This has always been an odd problem to me since the official install guide says to use the wget command from get.docker.com to install Docker. And I have never observed this problem on any install we did, which obviously follows the official guide slavishly.
wget -qO- https://get.docker.com/ | sh
So this implies people who do have this problem installed Docker in some oddball, non-install-guide way… somehow.
I dunno about the docker aspect… this instance has been running fine for over a year, through other docker upgrades even.
Today I did apt-get upgrade and I got fussed at about a lack of aufs. I don’t even think it was a docker issue, but a mismatch of kernel & image-extra. If ubuntu 16 resolves that issue, I’m going to put image-extra out of my life with an OS upgrade.
Not that I’m aware of… this host does nothing but run Discourse.
What I have seen is weirdness running apt-get dist-upgrade and I’d told myself never to run that again.
I assume that apt-get upgrade shows newer versions of packages that don’t match the kernel, and.or the kernel is silently upgraded without me knowing, causing a mismatch in the extras. (or maybe the silent upgrade is something only Linode does… I don’t know enough to know)
Regardless, I’ve come to distrust any docker upgrade because I can never tell if a bug in docker will cause an utter failure, or some other craziness.
Luckily, I have a forum that has very low use and can afford hours of downtime, so I use it as my guinea pig before I upgrade my three important ones.
The goal of this thread is to prevent such random failures… I’m hopeful that ubuntu16 does that. So far, my guinea pig forum upgraded to ubuntu16 just fine… my first real forum is busy rolling back since its boot volume was read-only after the upgrade.
Nope – but I use overlay2, I just recently shutdown the discourse instance on 14.04(moved it to a new server on 16.04) – which did use aufs due to overlay2 not working on that kernel line(3.13.x) – I upgraded the box regularly so I know it doesn’t cause issues…you were missing some package dependencies.
My first update to ubuntu 16 went fine, the second host’s upgrade resulted in a read-only filesystem (seems to be a common enough issue… I may simply move it to a new host as is recommended).
However, it seems that perhaps I never explicitly requested the install of the image-extras package which is required for AUFS. Since I ran the apt-get command @robbyoconnor suggested, all is well with the host/docker/discourse.