20 Useful Docker Volume Command Examples for Modern Developers

Docker has changed the way we package our programs since its
emergence in 2013. It allows developers to build cutting edge
software with minimal dependencies and makes deployment easier than
ever. If you’re an aspiring software engineer looking to master the
docker platform, you need to have a good understanding of various
docker volume commands. Volumes are a mechanism used by Docker for providing persistent data
storage. They provide significant benefits in terms of software
development and deployment. We have taken our time today to teach
you the basic building blocks of data volumes in Docker. ^[1]

Essential Docker Volume Command
Examples

This guide will teach you the current methodologies used by
developers to implement persistent data storage in commercial and
open-source projects. You will be able to create your own data
volumes and access them effortlessly from your docker containers
after completing this guide. If you’re an absolute beginner, we
suggest you review our guide on essential docker commands
before working with volumes.^[2]

1. Creating Docker
Volumes

It is very easy to create data volumes in Docker. You will need
to use the volume create command of the docker daemon for doing
this. Take a quick look at the below example to see how this
works.

$ docker volume create testVolume

This command creates a data volume name
testVolume that can be used by a specific
container or shared among a cluster of containers. You can now
mount this volume to a location inside of the container. Once done,
it will be very easy to store or access container data from the
host machine.

2. Displaying Available
Volumes

It is common for development environments to have a large number
of data volumes. So, it’s crucial to identify the specific volumes
you are working with. Luckily, it’s very easy to list all currently
declared data volumes using the volume ls sub-command of the docker
daemon.

$ docker volume ls

You will get a list of all docker volumes present in your host
by running the above command. It prints out the names of the data
volumes as well as the respective volume drivers. The data volumes
are stored in a specific portion of the host filesystem, namely
/var/lib/docker/volumes/ in Linux.

3. Inspecting Docker
Volumes

The volume inspects command of the docker daemon provides us
essential information about a particular volume. It displays
information like the volume driver, mount point, scope, and labels.
The below command demonstrates this using a practical example.

$ docker volume inspect testVolume

The resultant data shows that our testVolume is
mounted at the location
/var/lib/docker/volumes/testVolume/_data of our
host machine. It also displays the date of creation for this
information as well as any specified options. It makes
troubleshooting data volumes much easier for developers.

4. Deleting Specific
Volumes

If you have accumulated unused data volumes, it’s a good idea to
remove them. You can free up storage space in the host environment
in this way. The following example illustrates how you can delete a
single volume using its name attribute.

$ docker volume rm testVolume

So, you can delete a particular data volume by using the volume
rm sub-command, followed by the volume name. It will return the
name of the deleted volume in your Linux terminal emulator as a
confirmation. ^[3]

5. Deleting Multiple
Volumes

Deleting multiple data volumes is also quite straightforward.
Simply pass the name of the volumes you want to delete one after
another. The below command shows this in action.

$ docker volume rm testVolume newVolume otherVolume

This command will remove the three specified data volumes. Note
that we have not created newVolume and
otherVolume. They have been used here for
demonstration purposes only. So, make sure your data volumes exist
in the first place before deleting them.

6. Deleting All
Volumes

It is always a good idea to get rid of your data volumes once
your containers are moved onto the production environment from your
development machine. Luckily, the docker daemon allows developers
to remove all available docker volumes using a single command, as
illustrated below.

$ docker volume prune

Moreover, this docker volume command is graceful, meaning it
will not remove any volumes that are in use by an existing
container. Thus, it is very safe to use and helps to free up
much-needed space in development environments.

7. Creating Containers with Data
Volumes

We have only shown some basic volume operations so far. However,
you will need to mount your data volumes to a docker container in
most real-life scenarios. The following docker command shows you
how to create a docker container and mount a data volume to this
container.

$ docker run -d -it --name test-container -v "testVolume":/tmp ubuntu:xenial

$ docker run -d -it --name test-container --volume "testVolume":/tmp ubuntu:xenial

This command will create a container named test-container using
the ubuntu:xenial image and mount our data volume to the
/tmp location of this container. You can find more
information by running the below command and checking the “Mount”
section of the output.

$ docker inspect test-container

8. Mounting Data Volumes to
Containers

The –mount option in Docker can be used for
addressing an existing data volume to a specific part of the
container filesystem. Although the result will be totally similar
to the above command, it is more intuitive to many Linux
developers.

$ docker run -d -it --name test-container --mount source=testVolume,target=/tmp ubuntu:xenial

The –mount option a set of comma-separated
tuples. These are <key>=<value> pairs that
denote the attributes of the data volume.

9. Creating Bind Mounts in
Docker

Bind mounts are a persistence mechanism that has been available
since the early days of Docker. They provide somewhat limited
functionality compared to docker volumes but are more suitable in
some specific cases. Contrary to volumes, bind mounts depend on the
underlying host filesystem.

$ docker run -d -it --name test-container --mount type=bind,source=$(pwd),target=/tmp ubuntu:xenial

The above command creates a bind mount that maps the current
working directory of your Linux filesystem^[4]
to the /tmp location of the container. The
type=bind tuple denotes that this is a bind mount, rather
than a volume.

10. Pre-Populating Data
Volumes

Sometimes developers may require to pre-populate their data
volumes when creating docker containers. However, this technique
only applies if the target destination of the container holds data
prior to the volume creation.

$ docker run -d --name=nginxContainer -v nginxVol:/usr/share/nginx/html nginx:latest

This command first creates the volume nginxVol and populates it
with the contents of the /usr/share/nginx/html
location of the containers’ filesystem. Now, this data will be
accessible to all other containers that share the nginxVol volume.
You can use the mount syntax alternatively, as shown below.

$ docker run -d --name=nginxContainer --mount source=nginxVol,destination=/usr/share/nginx/html nginx:latest

11. Using Read Only
Volumes

By default, all containers have both read and write access to
their respective data volumes. However, not all containers need to
write data to a volume. Often simply reading data is good enough.
In such cases, you can assign read-only access for your container.
Check the docker volume commands to see how this works.

$ docker run -d --name=nginxContainer -v nginxVol:/usr/share/nginx/html:ro nginx:latest

So, by simply adding the ‘:ro‘ field after the
destination will prohibit the nginxContainer from writing data to
the nginxVol. You will need to use the ‘readonly‘ option
if you are creating volumes using the –mount option. Note the
difference in syntax carefully.

$ docker run -d --name=nginxContainer --mount source=nginxVol,destination=/usr/share/nginx/html,readonly nginx:latest

12. Creating Volumes using
Drivers

Volume drivers are a flexible mechanism used by Docker to
provide access to remote mounts, data encryption, and other
features. The below commands shows users how to create a docker
container using a specific volume driver.

$ docker volume create --driver vieux/sshfs -o [email protected]

^[5]:/home/session -o
password=testPassword sshVolume

This command creates a docker data volume using the vieux/sshfs driver^[6]. This driver allows
developers to attach remote directories using the SSHFS
technology.

13. Running Containers that
Creates Volumes using Drivers

You can use the following command to create and start containers
that use volume drivers for creating its data volume. This example
builds on the above one.

$ docker run -d --name sshfsContainer --volume-driver vieux/sshfs --mount src=sshVolume,target=/tmp,[email protected]

^[7]:/home/session,volume-opt=password=testPassword
nginx:latest

The volume-opt tuple passes the options. It’s not required for
every use case. However, if you’re specifying volume-opt, you must
use the –mount flag instead of -v
or –volume.

14. Creating Services that Use an
NFS Volume

NFS or Network File System is a distributed file-sharing system
that allows us to use remote filesystems as if they were part of
the local filesystem. The following command shows how to create a
service that uses an NFS volume.

$ docker service create -d --name nfs-service --mount 'type=volume,source=nfsVolume,target=/tmp,volume-driver=local,volume-opt=type=nfs,volume-opt=device=:/var/docker-nfs,volume-opt=o=addr=10.0.0.10' nginx:latest

This command assumes that our NGS server is running on
10.0.0.10, and it exposes the /var/docker-nfs
directory. It also uses NFSv3. So you’ll need to make some
adjustments before using this with NFSv4.

15. Backing Up
Containers

Volumes provide a flexible way for developers to backup
essential container data. For illustration purposes, we will first
create a new container named test-container.

$ docker run -v /data --name test-container ubuntu:xenial /bin/bash

So, test-container has a volume called /data.
Now, we shall launch another container and mount the
/data volume from test-container. We will then
mount a local directory of our filesystem as
/backup and then store the contents of
/data to the /backup
directory as backup.tar.

$ docker run --rm --volumes-from test-container -v $(pwd):/backup ubuntu:xenial tar cvf /backup/backup.tar /data

The –volumes-from option denotes that we are
actually mounting the data volume of test-container into our new
container.

16. Restoring Containers
Backups

It is also very easy to restore your containers from backup
files. You can restore the data to the same container or to a
specific container. We’ll show you how to restore the contents of
the backup.tar file created in the earlier example to a different
container here.

$ docker run -v /data --name test-container2 ubuntu /bin/bash

This command creates another new container with a
/data volume. Now we will extract the contents of
the backup.tar file in this new data volume.

$ docker run --rm --volumes-from test-container2 -v $(pwd):/backup ubuntu bash -c "cd /data && tar xvf /backup/backup.tar --strip 1"

You can automate your backups and restorations
using these simple yet flexible docker volume commands at ease.
^[8]

17. Removing Anonymous
Volumes

Earlier, we have seen how to delete a normal named volume.
However, Docker^[9]
also has another type of data volume called anonymous volumes. Take
a quick look at the below command to see how the deletion operation
differs among named and anonymous volumes.

$ docker run --rm -v /anon -v whats-in-a-name:/tmp busybox top

The above command will create an anonymous volume called
/anon and a named volume called
whats-in-a-name. Now, Docker will remove this
container automatically on exit. However, it will only delete the
/anon volume, not the whats-in-a-name volume. You
need to delete that using the docker volume command rm.

18. Specifying Mount
Propagation

Mount propagation denotes the flow of control between the
original mount and its replicas. By default, both bind mount and
volumes use the rprivate setting. This refrains
any propagation between the original mount and its replicas. You
can override this setting using the bind-propagation tuple of the
bind mount.

$ docker run -d -it --name test-container --mount type=bind,source="$(pwd)"/test,target=/tmp --mount type=bind,source="$(pwd)"/test,target=/temp,readonly,bind-propagation=shared nginx:latest

This command mounts the /test directory twice
into the container. Additionally, any new addition to the
/tmp mount will be reflected in the
/temp mount. However, you can not
override the propagation setting when using volumes. It only works
when using bind mount on a Linux host.

19. Displaying Volume Command
Manual

You can easily view the basic usage of the volume commands by
using the below command.

$ man docker volume

However, it does not provide in-depth explanations. So, we
suggest you consult the official docker documentation on volumes^[10] and bind mounts^[11].

20. Displaying Help Page for
Sub-Commands

Use the following command to display the primary options
available to docker volume.

$ docker volume --help

You can also display more information about a specific option by
using the following syntax.

$ docker volume COMMAND --help
$ docker volume ls --help

Ending Thoughts

Docker volumes provide a much-needed facility for modern
applications. They allow developers to create robust, cutting-edge
apps and services by eliminating storage concerns. Moreover, docker
volume commands also make it easy to create and maintain backups of
your container data. We have laid out this carefully thought guide
to help you master data volumes more easily. We highly recommend
you start with the basic commands first and then gradually move on
to complex, real-life scenarios. Hopefully, we provided you the
information you were looking for in this guide. Don’t forget to
leave us a comment if you have any questions.