## 安装 etcd 基于 Go 语言实现，因此，用户可以从 [项目主页](https://github.com/coreos/etcd) 下载源代码自行编译，也可以下载编译好的二进制文件，甚至直接使用制作好的 Docker 镜像文件来体验。 ### 二进制文件方式下载 编译好的二进制文件都在 [github.com/coreos/etcd/releases](https://github.com/coreos/etcd/releases/) 页面，用户可以选择需要的版本，或通过下载工具下载。 例如，下面的命令使用 curl 工具下载压缩包，并解压。 ``` curl -L https://github.com/coreos/etcd/releases/download/v2.0.0-rc.1/etcd-v2.0.0-rc.1-linux-amd64.tar.gz -o etcd-v2.0.0-rc.1-linux-amd64.tar.gz tar xzvf etcd-v2.0.0-rc.1-linux-amd64.tar.gz cd etcd-v2.0.0-rc.1-linux-amd64 ``` 解压后，可以看到文件包括 ``` $ ls etcd etcdctl etcd-migrate README-etcdctl.md README.md ``` 其中 etcd 是服务主文件，etcdctl 是提供给用户的命令客户端，etcd-migrate 负责进行迁移。 推荐通过下面的命令将三个文件都放到系统可执行目录 `/usr/local/bin/` 或 `/usr/bin/`。 ``` $ sudo cp etcd* /usr/local/bin/ ``` 运行 etcd，将默认组建一个两个节点的集群。数据库服务端默认监听在 2379 和 4001 端口，etcd 实例监听在 2380 和 7001 端口。显示类似如下的信息： ``` $ ./etcd 2014/12/31 14:52:09 no data-dir provided, using default data-dir ./default.etcd 2014/12/31 14:52:09 etcd: listening for peers on http://localhost:2380 2014/12/31 14:52:09 etcd: listening for peers on http://localhost:7001 2014/12/31 14:52:09 etcd: listening for client requests on http://localhost:2379 2014/12/31 14:52:09 etcd: listening for client requests on http://localhost:4001 2014/12/31 14:52:09 etcdserver: name = default 2014/12/31 14:52:09 etcdserver: data dir = default.etcd 2014/12/31 14:52:09 etcdserver: snapshot count = 10000 2014/12/31 14:52:09 etcdserver: advertise client URLs = http://localhost:2379,http://localhost:4001 2014/12/31 14:52:09 etcdserver: initial advertise peer URLs = http://localhost:2380,http://localhost:7001 2014/12/31 14:52:09 etcdserver: initial cluster = default=http://localhost:2380,default=http://localhost:7001 2014/12/31 14:52:10 etcdserver: start member ce2a822cea30bfca in cluster 7e27652122e8b2ae 2014/12/31 14:52:10 raft: ce2a822cea30bfca became follower at term 0 2014/12/31 14:52:10 raft: newRaft ce2a822cea30bfca [peers: [], term: 0, commit: 0, lastindex: 0, lastterm: 0] 2014/12/31 14:52:10 raft: ce2a822cea30bfca became follower at term 1 2014/12/31 14:52:10 etcdserver: added local member ce2a822cea30bfca [http://localhost:2380 http://localhost:7001] to cluster 7e27652122e8b2ae 2014/12/31 14:52:11 raft: ce2a822cea30bfca is starting a new election at term 1 2014/12/31 14:52:11 raft: ce2a822cea30bfca became candidate at term 2 2014/12/31 14:52:11 raft: ce2a822cea30bfca received vote from ce2a822cea30bfca at term 2 2014/12/31 14:52:11 raft: ce2a822cea30bfca became leader at term 2 2014/12/31 14:52:11 raft.node: ce2a822cea30bfca elected leader ce2a822cea30bfca at term 2 2014/12/31 14:52:11 etcdserver: published {Name:default ClientURLs:[http://localhost:2379 http://localhost:4001]} to cluster 7e27652122e8b2ae ``` 此时，可以使用 etcdctl 命令进行测试，设置和获取键值 `testkey: "hello world"`，检查 etcd 服务是否启动成功： ``` $ ./etcdctl set testkey "hello world" hello world $ ./etcdctl get testkey hello world ``` 说明 etcd 服务已经成功启动了。 当然，也可以通过 HTTP 访问本地 2379 或 4001 端口的方式来进行操作，例如查看 `testkey` 的值： ``` $ curl -L http://localhost:4001/v2/keys/testkey {"action":"get","node":{"key":"/testkey","value":"hello world","modifiedIndex":3,"createdIndex":3}} ``` ### Docker 镜像方式下载 镜像名称为 quay.io/coreos/etcd:v2.0.0_rc.1，可以通过下面的命令启动 etcd 服务监听到 4001 端口。 ``` $ sudo docker run -p 4001:4001 -v /etc/ssl/certs/:/etc/ssl/certs/ quay.io/coreos/etcd:v2.0.0_rc.1 ```