#!/usr/bin/env bash
# by: anryko
# date: 2017.03.12
# description: Script to backup mysql databases on Debian based OS

set -e
set -o pipefail

umask 0077
trap cleanup ERR INT TERM EXIT

# global variables
SCRIPT_NAME=mysql_backup
BACKUP_DATE=$(date +%F-%H-%M-%S)
BACKUP_DIR=/backup/tmp
BACKUP_SUBDIR=mysql_$BACKUP_DATE
BACKUP_STORE_DIR=/backup/mysql/$BACKUP_DATE

MYSQL_USER=$(grep -m1 ^user /etc/mysql/debian.cnf | awk '{print $NF}')
MYSQL_PASS=$(grep -m1 ^pass /etc/mysql/debian.cnf | awk '{print $NF}')
MYSQL_AUTH="--user=$MYSQL_USER --password=$MYSQL_PASS"
MYSQL_DBS=$(/usr/bin/mysql $MYSQL_AUTH -e 'show databases;' | egrep -v "Database|---|information_schema|performance_schema" | fmt -999)

# helper functions
log() {
  logger -i -t "$SCRIPT_NAME" -p "user.info" "$*"
  echo "$*"
}

cleanup() {
  log "cleanup started"
  cd $BACKUP_DIR
  rm -fr $BACKUP_SUBDIR
  log "cleanup finished"
}

mysql_backup() {
  # call with string of mysql db names to backup separated by ' '
  [[ ! -d $BACKUP_DIR/$BACKUP_SUBDIR ]] && mkdir -p $BACKUP_DIR/$BACKUP_SUBDIR

  mysql_db=$1
  while shift; do
    backup_file_path=$BACKUP_DIR/$BACKUP_SUBDIR/$mysql_db_${mysql_db}_$BACKUP_DATE.gz
    log "starting backup of $mysql_db database to $backup_file_path"
    /usr/bin/mysqldump $MYSQL_AUTH $mysql_db | gzip -9 > $backup_file_path
    log "finished backup of $mysql_db database to $backup_file_path"
    mysql_db=$1
  done

  [[ ! -d $BACKUP_STORE_DIR ]] && mkdir -p $BACKUP_STORE_DIR

  log "moving backups to $BACKUP_STORE_DIR"
  mv $BACKUP_DIR/$BACKUP_SUBDIR/* $BACKUP_STORE_DIR/
}

# main
log "starting mysql backup"
mysql_backup $MYSQL_DBS
log "mysql backup finished"