Move docker bind-mount to volume

Question

Actually, I run my containers like this, for example :

docker run -v /nexus-data:/nexus-data sonatype/nexus3
              ^

After reading the documentation, I discover volumes that are completely managed by docker. For some reasons, I want to change the way to run my containers, to do something like this :

docker run -v nexus-data:/nexus-data sonatype/nexus3
              ^

I want to transfer my existing bind-mount to volumes.

But I don't want to lose the data into /nexus-data folder, is there a possibility to transfer this folder, to the new volume, whitout restart everything ? Because I've also Jenkins and Sonar containers for example, I just want to change the way to have persistent data. The is a proper way to do this ?

There may well be a first-class way of doing this, but a hacky solution would just be to mount both into a container, and then copying from one to the other from inside the container. — Oliver Charlesworth, Apr 17 '18 at 21:52

score 6 · Accepted Answer · edited May 21 '23 at 17:50

6

You can try out following steps so that you will not loose your current nexus-data.

#>docker run -v nexus-data:/nexus-data sonatype/nexus3
#>docker cp /nexus-data/. <container-name-or-id>:/nexus-data/
#>docker stop <container-name-or-id>
#>docker start <container-name-or-id>

docker cp will copy data from your host-machine's /nexus-data folder to container's FS /nexus-data folder which is your mounted volume.

Let me know if you face any issue while performing following steps.

edited May 21 '23 at 17:50

Krokomot

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answered Apr 18 '18 at 04:13

fly2matrix

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What about the ports (-p flag), because they are already taken, I just put other and after it will be possible to come back with wanted ports ? – fmdaboville Apr 24 '18 at 15:15
For example, my nexus container take the 8081, and I prefer to not change it. – fmdaboville Apr 25 '18 at 20:03
2

Stop the first NEXUS container( which is actually using 8081) , since this container is already storing data in host's directory (/nexus)- you have all the required information outside of that container. Now start/create the new NEXUS container with mounted volume (nexus-data) and assigned the required port 8081, since at this point of time your 8081 port is free (old nexus-container is stopped) – fly2matrix Apr 26 '18 at 04:46
Indeed, storage of the data has little to do with the port your nexus container is listening to. You can start and stop containers without losing data – Peter F Aug 07 '20 at 07:47
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For me, `docker copy /nexus-data/* :/nexus-data` doesn't work, `docker cp /nexus-data/. :/nexus-data` works. [Copying files from host to Docker container - Stack Overflow](https://stackoverflow.com/questions/22907231/copying-files-from-host-to-docker-container). – Jason Law Aug 22 '20 at 04:50
@JasonLaw -- Edited the post to correct this. (First, alas incomplete, edit by [@besendorf](https://stackoverflow.com/users/7580219/besendorf)) – Krokomot May 21 '23 at 17:54

score 2 · Answer 2 · answered May 01 '22 at 19:41

Here's another way to do this, that I just used successfully with a Heimdall container. It's outlined in the documentation for the sonatype/nexus3 image:

Stop the running container (e.g. named nexus3)
Create a docker volume called nexus-data, creating it with the following command: docker volume create nexus-data)
By default, Docker will store the volume's content at /var/lib/docker/volumes/nexus-data/_data/
Simply copy the directory where you previously had been using a bind mount to the aforementioned volume directory (you'll need super user privileges to do this, or for the user to be part of the docker group): cp -R /path/to/nexus-data/* /var/lib/docker/volumes/nexus-data/_data/
Restart the nexus3 container with $ docker run -v nexus-data:/nexus-data sonatype/nexus3 --name=nexus3
Your container will be back up and running, with the files persisted in the directory /path/to/nexus-data/ now mirrored in the docker volume. Check if functionality is the same, of course, and if so, you can delete the /path/to/nexus-data/ directory

Q.E.D.

Move docker bind-mount to volume

2 Answers2