tests: do not run degraded test in autopkgtest env
The autopkgtest environment sometimes has failing services. This means that our degraded test leads to false positivies here. This PR disables the test in the autopkgtest environment because we have no control over the images in autopkgtest (unlike in our spread CI) so the test is not useful here.
This patch adds a workaround for apparmor and overlayfs not playing together on the ephemeral Ubuntu 18.10 server images. On such images there's an overlayfs mounted over / with the upper directory in /media/root-rw/overlay. Snapd detects this and generates a directive with read access to said directory. At runtime we get a denial, however, one that looks like this:
As we can see apparmor decided to resolve the path to "/overlay/" (which notably does not exist in the filesystem at all). The reason for that is not understood but as a special-case workaround we detect this and return "/overlay" instead.
tests: tweak greps, run only with strict confinement
The greps needed tweaking because the logged denial differs across kernel versions. The move away from sandbox-features is mandatory because on opensuse 43.2 we run with classic confinement instead, even though parts of apparmor are available in the kernel.
Signed-off-by: Zygmunt Krynicki <email address hidden>
