app-emulation/docker: use default cgroupdriver

[crawford]

Fixes coreos/bugs#1435.

/cc @aaronlevy @pbx0

[peebs]

Are you leaving $DOCKER_CGROUPS in the ExecStart line for compatibility reasons? I imagine most people override that line entirely rather then the Environment if they were customizing this setting.

Also, there are only two settings for this option anyway. So everyone is either moving from the systemd driver to cgroupfs or already on cgroupfs. Unless there exist configs that pin their daemon to use the systemd driver and do so by overriding the environment variable rather then the ExecStart line.

Otherwise, LGTM

[crawford]

Good point. @marineam do you think we should pull that option entirely? Anybody who overrode it to cgroupfs isn't going to be affected and I doubt anyone overrode the flag with the existing value (these cases would break).

[mischief]

🚢 🇮🇹 ?

[crawford]

@vcaputo and I talked it over and think it's good as is. We can deprecate the DOCKER_CGROUPS variable, but should probably leave it for now.

[vcaputo]

lgtm