前言

根據 MySQL 的官方網頁 (https://www.mysql.com/support/supportedplatforms/database.html)，MySQL 在 CentOS 7 作業系統支援的版本為5.6、5.7 與 8.0，等會我們就嘗試在 CentOS 7 安裝 MySQL 5.7 與 8.0 版本。

預先準備動作

• 安裝 yum-utils 套件，等會需要用到 yum-config-manager 指令

  $ sudo yum install yum-utils -y
  

• 安裝相對應套件，就會加入 MySQL 的 Yum 源，此 Yum 源已經將 MySQL 眾多軟體、眾多版本的套件都給內含了。

  $ sudo yum localinstall https://dev.mysql.com/get/mysql80-community-release-el7-3.noarch.rpm -y
  

MySQL 5.7 安裝步驟

• 如果要安裝的 MySQL 版本是 5.7：

  • 停用 MySQL 8.0 的 Yum 源，並啟用 MySQL 5.7 的 Yum 源

    $ sudo yum-config-manager --disable mysql80-community
    $ sudo yum-config-manager --enable mysql57-community
    

  • 檢查已啟用的 MySQL Yum 原是否為 5.7 版

    $ sudo yum repolist enabled | grep "mysql.*-community.*"
    mysql-connectors-community/x86_64       MySQL Connectors Community           118
    mysql-tools-community/x86_64            MySQL Tools Community                 95
    mysql57-community/x86_64                MySQL 5.7 Community Server           364
    

• 如果要安裝的 MySQL 版本是 8.0：

  • 無需更換 Yum 源，因為預設就是 MySQL 8.0 的 Yum 源

  • 檢查已啟用的 MySQL Yum 源是否為 8.0 版

    $ sudo yum repolist enabled | grep "mysql.*-community.*"
    mysql-connectors-community/x86_64       MySQL Connectors Community           118
    mysql-tools-community/x86_64            MySQL Tools Community                 95
    mysql80-community/x86_64                MySQL 8.0 Community Server           129
    

• 安裝 MySQL

  $ sudo yum install mysql-community-server -y
  

• 啟動 MySQL 服務

  $ sudo systemctl start mysqld
  

• 啟用 MySQL 服務，讓 MySQL 服務每次開機就會自動被帶起來

  $ sudo systemctl enable mysqld
  

• 檢視 MySQL 服務啟動狀態

  $ sudo systemctl status mysqld
   mysqld.service - MySQL Server
     Loaded: loaded (/usr/lib/systemd/system/mysqld.service; enabled; vendor preset: disabled)
     Active: active (running) since Tue 2019-09-10 20:37:18 CST; 48s ago
       Docs: man:mysqld(8)
             http://dev.mysql.com/doc/refman/en/using-systemd.html
   Main PID: 1825 (mysqld)
     CGroup: /system.slice/mysqld.service
             1825 /usr/sbin/mysqld --daemonize --pid-file=/var/run/mysqld/mysql...
  
  Sep 10 20:37:15 centos7-cli.lab.example.com systemd[1]: Starting MySQL Server...
  Sep 10 20:37:18 centos7-cli.lab.example.com systemd[1]: Started MySQL Server.
  

• 查目前 MySQL 資料庫系統內，root 帳號的暫時密碼（這部份是 MariaDB 所沒有的）

  $ sudo grep 'temporary password' /var/log/mysqld.log
  2019-09-10T13:28:00.598194Z 1 [Note] A temporary password is generated for root@localhost: uKx=wIr*K9.l
  

• 加強 MySQL 安裝的安全性

  $ sudo mysql_secure_installation 
  
  Securing the MySQL server deployment.
  
  Enter password for user root: 
  
  The existing password for the user account root has expired. Please set a new password.
  
  New password: 
  
  Re-enter new password: 
  The 'validate_password' plugin is installed on the server.
  The subsequent steps will run with the existing configuration
  of the plugin.
  Using existing password for root.
  
  Estimated strength of the password: 100 
  Change the password for root ? ((Press y|Y for Yes, any other key for No) : Y
  
  New password: 
  
  Re-enter new password: 
  
  Estimated strength of the password: 100 
  Do you wish to continue with the password provided?(Press y|Y for Yes, any other key for No) : Y
  By default, a MySQL installation has an anonymous user,
  allowing anyone to log into MySQL without having to have
  a user account created for them. This is intended only for
  testing, and to make the installation go a bit smoother.
  You should remove them before moving into a production
  environment.
  
  Remove anonymous users? (Press y|Y for Yes, any other key for No) : Y
  Success.
  
  
  Normally, root should only be allowed to connect from
  'localhost'. This ensures that someone cannot guess at
  the root password from the network.
  
  Disallow root login remotely? (Press y|Y for Yes, any other key for No) : Y
  Success.
  
  By default, MySQL comes with a database named 'test' that
  anyone can access. This is also intended only for testing,
  and should be removed before moving into a production
  environment.
  
  
  Remove test database and access to it? (Press y|Y for Yes, any other key for No) : Y
   - Dropping test database...
  Success.
  
   - Removing privileges on test database...
  Success.
  
  Reloading the privilege tables will ensure that all changes
  made so far will take effect immediately.
  
  Reload privilege tables now? (Press y|Y for Yes, any other key for No) : Y
  Success.
  
  All done! 
  

  • 這段 script 主要在做以下動作：
    • 設定 root 帳號的密碼（此 root 是 MySQL 資料庫系統內的帳號，跟作業系統層的 root 無關）。
    • 禁止 root 從非本機登入。
    • 移除 anonymous 匿名者帳號。
    • 移除測試資料庫。
  • 還有一點要說明，MySQL 比 MariaDB 多了 validate_password 這個預設安裝的外掛，他會檢查密碼是否符合複雜性要求：密碼至少包含一個大寫字母、一個小寫字母、一個數字、以及一個特殊符號，密碼長度至少八個字元。

• 查版本

  $ sudo mysqld -V
  mysqld  Ver 5.7.27 for Linux on x86_64 (MySQL Community Server (GPL))
  

• 登入資料庫進行簡單測試

  $ mysql -u root -h localhost -p
  Enter password: 
  Welcome to the MySQL monitor.  Commands end with ; or \g.
  Your MySQL connection id is 9
  Server version: 5.7.27 MySQL Community Server (GPL)
  
  Copyright (c) 2000, 2019, Oracle and/or its affiliates. All rights reserved.
  
  Oracle is a registered trademark of Oracle Corporation and/or its
  affiliates. Other names may be trademarks of their respective
  owners.
  
  Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
  
  mysql> show databases;
  +--------------------+
  | Database           |
  +--------------------+
  | information_schema |
  | mysql              |
  | performance_schema |
  | sys                |
  +--------------------+
  4 rows in set (0.01 sec)
  
  mysql> exit
  Bye
  

參考資料

• Installing MySQL on Linux Using the MySQL Yum Repository
• MySQL Yum Repository