MySql主从测试
参考: https://cloud.tencent.com/developer/article/2019481
参考: https://www.cpweb.top/2278
参考: https://blog.csdn.net/easylife206/article/details/122994676
背景
- 搭建一个
主从复制（Master-Slave）的MySQL集群 - 从节点可以水平扩展
- 所有的
写操作只能在MySQL主节点上执行 - 读操作可以在MySQL主从节点上执行
- 从节点能同步主节点的数据
部署
1，创建Namespace
apiVersion: v1
kind: Namespace
metadata:
name: test-mysql-ms
labels:
app: mysql2，创建数据库的配置文件configmap
使用ConfigMap为Master/Slave节点分配不同的配置文件
apiVersion: v1
kind: ConfigMap
metadata:
name: mysql
namespace: test-mysql-ms
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=mysql3，创建MySQL密码Secret
apiVersion: v1
kind: Secret
metadata:
name: mysql-secret
namespace: test-mysql-ms
labels:
app: mysql
type: Opaque
data:
password: MTIzNDU2 # echo -n "123456" | base644，使用Service为MySQL提供读写分离
- 用户所有写请求，必须以DNS记录的方式直接访问到Master节点，也就是mysql-0.mysql这条DNS记录。
- 用户所有读请求，必须访问自动分配的DNS记录可以被转发到任意一个Master或Slave节点上，也就是mysql-read这条DNS记录。
apiVersion: v1
kind: Service
metadata:
name: mysql
namespace: test-mysql-ms
labels:
app: mysql
spec:
ports:
- name: mysql
port: 3306
clusterIP: None
selector:
app: mysql
---
apiVersion: v1
kind: Service
metadata:
name: mysql-read
namespace: test-mysql-ms
labels:
app: mysql
spec:
ports:
- name: mysql
port: 3306
selector:
app: mysql5，创建MySQL集群实例
使用StatefulSet搭建MySQL主从集群，
整体的StatefulSet有两个Replicas，一个Master，一个Slave，然后使用init-mysql这个initContainers进行配置文件的初始化。接着使用clone-mysql这个initContainers进行数据的传输；同时使用xtrabackup这个sidecar 容器进行SQL初始化和数据传输功能。
apiVersion: apps/v1
kind: StatefulSet
metadata:
name: mysql
namespace: test-mysql-ms
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
image: mysql:5.7-debian
env:
- name: MYSQL_ROOT_PASSWORD
valueFrom:
secretKeyRef:
name: mysql-secret
key: password
command:
- bash
- "-c"
- |
set -ex
# 从Pod的序号，生成server-id
[[ $(hostname) =~ -([0-9]+)$ ]] || exit 1
ordinal=${BASH_REMATCH[1]}
echo [mysqld] > /mnt/conf.d/server-id.cnf
# 由于server-id不能为0，因此给ID加100来避开它
echo server-id=$((100 + $ordinal)) >> /mnt/conf.d/server-id.cnf
# 如果Pod的序号为0，说明它是Master节点，从ConfigMap里把Master的配置文件拷贝到/mnt/conf.d目录下
# 否则，拷贝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.tencentcloudcr.com/google-samples/xtrabackup:1.0
image: yizhiyong/xtrabackup
env:
- name: MYSQL_ROOT_PASSWORD
valueFrom:
secretKeyRef:
name: mysql-secret
key: password
command:
- bash
- "-c"
- |
set -ex
# 拷贝操作只需要在第一次启动时进行，所以数据已经存在则跳过
[[ -d /var/lib/mysql/mysql ]] && exit 0
# Master 节点（序号为 0）不需要这个操作
[[ $(hostname) =~ -([0-9]+)$ ]] || exit 1
ordinal=${BASH_REMATCH[1]}
[[ $ordinal == 0 ]] && exit 0
# 使用ncat指令，远程地从前一个节点拷贝数据到本地
ncat --recv-only mysql-$(($ordinal-1)).mysql 3307 | xbstream -x -C /var/lib/mysql
# 执行 --prepare，这样拷贝来的数据就可以用作恢复了
xtrabackup --prepare --target-dir=/var/lib/mysql
volumeMounts:
- name: data
mountPath: /var/lib/mysql
subPath: mysql
- name: conf
mountPath: /etc/mysql/conf.d
containers:
- name: mysql
#image: mysql:5.7
image: mysql:5.7-debian
env:
# - name: MYSQL_ALLOW_EMPTY_PASSWORD
# value: "1"
- name: MYSQL_ROOT_PASSWORD
valueFrom:
secretKeyRef:
name: mysql-secret
key: password
ports:
- name: mysql
containerPort: 3306
volumeMounts:
- name: data
mountPath: /var/lib/mysql
subPath: mysql
- name: conf
mountPath: /etc/mysql/conf.d
resources:
requests:
cpu: 500m
memory: 1Gi
livenessProbe:
exec:
command: ["mysqladmin", "ping", "-uroot", "-p${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.tencentcloudcr.com/google-samples/xtrabackup:1.0
image: yizhiyong/xtrabackup
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
# 从备份信息文件里读取MASTER_LOG_FILE和MASTER_LOG_POS这2个字段的值，用来拼装集群初始化SQL
if [[ -f xtrabackup_slave_info ]]; then
# 如果xtrabackup_slave_info文件存在，说明这个备份数据来自于另一个Slave节点
# 这种情况下，XtraBackup工具在备份的时候，就已经在这个文件里自动生成了“CHANGE MASTER TO”SQL语句
# 所以，只需要把这个文件重命名为change_master_to.sql.in，后面直接使用即可
mv xtrabackup_slave_info change_master_to.sql.in
# 所以，也就用不着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，说明备份来自于Master节点，就需要解析这个备份信息文件，读取所需的两个字段的值
[[ $(cat xtrabackup_binlog_info) =~ ^(.*?)[[:space:]]+(.*?)$ ]] || exit 1
rm xtrabackup_binlog_info
# 把两个字段的值拼装成SQL，写入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，就意味着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容器启动之后才能进行下一步连接MySQL的操作
echo "Waiting for mysqld to be ready（accepting connections）"
until mysql -h 127.0.0.1 -uroot -p${MYSQL_ROOT_PASSWORD} -e "SELECT 1"; do sleep 1; done
echo "Initializing replication from clone position"
# 将文件change_master_to.sql.in改个名字
# 防止这个Container重启的时候，因为又找到了change_master_to.sql.in，从而重复执行一遍初始化流程
mv change_master_to.sql.in change_master_to.sql.orig
# 使用change_master_to.sql.orig的内容，也就是前面拼装的SQL，组成一个完整的初始化和启动Slave的SQL语句
mysql -h 127.0.0.1 -uroot -p${MYSQL_ROOT_PASSWORD} << EOF
$(< change_master_to.sql.orig),
#MASTER_HOST='mysql-0.mysql.mysql',
MASTER_HOST='mysql-0.mysql.test-mysql-ms',
MASTER_USER='root',
MASTER_PASSWORD='${MYSQL_ROOT_PASSWORD}',
MASTER_CONNECT_RETRY=10;
START SLAVE;
EOF
fi
# 使用ncat监听3307端口。
# 它的作用是，在收到传输请求的时候，直接执行xtrabackup --backup命令，备份MySQL的数据并发送给请求者
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: csi-rbd-sc
resources:
requests:
storage: 10Gi可以看到，StatefulSet启动成功后，会有两个Pod运行。接下来，我们可以尝试向这个MySQL集群发起请求，执行一些SQL操作来验证它是否正常。整个过程因为拉取mysql和一个gcr.io/google-samples/xtrabackup:1.0（使用腾讯云加速镜像地址gcr.tencentcloudcr.com）国外的镜像会很慢,但是在创建mysql-0拉取一次之后，后续创建mysql-1就相对很快了。
这里将 mysql:5.7镜像换成了mysql:5.7-debian镜像(官方默认镜像好像切成了oraclelinux底层镜像, 默认没hostname命令)
xtrabackup的镜像, 本来应该是gcr.io/google-samples/xtrabackup:1.0, 加速镜像 gcr.tencentcloudcr.com/google-samples/xtrabackup:1.0好像也不能用. 网上找了个别人copy下来的yizhiyong/xtrabackup.
注意: 现在官方xtrabackup好像已经到版本8以上了. 可能需要更新.
主从初始化命令中MASTER_HOST='mysql-0.mysql.mysql'改成了MASTER_HOST='mysql-0.mysql.test-mysql-ms' 因为这里命名空间变了. (如果这里不小心初始化错了, 记得删pvc, 然后默认会自动删pv, 不然还是挂上次的卷)
检查容器和服务状态
root@wangjm-B550M-K-1:~/k8s/ns/test-mysql-ms# kubectl get all -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
pod/mysql-0 2/2 Running 0 2m10s 172.30.0.16 wangjm-b550m-k-1 <none> <none>
pod/mysql-1 2/2 Running 0 94s 172.30.2.26 wangjm-b550m-k-3 <none> <none>
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE SELECTOR
service/mysql ClusterIP None <none> 3306/TCP 2m10s app=mysql
service/mysql-read ClusterIP 172.31.12.58 <none> 3306/TCP 2m10s app=mysql
NAME READY AGE CONTAINERS IMAGES
statefulset.apps/mysql 2/2 2m10s mysql,xtrabackup mysql:5.7-debian,yizhiyong/xtrabackup
服务验证
1，验证主从关系
root@wangjm-B550M-K-1:~/k8s/ns/test-mysql-ms# kubectl 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.test-mysql-ms
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: 3f7fd4e3-158d-11ef-bd1f-5a45077593fd
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:
2，接下来，我们通过Master容器创建数据库和表、插入数据库。
kubectl exec mysql-0 -c mysql -- bash -c "mysql -uroot -p123456 -e 'create database test'"
kubectl exec mysql-0 -c mysql -- bash -c "mysql -uroot -p123456 -e 'use test;create table counter(c int);'"
kubectl exec mysql-0 -c mysql -- bash -c "mysql -uroot -p123456 -e 'use test;insert into counter values(123)'"3，然后，我们观察Slave节点是否都同步到数据了
root@wangjm-B550M-K-1:~/k8s/ns/test-mysql-ms# kubectl exec mysql-1 -c mysql -- bash -c "mysql -uroot -p123456 -e 'use test;select * from counter'"
mysql: [Warning] Using a password on the command line interface can be insecure.
c
123
扩展从节点
在有了StatefulSet以后，你就可以像Deployment那样，非常方便地扩展这个MySQL集群，比如：
root@wangjm-B550M-K-1:~/k8s/ns/test-mysql-ms# kubectl scale statefulset mysql --replicas=3
statefulset.apps/mysql scaled
root@wangjm-B550M-K-1:~/k8s/ns/test-mysql-ms# kubectl get pods
NAME READY STATUS RESTARTS AGE
mysql-0 2/2 Running 0 4m59s
mysql-1 2/2 Running 0 4m23s
mysql-2 0/2 Init:0/2 0 10s
root@wangjm-B550M-K-1:~/k8s/ns/test-mysql-ms# kubectl get pods
NAME READY STATUS RESTARTS AGE
mysql-0 2/2 Running 0 7m21s
mysql-1 2/2 Running 0 6m45s
mysql-2 2/2 Running 0 2m32s
这时候，一个新的mysql-2就创建出来了，我们继续验证新扩容的节点是否都同步到主节点的数据。
root@wangjm-B550M-K-1:~/k8s/ns/test-mysql-ms# kubectl exec mysql-2 -c mysql -- bash -c "mysql -uroot -p123456 -e 'use test;select * from counter'"
mysql: [Warning] Using a password on the command line interface can be insecure.
c
123
当看到输出结果，主从同步正常了。也就是说从StatefulSet为我们新创建的mysql-2上，同样可以读取到之前插入的记录。也就是说，我们的数据备份和恢复，都是有效的
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