Volume-less flavours

[kkurczewski]

Is this possible to add image flavour without hardcoded VOLUME?

I mean image tag would be: 3.11.4-no-volume instead 3.11.4 and will not have VOLUME clause. Old clients can use old convention and don't worry about persistence where others can choose how store that data if at all. I see one usage in tests where at this moment I need to remember to remove volumes.

Note this would be obsolete if moby/moby#18286 will be resolved (and applied in docker-compose).

Any thoughts?

[wglambert]

Other discussions on removing inherent volumes in images docker-library/mongo#306, redis/docker-library-redis#140, docker-library/postgres#404, docker-library/mysql#255

[tianon]

While I agree it's unfortunate Docker doesn't have a feature to disable inherited volumes, I really hesitate to add extra explicit variants that then need to be maintained to support this.

I've been able to work around this and get Cassandra storing data outside the volume successfully with something similar to the following:

FROM cassandra:3
RUN sed -i 's!/var/lib/cassandra!/tmp/cass!g' /etc/cassandra/cassandra.yaml

(Where /tmp/cass gets replaced with whatever directory you want the final image to store data in.)

[kkurczewski]

Yes, that kinda would work but I feel this is little hackish... I need afterall make my own image which will still have dangling empty volume.

Sorry if I'm sound annoying but still I'm not convinced to your standpoint.

Now let me summarize my arguments:

• there is demand for such thing (as @wglambert pointed out)
• I understand that implementing volumes-removal feature may be hard to implement & maintain so I don't touch this topic, (btw. I don't feel this is way to go)
• my proposal is simple & backward-compability complaint

My proposed solution:
tag=...;` sed 's/VOLUME.*//1' ./Dockerfile | docker build -t "${tag}-volumeless" . -f -

And that's all. I believe adjusting travis.yml would be sufficient, correct me if I wrong.

Of course, I could keep those volume-less images by myself in my private/public repository, but:

• I'm not trusted & highly secured party like docker is
• managing such fork would be repetitive and delayed in time (think about security holes & other bugs)
• declaration could look funny and/or less professional with my custom repository in name: kkurczewski/cassandra:3.1-volumeless

I mean, this is really simple thing to do useful at least for a bunch of people who care to comment about that.