#!/bin/bash

####################################################################################################
#### author: SlickStack ############################################################################
#### link: https://slickstack.io ###################################################################
#### mirror: http://mirrors.slickstack.io/bash/ss-install-mysql.txt ################################
#### path: /var/www/ss-install-mysql ###############################################################
#### destination: n/a (not a boilerplate) ##########################################################
#### purpose: Reinstalls the entire MySQL module for SlickStack servers (idempotent) ###############
#### module version: MySQL 8.0.x ###################################################################
#### sourced by: ss-install ########################################################################
#### bash aliases: ss install mysql ################################################################
####################################################################################################

## SS-CONFIG MUST BE PROPERLY CONFIGURED AND ON CURRENT BUILD BEFORE RUNNING SS-INSTALL ##
## ENSURE YOUR SS-CONFIG BUILD REMAINS CURRENT BY RUNNING SS-UPDATE OCCASIONALLY ##

## include SlickStack configuration ##
source /var/www/ss-config

## include SlickStack functions ##
source /var/www/ss-functions

####################################################################################################
#### SS-Install-MySQL: Message (Begin Script) ######################################################
####################################################################################################

## this is a simple message that announces to the shell the purpose of this bash script ##
## it will only be noticed by sudo users who manually call ss core bash scripts ##

## echo message ##
echo -e "${PURPLE}Running ss-install-mysql: Reinstalls the entire MySQL module for SlickStack servers (idempotent)... ${NOCOLOR}"
sleep "$SLEEP_MESSAGE_BEGIN"

####################################################################################################
#### SS-Install-MySQL: Cleanup Temporary Files #####################################################
####################################################################################################

## delete tmp files ##
# n/a

####################################################################################################
#### SS-Install-MySQL: Cleanup Any Existing MySQL Packages + Data ##################################
####################################################################################################

## first we backup the live database (and /var/lib/mysql) and kill any leftover processes ##
## then we proceed with purge/cleanup of MySQL packages to pepare a clean install ##

## run ss-dump (copies /var/lib/mysql to /var/www/meta/mysql.bak) ##
source /var/www/ss-dump

## TEMP ##
# echo -e "${YELLOW}SS-INSTALL-MYSQL: SINCE SS_BUILD JULY2020B MYSQL 8.0 USERS MIGHT NOT INSTALL COMPLETELY (PLEASE FINISH INSTALL MANUALLY IF ANY ISSUES)...${NOCOLOR}"
sleep 10s

## stop MySQL ##
/etc/init.d/mysql* stop
sleep 15s

## kill any remaining MySQL processes ##
killall mysql*
sleep 15s

## purge all MySQL packages and remove any previous MySQL configuration files ##
apt purge ^mysql
# rm /etc/mysql/*
# rm /var/lib/mysql/*

## cleanup potential conflicting files ##
apt autoremove
apt autoclean

## update repo cache ##
apt update

####################################################################################################
#### SS-Install-MySQL: Prepare Root User Authentication (Debconf) ##################################
####################################################################################################

## here we prepare the MySQL root password using the Debian/Ubuntu debconf utilities ##
## all SlickStack scripts connect to MySQL via root@localhost using sockets ##

# repair debconf (see: sudo debconf-show mysql-community-server-8.0) ##
sudo /usr/share/debconf/fix_db.pl

## purge any previous debconf/MySQL data ##
sudo echo PURGE | sudo debconf-communicate mysql-community-server
sudo echo PURGE | sudo debconf-communicate mysql-server
# sudo echo "mysql-community-server mysql-community-server/remove-data-dir boolean true" | sudo debconf-set-selections

## prepare root password for apt (PSA: sudo the shit out of these or it will fail) ##
# if [[ "${UBUNTU_VERSION}" = "20.04" || -z "${UBUNTU_VERSION}" ]]; then 
# sudo echo "mysql-community-server mysql-community-server/root-pass password ${DB_PASSWORD_ROOT}" | sudo debconf-set-selections
# sudo echo "mysql-community-server mysql-community-server/re-root-pass password ${DB_PASSWORD_ROOT}" | sudo debconf-set-selections
# sudo echo "mysql-community-server mysql-server/default-auth-override select Use Legacy Authentication Method (Retain MySQL 5.x Compatibility)" | sudo debconf-set-selections
# fi

####################################################################################################
#### SS-Install-MySQL: Install MySQL Package #######################################################
####################################################################################################

## this script will only install the MySQL packages if not set to false in ss-config ##
## remote database environments might not require localhost MySQL installed ##

## only run ss-install-mysql if not set to false in ss-config ##
# if [[ "$SS_MYSQL" != "false" ]]; then 
# fi

## install MySQL 8.0 if server is running Ubuntu 20.04 ##
if [[ "${UBUNTU_VERSION}" = "20.04" || -z "${UBUNTU_VERSION}" ]]; then 
    apt install mysql-server-8.0
fi

## install MySQL 5.7 if server is running Ubuntu 18.04 ##
if [[ "${UBUNTU_VERSION}" = "18.04" ]]; then
    apt install mysql-server-5.7
fi

####################################################################################################
#### SS-Install-MySQL: Configure Root + Admin User (Localhost/IPv4/IPv6) ###########################
####################################################################################################

## manually secure MySQL (noninteractive version of the mysql_secure_installation wizard) ##
## caching_sha2_password is better but mysql_native_password is more compatible ##

## mysql_secure_installation (alternative) via root@localhost ##
sudo mysql -e "UNINSTALL COMPONENT 'file://component_validate_password';" ## not installed by default on MySQL 8.0.x
sudo mysql -e "UNINSTALL PLUGIN validate_password;" ## not installed by default on MySQL 8.0.x
sudo mysql -e "DELETE FROM mysql.user WHERE user='';"
sudo mysql -e "DELETE FROM mysql.user WHERE user='root' AND host NOT IN ('localhost', '127.0.0.1', '::1');"
sudo mysql -e "DELETE FROM mysql.user WHERE user='admin' AND host NOT IN ('localhost', '127.0.0.1', '::1');"
sudo mysql -e "DROP DATABASE IF EXISTS test;"

####################################################################################################
#### SS-Install-MySQL: Configure WordPress Database + User + Privileges ############################
####################################################################################################

## we use root@localhost (auth_socket) and user@127.0.0.1 (TCP) for WordPress database ##
## the superuser admin@127.0.0.1 is also created to be used with phpMyAdmin, etc ##


## WORDPRESS (DEFAULT) ##

## create production database ##
sudo mysql -e "CREATE DATABASE IF NOT EXISTS ${DB_NAME};"

# if [[ "$SS_APP" == "wordpress" || -z "$SS_APP"  ]]; then
    # sudo mysql -e "CREATE DATABASE IF NOT EXISTS wordpress;"
# fi

## create dev database unless it is explicity disabled ##
if [[ "$DEV_SITE" != "false" ]]; then
    sudo mysql -e "CREATE DATABASE IF NOT EXISTS ${DB_NAME}_dev;" 
fi

# if [[ "$DEV_SITE" != "false" ]] && [[ "$SS_APP" == "wordpress" || -z "$SS_APP"  ]]; then
    # sudo mysql -e "CREATE DATABASE IF NOT EXISTS wordpress_dev;"   
# fi

## create staging database unless it is explictly disabled ##
if [[ "$STAGING_SITE" != "false" ]]; then
    sudo mysql -e "CREATE DATABASE IF NOT EXISTS ${DB_NAME}_staging;"
fi

# if [[ "$STAGING_SITE" != "false" ]] && [[ "$SS_APP" == "wordpress" || -z "$SS_APP"  ]]; then
    # sudo mysql -e "CREATE DATABASE IF NOT EXISTS wordpress_staging;"   
# fi


## OTHER APPS (COMING SOON) ##



## create admin superuser (can be used with Adminer/phpMyAdmin) ##
sudo mysql -e "ALTER USER IF EXISTS 'admin'@'localhost' IDENTIFIED WITH caching_sha2_password BY '${DB_PASSWORD_ROOT}';"
sudo mysql -e "ALTER USER IF EXISTS 'admin'@'127.0.0.1' IDENTIFIED WITH caching_sha2_password BY '${DB_PASSWORD_ROOT}';"
sudo mysql -e "ALTER USER IF EXISTS 'admin'@'::1' IDENTIFIED WITH mysql_native_password BY '${DB_PASSWORD_ROOT}';"
sudo mysql -e "CREATE USER IF NOT EXISTS 'admin'@'localhost' IDENTIFIED WITH mysql_native_password BY '${DB_PASSWORD_ROOT}';"
sudo mysql -e "CREATE USER IF NOT EXISTS 'admin'@'127.0.0.1' IDENTIFIED WITH mysql_native_password BY '${DB_PASSWORD_ROOT}';"
sudo mysql -e "CREATE USER IF NOT EXISTS 'admin'@'::1' IDENTIFIED WITH mysql_native_password BY '${DB_PASSWORD_ROOT}';"

## grant admin superuser all privileges on all databases (localhost/IPv4/IPv6) ##
sudo mysql -e "GRANT ALL ON *.* TO 'admin'@'localhost' WITH GRANT OPTION;"
sudo mysql -e "GRANT ALL ON *.* TO 'admin'@'127.0.0.1' WITH GRANT OPTION;"
sudo mysql -e "GRANT ALL ON *.* TO 'admin'@'::1' WITH GRANT OPTION;"

## create limited user for WordPress database ##
sudo mysql -e "ALTER USER IF EXISTS '${DB_USER}'@'localhost' IDENTIFIED WITH mysql_native_password BY '${DB_PASSWORD}';"
sudo mysql -e "ALTER USER IF EXISTS '${DB_USER}'@'127.0.0.1' IDENTIFIED WITH mysql_native_password BY '${DB_PASSWORD}';"
sudo mysql -e "ALTER USER IF EXISTS '${DB_USER}'@'::1' IDENTIFIED WITH mysql_native_password BY '${DB_PASSWORD}';"
sudo mysql -e "CREATE USER IF NOT EXISTS '${DB_USER}'@'localhost' IDENTIFIED WITH mysql_native_password BY '${DB_PASSWORD}';"
sudo mysql -e "CREATE USER IF NOT EXISTS '${DB_USER}'@'127.0.0.1' IDENTIFIED WITH mysql_native_password BY '${DB_PASSWORD}';"
sudo mysql -e "CREATE USER IF NOT EXISTS '${DB_USER}'@'::1' IDENTIFIED WITH mysql_native_password BY '${DB_PASSWORD}';"

## grant limited user privileges on WordPress database only (localhost/IPv4/IPv6) ##
sudo mysql -e "GRANT ALL ON ${DB_NAME}.* TO '${DB_USER}'@'localhost';"
sudo mysql -e "GRANT ALL ON ${DB_NAME}.* TO '${DB_USER}'@'127.0.0.1';"
sudo mysql -e "GRANT ALL ON ${DB_NAME}.* TO '${DB_USER}'@'::1';"

## install auth_socket plugin ##
sudo mysql -e "INSTALL PLUGIN auth_socket SONAME 'auth_socket.so';"

## create sudo@localhost user via auth_socket ##
sudo mysql -e "ALTER USER IF EXISTS '${SUDO_USER}'@'localhost' IDENTIFIED WITH auth_socket BY '';"
sudo mysql -e "CREATE USER IF NOT EXISTS '${SUDO_USER}'@'localhost' IDENTIFIED WITH auth_socket BY '';"
sudo mysql -e "GRANT ALL ON *.* TO '${SUDO_USER}'@'localhost' WITH GRANT OPTION;"

## ensure root@localhost user is using auth_socket ##
sudo mysql -e "ALTER USER IF EXISTS 'root'@'localhost' IDENTIFIED WITH auth_socket BY '';"
sudo mysql -e "CREATE USER IF NOT EXISTS 'root'@'localhost' IDENTIFIED WITH auth_socket BY '';"
sudo mysql -e "GRANT ALL ON *.* TO 'root'@'localhost' WITH GRANT OPTION;"
sudo mysql -e "FLUSH PRIVILEGES;"

####################################################################################################
#### SS-Install-MySQL: Optimize My.cnf (MySQL Configuration) Settings ##############################
####################################################################################################

## here we overwrite the default my.cnf with an optimized version (sub-config disabled) ##
## all MySQL logs should be found under /var/www/logs/ after install complete ##

## stop MySQL ##
/etc/init.d/mysql* stop
sleep 15s
# killall mysql*
# sleep 15s

## cleanup leftover files ##
rm /tmp/my.cnf

## install custom my.cnf config file ##
wget -O /tmp/my.cnf http://mirrors.slickstack.io/mysql/my-cnf.txt

#### MySQL Settings ####
## SQL mode ##
if [[ -z "$SQL_MODE" ]]; then 
    sed -i "s/@SQL_MODE/STRICT_TRANS_TABLES,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION/g" /tmp/my.cnf
else 
    sed -i "s/@SQL_MODE/${SQL_MODE}/g" /tmp/my.cnf
fi

## max allowed packet ##
if [[ -z "$SQL_MAX_ALLOWED_PACKET" ]]; then 
    sed -i "s/@SQL_MAX_ALLOWED_PACKET/256M/g" /tmp/my.cnf
else 
    sed -i "s/@SQL_MAX_ALLOWED_PACKET/${SQL_MAX_ALLOWED_PACKET}/g" /tmp/my.cnf
fi

## connect timeout ##
if [[ -z "$SQL_CONNECT_TIMEOUT" ]]; then 
    sed -i "s/@SQL_CONNECT_TIMEOUT/30/g" /tmp/my.cnf
else 
    sed -i "s/@SQL_CONNECT_TIMEOUT/${SQL_CONNECT_TIMEOUT}/g" /tmp/my.cnf
fi

## wait timeout ##
if [[ -z "$SQL_WAIT_TIMEOUT" ]]; then 
    sed -i "s/@SQL_WAIT_TIMEOUT/3600/g" /tmp/my.cnf
else 
    sed -i "s/@SQL_WAIT_TIMEOUT/${SQL_WAIT_TIMEOUT}/g" /tmp/my.cnf
fi

## interactive timeout ##
if [[ -z "$SQL_INTERACTIVE_TIMEOUT" ]]; then 
    sed -i "s/@SQL_INTERACTIVE_TIMEOUT/43200/g" /tmp/my.cnf
else 
    sed -i "s/@SQL_INTERACTIVE_TIMEOUT/${SQL_INTERACTIVE_TIMEOUT}/g" /tmp/my.cnf
fi

## net read timeout ##
if [[ -z "$SQL_NET_READ_TIMEOUT" ]]; then 
    sed -i "s/@SQL_NET_READ_TIMEOUT/30/g" /tmp/my.cnf
else 
    sed -i "s/@SQL_NET_READ_TIMEOUT/${SQL_NET_READ_TIMEOUT}/g" /tmp/my.cnf
fi

## net write timeout ##
if [[ -z "$SQL_NET_WRITE_TIMEOUT" ]]; then 
    sed -i "s/@SQL_NET_WRITE_TIMEOUT/60/g" /tmp/my.cnf
else 
    sed -i "s/@SQL_NET_WRITE_TIMEOUT/${SQL_NET_WRITE_TIMEOUT}/g" /tmp/my.cnf
fi


## set InnoDB buffer pool size (supports "auto" or manual via ss-config) ##
PERCENT_RAM_MB=$(free -m | awk 'NR==2{printf "%d", $2*0.50 }')

if [[ "$INNODB_BUFFER_POOL_SIZE" == "auto" ]]; then 
    sed -i "s/@INNODB_BUFFER_POOL_SIZE/${PERCENT_RAM_MB}M/g" /tmp/my.cnf
else 
    sed -i "s/@INNODB_BUFFER_POOL_SIZE/${INNODB_BUFFER_POOL_SIZE}/g" /tmp/my.cnf
fi

## set InnoDB flush method ##
if [[ -z "$INNODB_FLUSH_METHOD" ]]; then 
    sed -i "s/@INNODB_FLUSH_METHOD/O_DIRECT/g" /tmp/my.cnf
else 
    sed -i "s/@INNODB_FLUSH_METHOD/${INNODB_FLUSH_METHOD}/g" /tmp/my.cnf
fi

## set InnoDB log file size ##
if [[ -z "$INNODB_LOG_FILE_SIZE" ]]; then 
    sed -i "s/@INNODB_LOG_FILE_SIZE/256M/g" /tmp/my.cnf
else 
    sed -i "s/@INNODB_LOG_FILE_SIZE/${INNODB_LOG_FILE_SIZE}/g" /tmp/my.cnf
fi

## set InnoDB log files in group ##
if [[ -z "$INNODB_LOG_FILES_IN_GROUP" ]]; then 
    sed -i "s/@INNODB_LOG_FILES_IN_GROUP/1/g" /tmp/my.cnf
else 
    sed -i "s/@INNODB_LOG_FILES_IN_GROUP/${INNODB_LOG_FILES_IN_GROUP}/g" /tmp/my.cnf
fi

## set InnoDB flush_log_at_trx_commit ##
if [[ "$INNODB_FLUSH_LOG_AT_TRX_COMMIT" == "false" ]]; then
    sed -i "s/@INNODB_FLUSH_LOG_AT_TRX_COMMIT/0/g" /tmp/my.cnf
else 
    sed -i "s/@INNODB_FLUSH_LOG_AT_TRX_COMMIT/1/g" /tmp/my.cnf
fi

## safe/clean/slow shutdown MySQL before update config ##
# /etc/init.d/mysql stop ## too fast

## copy files to their destinations ##
cp /tmp/my.cnf /etc/mysql/my.cnf

## restart MySQL ##
/etc/init.d/mysql* restart

## cleanup tmp files ##
rm /tmp/init-mysql.txt*
rm /var/run/mysqld.bak*

####################################################################################################
#### SlickStack: External References Used To Improve This Script (Thanks, Interwebz) ###############
####################################################################################################

## mysql alias flags ##
    # command mysql --no-defaults --user=root --password=$DB_PASSWORD_ROOT --host=localhost --protocol=socket --socket=/var/run/mysqld/mysqld.sock --port=3306 --force "$@"

# sudo mysql -e "ALTER USER IF EXISTS 'root'@'127.0.0.1' IDENTIFIED WITH caching_sha2_password BY '${DB_PASSWORD_ROOT}';"
# sudo mysql -e "ALTER USER IF EXISTS 'root'@'::1' IDENTIFIED WITH caching_sha2_password BY '${DB_PASSWORD_ROOT}';"
# sudo mysql -e "CREATE USER IF NOT EXISTS 'root'@'127.0.0.1' IDENTIFIED WITH caching_sha2_password BY '${DB_PASSWORD_ROOT}';"
# sudo mysql -e "CREATE USER IF NOT EXISTS 'root'@'::1' IDENTIFIED WITH caching_sha2_password BY '${DB_PASSWORD_ROOT}';"
# sudo mysql -e "GRANT ALL ON *.* TO 'root'@'127.0.0.1' WITH GRANT OPTION;"
# sudo mysql -e "GRANT ALL ON *.* TO 'root'@'::1' WITH GRANT OPTION;"

## MYSQL IS PHASING OUT NATIVE PASSWORDS IN FAVOR OF UNIX SOCKETS AND/OR SHA2 HASHING ##
## WE USE SOCKETS FOR CORE SCRIPTS AND AIM TO USE TCP/SSL/SHA2 FOR WORDPRESS ##

## copy the default socket for keeps (might disappear during stop MySQL) ##
# cp /var/run/mysqld /var/run/mysqld.bak

## put back socket
# if [ ! -f "/var/run/mysqld/*sock" ]; then 
 #   mv /var/run/mysqld.bak /var/run/mysqld;
# fi

## start the MySQL service again ##
# systemctl unmask mysql.service
# mysqld_safe --init-file=<path to init file>init-file.txt &
# mysqld --init-file=<path to init file>init-file.txt &
# /usr/sbin/mysqld --user=mysql --skip-grant-tables --init-file=/tmp/init-mysql.txt &
# mysqld_safe --skip-grant-tables &

# mysqld --init-file=/tmp/init-mysql.txt &

# rm /tmp/init-mysql.txt*
# wget -O /tmp/init-mysql.txt http://mirrors.slickstack.io/mysql/init-mysql.txt
# sed -i "s/@DB_PASSWORD_ROOT/${DB_PASSWORD_ROOT}/g" /tmp/init-mysql.txt
# chown mysql:mysql /tmp/init-mysql.txt
# chmod 0775 /tmp/init-mysql.txt

## start MySQL without authentication (safe mode) ##
# mysqld --skip-grant-tables --user=mysql &
# bin/mysqld --initialize-insecure --user=mysql

## start MySQL ##
# mysql --skip-password
## grep "A temporary password" /var/log/mysqld.log

## ensure root@localhost uses mysql_native_password ##
#####sudo mysql -e "ALTER USER IF EXISTS 'root'@'localhost' IDENTIFIED WITH mysql_native_password BY '${DB_PASSWORD_ROOT}';"
#####sudo mysql -e "GRANT ALL ON *.* TO 'root'@'localhost' WITH GRANT OPTION;"
#####sudo mysql -e "FLUSH PRIVILEGES;"

## reset admin (root alternative) password and make mysql_native_password the default ##
#  -u root --skip-password --host="localhost" --protocol=socket --port=3306 
# UPDATE mysql.user SET plugin = 'mysql_native_password' WHERE user = 'root' AND plugin = 'auth_socket';
# mysql -e "UPDATE mysql.user SET plugin = 'mysql_native_password' WHERE user = 'admin';"

## caching_sha2_password requires TLS, sockets, or shared memory ##

# mysql --flush-privileges -e "ALTER USER 'root'@'localhost' IDENTIFIED WITH mysql_native_password BY '${DB_PASSWORD_ROOT}';"
# SELECT plugin from mysql.user where User='root';
# SELECT User,plugin from mysql.user where User='root';
# SELECT user,authentication_string,plugin,host FROM mysql.user;

####################################################################################################
#### SS-Install-MySQL: Reset Permissions (MySQL) ###################################################
####################################################################################################

## run ss-perms-mysql ##
source /var/www/ss-perms-mysql

####################################################################################################
#### SS-Install-MySQL: Cleanup Temporary Files #####################################################
####################################################################################################

## delete tmp files ##
# n/a

####################################################################################################
#### SS-Install-MySQL: Touch Timestamp File (End Script) ###########################################
####################################################################################################

## this is a dummy timestamp file that will remember the last time this script was run ##
## it can be useful for developer reference and is sometimes used by SlickStack ##

## script timestamp ##
touch /var/www/meta/.timestamp-ss-install-mysql

####################################################################################################
#### SlickStack: External References Used To Improve This Script (Thanks, Interwebz) ###############
####################################################################################################

## Ref: https://github.com/littlebizzy/slickstack/issues/23
## Ref: https://stackoverflow.com/questions/36301100/how-do-i-turn-off-the-mysql-password-validation
## Ref: https://dba.stackexchange.com/questions/4614/cannot-drop-anonymous-user-from-mysql-user
## Ref: https://www.networkinghowtos.com/howto/disable-remote-root-logins-into-mysql/
## Ref: https://www.oreilly.com/library/view/mysql-in-a/9780596514334/re39.html
## Ref: https://stackoverflow.com/questions/36463966/when-is-flush-privileges-in-mysql-really-needed
## Ref: https://askubuntu.com/questions/210976/apt-get-remove-with-wildcard-removed-way-more-than-expected-why
## Ref: https://dev.mysql.com/doc/refman/8.0/en/grant.html
## Ref: https://geert.vanderkelen.org/2018/mysql8-unattended-dpkg/
## Ref: https://stackoverflow.com/questions/50177216/how-to-grant-all-privileges-to-root-user-in-mysql-8-0
## Ref: https://www.techiediaries.com/ubuntu/install-mysql-8-ubuntu-20-04/
## Ref: https://kifarunix.com/install-mysql-8-on-ubuntu-20-04/
## Ref: https://www.digitalocean.com/community/tutorials/how-to-install-mysql-on-ubuntu-20-04
## Ref: https://mysqlserverteam.com/upgrading-to-mysql-8-0-default-authentication-plugin-considerations/
## Ref: https://dba.stackexchange.com/questions/209514/what-is-mysql-native-password
## Ref: https://linuxconfig.org/how-to-reset-root-mysql-password-on-ubuntu-18-04-bionic-beaver-linux
## Ref: https://askubuntu.com/questions/1242142/mysql-install-error-database-files-are-locked-daemon-already-running-warning
## Ref: https://stackoverflow.com/questions/11657829/error-2002-hy000-cant-connect-to-local-mysql-server-through-socket-var-run
## Ref: https://askubuntu.com/questions/1242142/mysql-install-error-database-files-are-locked-daemon-already-running-warning
## Ref: https://www.digitalocean.com/community/questions/connecting-to-mysql-without-pw-can-t-connect-to-local-mysql-server-through-socket-var-run-mysqld-mysqld-sock-2
## Ref: https://serverfault.com/questions/582866/mysql-socket-configuration-issue-in-my-cnf
## Ref: https://stackoverflow.com/questions/11990708/error-cant-connect-to-local-mysql-server-through-socket-var-run-mysqld-mysq
## Ref: https://medium.com/@aungzanbaw/how-to-reset-root-user-password-in-mysql-8-0-a5c328d098a8
## Ref: https://stackoverflow.com/questions/49931541/mysql-changing-authentication-type-from-standard-to-caching-sha2-password
## Ref: https://stackoverflow.com/questions/35978228/how-to-solve-innodb-unable-to-lock-ibdata1-mysql-error
## Ref: https://bobcares.com/blog/innodb-unable-to-lock-ibdata1-error-11/
## Ref: https://stackoverflow.com/questions/34954455/mysql-daemon-lock-issue/46779157
## Ref: https://dev.mysql.com/doc/refman/8.0/en/data-directory-initialization.html
## Ref: https://dev.mysql.com/doc/refman/8.0/en/server-options.html
## Ref: https://dev.mysql.com/doc/refman/8.0/en/server-system-variables.html#sysvar_init_file
## Ref: https://www.pixelstech.net/article/1545701135-How-to-reset-root-password-in-MySQL-8
## Ref: https://stackoverflow.com/questions/61430362/ubuntu-20-04-set-mysql-phpmyadmin-root-password
## Ref: https://www.cloudbooklet.com/how-to-install-mysql-on-ubuntu-20-04/
## Ref: https://www.tecmint.com/reset-root-password-in-mysql-8/
## Ref: https://dev.mysql.com/doc/refman/8.0/en/default-privileges.html
## Ref: https://serverfault.com/questions/500739/reinstall-mysql-and-keep-existing-database-tables-and-data
## Ref: https://askubuntu.com/questions/643251/having-trouble-installing-and-removing-mysql-in-ubuntu
## Ref: https://stackoverflow.com/questions/21620406/how-do-i-pause-my-shell-script-for-a-second-before-continuing
## Ref: https://subscription.packtpub.com/book/big_data_and_business_intelligence/9781788395809/1/ch01lvl1sec15/starting-or-stopping-mysql-8
## Ref: http://dev.cs.ovgu.de/db/mysql/Common-errors.html
## Ref: https://stackoverflow.com/questions/50093144/mysql-8-0-client-does-not-support-authentication-protocol-requested-by-server
## Ref: https://stackoverflow.com/questions/49194719/authentication-plugin-caching-sha2-password-cannot-be-loaded
## Ref: https://docs.oracle.com/cd/E17952_01/mysql-8.0-en/upgrading-from-previous-series.html
## Ref: https://dev.mysql.com/doc/mysql-secure-deployment-guide/8.0/en/secure-deployment-configure-authentication.html
## Ref: https://phoenixnap.com/kb/access-denied-for-user-root-localhost
## Ref: https://www.sqlshack.com/how-to-install-mysql-on-ubuntu-18-04/
## Ref: https://mysql.tutorials24x7.com/blog/reset-root-password-of-mysql
## Ref: https://phoenixnap.com/kb/how-to-reset-mysql-root-password-windows-linux
## Ref: https://www.oreilly.com/library/view/mysql-8-cookbook/9781788395809/7ea345a8-d753-48cd-a11b-8e6b6a06cacc.xhtml
## Ref: https://dev.mysql.com/doc/refman/8.0/en/resetting-permissions.html
## Ref: https://devanswers.co/install-secure-mysql-server-ubuntu-20-04/
## Ref: https://mariadb.com/kb/en/pluggable-authentication-overview/
## Ref: https://dev.mysql.com/doc/refman/8.0/en/connection-options.html
## Ref: https://stackoverflow.com/questions/41846000/mariadb-password-and-unix-socket-authentication-for-root
## Ref: https://www.percona.com/live/e18/sites/default/files/slides/Upgrading%20to%20MySQL%208.0%20and%20a%20More%20Automated%20Experience%20-%20FileId%20-%20159893.pdf
## Ref: https://superuser.com/questions/603026/mysql-how-to-fix-access-denied-for-user-rootlocalhost
## Ref: https://github.com/GoogleCloudPlatform/click-to-deploy/blob/master/vm/chef/cookbooks/mysql8-book/recipes/configure-apt-repo-version-8.0.rb
## Ref: https://dev.mysql.com/doc/mysql-apt-repo-quick-guide/en/
## Ref: https://unix.stackexchange.com/questions/457388/how-to-find-out-the-variable-names-for-debconf-set-selections
## Ref: https://www.codementor.io/@slaith/setting-a-root-password-on-mysql-in-silent-mode-in-ubuntu-y6do6ug2u
## Ref: https://stackoverflow.com/questions/23358918/preconfigure-an-empty-password-for-mysql-via-debconf-set-selections
## Ref: https://forums.mysql.com/read.php?11,666369,666533#msg-666533
## Ref: https://gist.github.com/ziadoz/dc935a0167c68fc23b4f35ee8593125f
## Ref: https://www.reddit.com/r/mysql/comments/3vch8p/uninstall_mysql_via_shell_without_prompt/
## Ref: https://ubuntu.pkgs.org/19.10/ubuntu-main-amd64/mysql-server-8.0_8.0.17-0ubuntu2_amd64.deb.html
## Ref: https://serverfault.com/questions/813210/does-debconf-set-selections-automatically-deletes-values-from-debconf-database-o
## Ref: https://askubuntu.com/questions/399903/unattended-phpmyadmin-install-end-up-throwing-errors
## Ref: https://severalnines.com/database-blog/moving-mysql-57-mysql-80-what-you-should-know
## Ref: https://medium.com/@benmorel/remove-the-mysql-root-password-ba3fcbe29870
## Ref: https://dev.mysql.com/doc/refman/8.0/en/validate-password-installation.html
## Ref: https://dev.mysql.com/doc/refman/8.0/en/default-privileges.html
## Ref: https://vander.host/knowledgebase/databases/cant-login-as-root-to-phpmyadmin-on-new-server-install/
## Ref: https://devanswers.co/phpmyadmin-access-denied-for-user-root-localhost/
## Ref: https://serverfault.com/questions/906490/mysql-rejects-connections-with-auth-socket
## Ref: https://bugs.mysql.com/bug.php?id=79269
## Ref: https://php.watch/articles/PHP-7.4-MySQL-8-server-gone-away-fix
## Ref: https://stackoverflow.com/questions/39281594/error-1698-28000-access-denied-for-user-rootlocalhost
## Ref: https://stackoverflow.com/questions/52364415/php-with-mysql-8-0-error-the-server-requested-authentication-method-unknown-to
## Ref: https://www.digitalocean.com/community/tutorials/how-to-install-mysql-on-ubuntu-20-04-quickstart
## Ref: https://www.percona.com/blog/2016/03/16/change-user-password-in-mysql-5-7-with-plugin-auth_socket/
## Ref: https://www.percona.com/blog/2019/11/01/use-mysql-without-a-password/
## Ref: https://gist.github.com/jessuppi/ab5517aa50b3bc83ac37abb8267e005b
## Ref: https://dev.mysql.com/doc/refman/8.0/en/option-file-options.html
## Ref: https://docs.oracle.com/cd/E17952_01/mysql-5.6-en/mysqld-safe.html
## Ref: http://doc.mawan.de/dictionaries-common/README.problems
## Ref: https://askubuntu.com/questions/429512/dpkg-or-something-related-is-corrupted
## Ref: https://www.digitalocean.com/community/tutorials/how-to-configure-ssl-tls-for-mysql-on-ubuntu-18-04
## Ref: https://dev.mysql.com/doc/refman/8.0/en/encrypted-connections.html
## Ref: https://unix.stackexchange.com/questions/47584/in-a-bash-script-using-the-conditional-or-in-an-if-statement

## SS_EOF