`data-container` with named or anonymous volumes - conceptual problems? (Discussion)

Question

a) Anonymous volumes

When using data-containers, you can either use anonymous volumes like this

version \'2\'
services:
  consumer:
    volume_from         


        

Answer 1

Short answer: named data volumes are preferred, data containers are no longer needed, so you should never use volumes-from on any new project.

Your version of named volumes is merging a named and data container, it should be:

version '2'
services:
  web:
    image: my-web-image
    volumes:
      - my-named-volume:/var/www

 volumes:
   my-named-volume:
     driver: local

By merging the two, you've added an extra layer of indirection to reach your named volume, without any added benefits. Named volumes were created in 1.9 to replace data containers which were themselves a somewhat hacked method to provide persistent data. Advantages of named volumes over data containers include:

• Your data management is separate from your container management, you can remove all running containers and still have your data available
• Data can be stored in different locations using volume drivers, which means you can put it on nfs, a distributed file system, or even a local persistent directory
• You may start and stop any container in any order without dependencies between containers
• When first created, a named volume will receive a copy of the image filesystem it is first mounted on top of, identical to the behavior of data containers, which means it's a seamless transition (note that this is not the behavior of a host volume, aka bind mount)

See also this question that also discusses named volumes vs data containers and this answer to another similar question. We also have a blog post on this by a company that I work for.