The aufs storage-driver is no longer supported in docker.io_20.10.7-0ubuntu1~20.04.1

[Alex Muntada]

$ sudo apt upgrade
Reading package lists... Done
Building dependency tree
Reading state information... Done
Calculating upgrade... Done
The following packages will be upgraded:
  docker.io
1 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
Need to get 36.9 MB of archives.
After this operation, 94.2 kB of additional disk space will be used.
Do you want to continue? [Y/n]
Get:1 http://ch.archive.ubuntu.com/ubuntu focal-updates/universe amd64 docker.io amd64 20.10.7-0ubuntu1~20.04.1 [36.9 MB]
Fetched 36.9 MB in 5s (6,777 kB/s)
Preconfiguring packages ...
(Reading database ... 115628 files and directories currently installed.)
Preparing to unpack .../docker.io_20.10.7-0ubuntu1~20.04.1_amd64.deb ...
The aufs storage-driver is no longer supported.
Please ensure that none of your containers are
/var/lib/docker/aufs and try again.
dpkg: error processing archive /var/cache/apt/archives/docker.io_20.10.7-0ubuntu1~20.04.1_amd64.deb (--unpack):
 new docker.io package pre-installation script subprocess returned error exit status 1
dpkg: error while cleaning up:
 installed docker.io package post-installation script subprocess returned error exit status 1
Errors were encountered while processing:
 /var/cache/apt/archives/docker.io_20.10.7-0ubuntu1~20.04.1_amd64.deb
needrestart is being skipped since dpkg has failed
E: Sub-process /usr/bin/dpkg returned an error code (1)

[Alex Muntada (alex.muntada)]

This is a breaking change for an update that should not happen on an LTS version.

Please, add support for aufs back to docker.io and plan a better upgrade path for users.

I'm holding further docker.io updates for now.

[Rörd Hinrichsen (roerd.hinrichsen)]

I can confirm I had the same problem. Ideally, the package upgrade should have offered an option to upgrade the images and containers from aufs to overlay2.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Antoine Pitrou (pitrou)]

Does anyone know how to upgrade the images and containers? Ideally the error message when upgrading should give a clue about that...

[Kristin Cowalcijk (kontinuation)]

I hit similar problem (my distro is ubuntu 18.04), and I followed this guide to switch my storage driver from aufs to overlay2: https://docs.docker.com/storage/storagedriver/overlayfs-driver/ , then the upgrade worked.

Migrating docker images from one storage driver to another is a really painful process: you have to save your images as tar files, switch the storage driver, then load them back one after another. An upgrade requiring so much manual intervention like this should never happen in an LTS release.

[Robie Basak (racb)]

Thank you for taking the time to report this bug and helping to make Ubuntu better.

Quoting multiple people here:

> This is a breaking change for an update that should not happen on an LTS version.

> An upgrade requiring so much manual intervention like this should never happen in an LTS release.

You're correct about this in the general case. Unfortunately Docker is an exception. We believe that most users expect newer Docker upstream releases to be available in stable Ubuntu releases, so this is what we do. Corollary: we think that if we didn't do this, most of our Docker-using users wouldn't want to use the Docker packages we shipped at all.

However it isn't practical to us to maintain feature compatibility when upstream don't choose to do that themselves. So, as an exception for Docker, we update to newer upstream releases without concern for backwards compatibility of the behaviour of Docker itself, instead relying entirely on upstream's decisions. In this case and based solely on the analysis already presented by others here, this means that we don't expect to be patching the aufs storage driver back in to our packaging ourselves.

This is documented at https://wiki.ubuntu.com/StableReleaseUpdates where you can see the exceptions that Ubuntu makes for specific packages, and at https://wiki.ubuntu.com/DockerUpdates for the Docker group of packages specifically.

You do still have the option of using the version of Docker that shipped with a release by pinning the package to the release pocket. See apt_preferences(5) for details. However, this means that you won't receive updates (security or otherwise) for the package (and sometimes its dependencies, if they end up effectively pinned as a consequence).

Following the policy as it stands, this isn't something we expect to fix, and therefore I'm marking this bug Won't Fix. Please feel free to continue to use this bug to coordinate with others affected - for example by communicating workarounds.

If you disagree with the policy and want to make a case for it to be changed, you're welcome to do that. https://discourse.ubuntu.com/ is probably the best venue for that, and if you do post there then please link to the thread from here. However, note that you're unlikely to be successful if your proposal effectively means that you're asking others to do additional work for you, unless you also provide a workable solution for where that engineering time would come from.

[Alex Muntada (alex.muntada)]

Robie, thanks for your thorough explanation. Now I understand better the docker support in Ubuntu, and that will help me pick the right setup in future scenarios.

Cheers,
Alex

[fermulator (fermulator)]

This is not acceptable practice on an LTS distribution. I'm on Ubuntu 18.04 LTS and got hit by this breaking change from docker package management -- please revert this package from being released to LTS Ubuntu.

[fermulator (fermulator)]

See https://docs.docker.com/engine/release-notes/18.09/#deprecation-notices (2019-09-03) deprecation notice was set.