#!/bin/bash
#
# A minimalistic backup tool for MySQL or files with auto-cleanup after a certain period, on a Ubuntu or Centos based environments.
# It can handle multiple projects (websites) located on the server where this tool is present. Add one or more *.conf files in the backup.d directory
# For each one of them we generate the md5 checksum.
#
# Requirements:
# - md5sum (usually present by default)
# - tar (usually present by default)
# - mysqldump (it comes with MySQL/MariaDB)
#
# Defaults:
# - If a project does not have any alert level for running low space a default value of 5 GB is used
# - If no email recipient(s) defined or email is not present as a service, the output is added into the log
#
# Important:
# - On low space the backup process will be stopped
# - On Centos 6 comment out the lines regarding available free space (from line 59 ... 78), because the `df` does not implement the GNU version of coreutils
#
# Feel free to contribute :)
#
# (c) mihai kelemen <mihai@webmanage.ro>
# January 24, 2019
#
# A single configuration file (must be placed in /root/backup.d) has the following entries:
#
#####################################################################
## database= # database name
## user= # database user
## password='' # database password (make sure that the password is between single quotes)
## backup_directory= # absolute directory path for storing the backup
## remove_after_number_of_days=30 # number of backup days, until we start removing old backups
## backup_files=true # create backup for files - boolean true|false
## backup_file_day=6 # when the files need to be backed up - day of week: Monday is 1 ... Sunday is 7.
## files_path= # absolute path where are the files located
## available_free_space_alert=10 # raise a notification when space is lower than 10 GB (always use GB)
## stop_on_full=false # if true stop on space is full, if false cleanup old backups - boolean true|false
## email=user@domain.com,user2@domain.com # email(s) to be notified on low space situation
####################################################################
#
# Set a cronjob to run daily (or how often is necessary)
# A typical cronjob is to run daily at midnight
# 0 0 * * * /bin/bash /root/backup.sh > /root/backup.log 2>&1

for config in /root/backup.d/*.conf;
	do
		# read configuration
		. $config;

		# if we do not have the directory then create it and set directory permission to 600
		if [ ! -d $backup_directory ]; then
			mkdir -p -m600 $backup_directory;
		fi

                # timestamp down to the second, so in this way we can have multiple daily without having the issue of overwritting existing backups
		timestamp=`date +%Y-%m-%d_%H-%M-%S`;
		cd $backup_directory;

		# get the available space available (in bytes)
		available_free_space=`df -k --output=avail "$PWD" | tail -n1`;

		# if no limit was setup, use the 5 GB value
		if [ -z "$available_free_space_alert" ]; then
			available_free_space_alert=5;
		fi

		if [[ $available_free_space -lt $(($available_free_space_alert * 1024 * 1024)) ]]; then

			body=`df -h "$PWD"`;

			if [ ! -z "$email" ] && [ -f `which mail` ]; then
				echo "<pre>$body</pre>" | mail -s "$(echo -e "Space is running low on $(hostname)\nContent-Type: text/html")" $email;
			fi

			echo "Space is running low:";
			echo $body;
			if [ -z "$stop_on_full" ] || [ $stop_on_full = 'true' ]; then
				exit 1;
            		fi

         		while [  $available_free_space -lt $(($available_free_space_alert * 1024 * 1024)) ]; do
				rm "$(ls -t | tail -1)";
	     			available_free_space=`df -k --output=avail "$PWD" | tail -n1`;
         		done

		fi

		# backup files
		# file name will be saved as files-YYYY-MM-DD_HH_MM_SS.tar.gz
		if [ $(date +%u) = $backup_file_day ] && [ $backup_files = 'true' ]; then
			/bin/tar -czpf $backup_directory/files-$timestamp.tar.gz --exclude=files-$timestamp.tar.gz $files_path
			md5sum files-$timestamp.tar.gz > files-$timestamp.md5
		fi

		# create the database backup as dump-YYYY-MM-DD_HH_MM_SS.sql.gz
		/usr/bin/mysqldump -u $user -p$password $database | gzip > $backup_directory/dump-$timestamp.sql.gz
		md5sum dump-$timestamp.sql.gz > dump-$timestamp.md5

		# make some cleanup: remove files older than $remove_after_number_of_days
		find $backup_directory/ -mtime +$remove_after_number_of_days -exec rm {} \;

done