k8s HA 高可用集群之etcd集群

etcd元件作為乙個高可用強一致性的服務發現儲存倉庫。我們此次在三個主機上搭建了乙個包含三個etcd節點的集群，實現了集群的動態擴充套件和收縮，並測試和驗證了etcd集群鍵——值儲存的一致性和高可用性。

一、環境準備

os: ubuntu 14.04

user: root

ipaddress: etcd01: 192.168.200.24

etcd02: 192.168.200.25

etcd03: 192.168.200.26

這裡用的是etcd-v2.3.7-linux-amd64.tar.gz

二、安裝配置etcd

etcd01上安裝

tar xf etcd-v2.3.7-linux-amd64.tar.gz

cd etcd-v2.3.7-linux-amd64

cp etcd* /usr/local/bin/

建立etcd01指令碼，可方便配置etcd啟動引數

#cat etcd01

/usr/local/bin/etcd -name etcd01 \

-data-dir /data/etcd01 \

-advertise-client-urls \

-listen-client-urls \

-initial-advertise-peer-urls

-listen-peer-urls \

-initial-cluster-token etcd-cluster-1 \

-initial-cluster etcd01= \

-initial-cluster-state new

引數說明：-name 指定名字

-data-dir 指定資料儲存目錄，預設是當前目錄

-initial-cluster-state 集群狀態 new為新建立集群 existing為已存在（可不指定）

在etcd02 etcd03上分別做相似操作

指令碼中-advertise-client-urls 和 -initial-advertis-peer-urls 引數修改一下即可

然後分別執行指令碼：nohup ./etcd01 &

三、測試

在任一台主機上執行etcdctl member list

#etcdctl member list

6a223770249e927d: name=etcd02 peerurls= clienturls= isleader=false

7e0ce16121dfea24: name=etcd01 peerurls= clienturls= isleader=true

bfc28be8765b503e: name=etcd03 peerurls= clienturls= isleader=false

可以看到集群的節點情況，並能看出哪個是leader節點

我們在etcd01上設定乙個key/value

root@etcd1:~# etcdctl set api_server

這時就可以在任意一台主機上獲取這個key/value

root@etcd2:~# etcdctl get api_server

root@etcd3:~# etcdctl get api_server

在member list上看到etcd01是leader ，這時把etcd01停掉（kill）

用etcdctl cluster-health檢視

root@etcd2:~# etcdctl cluster-health

member 6a223770249e927d is healthy: got healthy result from

failed to check the health of member 7e0ce16121dfea24 on get dial tcp 192.168.200.24:2379: getsockopt: connection refused

failed to check the health of member 7e0ce16121dfea24 on get dial tcp 192.168.200.24:4001: getsockopt: connection refused

member 7e0ce16121dfea24 is unreachable: [ are all unreachable

member bfc28be8765b503e is healthy: got healthy result from

cluster is healthy

並且集群leader進行了重新選舉

root@etcd2:~# etcdctl member list

6a223770249e927d: name=etcd02 peerurls= clienturls= isleader=true

7e0ce16121dfea24: name=etcd01 peerurls= clienturls= isleader=false

bfc28be8765b503e: name=etcd03 peerurls= clienturls= isleader=false

現在etcd02是leader了，這時我們在群集中設定兩個key/value

root@etcd2:~# etcdctl set test01 123456

123456

root@etcd2:~# etcdctl set test02 abcdefg

abcdefg

重新啟動etcd01

root@etcd1:~# etcdctl cluster-health

member 6a223770249e927d is healthy: got healthy result from

member 7e0ce16121dfea24 is healthy: got healthy result from

member bfc28be8765b503e is healthy: got healthy result from

cluster is healthy

root@etcd1:~# etcdctl get test01

123456

root@etcd1:~# etcdctl get test02

abcdefg

但這時在etcd01重新加入集群，並保持了key/value的全域性一致性，由此可見 etcd 搭建的集群是可以實現高可用的。

etcd集群如果收縮很簡單，直接在命令列輸入

etcdctl member remove

$memberid是你即將要刪除節點的etcd的id，etcd的擴充套件有一些地方需要注意一下，我在這裡操作的時候遇到了不少坑。從上文寫到現在，有乙個資料夾很重要，幾乎每個坑都與它有關，那就是-data-dir所宣告的資料夾，注意要擴充套件乙個etcd集群時，首先在集群內的任一台機器上輸入

etcdctl member add $etcd_name

$peer_url

$etcd_name：新加入的etcd節點的名字

$peer_url：一般為新加入的節點 ip:2380

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