How to copy data from docker volume to host?

Question

I have created a docker volume "hello" and it contains some data .

How can I copy the data to host ?

First :

kerydeMacBook-Pro:~ hu$ docker volume create --name hello
hello

checking :

kerydeMacBook-Pro:~ hu$ docker volume ls
DRIVER              VOLUME NAME
local               hello

volume "hello" inspect

kerydeMacBook-Pro:~ hu$  docker volume inspect hello
[
    {
        "Name": "hello",
        "Driver": "local",
        "Mountpoint": "/mnt/sda1/var/lib/docker/volumes/hello/_data"
    }
]

How can i copy the data on the volume "hello" to host?

I tried :

kerydeMacBook-Pro:~ hu$  docker cp hello:/mnt/sda1/var/lib/docker/volumes/hello/_data /Users/hu/Desktop/12
Error response from daemon: no such id: hello

It does not work as expected!

Who can help me ?

Bistre

Answer 1

Docker does not provide an interface to access volumes directly but you can use a container that has the volume mounted. This may need a temporary container to be created:

CID=$(docker run -d -v hello:/hello busybox true)

Copy a directory from volume to host

docker cp $CID:/hello ./

To copy a directory from the host to volume

cd local_dir
docker cp . $CID:/hello/

Then clean up (if using a temporary container).

docker rm $CID

Hurling

@Matt...yes,thanks,this question has resolved ! But ...Can i ask a deep question : How can i copy local data to docker volume hello, i try : CID=$(docker run -d -v hello:/hello busybox true) then : docker cp $CID: ./data /hello ,,it has en error:Error response from daemon: lstat /mnt/sda1/var/lib/docker/aufs/mnt/583e187 ..no such file or directory ..Can help me ? – Bistre

Close. The container id is part of the source or destination, like scp uses a host name – Hurling

@Matt...Sorry,i'm a newer to Docker , do not understand The container id is part of the source or destination, like scp uses a host name , Can you detail it ? and how to implement ? thanks ! – Bistre

No worries.. check the answer again. I edited it to show copying the other direction at the time of that comment, my scp comment was referring to those updates. – Hurling

Why do we need a temporary container? – Jillene

@Jillene Docker doesn't provide another interface to access data from a volume – Hurling

Worked for me thanks. You can also use a named container if you don't want to bother with IDs docker run --name temp-name -d -v hello:/hello busybox true, docker cp temp-name:/hello ./ – Postal

CID=$(docker run -d -v hello:/hello busybox true) will this return a container ID, and what if I already having a container in running state and I do have container ID, can I use it? as CID? – Bogle

@AhmadMujtaba yes, existing container ID or container name can be used – Hurling

Answer 2

You do not need to run any additional container you can perform this task with the existing container.

Copy files from container to local path

docker cp CONTAINER:/var/logs/ /tmp/app_logs

Copy a local file into container

docker cp ./some_file CONTAINER:/work

Autry

This is the simplest one. – Eduction

Answer 3

Here is a one liner:

docker run --rm -v <volume>:/src -v $(pwd)/<dir>:/dest alpine sh -c 'cp -R /src/* /dest/'

Replace <volume> by the volume name & <dir> by a directory on the host (from the current location pwd)

This will:

• Run a tiny alpine container
• Mount the volume on src
• Mount the host's <dir> on dest
• Recursively copy src to dest
• Stop the container
• Delete the container

Dalton

Answer 4

While upgrading the OS to a new version by side installing the new one and installing at the same time a SSD in addition to the old mech. HD, I've just transferred volumes from one system to another by a simple file copy at the host level. The system is Linux Mint, and it should work the same for any *nix based box. Sorry by I don't know for Windows.

While running the new system:

• create the Docker volumes
• mount the disk of the old install
• locate there the volumes to be copied (under /var/lib/docker/volumes/) based on the name
• copy (copy -a -r) their _data folder content to their counterpart
• enjoy

All these manipulations must be done as root of course.

After starting the Docker Compose stack on the new system, I've found all the data (including a PostgreSQL DB) there, exactly as they were in the old system.

Stanwinn

Simple and more performant than the options relying on mounting another container (if you have sudo access, of course) – Blackguard

Answer 5

We can do this by simply using Docker Desktop app. Volumes -> <look for the volume you want to export> -> click on export option next to the container id under Actions

Bogle