Backup and restore strategies in Docker - Commands & Configuration

Introduction

Backing up data means saving a copy of important information so you don't lose it. Restoring means putting that saved data back if something goes wrong. In Docker, this helps protect your app's data stored in containers or volumes.

When you want to save your database data before updating your app container

When you need to move your app data from one server to another

When you want to protect your files stored in Docker volumes from accidental deletion

When you want to create a snapshot of your app's state before testing new features

When you want to recover your app data after a container crash or failure

Commands

This command creates a backup of the /data directory inside the 'my-app-container' container. It uses a temporary busybox container to access the volume and saves the backup.tar file to your current folder.

Terminal

docker run --rm --volumes-from my-app-container -v $(pwd):/backup busybox tar cvf /backup/backup.tar /data

Expected Output

data/

data/file1.txt

data/file2.txt

→

--volumes-from - Mounts volumes from the specified container

→

-v - Binds a host directory to the container for saving the backup

→

--rm - Removes the temporary container after the command finishes

This command restores the backup.tar file from your current folder into the Docker volume named 'my-app-data'. It uses a temporary busybox container to extract the files into the volume.

Terminal

docker run --rm -v $(pwd):/backup -v my-app-data:/data busybox tar xvf /backup/backup.tar -C /data

Expected Output

data/

data/file1.txt

data/file2.txt

→

-v - Binds host folder and Docker volume to the container

→

--rm - Removes the temporary container after restoring

Lists all Docker volumes on your system to verify that the volume 'my-app-data' exists before restoring data.

Terminal

docker volume ls

Expected Output

DRIVER    VOLUME NAME

local     my-app-data

Shows all containers to check if your app container is running or stopped before backup or restore.

Terminal

docker ps -a

Expected Output

CONTAINER ID   IMAGE          COMMAND                  CREATED          STATUS                      PORTS     NAMES

abc123def456   my-app-image   "/bin/sh -c 'npm start'" 10 minutes ago   Up 10 minutes                         my-app-container

Key Concept

If you remember nothing else from this pattern, remember: use a temporary container with volume mounts to safely backup and restore Docker volumes.

Common Mistakes

Trying to copy files directly from a running container without using volume mounts

This can miss data stored in volumes or cause inconsistent backups

Use a temporary container with --volumes-from or mount the volume directly to access all data

Not removing the temporary container after backup or restore

Leads to leftover containers cluttering your system

Use the --rm flag to automatically clean up temporary containers

Restoring backup files to the wrong volume or directory

Data will not be restored correctly and app may fail

Double-check volume names and paths before running restore commands

Summary

Use a temporary container with volume mounts to create a backup archive of your app data.

Verify your Docker volumes and containers before backup and restore operations.

Restore data by extracting the backup archive into the correct Docker volume using a temporary container.