Docker上のWordPressで、突然MySQLが動かなくなりました

概要

ご覧いただきありがとうございます。
丸1日以上の調査の結果、 docker compose -p test up -d --build 時の wp-config.php ファイルの生成に問題がありそうと考えていますが、どうしても原因がわからず、皆様のお力をお貸しいただきたいです。

今回要因の一つになっていることが推測されるwp-config.php

php
1<?php
2/**
3 * The base configuration for WordPress
4 *
5 * The wp-config.php creation script uses this file during the installation.
6 * You don't have to use the web site, you can copy this file to "wp-config.php"
7 * and fill in the values.
8 *
9 * This file contains the following configurations:
10 *
11 * * MySQL settings
12 * * Secret keys
13 * * Database table prefix
14 * * ABSPATH
15 *
16 * This has been slightly modified (to read environment variables) for use in Docker.
17 *
18 * @link https://wordpress.org/support/article/editing-wp-config-php/
19 *
20 * @package WordPress
21 */
22
23// IMPORTANT: this file needs to stay in-sync with https://github.com/WordPress/WordPress/blob/master/wp-config-sample.php
24// (it gets parsed by the upstream wizard in https://github.com/WordPress/WordPress/blob/f27cb65e1ef25d11b535695a660e7282b98eb742/wp-admin/setup-config.php#L356-L392)
25
26// a helper function to lookup "env_FILE", "env", then fallback
27if (!function_exists('getenv_docker')) {
28    // https://github.com/docker-library/wordpress/issues/588 (WP-CLI will load this file 2x)
29    function getenv_docker($env, $default) {
30        if ($fileEnv = getenv($env . '_FILE')) {
31            return rtrim(file_get_contents($fileEnv), "\r\n");
32        }
33        else if (($val = getenv($env)) !== false) {
34            return $val;
35        }
36        else {
37            return $default;
38        }
39    }
40}
41
42// ** MySQL settings - You can get this info from your web host ** //
43/** The name of the database for WordPress */
44define( 'DB_NAME', getenv_docker('WORDPRESS_DB_NAME', 'wordpress') );
45
46/** MySQL database username */
47define( 'DB_USER', getenv_docker('WORDPRESS_DB_USER', 'example username') );
48
49/** MySQL database password */
50define( 'DB_PASSWORD', getenv_docker('WORDPRESS_DB_PASSWORD', 'example password') );
51
52/**
53 * Docker image fallback values above are sourced from the official WordPress installation wizard:
54 * https://github.com/WordPress/WordPress/blob/f9cc35ebad82753e9c86de322ea5c76a9001c7e2/wp-admin/setup-config.php#L216-L230
55 * (However, using "example username" and "example password" in your database is strongly discouraged.  Please use strong, random credentials!)
56 */
57
58/** MySQL hostname */
59define( 'DB_HOST', getenv_docker('WORDPRESS_DB_HOST', 'mysql') );
60
61/** Database charset to use in creating database tables. */
62define( 'DB_CHARSET', getenv_docker('WORDPRESS_DB_CHARSET', 'utf8') );
63
64/** The database collate type. Don't change this if in doubt. */
65define( 'DB_COLLATE', getenv_docker('WORDPRESS_DB_COLLATE', '') );
66
67/**#@+
68 * Authentication unique keys and salts.
69 *
70 * Change these to different unique phrases! You can generate these using
71 * the {@link https://api.wordpress.org/secret-key/1.1/salt/ WordPress.org secret-key service}.
72 *
73 * You can change these at any point in time to invalidate all existing cookies.
74 * This will force all users to have to log in again.
75 *
76 * @since 2.6.0
77 */
78define( 'AUTH_KEY',         getenv_docker('WORDPRESS_AUTH_KEY',         '2254296a55ca23263007c0028b03d61150895349') );
79define( 'SECURE_AUTH_KEY',  getenv_docker('WORDPRESS_SECURE_AUTH_KEY',  'b60fd478500e5f253072e6ca54177089a0dbe5dd') );
80define( 'LOGGED_IN_KEY',    getenv_docker('WORDPRESS_LOGGED_IN_KEY',    'f8fd9866fd51ee0388b5c7bfdcaf674a86e2a49d') );
81define( 'NONCE_KEY',        getenv_docker('WORDPRESS_NONCE_KEY',        '67d99a340e071d11a7d2d7b8623f3d6b62c5e2b3') );
82define( 'AUTH_SALT',        getenv_docker('WORDPRESS_AUTH_SALT',        '4b23626cc9644cbedb152b4143bbfee1402a77d6') );
83define( 'SECURE_AUTH_SALT', getenv_docker('WORDPRESS_SECURE_AUTH_SALT', 'e0563d3ac0c5639270c9bf5c3fa266339eef91db') );
84define( 'LOGGED_IN_SALT',   getenv_docker('WORDPRESS_LOGGED_IN_SALT',   'c9a546581ab2304c0c9cd1e3c242725f464d37bc') );
85define( 'NONCE_SALT',       getenv_docker('WORDPRESS_NONCE_SALT',       'bba66e2b3beded52a678e2008d8306a1ac9f6f09') );
86// (See also https://wordpress.stackexchange.com/a/152905/199287)
87
88/**#@-*/
89
90/**
91 * WordPress database table prefix.
92 *
93 * You can have multiple installations in one database if you give each
94 * a unique prefix. Only numbers, letters, and underscores please!
95 */
96$table_prefix = getenv_docker('WORDPRESS_TABLE_PREFIX', 'wp_');
97
98/**
99 * For developers: WordPress debugging mode.
100 *
101 * Change this to true to enable the display of notices during development.
102 * It is strongly recommended that plugin and theme developers use WP_DEBUG
103 * in their development environments.
104 *
105 * For information on other constants that can be used for debugging,
106 * visit the documentation.
107 *
108 * @link https://wordpress.org/support/article/debugging-in-wordpress/
109 */
110define( 'WP_DEBUG', !!getenv_docker('WORDPRESS_DEBUG', '') );
111
112/* Add any custom values between this line and the "stop editing" line. */
113
114// If we're behind a proxy server and using HTTPS, we need to alert WordPress of that fact
115// see also http://codex.wordpress.org/Administration_Over_SSL#Using_a_Reverse_Proxy
116if (isset($_SERVER['HTTP_X_FORWARDED_PROTO']) && $_SERVER['HTTP_X_FORWARDED_PROTO'] === 'https') {
117    $_SERVER['HTTPS'] = 'on';
118}
119// (we include this by default because reverse proxying is extremely common in container environments)
120
121if ($configExtra = getenv_docker('WORDPRESS_CONFIG_EXTRA', '')) {
122    eval($configExtra);
123}
124
125/* That's all, stop editing! Happy publishing. */
126
127/** Absolute path to the WordPress directory. */
128if ( ! defined( 'ABSPATH' ) ) {
129    define( 'ABSPATH', __DIR__ . '/' );
130}
131
132/** Sets up WordPress vars and included files. */
133require_once ABSPATH . 'wp-settings.php';

発生している問題・エラー

docker compose -p test up -d --buildすると、下記のようにdbのみ上手く立ち上がりません。

NAME                SERVICE             STATUS              PORTS
test_dev_db         db                  restarting          
test_dev_mailhog    mailhog             running             127.0.0.2:1025->1025/tcp, 127.0.0.2:8025->8025/tcp
test_dev_pma        phpmyadmin          running             127.0.0.2:8080->80/tcp
test_dev_wp         wordpress           running             127.0.0.2:80->80/tcp, 127.0.0.2:443->443/tcp

docker-compose.yml で restart: always を指定しているため、runningとrestartingを繰り返している状態です。

docker logs test_dev_db をした結果は、下記の通りです。

2021-06-18 06:33:51+00:00 [Note] [Entrypoint]: Entrypoint script for MySQL Server 8.0.25-1debian10 started.
2021-06-18 06:33:51+00:00 [Note] [Entrypoint]: Switching to dedicated user 'mysql'
2021-06-18 06:33:51+00:00 [Note] [Entrypoint]: Entrypoint script for MySQL Server 8.0.25-1debian10 started.
2021-06-18 06:33:51+00:00 [ERROR] [Entrypoint]: MYSQL_USER="root", MYSQL_USER and MYSQL_PASSWORD are for configuring a regular user and cannot be used for the root user
    Remove MYSQL_USER="root" and use one of the following to control the root user password:
    - MYSQL_ROOT_PASSWORD
    - MYSQL_ALLOW_EMPTY_PASSWORD
    - MYSQL_RANDOM_ROOT_PASSWORD

エラー文の提案通り、下記を変更すると立ち上がるようにはなりますが、 dev.test.com へアクセスすると「データベース接続確立エラー」の表示となってしまいます。

.env の MYSQL_USER を root から user へ変更
docker-compose.yml の MYSQL_USER と MYSQL_PASSWORD をコメントアウト

解決したいこと

docker compose -p test up -d --build した際、上に挙げた「今回要因の一つになっていることが推測されるwp-config.php」ではなく、「正常に動いていた以前のwp-config.php」のようなwp-config.phpが生成され、且つブラウザからアクセスできるように戻したいです。
ちなみにもう一台のデバイスでも試しましたが、そちらは同じ環境で正常に動いております。

ぜひお知恵をお貸しいただければ幸いでございます。
（字数の関係で環境で情報が足りない場合は、ご質問ください。）