Proposal: promote aufs.ko from -extra to main linux-image package

[Seth Forshee]

On Tue, Mar 14, 2017 at 08:07:29AM -0700, Kamal Mostafa wrote:
> We recently noticed that our kernel regression smoke test of 'aufs' was
> failing on test hosts that run on cloud instances, because the
> linux-image-extra package containing aufs.ko is (rightly) not installed by
> default.   (Maas test hosts do get -extra installed by default, which is
> why we didn't notice this before).
> 
> Docker requires aufs, and the Docker forums suggest that folks bump into
> this problem frequently enough ("oh, it turned out that I needed to install
> linux-image-extra to get it working").

I think docker can use overlayfs instead, but it does seem to perfer
aufs.

> Po-Hsu Lin points out that this bug is the same issue:
>     https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1671058
>     "docker service failed to start on s390x (zVM) Yakkety"
> 
> For linux-aws, we have promoted aufs.ko to the main linux-image package.
> 
> I propose that we promote it for *all* supported Ubuntu kernels and
> derivatives, so as to remove Docker's dependence on linux-image-extra.
> Promoting it should be a very low risk operation -- systems that do have
> linux-image-extra installed will still end up with aufs.ko in the same
> filesystem location; systems that don't will just get a new loadable driver.
> 
> Thoughts on this idea?

Seems to makes sense, especially if lots of folks are installing
linux-image-extra only for aufs. +1.

Seth