docker-compose.yml

version: '3.3'
services:
  db:
    image: mariadb:10.5
    restart: always
    environment:
      MYSQL_DATABASE: 'db'
      # So you don't have to use root, but you can if you like
      MYSQL_USER: 'user'
      # You can use whatever password you like
      MYSQL_PASSWORD: 'password'
      # Password for root access
      MYSQL_ROOT_PASSWORD: 'password'
    ports:
      # <Port exposed> : < MySQL Port running inside container>
      - '3306:3306'
    expose:
      # Opens port 3306 on the container
      - '3306'
      # Where our data will be persisted
    volumes:
      - my-db:/var/lib/mysql
# Names our volume
volumes:
  my-db:

Esencial_Docker.md

Esenciales Docker

Backup / Restore

Backup

Actually it should be done same way as written in official documentation. Data volume container stores it's data in "virtual root", so you should backup with next command:

docker run --rm \ 
  --volume [DOCKER_COMPOSE_PREFIX]_[VOLUME_NAME]:/[TEMPORARY_DIRECTORY_TO_STORE_VOLUME_DATA] \
  --volume $(pwd):/[TEMPORARY_DIRECTORY_TO_STORE_BACKUP_FILE] \
  ubuntu \
  tar cvf /[TEMPORARY_DIRECTORY_TO_STORE_BACKUP_FILE]/[BACKUP_FILENAME].tar /[TEMPORARY_DIRECTORY_TO_STORE_VOLUME_DATA]

where:_

• --rm means that the image created for this run command will be cleaned up
• DOCKER_COMPOSE_PREFIX in default is your project directory name
• VOLUME_NAME is the data-volume container name from compose file
• TEMPORARY_DIRECTORY_TO_STORE_VOLUME_DATA is a directory to mount your volume data
• TEMPORARY_DIRECTORY_TO_STORE_BACKUP_FILE is a directory virtually mapped to your current directory, where the backup will be placed
• BACKUP_FILENAME - a name of backup file (you find it in current directory)
• ubuntu - you may change image type to another container with tar :)

Example:

docker run --rm --volume mariadb_my-db:/v_data --volume %cd%:/backup ubuntu tar cvf /backup/backup.tar /v_data

Get data back into the volume (restore):

docker run --rm \ 
  --volume [DOCKER_COMPOSE_PREFIX]_[VOLUME_NAME]:/[TEMPORARY_DIRECTORY_STORING_EXTRACTED_BACKUP] \
  --volume $(pwd):/[TEMPORARY_DIRECTORY_TO_STORE_BACKUP_FILE] \
  ubuntu \
  tar xvf /[TEMPORARY_DIRECTORY_TO_STORE_BACKUP_FILE]/[BACKUP_FILENAME].tar -C /[TEMPORARY_DIRECTORY_STORING_EXTRACTED_BACKUP] --strip 1

where:

• TEMPORARY_DIRECTORY_STORING_EXTRACTED_BACKUP is a directory where the extracted files will be copied to (this is linked with the volume and will therefore write to it)
• -C - tell tar where to extract the contents
• --strip 1 - remove leading path elements (e.g. the parent directory if the backup contents are located in a /temp folder or similar)

Example:

docker run --rm --volume mariadb_my-db:/var/lib/mysql --volume %cd%:/backup ubuntu tar xvf /backup/backup.tar -C /var/lib/mysql --strip 1

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