How to List and Inspect Docker Volumes?

Docker volumes are important in containerization. They help us keep data that Docker containers create and use. With volumes, we can store data outside of the container’s filesystem. This way, our data stays safe even when we stop or delete containers. This is very important for apps that need to keep a steady state. For example, databases need to keep their data safe across different container lifecycles.

In this article, we will look at different parts of Docker volumes. We will learn how to list and check them. We will talk about what Docker volumes are and why we should use them. We will also go through how to list all volumes using the command line. Then, we will see how to check a specific volume. Plus, we will explain how to remove volumes that we don’t use anymore. We will also go over how to read the results from volume checks. By the end, we will understand how to manage Docker volumes well.

  • How to List and Check Docker Volumes?
  • What Are Docker Volumes and Why Do We Use Them?
  • How to List All Docker Volumes with Command Line?
  • How to Check a Specific Docker Volume?
  • How to Remove Unused Docker Volumes?
  • How to Understand Docker Volume Check Output?
  • Questions We Often Get

If we want to learn more about Docker, we can read about what Docker is and why we should use it or check out the benefits of using Docker in development.

What Are Docker Volumes and Why Use Them?

Docker volumes are a way to keep data that Docker containers make and use. Unlike the storage in the container’s filesystem, which goes away when we remove the container, volumes let us save data that can last longer than just one container.

Key Benefits of Using Docker Volumes:

  • Data Persistence: Data in volumes stays safe even if we stop or delete the container.
  • Sharing Data: We can share volumes with many containers. This helps us share data and work together.
  • Performance: Volumes work better than bind mounts. Docker manages them and makes them fit for container apps.
  • Ease of Backup and Migration: We can back up, restore, or move volumes easily between different Docker hosts.
  • Separation of Concerns: Volumes help keep application data separate from the application itself. This makes our architecture cleaner.

Types of Docker Volumes:

  1. Named Volumes: These are managed by Docker and have a name. They are the most common type of volume.
  2. Anonymous Volumes: These are created without a name. They are good for temporary storage but can be harder to manage.
  3. Bind Mounts: These connect a folder on the host directly to a folder in the container. They are flexible but can make it tricky to manage permissions and paths.

For more detailed information on how Docker volumes work, you can check What Are Docker Volumes and How Do They Work?.

How to List All Docker Volumes with Command Line?

We can list all Docker volumes using the command line. The command we use is docker volume ls. This command shows a simple list of all volumes that Docker manages on our system.

Command:

docker volume ls

Output:

When we run the command, we will see two columns. They are DRIVER and VOLUME NAME. The DRIVER shows which volume driver is used. It is usually local. The VOLUME NAME is the name for each volume.

Example:

DRIVER    VOLUME NAME
local     my_volume1
local     my_volume2
local     my_volume3

Additional Options:

If we want more details about the volumes, we can add the -f flag to filter the results. We can also use --quiet to see only the volume names:

docker volume ls -f "dangling=false"
docker volume ls --quiet

This command helps us manage Docker volumes. It is important when we want to check the volumes before doing things like inspecting or removing them. For more info about Docker volumes and how they work, you can look at What are Docker Volumes and How Do They Work?.

How to Inspect a Specific Docker Volume?

To check a specific Docker volume, we can use the docker volume inspect command. This command gives us detailed info about the volume. It shows its mount point, driver, and options.

Command Syntax

docker volume inspect VOLUME_NAME

Example

If we want to inspect a volume called my_volume, we run:

docker volume inspect my_volume

Output

The output comes in JSON format. It usually has these fields:

  • Name: The name of the volume.
  • Driver: The volume driver used, like local.
  • Mountpoint: The path where the volume is mounted on the host.
  • Labels: Any labels that are with the volume.
  • Options: Options specific to the driver.
  • Scope: The scope of the volume, either local or global.

Sample Output

[
    {
        "Name": "my_volume",
        "Driver": "local",
        "Mountpoint": "/var/lib/docker/volumes/my_volume/_data",
        "Labels": {},
        "Options": {},
        "Scope": "local"
    }
]

This command is very important for managing Docker volumes. It helps us check configurations and fix problems with volume usage. For more details on Docker volumes, we can check What Are Docker Volumes and How Do They Work?.

How to Remove Unused Docker Volumes?

We need to remove unused Docker volumes to keep our Docker environment clean and running well. Unused volumes take up disk space and can cause confusion. Let’s see how we can find and remove them easily.

First, to see all unused Docker volumes, we can use this command. It shows only volumes that are not in use by any container:

docker volume ls -f dangling=true

This command shows us volumes that are called “dangling”. To remove these unused volumes, we can run:

docker volume prune

This command will ask us to confirm if we want to remove all unused volumes. If we want to skip the confirmation step, we can run:

docker volume prune -f

If we want to remove a specific unused volume, we can do that using its name:

docker volume rm <volume_name>

Just replace <volume_name> with the name of the volume we want to remove.

For more details on Docker volumes and how to manage them, check out what are Docker volumes and how do they work.

How to Understand Docker Volume Inspection Output?

When we inspect a Docker volume, we get clear details about how the volume is set up and its current state. We can use the docker volume inspect command to get this information. The output shows in JSON format. This format includes different properties that describe the volume.

Key Properties in the Inspection Output:

  • Name: The name of the volume.
  • Driver: The volume driver used. It is usually local.
  • Mountpoint: The path on the host where the volume is kept.
  • Labels: Any tags that are linked with the volume.
  • Scope: The range of the volume. It can be either local or global.
  • Options: Any settings that are for the volume.
  • CreatedAt: The time when the volume was made.
  • UpdatedAt: The time when the volume was last changed.

Example Command:

To check a volume named my_volume, we use this command:

docker volume inspect my_volume

Sample Output:

[
    {
        "Name": "my_volume",
        "Driver": "local",
        "Mountpoint": "/var/lib/docker/volumes/my_volume/_data",
        "Labels": {},
        "Scope": "local",
        "Options": {},
        "CreatedAt": "2023-10-01T14:00:00Z",
        "UpdatedAt": "2023-10-01T14:00:00Z"
    }
]

Understanding the Output:

  • Mountpoint: This shows where the volume data is stored on the host. It is important for backup and restore tasks.
  • CreatedAt/UpdatedAt: These times help us follow the life of the volume.
  • Driver: Knowing the driver is helpful for fixing problems and understanding how the volume works with Docker.

For more info on Docker volumes, we can check what are Docker volumes and how do they work and how to create and use Docker volumes.

Frequently Asked Questions

1. What are Docker volumes and why are they important?

Docker volumes help us keep data that Docker containers create and use. When we remove a container, the volume data stays. This makes volumes very important for keeping data safe. Using Docker volumes, developers can share data between containers. They can also manage data without worrying about the container’s life cycle. This improves how reliable and flexible our applications are. Learn more about what are Docker volumes and how do they work.

2. How can I list all Docker volumes on my system?

To see all Docker volumes on our system, we can use the command line. We just need to run this command:

docker volume ls

This command shows a list of all Docker volumes that are available. It includes their names and details. Knowing how to list Docker volumes helps us manage containers and organize data better in our Docker setup.

3. How do I inspect a Docker volume to view its details?

To check a Docker volume and see its details, we use this command:

docker volume inspect <volume_name>

Just put the real name of the volume instead of <volume_name>. This command gives us detailed info, like the volume’s Mountpoint, when it was created, and which containers are linked to it. This helps us understand how we structure and manage our data.

4. What is the command to remove unused Docker volumes?

We can remove unused Docker volumes with this command:

docker volume prune

This command deletes all volumes that are not in use from our system. This frees up space on our disk. It is good to clean up unused volumes often to keep our Docker environment working well. We should be careful because this action cannot be undone.

5. How can I back up and restore Docker volumes?

We can back up a Docker volume by making a tarball of the volume’s data. We can do this with this command:

docker run --rm -v <volume_name>:/volume -v $(pwd):/backup alpine tar czf /backup/backup.tar.gz -C /volume .

To restore it, we use a similar command but in reverse. Backing up and restoring Docker volumes helps keep our data safe. We can get it back even if we delete the container or volume. For more details, check out our guide on how to backup and restore Docker volumes.