Creating and managing volumes in Docker - Step-by-Step CLI Walkthrough

Introduction

When you run containers, their data disappears when they stop. Volumes let you save data outside containers so it stays safe and can be shared.

When you want to keep database files safe even if the container is removed

When you need to share files between multiple containers running on the same host

When you want to back up important data created by a container

When you want to separate your app code from its data for easier updates

When you want to persist logs generated by containers for later analysis

Commands

This command creates a new volume named 'my-data-volume' to store data outside containers.

Terminal

docker volume create my-data-volume

Expected Output

my-data-volume

Runs an nginx container named 'my-container' and attaches the 'my-data-volume' to the container's /app/data folder to save data persistently.

Terminal

docker run -d --name my-container -v my-data-volume:/app/data nginx

Expected Output

a1b2c3d4e5f67890123456789abcdef0123456789abcdef0123456789abcdef0

→

-d - Run container in background (detached mode)

→

--name - Assign a name to the container for easy reference

→

-v - Attach a volume to a container path

Lists all volumes on the Docker host to verify 'my-data-volume' exists.

Terminal

docker volume ls

Expected Output

DRIVER    VOLUME NAME

local     my-data-volume

Shows detailed information about the 'my-data-volume' including its mount point on the host.

Terminal

docker volume inspect my-data-volume

Expected Output

[

    {

        "CreatedAt": "2024-06-01T12:00:00Z",

        "Driver": "local",

        "Labels": {},

        "Mountpoint": "/var/lib/docker/volumes/my-data-volume/_data",

        "Name": "my-data-volume",

        "Options": {},

        "Scope": "local"

    }

]

Deletes the 'my-data-volume' when it is no longer needed to free up space.

Terminal

docker volume rm my-data-volume

Expected Output

my-data-volume

Key Concept

If you remember nothing else from this pattern, remember: volumes keep your container data safe and separate from the container lifecycle.

Common Mistakes

Not creating a volume before using it in a container

Docker will create an anonymous volume but it is hard to manage and reuse later.

Always create named volumes explicitly with 'docker volume create' before attaching them.

Removing a volume while a container is still using it

Docker will refuse to remove the volume or data loss may occur if forced.

Stop and remove containers using the volume before deleting the volume.

Mounting volumes to wrong container paths

Data will not be saved where expected and the app may fail to find its files.

Check container documentation for correct paths to mount volumes.

Summary

Create a named volume with 'docker volume create' to store data persistently.

Run containers with '-v volume_name:/container/path' to attach volumes.

Use 'docker volume ls' and 'docker volume inspect' to manage and check volumes.

Remove volumes with 'docker volume rm' only after containers using them are stopped.