摘要：部署實現高可用常用的兩個工具連接多個，請求轉發單單，互為主輔結構結構主要部署步驟使用啟動個每個容器初始化腳本得到另一個節點的因為就兩個節點，不是就是判斷另一個節點的監聽狀態如果在監聽說明是主節點需要復制它，否則反之復制節點

memcached實現高可用常用的兩個工具：
1）magent：連接多個memcached，請求轉發
2）repcached：單master單slave，互為主輔

md-5c107eeae9fb1-0                  1/1       Running     0          59s
md-5c107eeae9fb1-1                  1/1       Running     0          49s

#得到另一個節點的HOSTNAME(因為就兩個節點，不是0就是1)
PARTNER=${HOSTNAME##*-}
if [ "${PARTNER}" = "0" ]; then
        PARTNER=${MY_POD_NAME}-1
fi
if [ "${PARTNER}" = "1" ]; then
        PARTNER=${MY_POD_NAME}-0
fi

#判斷另一個節點的監聽狀態(如果在監聽說明是主節點需要復制它，否則反之)

測試
主備切換
//啟動主節點后狀態為Listen，設置同步端口為22222
root@md-5c107eeae9fb1-0:/# memcached -p 11211 -X 22222 -v -d -u root -m 512
root@md-5c107eeae9fb1-0:/# replication: listen
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name
tcp        0      0 0.0.0.0:11211           0.0.0.0:*               LISTEN      260/memcached
tcp        0      0 0.0.0.0:22222           0.0.0.0:*               LISTEN      260/memcached
tcp6       0      0 :::11211                :::*                    LISTEN      260/memcached

//啟動復制節點，同樣設置同步端口為22222
root@md-5c107eeae9fb1-1:/# memcached -p 11211 -X 22222 -x md-5c107eeae9fb1-0.md-5c107eeae9fb1.itfarm3.svc.cluster.local -v -d -u root -m 512
root@md-5c107eeae9fb1-1:/# replication: connect (peer=10.244.5.50:22222)
replication: marugoto copying
replication: start

//從節點加入后，主節點狀態為accept并取消對22222的監聽
root@md-5c107eeae9fb1-0:/# replication: listen
replication: accept
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name
tcp        0      0 0.0.0.0:11211           0.0.0.0:*               LISTEN      263/memcached
tcp6       0      0 :::11211                :::*                    LISTEN      263/memcached

//kill掉主節點
root@md-5c107eeae9fb1-0:/# kill 263
replication: cleanup start
replication: close
root@md-5c107eeae9fb1-0:/# replication: cleanup complete

//此時從節點成Listen狀態，監聽復制端口22222，等待加入
root@md-5c107eeae9fb1-1:/# replication: connect (peer=10.244.5.50:22222)
replication: marugoto copying
replication: start
replication: close
replication: listen
Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name
tcp        0      0 0.0.0.0:11211           0.0.0.0:*               LISTEN      258/memcached
tcp        0      0 0.0.0.0:22222           0.0.0.0:*               LISTEN      258/memcached
tcp6       0      0 :::11211                :::*                    LISTEN      258/memcached
高可用
//啟動2個節點（一主一備）
md-5c107eeae9fb1-0                  1/1       Running     0          59s
md-5c107eeae9fb1-1                  1/1       Running     0          49s

//在主節點中添加item
$ telnet md-5c107eeae9fb1-0.md-5c107eeae9fb1.itfarm3.svc.cluster.local 11211
Trying 10.244.4.162...
Connected to md-5c107eeae9fb1-0.md-5c107eeae9fb1.itfarm3.svc.cluster.local.
Escape character is "^]".
set name 0 0 8
zhangsan
STORED
quit
Connection closed by foreign host.

//從節點查看item
$ telnet md-5c107eeae9fb1-1.md-5c107eeae9fb1.itfarm3.svc.cluster.local 11211
Trying 10.244.3.176...
Connected to md-5c107eeae9fb1-1.md-5c107eeae9fb1.itfarm3.svc.cluster.local.
Escape character is "^]".
get name
VALUE name 0 8
zhangsan
END

//模擬故障
$ kubectl.exe delete po md-5c107eeae9fb1-0
pod "md-5c107eeae9fb1-0" deleted

//重啟后數據恢復
$ telnet md-5c107eeae9fb1-0.md-5c107eeae9fb1.itfarm3.svc.cluster.local 11211
Trying 10.244.4.162...
Connected to md-5c107eeae9fb1-0.md-5c107eeae9fb1.itfarm3.svc.cluster.local.
Escape character is "^]".
get name
VALUE name 0 8
zhangsan
END
部署sasl安全認證的memcached

測試
//使用statefulset啟動N個memcached
md-5c11b67a6ae9b-0                  1/1       Running            0          1h
md-5c11b67a6ae9b-1                  1/1       Running            0          1h
md-5c11b67a6ae9b-2                  1/1       Running            0          1h
使用python連接memcached
$ python3
Python 3.5.2 (default, Nov 23 2017, 16:37:01)
[GCC 5.4.0 20160609] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import bmemcached
>>> client = bmemcached.Client(("md-5c11b67a6ae9b-ha:11211"), "md-5c11b67a6ae9b", "ZcUu1AVGbB3PnDzhxfOjRLJhatugwZBe")
>>> client.set("name", "zhangsan")
True
>>> client.get("name")
"zhangsan"
>>>
分布式存儲
使用無頭服務來區分多個memcache
#!/usr/bin/env python3
import bmemcached
client = bmemcached.Client(("md-5c11b67a6ae9b-0.md-5c11b67a6ae9b.itfarm3.svc.cluster.local:11211",
    "md-5c11b67a6ae9b-1.md-5c11b67a6ae9b.itfarm3.svc.cluster.local:11211",
    "md-5c11b67a6ae9b-1.md-5c11b67a6ae9b.itfarm3.svc.cluster.local:11211"), "md-5c11b67a6ae9b", "ZcUu1AVGbB3PnDzhxfOjRLJhatugwZBe")
print(client.set("name", "zhangsan"))
print(client.get("name"))
運行
$ python3 test.py
True
zhangsan
各客戶端連接開啟了sasl安全認證的memcached方案