The last two major autopkgtest releases (3.18 from November, and 3.19 fresh from yesterday) bring some new features that are worth spreading.

New LXD virtualization backend

3.19 debuts the new adt-virt-lxd virtualization backend. In case you missed it, LXD is an API/CLI layer on top of LXC which introduces proper image management, seamlessly use images and containers on remote locations, intelligently caching them locally, automatically configure performant storage backends like zfs or btrfs, and just generally feels really clean and much simpler to use than the “classic” LXC.

Setting it up is not complicated at all. Install the lxd package (possibly from the backports PPA if you are on 14.04 LTS), and add your user to the lxd group. Then you can add the standard LXD image server with

lxc remote add lco https://images.linuxcontainers.org:8443

and use the image to run e. g. the libpng test from the archive:

adt-run libpng --- lxd lco:ubuntu/trusty/i386
  adt-run libpng --- lxd lco:debian/sid/amd64

The adt-virt-lxd.1 manpage explains this in more detail, also how to use this to run tests in a container on a remote host (how cool is that!), and how to build local images with the usual autopkgtest customizations/optimizations using adt-build-lxd.

I have btrfs running on my laptop, and LXD/autopkgtest automatically use that, so the performance really rocks. Kudos to Stéphane, Serge, Tycho, and the other LXD authors!

The motivation for writing this was to make it possible to move our armhf testing into the cloud (which for $REASONS requires remote containers), but I now have a feeling that soon this will completely replace the existing adt-virt-lxc virt backend, as its much nicer to use.

It is covered by the same regression tests as the LXC runner, and from the perspective of package tests that you run in it it should behave very similar to LXC. The one problem I’m aware of is that autopkgtest-reboot-prepare is broken, but hardly anything is using that yet. This is a bit complicated to fix, but I expect it will be in the next few weeks.

MaaS setup script

While most tests are not particularly sensitive about which kind of hardware/platform they run on, low-level software like the Linux kernel, GL libraries, X.org drivers, or Mir very much are. There is a plan for extending our automatic tests to real hardware for these packages, and being able to run autopkgtests on real iron is one important piece of that puzzle.

MaaS (Metal as a Service) provides just that — it manages a set of machines and provides an API for installing, talking to, and releasing them. The new maas autopkgtest ssh setup script (for the adt-virt-ssh backend) brings together autopkgtest and real hardware. Once you have a MaaS setup, get your API key from the web UI, then you can run a test like this:

adt-run libpng --- ssh -s maas -- \
     --acquire "arch=amd64 tags=touchscreen" -r wily \
     http://my.maas.server/MAAS 123DEADBEEF:APIkey

The required arguments are the MaaS URL and the API key. Without any further options you will get any available machine installed with the default release. But usually you want to select a particular one by architecture and/or tags, and install a particular distro release, which you can do with the -r/--release and --acquire options.

Note that this is not wired into Ubuntu’s production CI environment, but it will be.

Selectively using packages from -proposed

Up until a few weeks ago, autopkgtest runs in the CI environment were always seeing/using the entirety of -proposed. This often led to lockups where an application foo and one of its dependencies libbar got a new version in -proposed at the same time, and on test regressions it was not clear at all whose fault it was. This often led to perfectly good packages being stuck in -proposed for a long time, and a lot of manual investigation about root causes.

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These days we are using a more fine-grained approach: A test run is now specific for a “trigger”, that is, the new package in -proposed (e. g. a new version of libbar) that caused the test (e. g. for “foo”) to run. autopkgtest sets up apt pinning so that only the binary packages for the trigger come from -proposed, the rest from -release. This provides much better isolation between the mush of often hundreds of packages that get synced or uploaded every day.

This new behaviour is controlled by an extension of the --apt-pocket option. So you can say

adt-run --apt-pocket=proposed=src:foo,libbar1,libbar-data ...

and then only the binaries from the foo source, libbar1, and libbar-data will come from -proposed, everything else from -release.

_Caveat:_Unfortunately apt’s pinning is rather limited. As soon as any of the explicitly listed packages depends on a package or version that is only available in -proposed, apt falls over and refuses the installation instead of taking the required dependencies from -proposed as well. In that case, adt-run falls back to the previous behaviour of using no pinning at all. (This unfortunately got worse with apt 1.1, bug report to be done). But it’s still helpful in many cases that don’t involve library transitions or other package sets that need to land in lockstep.

Unified testbed setup script

There is a number of changes that need to be made to testbeds so that tests can run with maximum performance (like running dpkg through eatmydata, disabling apt translations, or automatically using the host’s apt-cacher-ng), reliable apt sources, and in a minimal environment (to detect missing dependencies and avoid interference from unrelated services — these days the standard cloud images have a lot of unnecessary fat). There is also a choice whether to apply these only once (every day) to an autopkgtest specific base image, or on the fly to the current ephemeral testbed for every test run (via --setup-commands). Over time this led to quite a lot of code duplication between adt-setup-vm, adt-build-lxc, the new adt-build-lxd, cloud-vm-setup, and create-nova-image-new-release.

I now cleaned this up, and there is now just a single setup-commands/setup-testbed script which works for all kinds of testbeds (LXC, LXD, QEMU images, cloud instances) and both for preparing an image with adt-buildvm-ubuntu-cloud, adt-build-lx[cd] or nova, and with preparing just the current ephemeral testbed via --setup-commands.

While this is mostly an internal refactorization, it does impact users who previously used the adt-setup-vm script for e. g. building Debian images with vmdebootstrap. This script is now gone, and the generic setup-testbed entirely replaces it.

Misc

Aside from the above, every new version has a handful of bug fixes and minor improvements, see the git log for details. As always, if you are interested in helping out or contributing a new feature, don’t hesitate to contact me or file a bug report.