I need to support different Linux distributions (as of Ubuntu 12.04.1, CentOS 6, …) ideally with the same Docker image. My understanding is that, up to and including Docker 1.9, the image format was portable, but that a new image format was introduced with Docker 1.10 . I understand that new Docker versions will implicitly convert old image formats.
However, what happens when sending a new Docker image to an older Docker version, e.g. on Ubuntu 12.04.1 ? I guess that Docker itself will not necessarily be updated on older system repositories ? Is there a “backwards-compatible” flag on Docker, so that I can always work with the old image version for the time being ?
Thanks and Best Regards,