Kubernetes 部署 MySQL 主從服務(wù)

一般情況下 Kubernetes 可以通過 ReplicaSet 以一個 Pod 模板創(chuàng)建多個 pod 副本，但是它們都是無狀態(tài)的，任何時候它們都可以被一個全新的 pod 替換。然而有狀態(tài)的 pod 需要另外的方案確保當(dāng)一個有狀態(tài)的 pod 掛掉后，這個 pod 實例需要在別的節(jié)點上重建，但是新的實例必須與被替換的實例擁有相同的名稱、網(wǎng)絡(luò)標識和狀態(tài)。這就是 Statefulset 管理 pod 的手段。

對于容器集群，有狀態(tài)服務(wù)的挑戰(zhàn)在于，通常集群中的任何節(jié)點都并非100%可靠的，服務(wù)所需的資源也會動態(tài)地更新改變。當(dāng)節(jié)點由于故障或服務(wù)由于需要更多的資源而無法繼續(xù)運行在原有節(jié)點上時，集群管理系統(tǒng)會為該服務(wù)重新分配一個新的運行位置，從而確保從整體上看，集群對外的服務(wù)不會中斷。若采用本地存儲，當(dāng)服務(wù)漂移后數(shù)據(jù)并不會隨著服務(wù)轉(zhuǎn)移到新的節(jié)點，重啟服務(wù)就會出現(xiàn)數(shù)據(jù)丟失的困境。

本文目的是通過一個 mysql 的主從集群搭建，深入了解 kubernetes 的 statfulset 管理。為了降低實驗的外部依賴，存儲層面上，我采用的是本地存儲，當(dāng)然生產(chǎn)上不建議這樣做，生產(chǎn)環(huán)境的存儲推薦官方介紹到的的 gce、nfs、ceph等存儲方案，因為這些方案支持動態(tài)供給的特性，允許開發(fā)人員通過 pvc 的定義，快速實現(xiàn)數(shù)據(jù)有效存儲，所以你絕不應(yīng)該把一個宿主機上的目錄當(dāng)作 PV 使用， 只是本文用于實驗需要，采用 Local Persistent Volume 的手段，目的只是為了驗證 Statefulset 的狀態(tài)管理功能。

實驗環(huán)境

• kubernetes Master
• kubernetes Node（測試演示，所有的副本都會在其上運行）
• kubernetes DNS 服務(wù)已開啟

實驗?zāi)康?/span>

• 搭建一個主從復(fù)制（Master-Slave）的 MySQL 集群
• 從節(jié)點可以水平擴展
• 所有的寫操作只能在主節(jié)點上執(zhí)行
• 讀操作可以在主從節(jié)點上執(zhí)行
• 從節(jié)點能同步主節(jié)點的數(shù)據(jù)

本地存儲原理

為了快速搭建測試環(huán)境，我們這里使用了本地存儲，也就是說，用戶希望 Kubernetes 能夠直接使用宿主機上的本地磁盤目錄，而不依賴于遠程存儲服務(wù)，來提供持久化的容器 Volume。不過這里有個難點：

“

我們把存儲固定在一個節(jié)點上，但是pod在調(diào)度的時候，是飄來飄去的，怎么能讓pod通過pvc也能固定在pv上？

”

給這個 Pod 加上一個 nodeAffinity 行不行？

當(dāng)然行，但是這變相破壞了開發(fā)人員對資源對象的定義規(guī)范了，開發(fā)人員應(yīng)該不需要時刻考慮調(diào)度的細節(jié)。調(diào)度的改動應(yīng)該交給運維就行。所以我們?yōu)榱藢崿F(xiàn)本地存儲，我們采用了 延遲綁定 的方法。方法很簡單，我們都知道 storageclass 一般由運維人員設(shè)計，我們只需要在storageclass 指定 no-provisioner。這是因為 Local Persistent Volume 目前尚不支持 Dynamic Provisioning，所以它沒辦法在用戶創(chuàng)建 PVC 的時候，就自動創(chuàng)建出對應(yīng)的 PV。與此同時，這個 StorageClass 還定義了一個 volumeBindingMode=WaitForFirstConsumer 的屬性。它是 Local Persistent Volume 里一個非常重要的特性，即：延遲綁定

kind:?StorageClass
apiVersion:?storage.k8s.io/v1
metadata:
??name:?local-storage
provisioner:?kubernetes.io/no-provisioner
volumeBindingMode:?WaitForFirstConsumer

實驗步驟

一、先在node （實驗用的node節(jié)點IP是172.31.170.51 ）節(jié)點上，預(yù)先分配幾個pv (不建議在生產(chǎn)上這樣操作)

01-persistentVolume-1.yaml

apiVersion:?v1
kind:?PersistentVolume
metadata:
??name:?example-mysql-pv
spec:
??capacity:
????storage:?15Gi
??volumeMode:?Filesystem
??accessModes:
??-?ReadWriteOnce
??persistentVolumeReclaimPolicy:?Delete
??storageClassName:?local-storage
??local:
????path:?/data/svr/projects/mysql
??nodeAffinity:
????required:
??????nodeSelectorTerms:
??????-?matchExpressions:
????????-?key:?kubernetes.io/hostname
??????????operator:?In
??????????values:
??????????-?172.31.170.51

01-persistentVolume-2.yaml

apiVersion:?v1
kind:?PersistentVolume
metadata:
??name:?example-mysql-pv-2
spec:
??capacity:
????storage:?15Gi
??volumeMode:?Filesystem
??accessModes:
??-?ReadWriteOnce
??persistentVolumeReclaimPolicy:?Delete
??storageClassName:?local-storage
??local:
????path:?/data/svr/projects/mysql2
??nodeAffinity:
????required:
??????nodeSelectorTerms:
??????-?matchExpressions:
????????-?key:?kubernetes.io/hostname
??????????operator:?In
??????????values:
??????????-?172.31.170.51

01-persistentVolume-3.yaml

apiVersion:?v1
kind:?PersistentVolume
metadata:
??name:?example-mysql-pv-3
spec:
??capacity:
????storage:?15Gi
??volumeMode:?Filesystem
??accessModes:
??-?ReadWriteOnce
??persistentVolumeReclaimPolicy:?Delete
??storageClassName:?local-storage
??local:
????path:?/data/svr/projects/mysql3
??nodeAffinity:
????required:
??????nodeSelectorTerms:
??????-?matchExpressions:
????????-?key:?kubernetes.io/hostname
??????????operator:?In
??????????values:
??????????-?172.31.170.51

記住，這是在生產(chǎn)上不推薦的做法，我只是實驗用途才這樣手動預(yù)先創(chuàng)建，正規(guī)的做法應(yīng)該通過storageclass采用 Dynamic Provisioning， 而不是 Static Provisioning 機制生產(chǎn)PV。

kubectl?apply?-f?01-persistentVolume-{1..3}.yaml

persistentvolume/example-mysql-pv1?created
persistentvolume/example-mysql-pv2?created
persistentvolume/example-mysql-pv3?created

二、創(chuàng)建 StorageClass

02-storageclass.yaml

kind:?StorageClass
apiVersion:?storage.k8s.io/v1
metadata:
??name:?local-storage
provisioner:?kubernetes.io/no-provisioner
volumeBindingMode:?WaitForFirstConsumer

執(zhí)行創(chuàng)建

kubectl?apply?-f?02-storageclass.yaml

storageclass.storage.k8s.io/local-storage?created

三、創(chuàng)建Namespace

03-mysql-namespace.yaml

apiVersion:?v1
kind:?Namespace
metadata:
??name:?mysql
??labels:
????app:?mysql

執(zhí)行創(chuàng)建

kubectl?apply?-f?03-mysql-namespace.yaml

namespace/mysql?created

四、使用 ConfigMap 為 Master/Slave 節(jié)點分配不同的配置文件

04-mysql-configmap.yaml

apiVersion:?v1
kind:?ConfigMap
metadata:
??name:?mysql
??namespace:?mysql
??labels:
????app:?mysql
data:
??master.cnf:?|
????#?Master配置
????[mysqld]
????log-bin=mysqllog
????skip-name-resolve
??slave.cnf:?|
????#?Slave配置
????[mysqld]
????super-read-only
????skip-name-resolve
????log-bin=mysql-bin
????replicate-ignore-db=mysql

創(chuàng)建執(zhí)行

kubectl?apply?-f?04-mysql-configmap.yaml

configmap/mysql?created

五、創(chuàng)建mysql密碼Secret

05-mysql-secret.yaml

apiVersion:?v1
kind:?Secret
metadata:
??name:?mysql-secret
??namespace:?mysql
??labels:
????app:?mysql
type:?Opaque
data:
??password:?MTIzNDU2?#?echo?-n?"123456"?|?base64

創(chuàng)建執(zhí)行

kubectl?apply?-f?05-mysql-secret.yaml

secret/mysql-secret?created

六、使用 Service 為 MySQL 提供讀寫分離

06-mysql-services.yaml

apiVersion:?v1
kind:?Service
metadata:
??name:?mysql
??namespace:?mysql
??labels:
????app:?mysql
spec:
??ports:
??-?name:?mysql
????port:?3306
??clusterIP:?None
??selector:
????app:?mysql
---
apiVersion:?v1
kind:?Service
metadata:
??name:?mysql-read
??namespace:?mysql
??labels:
????app:?mysql
spec:
??ports:
??-?name:?mysql
????port:?3306
??selector:
????app:?mysql

用戶所有寫請求，必須以 DNS 記錄的方式直接訪問到 Master 節(jié)點，也就是 mysql-0.mysql 這條 DNS 記錄。

用戶所有讀請求，必須訪問自動分配的 DNS 記錄可以被轉(zhuǎn)發(fā)到任意一個 Master 或 Slave 節(jié)點上，也就是 mysql-read 這條 DNS 記錄

kubectl?apply?-f?06-mysql-services.yaml

$?kubectl?get?svc?-n?mysql
NAME?????????TYPE????????CLUSTER-IP???EXTERNAL-IP???PORT(S)????AGE
mysql????????ClusterIP???None?????????????????3306/TCP???20s
mysql-read???ClusterIP???10.0.0.63????????????3306/TCP???20s

七、使用 StatefulSet 搭建 MySQL 主從集群

07-mysql-statefulset.yaml

apiVersion:?apps/v1
kind:?StatefulSet
metadata:
??name:?mysql
??namespace:?mysql
??labels:
????app:?mysql
spec:
??selector:
????matchLabels:
??????app:?mysql
??serviceName:?mysql
??replicas:?2
??template:
????metadata:
??????labels:
????????app:?mysql
????spec:
??????initContainers:
??????-?name:?init-mysql
????????image:?mysql:5.7
????????env:
????????-?name:?MYSQL_ROOT_PASSWORD
??????????valueFrom:
????????????secretKeyRef:
??????????????name:?mysql-secret
??????????????key:?password
????????command:
????????-?bash
????????-?"-c"
????????-?|
??????????set?-ex
??????????#?從?Pod?的序號，生成?server-id
??????????[[?$(hostname)?=~?-([0-9]+)$?]]?||?exit?1
??????????ordinal=${BASH_REMATCH[1]}
??????????echo?[mysqld]?>?/mnt/conf.d/server-id.cnf
??????????#?由于?server-id?不能為?0，因此給?ID?加?100?來避開它
??????????echo?server-id=$((100?+?$ordinal))?>>?/mnt/conf.d/server-id.cnf
??????????#?如果?Pod?的序號為?0，說明它是?Master?節(jié)點，從?ConfigMap?里把?Master?的配置文件拷貝到?/mnt/conf.d?目錄下
??????????#?否則，拷貝?ConfigMap?里的?Slave?的配置文件
??????????if?[[?${ordinal}?-eq?0?]];?then
????????????cp?/mnt/config-map/master.cnf?/mnt/conf.d
??????????else
????????????cp?/mnt/config-map/slave.cnf?/mnt/conf.d
??????????fi
????????volumeMounts:
????????-?name:?conf
??????????mountPath:?/mnt/conf.d
????????-?name:?config-map
??????????mountPath:?/mnt/config-map
??????-?name:?clone-mysql
????????image:?gcr.io/google-samples/xtrabackup:1.0
????????env:
????????-?name:?MYSQL_ROOT_PASSWORD
??????????valueFrom:
????????????secretKeyRef:
??????????????name:?mysql-secret
??????????????key:?password
????????command:
????????-?bash
????????-?"-c"
????????-?|
??????????set?-ex
??????????#?拷貝操作只需要在第一次啟動時進行，所以數(shù)據(jù)已經(jīng)存在則跳過
??????????[[?-d?/var/lib/mysql/mysql?]]?&&?exit?0
??????????#?Master?節(jié)點（序號為?0）不需要這個操作
??????????[[?$(hostname)?=~?-([0-9]+)$?]]?||?exit?1
??????????ordinal=${BASH_REMATCH[1]}
??????????[[?$ordinal?==?0?]]?&&?exit?0
??????????#?使用?ncat?指令，遠程地從前一個節(jié)點拷貝數(shù)據(jù)到本地
??????????ncat?--recv-only?mysql-$(($ordinal-1)).mysql?3307?|?xbstream?-x?-C?/var/lib/mysql
??????????#?執(zhí)行?--prepare，這樣拷貝來的數(shù)據(jù)就可以用作恢復(fù)了
??????????xtrabackup?--prepare?--target-dir=/var/lib/mysql
????????volumeMounts:
????????-?name:?data
??????????mountPath:?/var/lib/mysql
??????????subPath:?mysql
????????-?name:?conf
??????????mountPath:?/etc/mysql/conf.d
??????containers:
??????-?name:?mysql
????????image:?mysql:5.7
????????env:
#????????-?name:?MYSQL_ALLOW_EMPTY_PASSWORD
#??????????value:?"1"
????????-?name:?MYSQL_ROOT_PASSWORD
??????????valueFrom:
????????????secretKeyRef:
??????????????name:?mysql-secret
??????????????key:?password
????????ports:
????????-?name:?mysql
??????????containerPort:?3306
????????volumeMounts:
????????-?name:?data
??????????mountPath:?/var/lib/mysql
??????????subPath:?mysql
????????-?name:?conf
??????????mountPath:?/etc/mysql/conf.d
????????resources:
??????????requests:
????????????cpu:?500m
????????????memory:?1Gi
????????livenessProbe:
??????????exec:
????????????command:?["mysqladmin",?"ping",?"-uroot",?"-p${MYSQL_ROOT_PASSWORD}"]
??????????initialDelaySeconds:?30
??????????periodSeconds:?10
??????????timeoutSeconds:?5
????????readinessProbe:
??????????exec:
????????????command:?["mysqladmin",?"ping",?"-uroot",?"-p${MYSQL_ROOT_PASSWORD}"]
??????????initialDelaySeconds:?5
??????????periodSeconds:?2
??????????timeoutSeconds:?1
??????-?name:?xtrabackup
????????image:?gcr.io/google-samples/xtrabackup:1.0
????????ports:
????????-?name:?xtrabackup
??????????containerPort:?3307
????????env:
????????-?name:?MYSQL_ROOT_PASSWORD
??????????valueFrom:
????????????secretKeyRef:
??????????????name:?mysql-secret
??????????????key:?password
????????command:
????????-?bash
????????-?"-c"
????????-?|
??????????set?-ex
??????????cd?/var/lib/mysql
??????????#?從備份信息文件里讀取?MASTER_LOG_FILE?和?MASTER_LOG_POS?這?2?個字段的值，用來拼裝集群初始化?SQL
??????????if?[[?-f?xtrabackup_slave_info?]];?then
????????????#?如果?xtrabackup_slave_info?文件存在，說明這個備份數(shù)據(jù)來自于另一個?Slave?節(jié)點
????????????#?這種情況下，XtraBackup?工具在備份的時候，就已經(jīng)在這個文件里自動生成了?"CHANGE?MASTER?TO"?SQL?語句
????????????#?所以，只需要把這個文件重命名為?change_master_to.sql.in，后面直接使用即可
????????????mv?xtrabackup_slave_info?change_master_to.sql.in
????????????#?所以，也就用不著?xtrabackup_binlog_info?了
????????????rm?-f?xtrabackup_binlog_info
??????????elif?[[?-f?xtrabackup_binlog_info?]];?then
????????????#?如果只是存在?xtrabackup_binlog_info?文件，說明備份來自于?Master?節(jié)點，就需要解析這個備份信息文件，讀取所需的兩個字段的值
????????????[[?$(cat?xtrabackup_binlog_info)?=~?^(.*?)[[:space:]]+(.*?)$?]]?||?exit?1
????????????rm?xtrabackup_binlog_info
????????????#?把兩個字段的值拼裝成?SQL，寫入?change_master_to.sql.in?文件
????????????echo?"CHANGE?MASTER?TO?MASTER_LOG_FILE='${BASH_REMATCH[1]}',\
??????????????????MASTER_LOG_POS=${BASH_REMATCH[2]}"?>?change_master_to.sql.in
??????????fi
??????????#?如果存在?change_master_to.sql.in，就意味著需要做集群初始化工作
??????????if?[[?-f?change_master_to.sql.in?]];?then
????????????#?但一定要先等?MySQL?容器啟動之后才能進行下一步連接?MySQL?的操作
????????????echo?"Waiting?for?mysqld?to?be?ready（accepting?connections）"
????????????until?mysql?-h?127.0.0.1?-uroot?-p${MYSQL_ROOT_PASSWORD}?-e?"SELECT?1";?do?sleep?1;?done
????????????echo?"Initializing?replication?from?clone?position"
????????????#?將文件?change_master_to.sql.in?改個名字
????????????#?防止這個?Container?重啟的時候，因為又找到了?change_master_to.sql.in，從而重復(fù)執(zhí)行一遍初始化流程
????????????mv?change_master_to.sql.in?change_master_to.sql.orig
????????????#?使用?change_master_to.sql.orig?的內(nèi)容，也就是前面拼裝的?SQL，組成一個完整的初始化和啟動?Slave?的?SQL?語句
????????????mysql?-h?127.0.0.1?-uroot?-p${MYSQL_ROOT_PASSWORD}?<??????????$(????????????MASTER_HOST='mysql-0.mysql.mysql',
????????????MASTER_USER='root',
????????????MASTER_PASSWORD='${MYSQL_ROOT_PASSWORD}',
????????????MASTER_CONNECT_RETRY=10;
??????????START?SLAVE;
??????????EOF
??????????fi
??????????#?使用 ncat 監(jiān)聽 3307 端口。
??????????#?它的作用是，在收到傳輸請求的時候，直接執(zhí)行?xtrabackup?--backup?命令，備份?MySQL?的數(shù)據(jù)并發(fā)送給請求者
??????????exec?ncat?--listen?--keep-open?--send-only?--max-conns=1?3307?-c?\
????????????"xtrabackup?--backup?--slave-info?--stream=xbstream?--host=127.0.0.1?--user=root?--password=${MYSQL_ROOT_PASSWORD}"
????????volumeMounts:
????????-?name:?data
??????????mountPath:?/var/lib/mysql
??????????subPath:?mysql
????????-?name:?conf
??????????mountPath:?/etc/mysql/conf.d
??????volumes:
??????-?name:?conf
????????emptyDir:?{}
??????-?name:?config-map
????????configMap:
??????????name:?mysql
??volumeClaimTemplates:
??-?metadata:
??????name:?data
????spec:
??????accessModes:
??????-?"ReadWriteOnce"
??????storageClassName:?local-storage
??????resources:
????????requests:
??????????storage:?3Gi

整體的statefulset有兩個replicas，一個Master, 一個Slave，然后使用 init-mysql 這個 initContainers 進行配置文件的初始化。接著使用 clone-mysql 這個 initContainers 進行數(shù)據(jù)的傳輸；同時使用 xtrabackup 這個 sidecar 容器進行SQL初始化和數(shù)據(jù)傳輸功能

創(chuàng)建 StatefulSet

kubectl?apply?-f?07-mysql-statefulset.yaml

$?kubectl?get?po?-n?mysql
NAME??????READY???STATUS????RESTARTS???AGE
mysql-0???2/2?????Running???0??????????70s
mysql-1???0/2?????Pending???0??????????5s

可以看到，StatefulSet 啟動成功后，會有兩個Pod運行。

接下來，我們可以嘗試向這個MySQL集群發(fā)起請求，執(zhí)行一些SQL操作來驗證它是否正常

服務(wù)驗證

驗證主從狀態(tài)

kubectl?-n?mysql?exec?mysql-1?-c?mysql?--?bash?-c?"mysql?-uroot?-p123456?-e?'show?slave?status?\G'"


mysql:?[Warning]?Using?a?password?on?the?command?line?interface?can?be?insecure.
***************************?1.?row?***************************
???????????????Slave_IO_State:?Waiting?for?master?to?send?event
??????????????????Master_Host:?mysql-0.mysql.mysql
??????????????????Master_User:?root
??????????????????Master_Port:?3306
????????????????Connect_Retry:?10
??????????????Master_Log_File:?mysqllog.000003
??????????Read_Master_Log_Pos:?154
???????????????Relay_Log_File:?mysql-1-relay-bin.000002
????????????????Relay_Log_Pos:?319
????????Relay_Master_Log_File:?mysqllog.000003
?????????????Slave_IO_Running:?Yes
????????????Slave_SQL_Running:?Yes
??????????????Replicate_Do_DB:?
??????????Replicate_Ignore_DB:?mysql
???????????Replicate_Do_Table:?
???????Replicate_Ignore_Table:?
??????Replicate_Wild_Do_Table:?
??Replicate_Wild_Ignore_Table:?
???????????????????Last_Errno:?0
???????????????????Last_Error:?
?????????????????Skip_Counter:?0
??????????Exec_Master_Log_Pos:?154
??????????????Relay_Log_Space:?528
??????????????Until_Condition:?None
???????????????Until_Log_File:?
????????????????Until_Log_Pos:?0
???????????Master_SSL_Allowed:?No
???????????Master_SSL_CA_File:?
???????????Master_SSL_CA_Path:?
??????????????Master_SSL_Cert:?
????????????Master_SSL_Cipher:?
???????????????Master_SSL_Key:?
????????Seconds_Behind_Master:?0
Master_SSL_Verify_Server_Cert:?No
????????????????Last_IO_Errno:?0
????????????????Last_IO_Error:?
???????????????Last_SQL_Errno:?0
???????????????Last_SQL_Error:?
??Replicate_Ignore_Server_Ids:?
?????????????Master_Server_Id:?100
??????????????????Master_UUID:?1bad4d64-6290-11ea-8376-0242ac113802
?????????????Master_Info_File:?/var/lib/mysql/master.info
????????????????????SQL_Delay:?0
??????????SQL_Remaining_Delay:?NULL
??????Slave_SQL_Running_State:?Slave?has?read?all?relay?log;?waiting?for?more?updates
???????????Master_Retry_Count:?86400
??????????????????Master_Bind:?
??????Last_IO_Error_Timestamp:?
?????Last_SQL_Error_Timestamp:?
???????????????Master_SSL_Crl:?
???????????Master_SSL_Crlpath:?
???????????Retrieved_Gtid_Set:?
????????????Executed_Gtid_Set:?
????????????????Auto_Position:?0
?????????Replicate_Rewrite_DB:?
?????????????????Channel_Name:?
???????????Master_TLS_Version:

接下來，我們通過Master容器創(chuàng)建數(shù)據(jù)庫和表、插入數(shù)據(jù)庫

kubectl?-n?mysql?exec?mysql-0?-c?mysql?--?bash?-c?"mysql?-uroot?-p123456?-e?'create?database?test’"
kubectl?-n?mysql?exec?mysql-0?-c?mysql?--?bash?-c?"mysql?-uroot?-p123456?-e?'use?test;create?table?counter(c?int);’"
kubectl?-n?mysql?exec?mysql-0?-c?mysql?--?bash?-c?"mysql?-uroot?-p123456?-e?'use?test;insert?into?counter?values(123)’"

然后，我們觀察Slave節(jié)點是否都同步到數(shù)據(jù)了

kubectl?-n?mysql?exec?mysql-1?-c?mysql?--?bash?-c?"mysql?-uroot?-p123456?-e?'use?test;select?*?from?counter’"??
c
123

當(dāng)看到輸出結(jié)果，主從同步正常了

擴展從節(jié)點

在有了 StatefulSet 以后，你就可以像 Deployment 那樣，非常方便地擴展這個 MySQL 集群，比如

kubectl?-n?mysql?scale?statefulset?mysql?-—replicas=3

$?kubectl?get?po?-n?mysql
NAME??????READY???STATUS????RESTARTS???AGE
mysql-0???2/2?????Running???0??????????22m
mysql-1???2/2?????Running???0??????????22m
mysql-2???2/2?????Running???0??????????20s

這時候，一個新的mysql-2就創(chuàng)建出來了，我們繼續(xù)驗證新擴容的節(jié)點是否都同步到主節(jié)點的數(shù)據(jù)

kubectl?-n?mysql?exec?mysql-2?-c?mysql?--?bash?-c?"mysql?-uroot?-p123456?-e?'use?test;select?*?from?counter’"??
c
123

當(dāng)看到輸出結(jié)果，主從同步正常了。也就是說從 StatefulSet 為我們新創(chuàng)建的 mysql-2 上，同樣可以讀取到之前插入的記錄。也就是說，我們的數(shù)據(jù)備份和恢復(fù)，都是有效的。

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原文鏈接：https://lihaoquan.me/2020/3/6/mysql-master-slave-statefulset.html

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