to get more flexability to my projects, docker (https://www.docker.com/) was a choice.
howto easy install take latest description from their webseite for your distribution.
curl -fsSL https://download.docker.com/linux/debian/gpg | sudo gpg --dearmor -o /usr/share/keyrings/docker-archive-keyring.gpg echo "deb [arch=$(dpkg --print-architecture) signed-by=/usr/share/keyrings/docker-archive-keyring.gpg] https://download.docker.com/linux/debian $(lsb_release -cs) stable" | sudo tee /etc/apt/sources.list.d/docker.list > /dev/null apt-get install docker-ce docker-ce-cli containerd.io docker run hello-world
to work with more comfortable gui → portainer
i found this page: https://github.com/alaub81/backup_docker_scripts and im confident. all volumes will be backed up now in a crontab