Comment 10 for bug 1732368

Tianon Gravi (tianon) wrote :

> The reason this is being done as a debconf question is because neither option is good. And *since* we are forced to ask the user to pick their poison, I consider it insufficient to ask this question only once. The question should by default be re-asked, at each package upgrade, so that the user has an opportunity to make the decision that is correct for them at that moment.

> In addition, the current default for the debconf question is "true"; so by default, which includes on non-interactive upgrades (unattended upgrades or the like), the behavior the user gets here is that the service is restarted, stopping any un-supervised containers. If the package is not able to detect whether all running containers will be automatically restarted, then if this is to be a supported use case at all, the default should be to not restart: because it is less disruptive to have the docker service become unavailable, than to have the docker containers become unavailable.

Fair enough, will update Git and poke Michael when it's ready (thanks for noting the exact pattern we ought to be using to accomplish this). :)

> "reconfigure" is not a valid argument to a postinst script. (And dpkg-reconfigure does not invoke it this way - it invokes it as 'postinst configure'.) So the first part of this test is always true and can be omitted.

I included that because I read on the lists that it was intended to be supported _eventually_, but I guess that was long enough ago (and the transition wouldn't be fun to implement across the archive) that it's probably safe to ignore that ever happened; fair enough. O:)

> And the check for status is not consistent with expected behavior of packages: upgrading the package should normally start the service even if it was currently not running, unless the administrator has explicitly disabled it through policy-rc.d.

So, this block of code is _only_ responsible for performing the daemon restart, hence why this bit was included. Starting the daemon happens in the following block.

To put it another way, if Docker isn't running, there's not really a good reason to even prompt the user whether we're OK to restart it -- we should just fire it up.

Would it make more sense to have this block just stop the daemon instead and let the following block start it up?

> This code includes a check for "$shouldStartRestart"; but this is the code to start the daemon on package initial installation, and the debconf question doesn't ask about starting, only about restarting. So I think this check shouldn't be there.

The "$shouldStartRestart" variable basically amounts to "Are we running this script because of package install or because of 'dpkg-reconfigure'?" -- if the user is simply running "dpkg-reconfigure", I don't think it's appropriate or necessary for us to fire up the Docker daemon (or bother restarting it -- we only care about doing that when upgrading or installing the package).

Since we're going to ditch the check for `[ "$1" != 'reconfigure' ]`, we can just use "$DEBCONF_RECONFIGURE" which will make this more clear.

So to summarize, the current code, as written, will restart the daemon based on the user's input, but only during package install/upgrade (not during "dpkg-reconfigure"), and if the daemon isn't running, will start it up during package install/upgrade (also not during "dpkg-reconfigure").