Backup your portainer instances periodically using this script/docker image.
docker build -t portainer-scheduled-backup .
docker run -d \
--name portainer-scheduled-backup \
-e BACKUP_DIR="/path/to/backup" \
-e PORTAINER_USERNAME="your_username" \
-e PORTAINER_PASSWORD="your_password" \
-e PORTAINER_API_URL="http://your-portainer-host/api" \
-e CRON_SCHEDULE="0 */6 * * *" \
portainer-scheduled-backup