kubernetes mysql多主_2020-11-02 使用K8s部署MySQL 双主集群

机器

角色

mysql-0

master\slave

mysql-1

slave\master

最近对线上集群做高可用升级，在对比了几个集群策略之后，综合现有资源、复杂度、可用度之后，选择了两个：

MySQL双主的互为备份的2节点集群

MySQL基于wsrep协议的Galera Cluster的mysql多主集群

初步处于复杂度考虑，选择了方案一。

方案一又有两个版本：

利用keepalived做活跃监督

利用k8s service做负载均衡，达到和活跃监督一样的效果

我们选择最简单的k8s service，先做测试。无论哪一种，首先都要实现双主的互为备份的2节点部署。

一、部署

选择 dockerhub上的MySQL：5.7.32作为基础镜像。依赖于镜像本身的启动命令，做修改，然后部署。

1.Dockerfile

以dockerhub上的mysql为基础镜像

From mysql:5.7.32

COPY my.cnf /etc/mysql/

COPY replication.sh /usr/local/bin/

COPY docker-entrypoint.sh /usr/local/bin/

ENV MYSQL_ROOT_PASSWORD=123456

RUN chmod 755 /usr/local/bin/replication.sh && \

chmod a+x /usr/local/bin/replication.sh && \

chmod 755 /usr/local/bin/docker-entrypoint.sh && \

chmod a+x /usr/local/bin/docker-entrypoint.sh && \

chmod 755 /etc/mysql/my.cnf && \

chmod a+x /etc/mysql/my.cnf && \

chown -R mysql:mysql /usr/local/bin/replication.sh && \

chown -R mysql:mysql /usr/sbin/mysqld && \

chown -R mysql:mysql /etc/mysql/

ENTRYPOINT ["docker-entrypoint.sh"]

EXPOSE 3306 33060

CMD ["mysqld"]

2.docker-entrypoint.sh

新增一个方法：mysql_replication

mysql_replication() {

echo 'start to do the mysql replication'

master_host=''

if [[ $MY_POD_NAME = 'mysql-0' ]];then

master_host='mysql-1.mysql.'${MY_POD_NAMESPACE}'.svc.cluster.local'

else

master_host='mysql-0.mysql.'${MY_POD_NAMESPACE}'.svc.cluster.local'

fi

echo 'add the master and slave roles, the master host is:' $master_host

replication_user=${MYSQL_REPLICATION_USER:-replication}

replication_password=${MYSQL_REPLICATION_PASSWORD:-replication_password}

echo 'the replication user is: '$replication_user ', pass is: '$replication_password

docker_process_sql --database=mysql <

CREATE USER '$replication_user'@'%' IDENTIFIED BY '$replication_password' ;

GRANT REPLICATION SLAVE ON *.* TO '$replication_user'@'%' IDENTIFIED BY '$replication_password' ;

FLUSH PRIVILEGES ;

EOSQL

echo 'created the replication user.'

echo 'start to register to master: ' $master_host

master_bin_fetch=`

docker_process_sql --database=mysql <

show master status;

EOSQL

`

echo 'fetch the master status.'

title='File Position Binlog_Do_DB Binlog_Ignore_DB Executed_Gtid_Set'

title_length=${#title}

master_bin_info=${master_bin_fetch: $title_length+1}

echo 'master bin info is: '$master_bin_info

bin_name='mysql-bin.000002'

bin_length=${#bin_name}

bin_file==${master_bin_info: 0 :$bin_length+1}

position_number=${master_bin_info: $bin_length+1}

echo 'the master bin file is: '$bin_file ', the position number is: '$position_number

#从本地文件读取最新的BIN_FILE,不过现在没有用了，作废了

bin_file=`ls /var/log/mysql | grep mysql-bin.0 | sort -n | tail -1`

echo 'the master bin file is: '$bin_file ', the position number is set to 0'

#不设置MASTER_BIN_FILE和MASTER_LOG_POSITION,去除了master pod的区别设置，依赖MySQL自己去发现

docker_process_sql --database=mysql <

STOP SLAVE;

RESET SLAVE;

CHANGE MASTER TO master_host='$master_host', master_user='$replication_user', master_password='$replication_password';

CHANGE REPLICATION FILTER REPLICATE_WILD_IGNORE_TABLE = ('mysql.%');

START SLAVE;

EOSQL

3.my.cnf

这里有一个报错：

2020-11-02T07:35:58.108646Z 2 [ERROR] Slave SQL for channel '': Error 'Operation CREATE USER failed for 'replication'@'%'' on query. Default database: 'mysql'. Query: 'CREATE USER 'replication'@'%' IDENTIFIED WITH 'mysql_native_password' AS '*1A629BF5797BF6AE523D06B26B94561098D18F4C'', Error_code: 1396

2020-11-02T07:35:58.108692Z 2 [Warning] Slave: Operation CREATE USER failed for 'replication'@'%' Error_code: 1396

2020-11-02T07:35:58.108701Z 2 [ERROR] Error running query, slave SQL thread aborted. Fix the problem, and restart the slave SQL thread with "SLAVE START". We stopped at log 'mysql-bin.000002' position 3071516.

是因为主从复制还带有master、slave中的User表，我们新增了用户，在log bin中写有日志，两个MySQL已启动就去同步log bin，造成原有用户已存在，同步失败的错误。

解决这个错误，就要忽略User表的变化，修改my.cnf中的replicate-ignore-db

或者修改REPLICATE_WILD_IGNORE_TABLE

这个还需要调研

# Copyright (c) 2014, 2016, Oracle and/or its affiliates. All rights reserved.

#

# This program is free software; you can redistribute it and/or modify

# it under the terms of the GNU General Public License as published by

# the Free Software Foundation; version 2 of the License.

#

# This program is distributed in the hope that it will be useful,

# but WITHOUT ANY WARRANTY; without even the implied warranty of

# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the

# GNU General Public License for more details.

#

# You should have received a copy of the GNU General Public License

# along with this program; if not, write to the Free Software

# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA

#

# The MySQL Server configuration file.

#

# For explanations see

# http://dev.mysql.com/doc/mysql/en/server-system-variables.html

[mysqld]

#这里的ID只能是纯数子，多么痛的领悟

server-id=

log-bin=/var/log/mysql/mysql-bin.log

replicate-ignore-db = mysql

log_bin_index = /var/log/mysql/mysql-bin.log.index

relay_log = /var/log/mysql/mysql-relay-bin

relay_log_index = /var/log/mysql/mysql-relay-bin.index

#log-error=/usr/local/mysql/log/error.log

#log=/usr/local/mysql/log/mysql.log

character-set-client-handshake = FALSE

character-set-server = utf8mb4

collation-server = utf8mb4_unicode_ci

init_connect='SET NAMES utf8mb4'

pid-file = /var/run/mysqld/mysqld.pid

socket = /var/run/mysqld/mysqld.sock

datadir = /var/lib/mysql

#log-error = /var/log/mysql/error.log

# By default we only accept connections from localhost

#bind-address = 127.0.0.1

# Disabling symbolic-links is recommended to prevent assorted security risks

symbolic-links=0

sql_mode="IGNORE_SPACE,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION"

[client]

default-character-set = utf8mb4

[mysql]

default-character-set = utf8mb4

4.mysql.yaml

apiVersion: apps/v1

kind: StatefulSet

metadata:

name: mysql

labels:

app: mysql

spec:

replicas: 2

updateStrategy:

type: RollingUpdate

serviceName: "mysql"

selector:

matchLabels:

app: mysql

template:

metadata:

labels:

app: mysql

spec:

nodeSelector:

mysql: "true"

securityContext:

runAsUser: 0

containers:

- name: mysql

image: test/mysql:mysql1

env:

- name: MY_POD_NAMESPACE

valueFrom:

fieldRef:

fieldPath: metadata.namespace

- name: MY_POD_NAME

valueFrom:

fieldRef:

fieldPath: metadata.name

imagePullPolicy: Never

ports:

- containerPort: 3306

---

kind: Service

apiVersion: v1

metadata:

name: mysql

spec:

ports:

- port: 3306

targetPort: 3306

selector:

app: mysql

二、测试

分别登陆到两个MySQL，使用

show slave status\G;

创建新的数据库

create database test;

观察新数据库有没有同步到另一个MySQL上面。