Migrate Docker Volumes from one Host to another // backup and restore

Introduction

This tutorial will guide you through the process of migrating Docker volumes from one host to another. You'll learn how to back up and restore your Docker volumes, making it easy to transfer your container data between different systems. This is particularly useful for data management in development and production environments.

Step 1: Understand Docker Data Storage

• Docker uses containers to run applications, and these containers can store data in two primary ways: volumes and bind mounts.
• Volumes are stored in a part of the host filesystem managed by Docker (/var/lib/docker/volumes/), making them portable across different systems.
• Bind mounts map a specific path on the host to a path in the container, giving you direct access to the host’s filesystem.

Step 2: Identify Your Docker Volumes

• To list all Docker volumes on your current host, use the following command:

  docker volume ls
  

• Identify the volume you wish to back up and migrate.

Step 3: Access Files Inside Named Volumes

• To explore the content of a Docker volume, you can create a temporary container that mounts the volume. Use the following command, replacing your_volume_name with the name of your volume:

  docker run --rm -it -v your_volume_name:/data alpine sh
  

• This command launches an Alpine Linux container and gives you a shell inside it, where you can navigate to /data to view the volume's content.

Step 4: Backup Your Docker Volume

• To back up the contents of a volume, you can use the following command, which creates a tarball of the volume's content:

  docker run --rm -v your_volume_name:/from -v $(pwd):/to alpine sh -c "cd /from && tar czvf /to/backup.tar.gz ."
  

• This will create a backup.tar.gz file in your current working directory, containing all the data from the specified volume.

Step 5: Restore Your Docker Volume on Another Host

• Transfer the backup file to the new host using your preferred method (e.g., SCP, SFTP).
• On the new host, create a new volume with:

  docker volume create your_new_volume_name
  

• Restore the backup into the new volume with the following command:

  docker run --rm -v your_new_volume_name:/to -v $(pwd):/from alpine sh -c "cd /from && tar xzvf backup.tar.gz -C /to --strip 1"
  

• This command extracts the contents of backup.tar.gz into the new volume.

Conclusion

You have now learned how to effectively back up and migrate Docker volumes from one host to another. By understanding how Docker stores data and using the provided commands, you can manage your container data with ease. For next steps, consider exploring Docker’s official documentation for more advanced volume management techniques or add this process to your regular backup routine.