbb287a01 (writer) 2017-12-25 08:19:30.184139 I | rafthttp: started streaming with peer c88e2cccbb287a01 (writer) 2017-12-25 08:19:30.184232 I | rafthttp: started streaming with peer c88e2cccbb287a01 (stream MsgApp v2 reader) 2017-12-25 08:19:30.185142 I | rafthttp: started streaming with peer c88e2cccbb287a01 (stream Message reader) 2017-12-25 08:19:30.186518 I | etcdserver/membership: removed member cbd7fa8d01297113 from cluster f84185fa5f91bdf6 2017-12-25 08:19:30.186573 I | rafthttp: stopping peer cbd7fa8d01297113... 2017-12-25 08:19:30.186614 I | rafthttp: started streaming with peer cbd7fa8d01297113 (writer) 2017-12-25 08:19:30.186786 I | rafthttp: stopped streaming with peer cbd7fa8d01297113 (writer) 2017-12-25 08:19:30.186815 I | rafthttp: started streaming with peer cbd7fa8d01297113 (writer) 2017-12-25 08:19:30.186831 I | rafthttp: stopped streaming with peer cbd7fa8d01297113 (writer) 2017-12-25 08:19:30.186876 I | rafthttp: started streaming with peer cbd7fa8d01297113 (stream MsgApp v2 reader) 2017-12-25 08:19:30.187224 I | rafthttp: started streaming with peer cbd7fa8d01297113 (stream Message reader) 2017-12-25 08:19:30.187647 I | rafthttp: stopped HTTP pipelining with peer cbd7fa8d01297113 2017-12-25 08:19:30.187682 I | rafthttp: stopped streaming with peer cbd7fa8d01297113 (stream MsgApp v2 reader) 2017-12-25 08:19:30.187873 I | rafthttp: stopped streaming with peer cbd7fa8d01297113 (stream Message reader) 2017-12-25 08:19:30.187895 I | rafthttp: stopped peer cbd7fa8d01297113 2017-12-25 08:19:30.187911 I | rafthttp: removed peer cbd7fa8d01297113 2017-12-25 08:19:30.188034 I | etcdserver/membership: added member b2b0bca2e0cfcc19 [http://192.168.99.102:2380] to cluster f84185fa5f91bdf6 2017-12-25 08:19:30.188059 I | rafthttp: starting peer b2b0bca2e0cfcc19... 2017-12-25 08:19:30.188075 I | rafthttp: started HTTP pipelining with peer b2b0bca2e0cfcc19 2017-12-25 08:19:30.188510 I | rafthttp: started peer b2b0bca2e0cfcc19 2017-12-25 08:19:30.188533 I | rafthttp: added peer b2b0bca2e0cfcc19 2017-12-25 08:19:30.188795 I | etcdserver/membership: removed member 773d30c9fc6640b4 from cluster f84185fa5f91bdf6 2017-12-25 08:19:30.193643 I | rafthttp: started streaming with peer b2b0bca2e0cfcc19 (writer) 2017-12-25 08:19:30.193730 I | rafthttp: started streaming with peer b2b0bca2e0cfcc19 (writer) 2017-12-25 08:19:30.193797 I | rafthttp: started streaming with peer b2b0bca2e0cfcc19 (stream MsgApp v2 reader) 2017-12-25 08:19:30.194782 I | rafthttp: started streaming with peer b2b0bca2e0cfcc19 (stream Message reader) 2017-12-25 08:19:30.195663 I | raft: 773d30c9fc6640b4 [term: 11] received a MsgHeartbeat message with higher term from b2b0bca2e0cfcc19 [term: 12] 2017-12-25 08:19:30.195716 I | raft: 773d30c9fc6640b4 became follower at term 12 2017-12-25 08:19:30.195736 I | raft: raft.node: 773d30c9fc6640b4 elected leader b2b0bca2e0cfcc19 at term 12 2017-12-25 08:19:30.196617 E | rafthttp: streaming request ignored (ID mismatch got 22b0de6ffcd98f00 want 773d30c9fc6640b4) 2017-12-25 08:19:30.197064 E | rafthttp: streaming request ignored (ID mismatch got 22b0de6ffcd98f00 want 773d30c9fc6640b4) 2017-12-25 08:19:30.197846 E | rafthttp: streaming request ignored (ID mismatch got 22b0de6ffcd98f00 want 773d30c9fc6640b4) 2017-12-25 08:19:30.198242 E | rafthttp: streaming request ignored (ID mismatch got 22b0de6ffcd98f00 want 773d30c9fc6640b4) 2017-12-25 08:19:30.201771 E | etcdserver: the member has been permanently removed from the cluster 2017-12-25 08:19:30.202060 I | etcdserver: the data-dir used by this member must be removed. 2017-12-25 08:19:30.202307 E | etcdserver: publish error: etcdserver: request cancelled 2017-12-25 08:19:30.202338 I | etcdserver: aborting publish because server is stopped 2017-12-25 08:19:30.202364 I | rafthttp: stopping peer b2b0bca2e0cfcc19... 2017-12-25 08:19:30.202482 I | rafthttp: stopped streaming with peer b2b0bca2e0cfcc19 (writer) 2017-12-25 08:19:30.202504 I | rafthttp: stopped streaming with peer b2b0bca2e0cfcc19 (writer) 2017-12-25 08:19:30.204143 I | rafthttp: stopped HTTP pipelining with peer b2b0bca2e0cfcc19 2017-12-25 08:19:30.204186 I | rafthttp: stopped streaming with peer b2b0bca2e0cfcc19 (stream MsgApp v2 reader) 2017-12-25 08:19:30.204205 I | rafthttp: stopped streaming with peer b2b0bca2e0cfcc19 (stream Message reader) 2017-12-25 08:19:30.204217 I | rafthttp: stopped peer b2b0bca2e0cfcc19 2017-12-25 08:19:30.204228 I | rafthttp: stopping peer c88e2cccbb287a01... 2017-12-25 08:19:30.204241 I | rafthttp: stopped streaming with peer c88e2cccbb287a01 (writer) 2017-12-25 08:19:30.204255 I | rafthttp: stopped streaming with peer c88e2cccbb287a01 (writer) 2017-12-25 08:19:30.204824 I | rafthttp: stopped HTTP pipelining with peer c88e2cccbb287a01 2017-12-25 08:19:30.204860 I | rafthttp: stopped streaming with peer c88e2cccbb287a01 (stream MsgApp v2 reader) 2017-12-25 08:19:30.204878 I | rafthttp: stopped streaming with peer c88e2cccbb287a01 (stream Message reader) 2017-12-25 08:19:30.204891 I | rafthttp: stopped peer c88e2cccbb287a01

这么长的日志，说明啥问题呢，就是说我们虽然重新执行的 etcd 创建命令，但因为读取之前配置文件的关系，etcd 会恢复之前的集群成员，但之前的集群节点已经被移除了，所以集群节点就一直处于停止状态。

怎么解决呢？很简单，就是将我们之前创建的etcd-data数据卷轴删掉，命令：

$ docker volume ls DRIVER VOLUME NAME local etcd-data$ docker volume rm etcd-data etcd-data

然后，再在node2节点，重新执行 Docker etcd 集群配置命令（上面），会发现执行是成功的。

我们再执行下查看集群成员命令（v2 版本）：

$ etcdctl member list 22b0de6ffcd98f00: name=node2 peerURLs=http://192.168.99.101:2380 clientURLs=http://192.168.99.101:2379 isLeader=false b2b0bca2e0cfcc19: name=node3 peerURLs=http://192.168.99.102:2380 clientURLs=http://192.168.99.102:2379 isLeader=true c88e2cccbb287a01: name=node1 peerURLs=http://192.168.99.100:2380 clientURLs=http://192.168.99.100:2379 isLeader=false

3. API 操作

etcd REST API 被用于键值操作和集群成员操作，这边就简单说几个，详细的 API 查看附录说明。

1. 键值管理

设置键值命令：

$ curl http://127.0.0.1:2379/v2/keys/hello -XPUT -d value="hello world" {"action":"set","node":{"key":"/hello","value":"hello world","modifiedIndex":17,"createdIndex":17}}

查看键值命令：

$ curl http://127.0.0.1:2379/v2/keys/hello {"action":"get","node":{"key":"/hello","value":"hello world","modifiedIndex":17,"createdIndex":17}}

删除键值命令：

$ curl http://127.0.0.1:2379/v2/keys/hello -XDELETE {"action":"delete","node":{"key":"/hello","modifiedIndex":19,"createdIndex":17},"prevNode":{"key":"/hello","value":"hello world","modifiedIndex":17,"createdIndex":17}}

2. 成员管理

列出集群中的所有成员：

$ curl http://127.0.0.1:2379/v2/members {"members":[{"id":"22b0de6ffcd98f00","name":"node2","peerURLs":["http://192.168.99.101:2380"],"clientURLs":["http://192.168.99.101:2379"]},{"id":"b2b0bca2e0cfcc19","name":"node3","peerURLs":["http://192.168.99.102:2380"],"clientURLs":["http://192.168.99.102:2379"]},{"id":"c88e2cccbb287a01","name":"node1","peerURLs":["http://192.168.99.100:2380"],"clientURLs":["http://192.168.99.100:2379"]}]}

查看当前节点是否为管理节点：

$ curl http://127.0.0.1:2379/v2/stats/leader {"leader":"b2b0bca2e0cfcc19","followers":{"22b0de6ffcd98f00":{"latency":{"current":0.001051,"average":0.0029195000000000002,"standardDeviation":0.001646769458667484,"minimum":0.001051,"maximum":0.006367},"counts":{"fail":0,"success":10}},"c88e2cccbb287a01":{"latency":{"current":0.000868,"average":0.0022389999999999997,"standardDeviation":0.0011402923601720172,"minimum":0.000868,"maximum":0.004725},"counts":{"fail":0,"success":12}}}}

查看当前节点信息：

$ curl http://127.0.0.1:2379/v2/stats/self {"name":"node3","id":"b2b0bca2e0cfcc19","state":"StateLeader","startTime":"2017-12-25T06:00:28.803429523Z","leaderInfo":{"leader":"b2b0bca2e0cfcc19","uptime":"36m45.45263851s","startTime":"2017-12-25T08:13:02.103896843Z"},"recvAppendRequestCnt":6,"sendAppendRequestCnt":22}

查看集群状态：

$ curl http://127.0.0.1:2379/v2/stats/store {"getsSuccess":9,"getsFail":4,"setsSuccess":9,"setsFail":0,"deleteSuccess":3,"deleteFail":0,"updateSuccess":0,"updateFail":0,"createSuccess":7,"createFail":0,"compareAndSwapSuccess":0,"compareAndSwapFail":0,"compareAndDeleteSuccess":0,"compareAndDeleteFail":0,"expireCount":0,"watchers":0}

当然也可以通过 API 添加和删除集群成员。

4. API 说明和 etcdctl 命令说明

etcd REST API 说明（v2 版本）：

命令	说明
curl -L http://127.0.0.1:2379/version	查看版本
curl http://127.0.0.1:2379/v2/keys/message -XPUT -d value="Hello world"	添加键值
curl http://127.0.0.1:2379/v2/keys/message	获取键值
curl http://127.0.0.1:2379/v2/keys/message -XPUT -d value="Hello etcd"	更新键值
curl http://127.0.0.1:2379/v2/keys/message -XDELETE	删除键值
curl http://127.0.0.1:2379/v2/keys/foo -XPUT -d value=bar -d ttl=5	添加 TTL 键值（过期时间）
curl http://127.0.0.1:2379/v2/keys/foo	获取 TTL 键值
curl http://127.0.0.1:2379/v2/keys/foo -XPUT -d value=bar -d ttl= -d prevExist=true	更新 TTL 键值
curl http://127.0.0.1:2379/v2/keys/foo?wait=true
curl http://127.0.0.1:2379/v2/keys/foo -XPUT -d value=bar
curl 'http://127.0.0.1:2379/v2/keys/foo?wait=true&waitIndex=7'
curl http://127.0.0.1:2379/v2/keys/queue -XPOST -d value=Job1
curl -s 'http://127.0.0.1:2379/v2/keys/queue?recursive=true&sorted=true'
curl http://127.0.0.1:2379/v2/keys/dir -XPUT -d ttl=30 -d dir=true
curl http://127.0.0.1:2379/v2/keys/dir -XPUT -d ttl=30 -d dir=true -d prevExist=true
curl 'http://127.0.0.1:2379/v2/keys/dir?wait=true'
curl http://127.0.0.1:2379/v2/keys/dir -XPUT -d dir=true	创建目录
curl http://127.0.0.1:2379/v2/keys/foo_dir/foo -XPUT -d value=bar	在目录下添加键值
curl http://127.0.0.1:2379/v2/keys/?recursive=true	获取目录下的键值
curl 'http://127.0.0.1:2379/v2/keys/foo_dir?dir=true' -XDELETE	删除目录
curl http://10.0.0.10:2379/v2/members	查看集群成员
curl http://10.0.0.10:2379/v2/members -XPOST -H "Content-Type: application/json" -d '{"peerURLs":["http://10.0.0.10:2380"]}'	添加集群成员
curl http://10.0.0.10:2379/v2/members/272e204152 -XDELETE	删除集群成员
curl http://10.0.0.10:2379/v2/members/272e204152 -XPUT -H "Content-Type: application/json" -d '{"peerURLs":["http://10.0.0.10:2380"]}'	更新集群成员

更多 API 请查看：etcd API 和 Members API

etcdctl 命令说明：

命令	说明
etcdctl set key value	添加键值
etcdctl get key	获取键值
etcdctl update key value	更新键值
etcdctl rm key	删除键值
etcdctl mkdir dirname	添加目录（不存在的话创建）
etcdctl setdir	添加目录（都创建）
etcdctl updatedir	更新目录
etcdctl rmdir	删除目录
etcdctl ls	列出目录
etcdctl watch	监控键值
etcdctl exec-watch	监控键值（执行命令）
etcdctl list	查看集群成员
etcdctl member add	添加集群成员
etcdctl remove	移除集群成员