The latest GH Action runners started using 32-bit entropy for ASLR,
which makes it incompatible with llvm-14. This was fixed in later llvm
releases, but these aren't available on Ubuntu Jammy (22.04). Let's
reduce the ASLR entropy to 28-bit, which should make llvm happy again,
until the issue is resolved.
See: https://github.com/actions/runner-images/issues/9491
Instead of running meson install and hoping for the best, let's build
distribution packages from the downstream packaging specs. This gets
us the following:
- Vastly simplified mkosi scripts since we don't need a separate initrd
image anymore but can just reuse the default mkosi initrd.
- Almost everything can move to the base image as its not the basis
anymore for the initrd and as such we don't need to care about the
size anymore.
- The systemd packages that get pulled in as dependencies of other
packages get properly uninstalled and replaced with our packages that
we built instead of just installing on top of an existing systemd
installation with no guarantee that everything from that previous
installation was removed.
- Much better testing coverage as what we're testing is much closer
to what will actually be deployed in distributions.
- Immediate feedback if something we change breaks distribution packaging
- We get integration with the distribution for free as we'll automatically
use the proper directories and such instead of having to hack this
into a mkosi build script.
- ...
For some reason root in GH actions is able to _decrease_ its oom score
even after dropping all capabilities (including CAP_SYS_RESOURCE), until
the oom score is changed explicitly after sudo:
$ systemd-detect-virt
microsoft
$ sudo su -
~# capsh --drop=all -- -c 'capsh --print; grep -H . /proc/self/oom*; choom -p $$ -n -101'
Current: =
Bounding set =
Ambient set =
Current IAB: !cap_chown,!cap_dac_override,!cap_dac_read_search,...,!cap_sys_resource,...,!cap_checkpoint_restore
Securebits: 00/0x0/1'b0
secure-noroot: no (unlocked)
secure-no-suid-fixup: no (unlocked)
secure-keep-caps: no (unlocked)
secure-no-ambient-raise: no (unlocked)
uid=0(root) euid=0(root)
gid=0(root)
groups=0(root)
Guessed mode: UNCERTAIN (0)
/proc/self/oom_adj:8
/proc/self/oom_score:1000
/proc/self/oom_score_adj:500
pid 22180's OOM score adjust value changed from 500 to -101
~# choom -p $$ -n 500
pid 22027's OOM score adjust value changed from 500 to 500
~# capsh --drop=all -- -c 'capsh --print; grep -H . /proc/self/oom*; choom -p $$ -n -101'
Current: =
Bounding set =
Ambient set =
...
uid=0(root) euid=0(root)
gid=0(root)
groups=0(root)
Guessed mode: UNCERTAIN (0)
/proc/self/oom_adj:8
/proc/self/oom_score:1000
/proc/self/oom_score_adj:500
choom: failed to set score adjust value: Permission denied
I have no idea what's going on, but it breaks
exec-oomscoreadjust-negative.service from test-execute when running
unprivileged.
Otherwise the unprivileged part of test-execute gets silently skipped:
/* test_run_tests_unprivileged */
Successfully forked off '(test-execute-unprivileged)' as PID 20998.
...
pin_callout_binary: build dir binary: /home/runner/work/systemd/systemd/build/systemd-executor
pin_callout_binary: open(/home/runner/work/systemd/systemd/build/systemd-executor)=-13
Failed to pin executor binary: No such file or directory
(test-execute-unprivileged): manager_new, skipping tests: No such file or directory
(test-execute-unprivileged) succeeded.
The runner has a lot of useless things installed, taking ~10GB, and
jobs have started to fail when booting images due to lack of disk
space, so delete some directories to make room.
2024-02-27T20:20:58.0998709Z ##[warning]You are running out of disk space. The runner will stop working when the machine runs out of disk space. Free space left: 0 MB
Co-authored-by: Daan De Meyer <daan.j.demeyer@gmail.com>
Both building and booting a directory image is much faster than
building or booting a disk image so let's default to a directory
image.
In CI, we stick to a disk image to make sure that keeps working as
well.
The only extra dependency this introduces is virtiofsd which is
packaged in all distributions except Debian stable. For users
hacking on systemd on Debian stable, a disk image can be built by
writing the following to mkosi.local.conf:
```
[Output]
Format=disk
```
The mkosi github action doesn't set up the host machine for building
full images anymore. Instead, only sufficient packages are installed
to be able to build tools trees so we configure a fedora tools tree
to build the actual images.
- Use mkosi.images/ instead of mkosi.presets/
- Use the .chroot suffix to run scripts in the image
- Use BuildSources= match for the kernel build
- Move 10-systemd.conf to mkosi.conf and rely on mkosi.local.conf
for local configuration
This will bring in the fix for rawhide/tumbleweed builds (new libsolv
capable of handling zstd). If all goes well it will migrate to jammy
proper in a week and it can be reverted
mkosi detects whether /dev/kvm is available and uses it if it is. But
some GHA hosts have it, but it's broken and not supported, so we need
to explicitly disable it.
