CODEWITHSUNDEEP
mysqldockerdocker-compose
gungu
gungu

Reputation: 161

converting a docker mysql volume from container to shared directory

I would like to change an existing docker mysql volume that contains my databases in a container from:

/var/lib/docker/volumes/docker_data

to a shared volume, eg

/mysql_data

but when I change the docker-compose.yml volume parameter from:

- data:/var/lib/mysql

to

- /mysql_data:/var/lib/mysql

I lose all my database files and mysql starts as vanilla install.

How can I move or otherwise change the existing container mysql storage to the shared storage?

Upvotes: 0

Views: 1597

Answers (2)

David Maze
David Maze

Reputation: 158714

If you create a container that has both mounts, you can copy data from one place to the other.

docker run \
  --rm \                 # don't keep this container after exit
  -v docker_data:/old \  # mount the old directory
  -v /mysql_data:/new \  # mount the new directory
  -w /old \              # cd /old
  busybox \              # image to run
  cp -a . /new           # command to run

For the most part you need to actually be inside a Docker container to access Docker volumes. The Docker documentation's discussion on backing up and restoring volumes also uses this technique.

Upvotes: 1

Anil Kumar Gupta
Anil Kumar Gupta

Reputation: 179

First, you need to create a data volume container which is pretty straightforward.

$ docker create -v /var/lib/mysql --name mysqldata mysql

Next, you need to mount the data volume container "mysqldata" when you run the MySQL container which will have MySQL running.

$ docker run --name mysqldb --volumes-from mysqldata -e MYSQL_ROOT_PASSWORD=password -p 3307:3306 mysql

To quick test add few data and delete your existing container and rerun new one. you will see your data are persistent .

Same equivalent command you can use in your yaml file.

Upvotes: 1

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