Luca Boccassi
9f08885b0e
Even after switching the wait loop to a polling `journalctl --grep`, the
test still fails intermittently because the very first messages emitted by
the freshly-spawned systemd-networkd-wait-online process can carry stale
journald metadata. journald associates `_SYSTEMD_UNIT=` (and friends) with
each entry by reading `/proc/$pid/cgroup` of the originating PID; if those
messages are produced before journald notices the cgroup migration into the
new service, they get tagged with `_SYSTEMD_UNIT=init.scope`. The
`-u $unit` filter then fails to match them.
Capture a journal cursor before launching the unit, and grep using
`--after-cursor=` plus `SYSLOG_IDENTIFIER=systemd-networkd-wait-online`
instead of `-u $unit`. SYSLOG_IDENTIFIER is set by the program itself, so
it's not subject to the cgroup-discovery race. The cursor bounds the search
to entries produced by this invocation, so prior wait-online runs in
earlier testcases don't interfere.
Logs from the failing run showing the messages exist but are tagged with
the wrong unit:
[ 2570.948554] TEST-75-RESOLVED.sh[2178]: + unit=wait-online-dns-ede81407-b93b-459d-8e5d-69292b42d2ae.service
[ 2571.023162] TEST-75-RESOLVED.sh[2178]: + systemd-run -u wait-online-dns-ede81407-b93b-459d-8e5d-69292b42d2ae.service ...
[ 2571.049189] TEST-75-RESOLVED.sh[2178]: + timeout 30 bash -c 'until journalctl -b -u wait-online-dns-ede81407-b93b-459d-8e5d-69292b42d2ae.service --grep ...'
[ 2571.964986] systemd-networkd-wait-online[2190]: dns0: No DNS server is accessible.
[ 2601.051088] TEST-75-RESOLVED.sh[2178]: ++ cleanup
And for that 2571.964986 entry:
_SYSTEMD_CGROUP=/init.scope
_SYSTEMD_UNIT=init.scope
_EXE=/usr/lib/systemd/systemd-executor
_CMDLINE=/usr/lib/systemd/systemd-executor --deserialize 68 ...
SYSLOG_IDENTIFIER=systemd-networkd-wait-online
MESSAGE=dns0: No DNS server is accessible.
Follow-up for d4bc62713e
Co-developed-by: Claude Opus 4.7 <noreply@anthropic.com>
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