Docker data volume container

If you have some continuously updated data that needs to be shared between containers, it's a good idea to create a data volume container.

A data volume container is in fact a normal container that is designed to provide data volumes for other containers to mount.

First, create a named data volume container dbdata:

$ sudo docker run -d -v /dbdata --name dbdata training/postgres echo Data-only container for postgres

Then, use --volumes-from to mount the data volumes in the dbdata container.

$ sudo docker run -d --volumes-from dbdata --name db1 training/postgres
$ sudo docker run -d --volumes-from dbdata --name db2 training/postgres

You can also use --volumes-from parameters to mount multiple data volumes from multiple containers. You can also mount a data volume from another container that already has a data volume mounted.

$ sudo docker run -d --name db3 --volumes-from db1 training/postgres

Note: Containers --volumes-from parameter do not need to remain operational themselves.

If you delete mounted containers, including dbdata, db1, and db2, the data volume is not automatically deleted. I f you want to delete a data volume, you must use the docker rm -v command to specify that the associated container be deleted at the same time when deleting the last container that still has it. T his allows users to upgrade and move data volumes between containers. Specific actions will be covered in the next section.