26

I need to create a persistent volume for Docker. The volume must be named extra-addons and located in /mnt/.

I run this command:

sudo docker volume create /mnt/extra-addons

I got this error message:

Error response from daemon: create /mnt/extra-addons: "/mnt/extra-addons" includes invalid characters for a local volume name, only "[a-zA-Z0-9][a-zA-Z0-9_.-]" are allowed. If you intended to pass a host directory, use absolute path

Note that when I simply run: sudo docker volume create extra-addons, I do not face this problem but when I inspect the volume in question using sudo docker inspect extra-addons, I see it is located in a place I do not want:

[
    {
        "CreatedAt": "2018-04-21T14:40:25+03:00",
        "Driver": "local",
        "Labels": {},
        "Mountpoint": "/var/lib/docker/volumes/extra-addons/_data",
        "Name": "extra-addons",
        "Options": {},
        "Scope": "local"
    }
]

I mean I rather want to see the volume like this: /mnt/extra-addons

Any idea?

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3 Answers 3

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20

I found the solution:

I had to install local-persist plugin.

I had to mount the volume to create to the mount point as follows:

 sudo docker volume create -d local-persist -o mountpoint=/mnt/ --name=extra-addons

Check if I got what I expected:

sudo docker volume inspect extra-addons

Result: 

[
    {
        "CreatedAt": "0001-01-01T00:00:00Z",
        "Driver": "local-persist",
        "Labels": {},
        "Mountpoint": "/mnt/",
        "Name": "extra-addons",
        "Options": {
            "mountpoint": "/mnt/"
        },
        "Scope": "local"
    }
]

That was what I am looking for.

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15

If you don't want to install any plugins to your docker, I would recommend to create a symbolic link for your volume:

$ docker volume create <myVolume>
$ docker volume inspect <myVolume> 
[
    {
        "CreatedAt": "0001-01-01T00:00:00Z",
        "Driver": "local",
        "Labels": {},
        "Mountpoint": "/var/lib/docker/volumes/<myVolume>/_data",
        "Name": "<myVolume>",
        "Options": {},
        "Scope": "local"
    }
]
$ mkdir /mnt/<myVolume>
# if you already have data in your volume, you should copy it to `/mnt/<myVolume>` now
$ sudo rm -rf /var/lib/docker/volumes/<myVolume>/_data
$ sudo ln -s /mnt/<myVolume> /var/lib/docker/volumes/<myVolume>/_data

Now feel free to use your volume as usual (with all your data beeing in /mnt as you wanted)

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1
  • Don't think it's a good idea deleting docker managed volumes. Use a mount instead to mount a host directory into docker. Commented Jul 22, 2019 at 22:43
7

I don't think using the local-persist driver is the way to go. It hasn't been updated in a while. You can mount a local (host) directory into a docker container using docker mount.

Running the following creates a new container with a mounted directory mapped to my desktop.

mkdir extra-addons
docker run -it -v /Users/me/Desktop/extra-addons:/mnt/extra-addons busybox /bin/sh
ls

You can now see a mnt folder in root of your container.

bin dev etc home mnt proc root sys tmp usr var

Creating a new file in the container

touch /mnt/extra-addons/test.txt

Creates a test.txt file on my host machine. At the specified path. This is now a two way read/write shared folder. Multiple containers can mount the same folder. And it'll persist once you shut your container/s down.

enter image description here

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5
  • Thanks, this saved me a step. I was trying to add a volume. just mount the dir Commented Jul 31, 2019 at 4:50
  • 2
    this creates a bind mount, docker suggest to use volumes, and have several advantages docs.docker.com/storage/volumes Commented Mar 13, 2020 at 8:45
  • @JoeCabezas yeah volumes are a better choice for production given they're docker managed and isolated from other operating system tasks. But for this question in a specific directory bind mounts are the answer. It does enhance the answer distinguishing the two. Commented Mar 13, 2020 at 20:07
  • thanks for the insight, you are right, in order to answer the question a bind volume is enough. Commented Mar 14, 2020 at 1:08
  • I specifically wanted to use a bind mount but was having issues with PostgreSQL until I found a good answer. Just sharing because I ended up here when looking for a solution. Even though the question is for Windows, I had the same error on Linux. Commented Nov 23, 2021 at 14:44

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