[anotherdpk]

> Each version of the CLI is incompatible with the last version of the CLI.

Sure, but I don't think this is a show stopper. You can and should only carefully upgrade between versions of Docker (and other mission-critical software). The process is functionally identical to the process you'd use to perform a zero-downtime migration between versions of the Linux kernel -- bring up a new server with the version of Docker you want to use, start your services on that new server, stop them on the old server, shut down the old server, done.

I don't mean to suggest this is trivial, only to suggest that it is no more complicated than tasks that you/we are already expected to perform.

[coldtea]

>Sure, but I don't think this is a show stopper. You can and should only carefully upgrade between versions of Docker (and other mission-critical software).

Whether I upgrade carefully or not, the Docker CLI should work with all versions of Docker.

[anotherdpk]

I don't get why this is a sticking point. There's no reason to update the Docker CLI independent of the Docker server, and it would be silly to run two versions of Docker on the same host, so why would it matter?

[StreamBright]

I think you are missing the point. It is not about upgrading the production cluster, more like erasing muscle memory and re-learning docker cli again. How often do you re-learn grep, awk, ls, ps, or other command line tools? How mad would you be if these were developed the same manner as Docker CLI? I would be definitely not happy.