安陽做網(wǎng)站推廣網(wǎng)站排名優(yōu)化怎樣做
目錄
哨兵的作用和工作原理
服務(wù)狀態(tài)監(jiān)控
選舉新的 master
如何實現(xiàn)故障轉(zhuǎn)移
搭建哨兵集群
哨兵的作用和工作原理
Redis 提供了哨兵 (Sentinel) 機制來實現(xiàn)主從集群的自動故障恢復(fù)。哨兵的結(jié)構(gòu)和作用如下
-
監(jiān)控：Sentinel 會不斷檢查你的 master 和 slave 是否按預(yù)期工作
-
自動故障恢復(fù)：如果 master 故障， Sentinel 會將一個 Slave 提成為 master ，當故障實例恢復(fù)后也還是以新的 master 為主
-
通知：Sentinel 充當 Redis 客戶端的服務(wù)發(fā)現(xiàn)來源，當集群發(fā)生故障轉(zhuǎn)移時，會將最新消息推送至 Redis 客戶端
服務(wù)狀態(tài)監(jiān)控
Sentinel 基于心跳機制檢測服務(wù)狀態(tài)，每隔 1 秒向集群的每個實例發(fā)送ping 命令
-
主管下線：如果某 Sentinel 節(jié)點發(fā)現(xiàn)某實例未在規(guī)定時間內(nèi)響應(yīng)，則認為該實例主觀下線
-
客觀下線：若超過指定數(shù)量（quorum）的 sentinel 都認為該實例主觀下線，則該實例客觀下線。quorum 值最好超過 Sentinel 實例數(shù)量的一半
選舉新的 master
一旦發(fā)現(xiàn) master 故障，sentinel 需要在 slave 中選擇一個作為新的 master ：
-
首先會判斷 slave 節(jié)點與 master 節(jié)點斷開的時間長短，如果超出指定值 （down-after-milliseconds * 10）則會排除該 slave 節(jié)點
-
然后判斷 slave 節(jié)點的 slave-priority 值，越小優(yōu)先級越高，如果是 0 則永遠不參與選舉
-
如果 slave-prority 一樣，則判斷 slave 節(jié)點的 offset 值，越大說明數(shù)據(jù)越新，優(yōu)先級越高
-
最后是判斷 slave 節(jié)點的運行 id 大小，越小優(yōu)先級越高
如何實現(xiàn)故障轉(zhuǎn)移
當選中了其中一個 slave 為新的 master 后，故障的轉(zhuǎn)移的步驟如下
-
sentinel 給備選的 slave 節(jié)點發(fā)送 slaveof no one 命令，讓該節(jié)點成為 master
-
sentinel 給所有其他 slave 發(fā)送 slaveof 192.168.142.152 6379 命令，讓這些 slave 成為新的 master 的從節(jié)點，開始從新的 master 上同步數(shù)據(jù)
-
最后，sentinel 將故障節(jié)點標記為 slave ，當故障節(jié)點恢復(fù)后會自動成為新的 master 的 slave 節(jié)點
搭建哨兵集群
| IP | PORT | ROLE |
|---|---|---|
| 192.168.142.157 | 6379 | master |
| 192.168.142.156 | 6379 | slave |
| 192.168.142.155 | 6379 | slave02 |
| 192.168.142.157 | 26379 | sentinel |
| 192.168.142.156 | 26379 | sentinel |
| 192.168.142.155 | 26379 | sentinel |
我這里省事，只用了三臺服務(wù)
master , sentinel
docker-compose.yml
services:redis-master:image: hub.atomgit.com/amd64/redis:7.0.13restart: alwayscontainer_name: redis-masterprivileged: trueports:- '6379:6379'volumes:- redis-data:/opt/bitnami/redis/data- /root/redis.conf:/etc/redis.conf- /etc/localtime:/etc/localtime:rocommand:- /bin/sh- -c- redis-server /etc/redis.confredis-sentinel:image: hub.atomgit.com/amd64/redis:7.0.13restart: alwayscontainer_name: redis-sentinelprivileged: trueports:- '26379:26379'volumes:- /root/sentinel.conf:/etc/sentinel.conf- /etc/localtime:/etc/localtime:rocommand:- /bin/sh- -c- redis-server /etc/sentinel.conf --sentinel
volumes:redis-data:
redis.conf
daemonize no
port 6379
protected-mode no
bind 0.0.0.0
requirepass 123456
sentinel.conf
port 26379
protected-mode no
sentinel monitor mymaster 192.168.142.157 6379 2
sentinel auth-pass mymaster 123456
sentinel down-after-milliseconds mymaster 5000
sentinel parallel-syncs mymaster 1
sentinel failover-timeout mymaster 3000
slave , sentinel
docker-compose.yml
services:redis-slave:image: hub.atomgit.com/amd64/redis:7.0.13restart: alwayscontainer_name: redis-slaveprivileged: trueports:- '6379:6379'volumes:- redis-data:/opt/bitnami/redis/data- /root/redis.conf:/etc/redis.conf- /etc/localtime:/etc/localtime:rocommand:- /bin/sh- -c- redis-server /etc/redis.confredis-sentinel:image: hub.atomgit.com/amd64/redis:7.0.13restart: alwayscontainer_name: redis-sentinelprivileged: trueports:- '26379:26379'volumes:- /root/sentinel.conf:/etc/sentinel.conf- /etc/localtime:/etc/localtime:rocommand:- /bin/sh- -c- redis-server /etc/sentinel.conf --sentinel
volumes:redis-data:
redis.conf
daemonize no
port 6379
protected-mode no
masterauth 123456
requirepass 123456
slave-read-only yes
bind 0.0.0.0
slaveof 192.168.142.157 6379
sentinel.conf
port 26379
protected-mode no
sentinel monitor mymaster 192.168.142.157 6379 2
sentinel auth-pass mymaster 123456
sentinel down-after-milliseconds mymaster 5000
sentinel parallel-syncs mymaster 1
sentinel failover-timeout mymaster 3000slave02 , sentinel
docker-compose.yml
services:redis-slave02:image: hub.atomgit.com/amd64/redis:7.0.13restart: alwayscontainer_name: redis-slave02privileged: trueports:- '6379:6379'volumes:- redis-data:/opt/bitnami/redis/data- /root/redis.conf:/etc/redis.conf- /etc/localtime:/etc/localtime:rocommand:- /bin/sh- -c- redis-server /etc/redis.confredis-sentinel:image: hub.atomgit.com/amd64/redis:7.0.13restart: alwayscontainer_name: redis-sentinelprivileged: trueports:- '26379:26379'volumes:- /root/sentinel.conf:/etc/sentinel.conf- /etc/localtime:/etc/localtime:rocommand:- /bin/sh- -c- redis-server /etc/sentinel.conf --sentinel
volumes:redis-data:
redis.conf
daemonize no
port 6379
protected-mode no
masterauth 123456
requirepass 123456
slave-read-only yes
bind 0.0.0.0
slaveof 192.168.142.157 6379
sentinel.conf
port 26379
protected-mode no
sentinel monitor mymaster 192.168.142.157 6379 2
sentinel auth-pass mymaster 123456
sentinel down-after-milliseconds mymaster 5000
sentinel parallel-syncs mymaster 1
sentinel failover-timeout mymaster 3000
哨兵就盯著 master 看，一旦 master g了就立刻預(yù)警，就可以開始啟動 docker 了
啟動 docker
在三臺主機上分別執(zhí)行
docker compose up -d
查看狀態(tài) Up 表示成功啟動
root@master:~# docker ps -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
aa6466e6fa15 hub.atomgit.com/amd64/redis:7.0.13 "docker-entrypoint.s…" 27 minutes ago Up 21 minutes 6379/tcp, 0.0.0.0:26379->26379/tcp, :::26379->26379/tcp redis-sentinel
27a2f19d8040 hub.atomgit.com/amd64/redis:7.0.13 "docker-entrypoint.s…" 27 minutes ago Up 21 minutes 0.0.0.0:6379->6379/tcp, :::6379->6379/tcp redis-master
root@slave:~# docker ps -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
1d3df2c507f5 hub.atomgit.com/amd64/redis:7.0.13 "docker-entrypoint.s…" 25 minutes ago Up 21 minutes 6379/tcp, 0.0.0.0:26379->26379/tcp, :::26379->26379/tcp redis-sentinel
b9b981917f2d hub.atomgit.com/amd64/redis:7.0.13 "docker-entrypoint.s…" About an hour ago Up 21 minutes 0.0.0.0:6379->6379/tcp, :::6379->6379/tcp redis-slave
root@slave02:~# docker ps -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
774fb813bbf2 hub.atomgit.com/amd64/redis:7.0.13 "docker-entrypoint.s…" 23 minutes ago Up 20 minutes 6379/tcp, 0.0.0.0:26379->26379/tcp, :::26379->26379/tcp redis-sentinel
02a276c8edc8 hub.atomgit.com/amd64/redis:7.0.13 "docker-entrypoint.s…" About an hour ago Up 20 minutes 0.0.0.0:6379->6379/tcp, :::6379->6379/tcp redis-slave02
啟動成功就可以去查看 sentinel 的狀態(tài)了
root@master:~# docker exec redis-sentinel redis-cli -p 26379 -c info sentinel
# Sentinel
sentinel_masters:1
sentinel_tilt:0
sentinel_tilt_since_seconds:-1
sentinel_running_scripts:0
sentinel_scripts_queue_length:0
sentinel_simulate_failure_flags:0
master0:name=mymaster,status=ok,address=192.168.142.157:6379,slaves=2,sentinels=1
root@slave:~# docker exec -it redis-sentinel redis-cli -p 26379 -c info sentinel
# Sentinel
sentinel_masters:1
sentinel_tilt:0
sentinel_tilt_since_seconds:-1
sentinel_running_scripts:0
sentinel_scripts_queue_length:0
sentinel_simulate_failure_flags:0
master0:name=mymaster,status=ok,address=192.168.142.157:6379,slaves=0,sentinels=1
root@slave02:~# docker exec -it redis-sentinel redis-cli -p 26379 -c info sentinel
# Sentinel
sentinel_masters:1
sentinel_tilt:0
sentinel_tilt_since_seconds:-1
sentinel_running_scripts:0
sentinel_scripts_queue_length:0
sentinel_simulate_failure_flags:0
master0:name=mymaster,status=ok,address=192.168.142.157:6379,slaves=0,sentinels=1
出現(xiàn)本機 ip 和 ok 狀態(tài)就代表哨兵啟動成功
測試
假設(shè) master 宕機
root@master:~# docker stop redis-master查看 slave
root@slave:~# docker exec redis-slave redis-cli -a 123456 -c role
slave
192.168.142.157
6379
connect
-1
Warning: Using a password with '-a' or '-u' option on the command line interface may not be safe.
查看 slave02
root@slave02:~# docker exec -it redis-slave02 redis-cli -a 123456 -c role
Warning: Using a password with '-a' or '-u' option on the command line interface may not be safe.
1) "master"
2) (integer) 19487
3) 1) 1) "192.168.142.156"2) "6379"3) "19347"
到此，哨兵搭建完成
補充
關(guān)于 sentinel.conf 講解
-
sentinel monitor mymaster 192.168.142.157?6379 2 指定主節(jié)點信息
-
mymaster 主節(jié)點名稱，自定義
-
192.168.142.157?6379 主節(jié)點 IP 和端口
-
2 選舉 master 時的 quorum 值
-
-
sentinel down-after-milliseconds mymaster 5000 salve 與 master 斷開的超時時間
-
sentinel failover-timeout mymaster 60000 故障恢復(fù)的超時時間
-
sentinel auth-pass mymaster 123456 主節(jié)點密碼
-
sentinel parallel-syncs mymaster 1
這條指令告訴 Sentinel，對于名為mymaster的 Redis 主節(jié)點，在進行故障轉(zhuǎn)移時，只允許一個從節(jié)點同時對新的主節(jié)點進行數(shù)據(jù)同步。這意味著在故障轉(zhuǎn)移過程中，只有一個從節(jié)點會開始與新的主節(jié)點同步數(shù)據(jù)，其他從節(jié)點會等待，直到該從節(jié)點完成同步后才開始。設(shè)置
parallel-syncs為 1 可以確保在故障轉(zhuǎn)移期間，只有一個從節(jié)點在任何給定時間與新的主節(jié)點進行數(shù)據(jù)同步。這樣做的好處是可以減少對新主節(jié)點的負載，避免在故障轉(zhuǎn)移期間對新主節(jié)點造成過大的壓力，從而影響其性能。然而，這也意味著故障轉(zhuǎn)移過程可能會花費更長的時間，因為從節(jié)點需要一個接一個地進行數(shù)據(jù)同步。