在进行Docker MySQL容器创建时,业界推荐采用Dockerfile构建方式,而不是通过docker commit提交镜像。尽管后者也能实现,但团队协作中难以追溯容器内的具体变更,可维护性较差。本教程的方案基于Dockerfile,并引入supervisord多服务管理——由于Dockerfile仅允许单个CMD指令生效,若需同时启动MySQL和SSH管理,单一CMD无法满足需求。虽然容器管理不一定依赖SSH(数据备份可通过--volumes-from,重启使用docker restart),但许多运维人员习惯SSH登录管理,因此镜像中集成了SSH服务。
如何用Docker创建MySQL容器
首先确认当前Docker版本(本文示例为1.6.0-rc5):
[root@private_network mysql]# docker version
Client version: 1.6.0-rc5
Client API version: 1.18
Go version (client): go1.4.2
Git commit (client): fc4825d
OS/Arch (client): linux/amd64
Server version: 1.6.0-rc5
Server API version: 1.18
Go version (server): go1.4.2
Git commit (server): fc4825d
OS/Arch (server): linux/amd64
准备以下目录与文件结构:
mysql/
|-- cmake-3.2.2.tar.gz
|-- create_mysql_user.sh # mysql用户初始化脚本
|-- Dockerfile
|-- install_mysql-5.6.24.sh # mysql服务安装脚本
|-- my.cnf # mysql服务配置文件
|-- mysql-5.6.24.tar.gz
`-- supervisord.conf # 服务管理工具配置文件
Dockerfile核心配置解析:
# FROM: 依赖的镜像
FROM ted1993/mysql:5.6.24
# RUN: 执行命令
RUN yum -y install tar gcc-c++ supervisor ncurses-devel libtool bison bison-devel pwgen
RUN mkdir -p /var/log/supervisor
# ADD: 添加本地文件到容器中,如果是压缩包会在目标目录自动解压
ADD ./supervisord.conf /etc/supervisord.conf
ADD ./cmake-3.2.2.tar.gz /root/tools/
ADD ./mysql-5.6.24.tar.gz /root/tools/
ADD ./install_mysql-5.6.24.sh /root/tools/
ADD ./create_mysql_user.sh /create_mysql_user.sh
# WORKDIR: 当前工作目录
WORKDIR /root/tools/
RUN sh install_mysql-5.6.24.sh
ADD ./my.cnf /data/server/mysql-5.6.24/etc/my.cnf
RUN rm -rf /root/tools/mysql-5.6.24
RUN rm -rf /root/tools/mysql-5.6.24.tar.gz
RUN rm -rf /root/tools/cmake-3.2.2
RUN rm -rf /root/tools/cmake-3.2.2.tar.gz
# EXPOSE: 暴露的端口
EXPOSE 22 3306
# CMD: 容器启动执行的命令,一个Dockerfile只有一个CMD生效
CMD ["/usr/bin/supervisord"]
supervisord配置文件用于统一管理MySQL与SSH服务:
[supervisord]
nodaemon=true
[program:mysqld]
command=/etc/init.d/mysqld start
numprocs=1
autostart=true
autorestart=true
[program:sshd]
command=/usr/sbin/sshd -D
numprocs=1
autostart=true
autorestart=true
MySQL安装脚本(install_mysql-5.6.24.sh)实现编译与初始化操作:
#!/bin/bash
grep "^mysql:" /etc/passwd &> /dev/null || groupadd mysql && useradd -g mysql -s /sbin/nologin mysql
if [ ! -d cmake-3.2.2 ];then
tar xzvf cmake-3.2.2.tar.gz
fi
cd cmake-3.2.2
./bootstrap && gmake && gmake install && cd ..
if [ ! -d mysql-5.6.24 ];then
tar xzf mysql-5.6.24.tar.gz
fi
cd mysql-5.6.24
cmake \
-DCMAKE_INSTALL_PREFIX=/data/server/mysql-5.6.24 \
-DMYSQL_UNIX_ADDR=/tmp/mysql.sock \
-DMYSQL_DATADIR=/data/mysql-5.6.24/ \
-DSYSCONFDIR=/data/server/mysql-5.6.24/etc/ \
-DWITH_INNOBASE_STORAGE_ENGINE=1 \
-DWITH_MYISAM_STORAGE_ENGINE=1 \
-DWITH_PARTITION_STORAGE_ENGINE=1 \
-DWITH_PERFSCHEMA_STORAGE_ENGINE=1 \
-DWITH_ARCHIVE_STORAGE_ENGINE=1 \
-DWITH_BLACKHOLE_STORAGE_ENGINE=1 \
-DWITH_EXTRA_CHARSETS=complex \
-DENABLED_LOCAL_INFILE=1 \
-DDEFAULT_CHARSET=utf8 \
-DDEFAULT_COLLATION=utf8_unicode_ci \
-DWITH_DEBUG=0
CPU_NUM=$(cat /proc/cpuinfo | grep processor | wc -l)
if [ $CPU_NUM -gt 1 ];then
make -j$CPU_NUM
else
make
fi
make install
echo "PATH=\$PATH:/data/server/mysql/bin" >> /etc/profile && . /etc/profile
ln -s /data/server/mysql-5.6.24/ /data/server/mysql
rm -rf /etc/my.cnf
mkdir -p /data/server/mysql-5.6.24/etc/
mkdir -p /data/server/mysql/data/
mkdir -p /data/log/mysql/
chown -R mysql:mysql /data/server/mysql/
chown -R mysql:mysql /data/server/mysql/data/
chown -R mysql:mysql /data/log/mysql
\cp -f /data/server/mysql/support-files/mysql.server /etc/init.d/mysqld
sed -i 's#^basedir=$#basedir=/data/server/mysql#' /etc/init.d/mysqld
sed -i 's#^datadir=$#datadir=/data/server/mysql/data#' /etc/init.d/mysqld
chmod 755 /etc/init.d/mysqld
/data/server/mysql/scripts/mysql_install_db --datadir=/data/server/mysql/data/ --basedir=/data/server/mysql --user=mysql
用户初始化脚本(create_mysql_user.sh)在容器启动时自动生成随机密码:
#!/bin/bash
/data/server/mysql/bin/mysqld_safe >> /dev/null 2>&1 &
RET=1
while [[ RET -ne 0 ]]; do
echo "=> Waiting for confirmation of MySQL service startup"
sleep 5
/data/server/mysql/bin/mysql -uroot -e "status" > /dev/null 2>&1
RET=$?
done
echo "============================MYSQL_PASS_INFO=============================== "
echo ""
PASS_ROOT=${MYSQL_PASS:-$(pwgen -s 8 1)}
PASS_DBA=${MYSQL_PASS:-$(pwgen -s 8 1)}
echo ""
echo "=> Creating MySQL root user with ${PASS_ROOT} password"
echo "=> Creating MySQL dba user with ${PASS_DBA} password"
echo ""
/data/server/mysql/bin/mysql -uroot -e "grant all privileges on *.* to 'dba'@'%' identified by '${PASS_DBA}'";
/data/server/mysql/bin/mysql -uroot -e "update mysql.user set password=PASSWORD('${PASS_ROOT}') where user='root' and host='localhost'";
echo ""
echo "===================================END====================================="
echo ""
echo "=> Done!"
echo ""
echo ""
echo "==============================REMOTE_MYSQL_PASSWORD====================="
echo "You can now connect to this MySQL Server using:"
echo ""
echo " mysql -udba -p${PASS_DBA} -h -P"
echo ""
echo "Please remember to change the above password as soon as possible!"
echo "MySQL user 'root' has no password but only allows local connections"
echo "========================================================================"
完成上述配置后,执行以下命令构建Docker镜像:
docker build -t ted1993/mysql:5.6.24 . # 注意最后面有一个"."
使用docker images命令查看已构建的镜像:
[root@private_network mysql]# docker images
REPOSITORY TAG IMAGE ID CREATED VIRTUAL SIZE
ted1993/mysql 5.6.24 d3ed9c578f4c 5 days ago 902.8 MB
启动容器时,可使用-P随机映射端口,或指定-p 3306:3306固定映射:
docker run -d -P ted1993/mysql:5.6.24
检查容器运行状态:
[root@private_network mysql]# docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
ab622592bf1e mysql:5.6.24 "/usr/bin/supervisor 3 days ago Up 3 days 0.0.0.0:5000->22/tcp, 0.0.0.0:5001->3306/tcp jolly_swartz
若需将运行中的容器保存为新镜像,可执行docker commit:
docker commit ab622592bf1e ted1993/mysql:2015-06-02
使用Docker Link实现容器互联
在生产环境中,多个容器常常需要协同工作,例如一个MySQL服务器容器与多个客户端容器的通信。Docker的--link标志正是为容器间安全连接而设计的。
首先需要准备两个镜像:MySQL服务器镜像和仅包含mysql命令行工具的客户端镜像。
在mysql_server目录下创建Dockerfile,内容如下:
FROM centos:centos6
RUN yum install -y mysql-server mysql
RUN /etc/init.d/mysqld start &&\
mysql -e "grant all privileges on *.* to 'root'@'%' identified by 'letmein';"&&\
mysql -e "grant all privileges on *.* to 'root'@'localhost' identified by 'letmein';"&&\
mysql -u root -pletmein -e "show databases;"
EXPOSE 3306
CMD ["/usr/bin/mysqld_safe"]
执行以下命令构建服务器镜像:
sudo docker build -t kongxx/mysql_server .
接着创建mysql_client目录,Dockerfile内容如下:
FROM centos:centos6
RUN yum install -y mysql
构建客户端镜像:
sudo docker build -t kongxx/mysql_client .
验证已构建的镜像列表:
$ sudo docker images | grep kongxx
kongxx/mysql_client latest aa31f22f6fc5 2 hours ago 303.7 MB
kongxx/mysql_server latest 3b9b08c8dda4 2 hours ago 353.3 MB
启动MySQL服务端容器:
sudo docker run --name=mysql_server -d -P kongxx/mysql_server
创建两个客户端容器,并使用--link参数连接到服务器容器,设置别名为db:
sudo docker run --name=mysql_client1 --link=mysql_server:db -t -i kongxx/mysql_client /usr/bin/mysql -h db -u root -pletmein
sudo docker run --name=mysql_client2 --link=mysql_server:db -t -i kongxx/mysql_client /usr/bin/mysql -h db -u root -pletmein
注意,--link=mysql_server:db将服务器容器的主机名解析为db,因此在客户端容器中可直接通过-h db连接。执行完毕后,查看容器状态:
sudo docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
ac0c76c627c0 kongxx/mysql_client:latest /usr/bin/mysql -h db 10 seconds ago Up 9 seconds mysql_client2
763c4825722d kongxx/mysql_client:latest /usr/bin/mysql -h db 41 minutes ago Up 40 minutes mysql_client
32f7839f7e9d kongxx/mysql_server:latest /usr/bin/mysqld_safe About an hour ago Up About an hour 0.0.0.0:49153->3306/tcp mysql_client1/db,mysql_client2/db,mysql_server
在输出结果的NAMES列中,显示了“mysql_client1/db,mysql_client2/db,mysql_server”,表明两个客户端已成功关联至服务器容器。利用Docker Link机制,容器间的服务发现与连接变得极为简便,无需手动配置IP,由Docker自动管理主机名解析。
