Similarly to "setup" vs. "set up", "fallback" is a noun, and "fall back"
is the verb. (This is pretty clear when we construct a sentence in the
present continous: "we are falling back" not "we are fallbacking").
The usual behaviour when a timeout expires is to terminate/kill the
service. This is what user usually want in production systems. To debug
services that fail to start/stop (especially sporadic failures) it
might be necessary to trigger the watchdog machinery and write core
dumps, though. Likewise, it is usually just a waste of time to
gracefully stop a stuck service. Instead it might save time to go
directly into kill mode.
This commit adds two new options to services: TimeoutStartFailureMode=
and TimeoutStopFailureMode=. Both take the same values and tweak the
behavior of systemd when a start/stop timeout expires:
* 'terminate': is the default behaviour as it has always been,
* 'abort': triggers the watchdog machinery and will send SIGABRT
(unless WatchdogSignal was changed) and
* 'kill' will directly send SIGKILL.
To handle the stop failure mode in stop-post state too a new
final-watchdog state needs to be introduced.
Suppose a service has WatchdogSec set to 2 seconds in its unit file. I
then start the service and WatchdogUSec is set correctly:
% systemctl --user show psi-notify -p WatchdogUSec
WatchdogUSec=2s
Now I call `sd_notify(0, "WATCHDOG_USEC=10000000")`. The new timer seems
to have taken effect, since I only send `WATCHDOG=1` every 4 seconds,
and systemd isn't triggering the watchdog handler. However, `systemctl
show` still shows WatchdogUSec as 2s:
% systemctl --user show psi-notify -p WatchdogUSec
WatchdogUSec=2s
This seems surprising, since this "original" watchdog timer isn't the
one taking effect any more. This patch makes it so that we instead
display the new watchdog timer after sd_notify(WATCHDOG_USEC):
% systemctl --user show psi-notify -p WatchdogUSec
WatchdogUSec=10s
Fixes#15726.
Only log at LOG_INFO level, i.e. make this informational. During start
let's leave it at LOG_WARNING though.
Of course, it's ugly leaving processes around like that either in start
or in stop, but at start its more dangerous than on stop, so be tougher
there.
Indicates that the tags list cannot be modified by notify_message function.
Since the tags list is created only once for multiple call to
notify_message functions.
In all the other cases, I think the code was clearer with the static table.
Here, not so much. And because of the existing dump code, the vtables cannot
be made static and need to remain exported. I still think it's worth to do the
change to have the cmdline introspection, but I'm disappointed with how this
came out.
A service can specify FDSTORE=1 FDPOLL=0 to request that PID1 does not
poll the fd to remove them on error. If set, fds will only be removed on
FDSTOREREMOVE=1 or when the service is done.
Fixes: #12086
With cgroup v2 the cgroup freezer is implemented as a cgroup
attribute called cgroup.freeze. cgroup can be frozen by writing "1"
to the file and kernel will send us a notification through
"cgroup.events" after the operation is finished and processes in the
cgroup entered quiescent state, i.e. they are not scheduled to
run. Writing "0" to the attribute file does the inverse and process
execution is resumed.
This commit exposes above low-level functionality through systemd's DBus
API. Each unit type must provide specialized implementation for these
methods, otherwise, we return an error. So far only service, scope, and
slice unit types provide the support. It is possible to check if a
given unit has the support using CanFreeze() DBus property.
Note that DBus API has a synchronous behavior and we dispatch the reply
to freeze/thaw requests only after the kernel has notified us that
requested operation was completed.
UnitStatusMessageFormats.finished_job, if present,
will be called with the same arguments as
job_get_done_status_message_format() to provide a format string
appropriate for the context
This commit replaces "Started" with "Finished" for started oneshot
units, as mentioned in the referenced issue
Closes#2458.
Similar, refuse triggering deps on units that cannot trigger.
And rework how we ignore After= dependencies on device units, to work
the same way.
See: #14142
Previously, when first connecting to the bus after connecting to it we'd
issue a ListNames() bus call to the driver to figure out which bus names
are currently active. This information was then used to initialize the
initial state for services that use BusName=.
This change removes the whole code for this and replaces it with
something vastly simpler.
First of all, the ListNames() call was issues synchronosuly, which meant
if dbus was for some reason synchronously calling into PID1 for some
reason we'd deadlock. As it turns out there's now a good chance it does:
the nss-systemd userdb hookup means that any user dbus-daemon resolves
might result in a varlink call into PID 1, and dbus resolves quite a lot
of users while parsing its policy. My original goal was to fix this
deadlock.
But as it turns out we don't need the ListNames() call at all anymore,
since #12957 has been merged. That PR was supposed to fix a race where
asynchronous installation of bus matches would cause us missing the
initial owner of a bus name when a service is first started. It fixed it
(correctly) by enquiring with GetOwnerName() who currently owns the
name, right after installing the match. But this means whenever we start watching a bus name we anyway
issue a GetOwnerName() for it, and that means also when first connecting
to the bus we don't need to issue ListNames() anymore since that just
tells us the same info: which names are currently owned.
hence, let's drop ListNames() and instead make better use of the
GetOwnerName() result: if it failed the name is not owned.
Also, while we are at it, let's simplify the unit's owner_name_changed()
callback(): let's drop the "old_owner" argument. We never used that
besides logging, and it's hard to synthesize from just the return of a
GetOwnerName(), hence don't bother.
I see we log this during every boot, even though it is a routine expected event:
Nov 12 14:50:01 krowka systemd[1]: systemd-journald.service: Service has no hold-off time (RestartSec=0), scheduling restart.
(and for other services too). Let's downgrade this to debug level.
https://bugzilla.redhat.com/show_bug.cgi?id=1614871
Discussed in #13743, the -.service semantic conflicts with the
existing root mount and slice names, making this feature not
uniformly extensible to all types. Change the name to be
<type>.d instead.
Updating to this format also extends the top-level dropin to
unit types.
chase_symlinks() would return negative on error, and either a non-negative status
or a non-negative fd when CHASE_OPEN was given. This made the interface quite
complicated, because dependning on the flags used, we would get two different
"types" of return object. Coverity was always confused by this, and flagged
every use of chase_symlinks() without CHASE_OPEN as a resource leak (because it
would this that an fd is returned). This patch uses a saparate output parameter,
so there is no confusion.
(I think it is OK to have functions which return either an error or an fd. It's
only returning *either* an fd or a non-fd that is confusing.)
There is a slight functional change when load_state == UNIT_MERGED. Before,
we would not call unit_load_dropin(), but now we do. I'm not sure if this
causes an actual difference in behaviour, but since all other unit types do
this, I think it's better to do the same thing here too.
This is the most basic consumer of the new systemd-vs-kernel checker,
both acting as a reasonable standalone exerciser of the code, and also
as a way for easy inspection of deviations from systemd internal state.
v2:
- if RestartKillSignal= is not specified, fall back to KillSignal=. This is necessary
to preserve backwards compatibility (and keep KillSignal= generally useful).
The "Ex" variant was originally only added for ExecStartXYZ= but it makes
sense to have feature parity for the rest of the exec command properties
as well (e.g. ExecReload=, ExecStop=, etc).
In high load scenarios it is possible for services to be started
before the NameOwnerChanged signal is properly installed.
Emulate a callback by also queuing a GetNameOwner when the match is
installed.
Fixes: #12956
Zbigniew Jędrzejewski-Szmek