Generate wp-config.php from env variables

wp-config.sh

#!/bin/sh

set -e

if [ -z "$1" ]; then
  echo "Usage: ./wp-config.sh <wp-config.php-path>"
  exit 1
fi

WP_CONFIG_FILE=$1

# Ensure all variables are bound
if \
  [ -z "$DB_NAME" ] || [ -z "$DB_HOST" ] || [ -z "$DB_PORT" ] || [ -z "$DB_USER" ] || \
  [ -z "$DB_PASS" ] || [ -z "$DB_PREFIX" ] || [ -z "$WP_DEBUG" ] || \
  [ -z "$WP_AUTH_KEY" ] || [ -z "$WP_SECURE_AUTH_KEY" ] || [ -z "$WP_LOGGED_IN_KEY" ] || \
  [ -z "$WP_NONCE_KEY" ] || [ -z "$WP_AUTH_SALT" ] || [ -z "$WP_SECURE_AUTH_SALT" ] || \
  [ -z "$WP_LOGGED_IN_SALT" ] || [ -z "$WP_NONCE_SALT" ]; then
  echo "All variables have to be defined."
  exit 1
fi

# Original wp-config.php file from Wordpress 4.9.6
cat > $WP_CONFIG_FILE << 'EOM'
<?php
/**
 * The base configuration for WordPress
 *
 * The wp-config.php creation script uses this file during the
 * installation. You don't have to use the web site, you can
 * copy this file to "wp-config.php" and fill in the values.
 *
 * This file contains the following configurations:
 *
 * * MySQL settings
 * * Secret keys
 * * Database table prefix
 * * ABSPATH
 *
 * @link https://codex.wordpress.org/Editing_wp-config.php
 *
 * @package WordPress
 */

// ** MySQL settings - You can get this info from your web host ** //
/** The name of the database for WordPress */
define('DB_NAME', 'database_name_here');

/** MySQL database username */
define('DB_USER', 'username_here');

/** MySQL database password */
define('DB_PASSWORD', 'password_here');

/** MySQL hostname */
define('DB_HOST', 'localhost');

/** Database Charset to use in creating database tables. */
define('DB_CHARSET', 'utf8');

/** The Database Collate type. Don't change this if in doubt. */
define('DB_COLLATE', '');

/**#@+
 * Authentication Unique Keys and Salts.
 *
 * Change these to different unique phrases!
 * You can generate these using the {@link https://api.wordpress.org/secret-key/1.1/salt/ WordPress.org secret-key service}
 * You can change these at any point in time to invalidate all existing cookies. This will force all users to have to log in again.
 *
 * @since 2.6.0
 */
define('AUTH_KEY',         'put your unique phrase here');
define('SECURE_AUTH_KEY',  'put your unique phrase here');
define('LOGGED_IN_KEY',    'put your unique phrase here');
define('NONCE_KEY',        'put your unique phrase here');
define('AUTH_SALT',        'put your unique phrase here');
define('SECURE_AUTH_SALT', 'put your unique phrase here');
define('LOGGED_IN_SALT',   'put your unique phrase here');
define('NONCE_SALT',       'put your unique phrase here');

/**#@-*/

/**
 * WordPress Database Table prefix.
 *
 * You can have multiple installations in one database if you give each
 * a unique prefix. Only numbers, letters, and underscores please!
 */
$table_prefix  = 'wp_';

/**
 * For developers: WordPress debugging mode.
 *
 * Change this to true to enable the display of notices during development.
 * It is strongly recommended that plugin and theme developers use WP_DEBUG
 * in their development environments.
 *
 * For information on other constants that can be used for debugging,
 * visit the Codex.
 *
 * @link https://codex.wordpress.org/Debugging_in_WordPress
 */
define('WP_DEBUG', false);

/* That's all, stop editing! Happy blogging. */

/** Absolute path to the WordPress directory. */
if ( !defined('ABSPATH') )
	define('ABSPATH', dirname(__FILE__) . '/');

/** Sets up WordPress vars and included files. */
require_once(ABSPATH . 'wp-settings.php');
EOM

# Replace DB config
sed -i $WP_CONFIG_FILE \
  -e "s/database_name_here/$DB_NAME/" \
  -e "s/username_here/$DB_USER/" \
  -e "s/password_here/$DB_PASS/" \
  -e "s/localhost/$DB_HOST:$DB_PORT/" \
  -e "s/wp_/$DB_PREFIX/"

# Replace constants value
sed -i $WP_CONFIG_FILE \
  -e "s/WP_DEBUG', false/WP_DEBUG', ${WP_DEBUG:-false}/"

# Replace salts hashs
sed -i $WP_CONFIG_FILE -e "1,/put your unique phrase here/s/put your unique phrase here/$(echo $WP_AUTH_KEY | sed -e 's/[\/&]/\\&/g')/"
sed -i $WP_CONFIG_FILE -e "1,/put your unique phrase here/s/put your unique phrase here/$(echo $WP_SECURE_AUTH_KEY | sed -e 's/[\/&]/\\&/g')/"
sed -i $WP_CONFIG_FILE -e "1,/put your unique phrase here/s/put your unique phrase here/$(echo $WP_LOGGED_IN_KEY | sed -e 's/[\/&]/\\&/g')/"
sed -i $WP_CONFIG_FILE -e "1,/put your unique phrase here/s/put your unique phrase here/$(echo $WP_NONCE_KEY | sed -e 's/[\/&]/\\&/g')/"
sed -i $WP_CONFIG_FILE -e "1,/put your unique phrase here/s/put your unique phrase here/$(echo $WP_AUTH_SALT | sed -e 's/[\/&]/\\&/g')/"
sed -i $WP_CONFIG_FILE -e "1,/put your unique phrase here/s/put your unique phrase here/$(echo $WP_SECURE_AUTH_SALT | sed -e 's/[\/&]/\\&/g')/"
sed -i $WP_CONFIG_FILE -e "1,/put your unique phrase here/s/put your unique phrase here/$(echo $WP_LOGGED_IN_SALT | sed -e 's/[\/&]/\\&/g')/"
sed -i $WP_CONFIG_FILE -e "1,/put your unique phrase here/s/put your unique phrase here/$(echo $WP_NONCE_SALT | sed -e 's/[\/&]/\\&/g')/"

Works now with GNU and BSD sed.