Add the VOLUME instruction to the Dockerfile builder.

FROM ubuntu
VOLUME ["/data"]

OR

FROM ubuntu
VOLUME /data

Hey @crosbymichael, thanks for contributing this. Would you mind adding a test which makes sure that the built image does indeed expose a volume at the given path? Your test does verify that the keyword doesn't cause a build to fail, but that's currently the case for all keywords since they are ignored by default.

Happy to help, and looking forward to merging this.

Thanks for the feedback. Done!

+ Builder: Add VOLUME instruction to buildfile

Is volume host:container supported? Or volume [host:container]?

I wasn't able to get that working.

@crosbymichael should they be? It seems like an asymmetry between the CLI and the Dockerfile.

Oh good point, so it seems like VOLUME is more to serve volumes-from then because an empty volume inside a container isn't very useful