Docker命名卷与DOC（仅数据容器）

Question

Up to recent version of Docker (v1.10), we were thought that we can use DOC: data-only containers . So I would create such DOC (based on eg busybox) and use --volumes-from to link it to my container. You can still read about this in Docker documentation .

With new version of docker, it is said that instead of DOC we should use named volumes . Here is an example of docker-compose.yml :

version: '2'    
services:
  elasticsearch:
    image: elasticsearch:2.2.0
    command: elasticsearch -Des.network.host=0.0.0.0
    ports:
      - "9201:9200"
    volumes:
      - "es-data:/usr/share/elasticsearch/data"

volumes:    
  es-data:

Here we created and use named volume es-data .

There is still not much documentation on this new feature. I am asking:

• Can we replace DOC with named containers? How long volume is persisted? What if I remove the container that is using it?
• How can we eg backup now? Previously, I could docker run --rm --volumes-from es-data ... and then tar it.

Answer 1

Can we replace DOC with named containers?

In many cases, yes, named containers will be a better option.

How long volume is persisted? What if I remove the container that is using it?

If you remove the container, the volume will still be there. The only way to remove the volume is to use docker-compose down -v or docker volume rm <volume name> .

How can we eg backup now? Previously, I could docker run --rm --volumes-from es-data ... and then tar it.

Instead of --volumes-from , you can use --volume=<volume name> .

Note that volumes created by docker-compose are always prefixed with the project name, so if you use it with a docker command the full name is actually <project_name>_es-data .