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基于Kubernetes搭建MySQL主从集群

96
lipuan
2018.01.05 17:20* 字数 895

愿你,忠于自己,活得像自己。

清单:
Name Version
CentOS 7
Kubernetes 1.9.0
Docker 17.09.1-ce
MySQL 5.7

前言

令我始料不及的出差活动中,开始接触Kubernetes并被要求搭建基于此的MySQL主从集群,由于笔者在Linux、Kubernetes等方面都是小白,故此展开了填坑活动,写本文目的只是为了让其他程序猿少踩坑,下面简单介绍下MySQL主从集群。
我们用MySQL集群的分布式部署来实现MySQL主从模式,在MySQL集群中,Master节点主要负责数据的分发和slave节点的管理。因此Master节点主要负责数据的写入和分发(包括insert、update、delete)。而slave节点主要负责数据的读取(包括select)。基本的master和slave的分工作业,如下图所示。


MySQL集群架构

MySQL集群在主从模式下实现一台服务充当主服务器,其他一台或者多台服务器充当从服务器。下面我们开始搭建。

一、安装MySQL

二、构建Docker镜像

  • 构建镜像需要以下操作,先简单说明后面步骤将此部分内容写入Dockerfile中

master配置

  1. 文件/etc/my.cnf中[mysqld]下添加配置
log-bin=mysql-bin
server-id=1
  1. 重启MySQL
    # service mysqld restart
  2. 创建同步账号
# mysql -u root -p
# create user 'sync'@'%' identified by 'MySQL@lipuan.2018';
  1. 赋予同步账号远程权限
    # grant replication slave on *.* to 'sync'@'%' identified by 'MySQL@lipuan.2018';

slave配置

  1. 文件/etc/my.cnf中[mysqld]下添加配置
log-bin=mysql-bin
server-id=2
  1. 重启MySQL
    # service mysqld restart
  2. 配置主机IP
# mysql -u root -p
# change master to master_host='x.x.x.x',master_user='sync',master_password='MySQL@lipuan.2018';

注意: server-id为主机标识,不能重复。x.x.x.x'为master服务器IP

  • 下面我们将以上的配置写入Dockerfile中

准备master镜像

  1. 下载MySQL官方Docker镜像文件,并解压
# wget https://codeload.github.com/docker-library/mysql/zip/master
# unzip master
# mkdir /home/lipuan/mysqlDockerFile
# cp -Rf mysql-master/5.7/Dockerfile /home/lipuan/mysqlDockerFile
# cp -Rf mysql-master/5.7/docker-entrypoint.sh /home/lipuan/mysqlDockerFile
# rm -rf mysql-master
# chmod +x docker-entrypoint.sh
  1. Dockerfile中添加,位置如下图所示
RUN sed -i '/\[mysqld\]/a server-id=1\nlog-bin' /etc/mysql/mysql.conf.d/mysqld.cnf
Dockerfile-master
  1. docker-entrypoint.sh中添加,位置如下图所示
echo "CREATE USER '$MYSQL_REPLICATION_USER'@'%' IDENTIFIED BY '$MYSQL_REPLICATION_PASSWORD' ;" | "${mysql[@]}"
echo "GRANT REPLICATION SLAVE ON *.* TO '$MYSQL_REPLICATION_USER'@'%' IDENTIFIED BY '$MYSQL_REPLICATION_PASSWORD' ;" | "${mysql[@]}"

echo 'FLUSH PRIVILEGES ;' | "${mysql[@]}"
entrypoint-master

准备slave的镜像

  1. 下载MySQL官方Docker镜像文件
# wget https://codeload.github.com/docker-library/mysql/zip/master
# unzip master
# mkdir /home/lipuan/mysqlDockerFile
# cd ~
# cp -Rf mysql-master/5.7/Dockerfile /home/lipuan/mysqlDockerFile
# cp -Rf mysql-master/5.7/docker-entrypoint.sh /home/lipuan/mysqlDockerFile
# rm -rf mysql-master
# chmod +x docker-entrypoint.sh
  1. Dockerfile中添加,位置如下图所示
RUN RAND="$(date +%s | rev | cut -c 1-2)$(echo ${RANDOM})" && sed -i '/\[mysqld\]/a server-id='$RAND'\nlog-bin' /etc/mysql/mysql.conf.d/mysqld.cnf

此处server-id用的是随机数


Dockerfile-slave

2.3 docker-entrypoint.sh中添加,位置如下图所示

echo "STOP SLAVE;" | "${mysql[@]}"
echo "CHANGE MASTER TO master_host='$MYSQL_MASTER_SERVICE_HOST', master_user='$MYSQL_REPLICATION_USER', master_password='$MYSQL_REPLICATION_PASSWORD' ;" | "${mysql[@]}"

echo "START SLAVE;" | "${mysql[@]}"

slave配置中,master_host一项用的是$MYSQL_MASTER_SERVICE_HOST,这个环境变量(enviromnent variable)是由k8s生成的。


entrypoint-slave.png
  1. 构建master镜像
# cd /home/lipuan/mysqlDockerFile/
# docker build -t paulliu/mysql-master:0.1 .
  1. 构建slave镜像
# cd /home/lipuan/mysqlDockerFile/
# docker build -t paulliu/mysql-slave:0.1 .
  1. 上传镜像
# docker login
# docke push paulliu/mysql-master:0.1
# docke push paulliu/mysql-slave:0.1

三、MySQL集群部署

  • # cd /home/lipuan/DockerBuild此后内容若无指出均在此目录下执行
  • 此部分操作,所有yaml文件缩进空格必须严格,否则无法构建成功

master

  1. 新建mysql-master-rc.yaml文件
    # touch mysql-master-rc.yaml
    添加内容
apiVersion: v1
kind: ReplicationController
metadata:
  name: mysql-master
  labels:
    name: mysql-master
spec:
  replicas: 1
  selector:
    name: mysql-master
  template:
    metadata:
      labels:
        name: mysql-master
    spec:
      containers:
      - name: master
        image: paulliu/mysql-master:0.1
        ports:
        - containerPort: 3306
        env:
        - name: MYSQL_ROOT_PASSWORD
          value: "MySQL@lipuan.2018"
        - name: MYSQL_REPLICATION_USER
          value: "sync"
        - name: MYSQL_PASSWORD
          value: "MySQL@lipuan.2018"
  1. 新建mysql-master-service.yaml文件
    # touch mysql-master-service.yaml
    添加内容
apiVersion: v1
kind: Service
metadata:
  name: mysql-master
  labels:
    name: mysql-master
spec:
  ports:
  - port: 3306
    targetPort: 3306
  selector:
    name: mysql-master
  1. 部署MySQL master服务
# kubectl create -f mysql-master-rc.yaml
# kubectl create -f mysql-master-service.yaml
  1. 查看运行情况
    # kubectl get pods,service,rc

slave

  1. 新建mysql-slave-rc.yaml文件
    # touch mysql-slave-rc.yaml
    添加内容
apiVersion: v1
kind: ReplicationController
metadata:
  name: mysql-slave
  labels:
    name: mysql-slave
spec:
  replicas: 1
  selector:
    name: mysql-slave
  template:
    metadata:
      labels:
        name: mysql-slave
    spec:
      containers:
      - name: master
        image: paulliu/mysql-slave:0.1
        ports:
        - containerPort: 3306
        env:
        - name: MYSQL_ROOT_PASSWORD
          value: "MySQL@lipuan.2018"
        - name: MYSQL_REPLICATION_USER
          value: "sync"
        - name: MYSQL_PASSWORD
          value: "MySQL@lipuan.2018"
  1. 新建mysql-slave-service.yaml文件
    # touch mysql-slave-service.yaml
    添加内容
apiVersion: v1
kind: Service
metadata:
  name: mysql-slave
  labels:
    name: mysql-slave
spec:
  ports:
  - port: 3306
    targetPort: 3306
  selector:
    name: mysql-slave
  1. 部署MySQL slave服务
# kubectl create -f mysql-slave-rc.yaml
# kubectl create -f mysql-slave-service.yaml
  1. 查看运行情况
    # kubectl get pods,service,rc

写在文末

写到这里基于Kubernetes的MySQL主从集群就搭建成功了,如果有哪位朋友对于其中步骤不是很清楚,欢迎互相学习。
本文是笔者首次写技术博客,如有错漏等问题,还望各位大大指出批评!

更新日志

  1. 2018.01.13 在准备镜像部分添加了对于docker-entrypoint.sh文件授予可执行权限,若无此步骤可能导致镜像无法运行;
笔记
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