etcd 一個(gè)分布式一致性鍵值存儲(chǔ)系統(tǒng)

etcd是一個(gè)分布式一致性鍵值存儲(chǔ)系統(tǒng)，用于共享配置和服務(wù)發(fā)現(xiàn)，專注于：
*簡(jiǎn)單：良好定義的面向用戶的API
*安全：帶有可選客戶端證書(shū)認(rèn)證的自動(dòng)TLS
*快速：測(cè)試驗(yàn)證，每秒10000寫(xiě)入
*可靠：使用Raft適當(dāng)分布
etcd 是Go編寫(xiě)，并使用Raft一致性算法來(lái)管理高可用復(fù)制日志，架構(gòu)圖如下圖所示

image.png

測(cè)試

$ cd $GOPATH
$ ./bin/etcd

$ cd $GOPATH
$ ETCDCTL_API=3 ./bin/etcdctl put foo bar

# 輸出結(jié)果顯示OK，表示安裝成功
OK

搭建本地集群

$ go get github.com/mattn/goreman

$ cd $GOPATH/src/github.com/coreos/etcd
$ goreman -f Procfile start

查看本地集群的服務(wù)器列表

$ cd $GOPATH/src/github.com/coreos/etcd

$ ./bin/etcdctl member list

# 顯示結(jié)果

8211f1d0f64f3269: name=infra1 peerURLs=http://127.0.0.1:12380 clientURLs=http://127.0.0.1:2379 isLeader=false
91bc3c398fb3c146: name=infra2 peerURLs=http://127.0.0.1:22380 clientURLs=http://127.0.0.1:22379 isLeader=true
fd422379fda50e48: name=infra3 peerURLs=http://127.0.0.1:32380 clientURLs=http://127.0.0.1:32379 isLeader=false

存儲(chǔ)數(shù)據(jù)

export ETCDCTL_API=3

$ ./bin/etcdctl put foo "Hello World!"

OK

$ ./bin/etcdctl get foo

foo
Hello World!


$ ./bin/etcdctl  --write-out="json" get foo

{"header":{"cluster_id":17237436991929493444,"member_id":9372538179322589801,"revision":2,"raft_term":2},"kvs":[{"key":"Zm9v","create_revision":2,"mod_revision":2,"version":1,"value":"SGVsbG8gV29ybGQh"}],"count":1}

根據(jù)前綴查詢

$ ./bin/etcdctl put web1 value1
$ ./bin/etcdctl put web2 value2
$ ./bin/etcdctl put web3 value3

$ ./bin/etcdctl get web --prefix

web1
value1
web2
value2
web3
value3

刪除數(shù)據(jù)

$ ./bin/etcdctl put key myvalue
$ ./bin/etcdctl del key
1
$ ./bin/etcdctl get key
// 查詢結(jié)果為空

$ ./bin/etcdctl put k1 value1
$ ./bin/etcdctl put k2 value2
$ ./bin/etcdctl del k --prefix
2
$ ./bin/etcdctl get k --prefix
// 查詢結(jié)果為空

事務(wù)寫(xiě)入

$ ./bin/etcdctl put user1 bad
OK
$ ./bin/etcdctl txn --interactive

compares:
// 輸入以下內(nèi)容，輸入結(jié)束按 兩次回車
value("user1") = "bad"      

//如果 user1 = bad，則執(zhí)行 get user1 
success requests (get, put, del):
get user1

//如果 user1 != bad，則執(zhí)行 put user1 good
failure requests (get, put, del):
put user1 good

// 運(yùn)行結(jié)果，執(zhí)行 success
SUCCESS

user1
bad



$ ./bin/etcdctl txn --interactive
compares:
value("user1") = "111"  

// 如果 user1 = 111，則執(zhí)行 get user1 
success requests (get, put, del):
get user1

//如果 user1 != 111，則執(zhí)行 put user1 2222
failure requests (get, put, del):
put user1 2222

// 運(yùn)行結(jié)果，執(zhí)行 failure
FAILURE

OK

$ ./bin/etcdctl get user1
user1
2222

watch

// 當(dāng) stock1 的數(shù)值改變（ put 方法）的時(shí)候，watch 會(huì)收到通知
$ ./bin/etcdctl watch stock1

// 新打開(kāi)終端
$ export ETCDCTL_API=3
$ ./bin/etcdctl put stock1 1000

//在watch 終端顯示
PUT
stock1
1000


$ ./bin/etcdctl watch stock --prefix
$ ./bin/etcdctl put stock1 10
$ ./bin/etcdctl put stock2 20

lease

$ ./bin/etcdctl lease grant 300
# lease 326963a02758b527 granted with TTL(300s)

$ ./bin/etcdctl put sample value --lease=326963a02758b527
OK

$ ./bin/etcdctl get sample

$ ./bin/etcdctl lease keep-alive 326963a02758b520
$ ./bin/etcdctl lease revoke 326963a02758b527
lease 326963a02758b527 revoked

# or after 300 seconds
$ ./bin/etcdctl get sample

Distributed locks

//第一終端
$ ./bin/etcdctl lock mutex1
mutex1/326963a02758b52d

# 第二終端
$ ./bin/etcdctl lock mutex1

// 當(dāng)?shù)谝粋€(gè)終端結(jié)束了，第二個(gè)終端會(huì)顯示
mutex1/326963a02758b531

Elections

$ ./bin/etcdctl elect one p1

one/326963a02758b539
p1


# another client with the same name blocks
$ ./bin/etcdctl elect one p2

//結(jié)束第一終端，第二終端顯示
one/326963a02758b53e
p2

Cluster status

集群狀態(tài)

$ ./bin/etcdctl --write-out=table endpoint status

$ ./bin/etcdctl endpoint health

Snapshot

./bin/etcdctl snapshot save my.db

Snapshot saved at my.db

./bin/etcdctl --write-out=table snapshot status my.db

Member

./bin/etcdctl member list -w table