etcd

分布式一致性key-value存储

版本

v2

使用场景

1. 注册中心，服务注册与发现
2. 配置中心，配置推送
3. 分布式锁
4. 消息发布与订阅
5. 分布式cas
6. 分布式队列

特点

1. 简单，api友好（gPRC）
2. 安全，tls支持
3. 性能，10000/s写入速度
4. 可靠，使用Raft协议

REST命令

查看版本 curl -L http://127.0.0.1:2379/version
获得值 curl http://127.0.0.1:2379/v2/keys/message
插入值 curl http://127.0.0.1:2379/v2/keys/message -XPUT -d value="Hello world"
修改值 curl http://127.0.0.1:2379/v2/keys/message -XPUT -d value="Hello etcd"
删除值 curl http://127.0.0.1:2379/v2/keys/message -XDELETE
使用ttl curl http://127.0.0.1:2379/v2/keys/foo -XPUT -d value=bar -d ttl=5
监听 curl http://127.0.0.1:2379/v2/keys/foo?wait=true
创建文件夹 curl http://127.0.0.1:2379/v2/keys/dir -XPUT -d dir=true
删除文件夹 curl http://127.0.0.1:2379/v2/keys/foo_dir?dir=true -XDELETE
上传文件 curl http://127.0.0.1:2379/v2/keys/afile -XPUT --data-urlencode value@afile.txt
主信息 curl http://127.0.0.1:2379/v2/stats/leader
节点信息 curl http://127.0.0.1:2379/v2/stats/self
存储信息 curl http://127.0.0.1:2379/v2/stats/store
cas curl http://127.0.0.1:2379/v2/keys/foo?prevValue=one -XPUT -d value=two

集群搭建

1. 静态，在集群启动之前就知道集群机器情况

示例:准备三台机器，安装完成etcd

192.168.1.100
192.168.1.101
192.168.1.102

每个机器上分别执行命令

$ etcd --name infra0 --initial-advertise-peer-urls http://192.168.1.100:2380 \
  --listen-peer-urls http://192.168.1.100:2380 \
  --listen-client-urls http://192.168.1.100:2379 \
  --advertise-client-urls http://192.168.1.100:2379 \
  --initial-cluster-token etcd-cluster-1 \
  --initial-cluster infra0=http://192.168.1.100:2380,infra1=http://192.168.1.101:2380,infra2=http://192.168.1.102:2380 \
  --initial-cluster-state new
    
$ etcd --name infra1 --initial-advertise-peer-urls http://192.168.1.101:2380 \
  --listen-peer-urls http://192.168.1.101:2380 \
  --listen-client-urls http://192.168.1.101:2379 \
  --advertise-client-urls http://192.168.1.101:2379 \
  --initial-cluster-token etcd-cluster-1 \
  --initial-cluster infra0=http://192.168.1.100:2380,infra1=http://192.168.1.101:2380,infra2=http://192.168.1.102:2380 \
  --initial-cluster-state new
    
$ etcd --name infra2 --initial-advertise-peer-urls http://192.168.1.102:2380 \
  --listen-peer-urls http://192.168.1.102:2380 \
  --listen-client-urls http://192.168.1.102:2379 \
  --advertise-client-urls http://192.168.1.102:2379 \
  --initial-cluster-token etcd-cluster-1 \
  --initial-cluster infra0=http://192.168.1.100:2380,infra1=http://192.168.1.101:2380,infra2=http://192.168.1.102:2380 \
  --initial-cluster-state new

2. etcd发现

• 使用存在的etcd集群做自动发现

  指定集群数目

   $ curl -X PUT https://myetcd.local/v2/keys/discovery/6c007a14875d53d9bf0ef5a6fc0257c817f0fb83/_config/size -d value=3

​ 启动集群

   $ etcd --name infra0 --initial-advertise-peer-urls http://10.0.1.10:2380 \
     --listen-peer-urls http://10.0.1.10:2380 \
     --listen-client-urls http://10.0.1.10:2379,http://127.0.0.1:2379 \
     --advertise-client-urls http://10.0.1.10:2379 \
     --discovery https://myetcd.local/v2/keys/discovery/6c007a14875d53d9bf0ef5a6fc0257c817f0fb83

   $ etcd --name infra1 --initial-advertise-peer-urls http://10.0.1.11:2380 \
     --listen-peer-urls http://10.0.1.11:2380 \
     --listen-client-urls http://10.0.1.11:2379,http://127.0.0.1:2379 \
     --advertise-client-urls http://10.0.1.11:2379 \
     --discovery https://myetcd.local/v2/keys/discovery/6c007a14875d53d9bf0ef5a6fc0257c817f0fb83

   $ etcd --name infra2 --initial-advertise-peer-urls http://10.0.1.12:2380 \
     --listen-peer-urls http://10.0.1.12:2380 \
     --listen-client-urls http://10.0.1.12:2379,http://127.0.0.1:2379 \
     --advertise-client-urls http://10.0.1.12:2379 \
     --discovery https://myetcd.local/v2/keys/discovery/6c007a14875d53d9bf0ef5a6fc0257c817f0fb83

• 使用公共服务

   $ curl https://discovery.etcd.io/new?size=3
   https://discovery.etcd.io/3e86b59982e49066c5d813af1c2e2579cbf573de

   $ etcd --name infra0 --initial-advertise-peer-urls http://10.0.1.10:2380 \
     --listen-peer-urls http://10.0.1.10:2380 \
     --listen-client-urls http://10.0.1.10:2379,http://127.0.0.1:2379 \
     --advertise-client-urls http://10.0.1.10:2379 \
     --discovery https://discovery.etcd.io/3e86b59982e49066c5d813af1c2e2579cbf573de
   $ etcd --name infra1 --initial-advertise-peer-urls http://10.0.1.11:2380 \
     --listen-peer-urls http://10.0.1.11:2380 \
     --listen-client-urls http://10.0.1.11:2379,http://127.0.0.1:2379 \
     --advertise-client-urls http://10.0.1.11:2379 \
     --discovery https://discovery.etcd.io/3e86b59982e49066c5d813af1c2e2579cbf573de
   $ etcd --name infra2 --initial-advertise-peer-urls http://10.0.1.12:2380 \
     --listen-peer-urls http://10.0.1.12:2380 \
     --listen-client-urls http://10.0.1.12:2379,http://127.0.0.1:2379 \
     --advertise-client-urls http://10.0.1.12:2379 \
     --discovery https://discovery.etcd.io/3e86b59982e49066c5d813af1c2e2579cbf573de

3.DNA发现

节点监控

curl http://127.0.0.1:2379/v2/stats/leader

id: the unique identifier for the member
leaderInfo.leader: id of the current leader member
leaderInfo.uptime: amount of time the leader has been leader
name: this member's name
recvAppendRequestCnt: number of append requests this node has processed
recvBandwidthRate: number of bytes per second this node is receiving (follower only)
recvPkgRate: number of requests per second this node is receiving (follower only)
sendAppendRequestCnt: number of requests that this node has sent
sendBandwidthRate: number of bytes per second this node is sending (leader only). This value is undefined on single member clusters.
sendPkgRate: number of requests per second this node is sending (leader only). This value is undefined on single member clusters.
state: either leader or follower
startTime: the time when this node was started

curl http://127.0.0.1:2379/v2/stats/self

curl http://127.0.0.1:2379/v2/stats/store

参考

1. https://github.com/coreos/etcd
2. https://raft.github.io/
3. http://www.ruanyifeng.com/blog/2011/09/curl.html