$ sudo cat /var/log/mysqld.log | grep "A temporary password"
2021-01-16T09:30:18.257989Z 1 [Note] A temporary password is generated for root@localhost: XXXXXXXXX 

$ mysql_secure_installation

# ログで確認したパスワード
Enter password for user root: 

The existing password for the user account root has expired. Please set a new password.

# パスワードの変更を要求される
New password: (新しいパスワード)

# rootのパスワードを変更するか？
Change the password for root ? ((Press y|Y for Yes, any other key for No) : N

# 匿名ユーザを削除するか？
Remove anonymous users? (Press y|Y for Yes, any other key for No) : Y

# rootでのリモートログインを禁止するか？
Disallow root login remotely? (Press y|Y for Yes, any other key for No) : Y

# テストデータベースを削除するか？
Remove test database and access to it? (Press y|Y for Yes, any other key for No) : Y

# 今すぐ権限テーブルを読み込むか？
Reload privilege tables now? (Press y|Y for Yes, any other key for No) : Y

All done! 

$ sudo vi /etc/my.cnf

[mysqld]
(省略)
character-set-server = utf8
default_password_lifetime = 0

# サービス再起動しておく
$ sudo service mysqld restart

$ mysql -u root -p
Enter password: 

# WordPress用のデータベース作成
mysql> CREATE DATABASE データベース名;
Query OK, 1 row affected (0.01 sec)

# ユーザ作成
mysql> GRANT ALL PRIVILEGES ON *.* TO 'ユーザ名'@'localhost' IDENTIFIED BY '作成ユーザのパスワード';

Query OK, 0 rows affected, 1 warning (0.00 sec)

mysql> exit

# OS 結果：アップデート不要
$ sudo yum -y update
Loaded plugins: extras_suggestions, langpacks, priorities, update-motd
261 packages excluded due to repository priority protections
No packages marked for update

# Apache 結果：アップデート不要
$ sudo yum install -y httpd24
Loaded plugins: extras_suggestions, langpacks, priorities, update-motd
amzn2-core                                                                                                       | 3.7 kB  00:00:00     
261 packages excluded due to repository priority protections
No package httpd24 available.
Error: Nothing to do

# PHP 結果：アップデート不要
$ sudo yum install -y php56
Loaded plugins: extras_suggestions, langpacks, priorities, update-motd
261 packages excluded due to repository priority protections
No package php56 available.
Error: Nothing to do

# Apache起動 (起動済だったかも)
$ sudo service httpd start 
$ sudo service httpd status
● httpd.service - The Apache HTTP Server
   Loaded: loaded (/usr/lib/systemd/system/httpd.service; disabled; vendor preset: disabled)
  Drop-In: /usr/lib/systemd/system/httpd.service.d
           └─php-fpm.conf
   Active: active (running)

# MySQL起動 (起動済だったかも)
$ sudo service mysqld start
$ sudo service mysqld status
● mysqld.service - MySQL Server
   Loaded: loaded (/usr/lib/systemd/system/mysqld.service; enabled; vendor preset: disabled)
   Active: active (running)