Hi !
My goal was to properly backup all my databases as plain files, so they could be embedded in my hosting provider daily plain-file backup.
Of course I installed the NextBackup app in NextCloud, but it is … limited to NextCloud 
We also have a postfix database to backup (very important), and I have 2 more personal Docker apps with their databases managed by /e/ mariadb Docker container.
One note about databases backups : backing up a running transactional DB engine files is never a good way, as it can’t ensure database integrity (i.e. transaction logs files not backed up because of locks, activity during backup, memory not committed, …).
So I decided to use schnitzler/mysqldump Docker image to make these backups with SQL dumps.
Why this image ? It is small, fast, has BusyBox embedded, and it has a GitHub page.
1st step : creating the files
This image needs a storage space for backups, some backup scripts, and optional cron files.
So for /e/ Cloud I created :
/mnt/backup/mariadb/bin/
/mnt/backup/mariadb/backup/
/mnt/backup/mariadb/bin/backup_nc
#!/bin/sh
now=$(date +"%Y-%m-%d_%s")
/usr/bin/mysqldump --opt -h ${MYSQL_HOST} -u ${MYSQL_USER_NC} -p${MYSQL_PASSWORD_NC} ${MYSQL_DATABASE_NC} | gzip > "/backup/${now}_${MYSQL_DATABASE_NC}.gz"
find /backup -type f -iname "*_${MYSQL_DATABASE_NC}.gz" -mmin +2875 -delete
/mnt/backup/mariadb/bin/backup_pf
#!/bin/sh
now=$(date +"%Y-%m-%d_%s")
/usr/bin/mysqldump --opt -h ${MYSQL_HOST} -u ${MYSQL_USER_PF} -p${MYSQL_PASSWORD_PF} ${MYSQL_DATABASE_PF} | gzip > "/backup/${now}_${MYSQL_DATABASE_PF}.gz"
find /backup -type f -iname "*_${MYSQL_DATABASE_PF}.gz" -mmin +2875 -delete
Don’t forget to create+chmod dir for storage : /mnt/backup/mariadb/backup
2nd step : added the container to Docker Compose (/mnt/repo-base/docker-compose.yml) :
mysqldump:
image: schnitzler/mysqldump:latest
container_name: mysqldump
restart: always
networks:
- serverbase
environment:
- MYSQL_HOST=mariadb
- MYSQL_DATABASE_NC=${MYSQL_DATABASE_NC}
- MYSQL_USER_NC=${MYSQL_USER_NC}
- MYSQL_PASSWORD_NC=${MYSQL_PASSWORD_NC}
- MYSQL_DATABASE_PF=${PFDB_DB}
- MYSQL_USER_PF=${PFDB_USR}
- MYSQL_PASSWORD_PF=${PFDB_PW}
volumes:
# Example for user crontab
# - /mnt/backup/mariadb/bin/crontab:/var/spool/cron/crontabs/root
# - /mnt/backup/mariadb/bin/backup_nc:/usr/local/bin/backup_nc
# Backup scripts, scheduled using system-provided cron
- /mnt/backup/mariadb/bin/backup_nc:/etc/periodic/daily/backup_nc
- /mnt/backup/mariadb/bin/backup_pf:/etc/periodic/daily/backup_pf
- /mnt/backup/mariadb/backup:/backup
command: ["-l", "8", "-d", "8"]
depends_on:
- mariadb
3rd step : fired up with
docker-compose up -d
(at first run, Docker will download the image)
And it’s done 
, the day after I could find the following files in /mnt/backup/mariadb/backup :
-rw-r--r-- 1 root root 1165149 Jul 31 04:00 2020-07-31_1596160800_ncdb_Bw6l.gz
-rw-r--r-- 1 root root 3912 Jul 31 04:00 2020-07-31_1596160801_postfix.gz
Notes :
- files are kept 2 days only to save storage
- all vars are from /mnt/repo-base/.env
- once working fine on a daily basis, postfix backups can be done weekly. Just map the script to /etc/periodic/weekly/backup_pf and adjust time search in “find” command
EDIT 2020/08/08 : changed the “find” criteria from “-mtime +1” to “+mmin +2875” to include files up to 5mn past backup hour (i.e. today at 04:00, 2-days-before file is 04:02)
Some cosmetics
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