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dockervolumes
Ma Sch
Ma Sch

Reputation: 641

Copy docker volumes

I want to update some container. For testing, I want to create a copy of the corresponding volume. Set up a new container for this new volume.

Is this as easy as doing cp -r volumeOld volumeNew?

Or do I have to pay attention to something?

Upvotes: 42

Views: 71656

Answers (4)

MauriceNino
MauriceNino

Reputation: 6747

To clone docker volumes, you can transfer your files from one volume to another one. For that, you have to manually create a new volume and then spin up a container to copy the contents.

Here is an example on how to do that:

# Supplement "old_volume" and "new_volume" for your real volume names

docker volume create --name new_volume

docker container run --rm -it \
           -v old_volume:/from \
           -v new_volume:/to \
           ubuntu bash -c "cd /from ; cp -av . /to"

Upvotes: 64

anemyte
anemyte

Reputation: 20176

On Linux it can be as easy as copying a directory. Docker keeps volumes in /var/lib/docker/volumes/<volume_name>, so you can simply copy contents of the source volume into a directory with another name:

# -a to preserve all file attributes (permissions, ownership, etc)
sudo cp -a /var/lib/docker/volumes/source_volume /var/lib/docker/volumes/target_volume

Upvotes: 50

Cristi B.
Cristi B.

Reputation: 41

Try to clone the volume using the "Volumes Backup & Share" Docker extension.

See https://www.docker.com/blog/back-up-and-share-docker-volumes-with-this-extension/

Upvotes: 4

Peter Rullmann
Peter Rullmann

Reputation: 111

Should you want to copy volumes managed by docker-compose, you'll also need to copy the specific labels when creating the new volume. Else docker-compose will throw something like Volume already exists but was not created by Docker Compose.

Extending on the solution by MauriceNino, these lines worked for me:

# Supplement "proj1_vol1" and "proj2_vol2" for your real volume names

docker volume inspect proj1_vol1  # Look at labels of old volume

docker volume create \
           --label com.docker.compose.project=proj2 \
           --label com.docker.compose.version=2.2.1 \
           --label com.docker.compose.volume=vol2 \
           proj2_vol2

docker container run --rm -it \
           -v proj1_vol1:/from \
           -v proj2_vol2:/to \
           alpine ash -c "cd /from ; cp -av . /to"

Btw, this also seems to be the only way to rename Docker volumes.

Upvotes: 11

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