We already support exponential backoff for automatic restarts via
RestartSec=/RestartSteps=/RestartMaxDelaySec=, but there is no way to
randomize the restart delay. When many instances of a service fail at
the same time (e.g. because a shared resource briefly went away) they
are all restarted in lockstep, creating a thundering herd problem.
So this commit adds a simple `RestartRandomizedDelaySec=` service
option which is similar to the timer `RandomizedDelaySec=` and
adds a randomized restart delay.
Acquiring a LUO session from /dev/liveupdate requires privileges,
and also the device is a single-owner driver so only a single
process can open it at any given time.
Add a LUOSession= service settings that allows units running
without privileges to get a session assigned to them.
The kernel imposes a 64 chars limit on session names, which is
too short to avoid clashes, so derive a hash from joining the
unit name with the parameter name, that way two units using
the same setting don't clash.
This allows controlling resources to be refreshed before performing
reload, with one extra benefit that in the future we can permit
"seemless reload"s, i.e. no active signaling is done to the main process
after refreshing get updated. This could come in handy for programs
that loads stuff on demand or watches changes via inotify.
* Make sure ret_options is initialized on success.
* Return empty mount options as-is rather than NULL-ing it -
dbus property parser for RootImageOptions relies on it
for resetting options for a specific partition designator.
* Format partition:options properly with strextendf, currently
multiple ":" will be emitted.
* Allow separator to be unset if in_out_format_str is not
needed.
Before doing anything with the root directory file descriptor, let's
make sure we clone it first so that the caller can't mess with mount fd
attributes via mount_setattr() anymore.
We clone during parsing instead of in executor so that the caller can't
mess with the mount fd between invocations.
When Type=notify-reload got introduced, it wasn't intended to be
mutually exclusive with ExecReload=. However, currently ExecReload=
is immediately forked off after the service main process is signaled,
leaving states in between essentially undefined. Given so broken
it is I doubt any sane user is using this setup, hence I took a stab
to rework everything:
1. Extensions are refreshed (unchanged)
2. ExecReload= is forked off without signaling the process
3a. If RELOADING=1 is sent during the ExecReload= invocation,
we'd refrain from signaling the process again, instead
just transition to SERVICE_RELOAD_NOTIFY directly and
wait for READY=1
3b. If not, signal the process after ExecReload= finishes
(from now on the same as Type=notify-reload w/o ExecReload=)
4. To accomodate the use case of performing post-reload tasks,
ExecReloadPost= is introduced which executes after READY=1
The new model greatly simplifies things, as no control processes
will be around in SERVICE_RELOAD_SIGNAL and SERVICE_RELOAD_NOTIFY
states.
See also: https://github.com/systemd/systemd/issues/37515#issuecomment-2891229652
RootDirectory= but via a open_tree() file descriptor. This allows
setting up the execution environment for a service by the client in
a mount namespace and then starting a transient unit in that execution
environment using the new property.
We also add --root-directory= and --same-root-dir= to systemd-run to
have it run services within the given root directory. As systemd-run
might be invoked from a different mount namespace than what systemd is
running in, systemd-run opens the given path with open_tree() and then
sends it to systemd using the new RootDirectoryFileDescriptor= property.
Admittedly, some of our glyphs _are_ special, e.g. "O=" for SPECIAL_GLYPH_TOUCH ;)
But we don't need this in the name. The very long names make some invocations
very wordy, e.g. special_glyph(SPECIAL_GLYPH_SLIGHTLY_UNHAPPY_SMILEY).
Also, I want to add GLYPH_SPACE, which is not special at all.
Let's debug log the returned dbus error where we want the logging, but
don't log it, where we don't.
This removes the noisy logging from the property handler for the
CanLiveMount property, but keeps it in place for the MountImage() method
call where we want it.
Alternative to #34175
Follow-up for 5162829ec8 and 1cafbecabe
Follow-up for 3543456f84
I don't think list is particularly useful here. The passed fds are
constant for the lifetime of service, and with this commit we track
the number of extra fds in a dedicated var anyway.
This adds the ExtraFileDescriptor property to StartTransient dbus API
with format "a(hs)" - array of (file descriptor, name) pairs. The FD
will be passed to the unit via sd_notify like Socket and OpenFile.
systemctl show also shows ExtraFileDescriptorName for these transient
units. We only show the name passed to dbus as the FD numbers will
change once passed over the unix socket and are duplicated, so its
confusing to display the numbers.
We do not add this functionality for systemd-run or general systemd
service units as it is not useful for general systemd services.
Arguably, it could be useful for systemd-run in bash scripts but we
prefer to be cautious and not expose the API yet.
Fixes: #34396
These operations might require slow I/O, and thus might block PID1's main
loop for an undeterminated amount of time. Instead of performing them
inline, fork a worker process and stash away the D-Bus message, and reply
once we get a SIGCHILD indicating they have completed. That way we don't
break compatibility and callers can continue to rely on the fact that when
they get the method reply the operation either succeeded or failed.
To keep backward compatibility, unlike reload control processes, these
are ran inside init.scope and not the target cgroup. Unlike ExecReload,
this is under our control and is not defined by the unit. This is necessary
because previously the operation also wasn't ran from the target cgroup,
so suddenly forking a copy-on-write copy of pid1 into the target cgroup
will make memory usage spike, and if there is a MemoryMax= or MemoryHigh=
set and the cgroup is already close to the limit, it will cause an OOM
kill, where previously it would have worked fine.
The credential mounts should be managed singlehandedly by pid1.
Preparation for the future introduction of RefreshOnReload=credential,
where refreshing creds will be properly supported on reload.
Perform some checks earlier to avoid pointless polkit auth.
Plus, the missing unit_get_exec_context() shall not be
a formalized error. As it's our internal representation
and in the normal operation should never happen.
Since we use varargs for sd_message_append() we need to make sure the
parameters we pass are actually 64bit wide, if "t" is used. Hence cast
appropriately if necessary.
I went through the whole tree, and in most cases we got it right, but
there are some cases we missed so far.
Inspired by: #31420
This simplifies bus_verify_polkit_async() and related calls quite a bit:
1. This removes any support for authentication-by-Linux-capability. This
is ultimately a kdbus leftover: with classic AF_UNIX transports we
cannot authenticate by capabilities securely (because we cannot
acquire it from the peer without races), hence we never actually did.
Since the necessary kernel work didn't materialize in the last 10y,
and is unlikely to be added, let's just kill this context. We cannot
quite remove the caps stuff from sd-bus for API compat, but for our
polkit logic let's kill it.
2. The "good_uid" and "interactive" params are only necessary in very
few cases, hence let's move them to a new call
bus_verify_polkit_async_full() and make bus_verify_polkit_async() a
wrapper around it without those two parameters.
This also fixes a bunch of wrong uses of the "interactive" bool. The
bool makes no sense today as the ALLOW_INTERACTIVE_AUTHORIZATION field
in the D-Bus message header replaces it fully. We only need it to
implement method calls we introduced prior to that header field becoming
available in D-Bus. And it should only be used on such old method calls,
and otherwise always be set to false.
This does not change behaviour in any way. Just simplifies stuff.
Fixes: #21586
This ports over unit_main_pid() + unit_control_pid() to return PidRef*
pointers (which also means the underlying UnitVTable function pointers
are changed accordingly).
This then uses te functions to simplify the unit_kill() call, by
avoiding the kill() vtable indirection and instead just suing
unit_main_pid() and unit_control_pid() directly.
The first conversion to PidRef. It's mostly an excercise of
search/replace, but with some special care taken for life-cycle (i.e. we
need to destroy the structure properly once done, to release the pidfd).
It also uses pidfd based killing for some of the killing but leaves most
as it is to make the conversion minimal.
When this option is set to direct, the service restarts without entering a failed
state. Dependent units are not notified of transitory failure.
This is useful for the following use case:
We have a target with Requires=my-service, After=my-service.
my-service.service is a oneshot service and has Restart=on-failure in
its definition.
my-service.service can get stuck for various reasons and time out, in
which case it is restarted. Currently, when it fails the first time, the
target fails, even though my-service is restarted.
The behavior we're looking for is that until my-service is not restarted
anymore, the target stays pending waiting for my-service.service to
start successfully or fail without being restarted anymore.
The property name is called ExecStartEx, but we have to write it as ExecStart=
in the unit file. :(
Bug introduced in b3d593673c when ex-properties
were initially added.
In addition, we cannot escape $ as $$, because when ":" is used, we wouldn't
unescape $$ back to $.
Oftentimes it is useful to allow the per-service fd store to survive
longer than for a restart. This is useful in various scenarios:
1. An fd to some security relevant object needs to be stashed somewhere,
that should not be cleaned automatically, because the security
enforcement would be dropped then.
2. A user namespace fd should be allocated on first invocation and be
kept around until the user logs out (i.e. systemd --user ends), á la
#16328 (This does not implement what #16318 asks for, but should
solve the use-case discussed there.)
3. There's interest in allow a concept of "userspace reboots" where the
kernel stays running, and userspace is swapped out (i.e. all services
exit, and the rootfs transitioned into a new version of it) while
keeping some select resources pinned, very similar to how we
implement a switch root. Thus it is useful to allow services to exit,
while leaving their fds around till the very end.
This is exposed through a new FileDescriptorStorePreserve= setting that
is closely modelled after RuntimeDirectoryPreserve= (in fact it reused
the same internal type), since we want similar behaviour in the end, and
quite often they probably want to be used together.
Since da6053d0a7 this is a size_t, not an
unsigned. The difference doesn't matter on LE archs, but it matters on
BE (i.e. s390x), since we'll return entirely nonsensical data.
Let's fix that.
Follow-up-for: da6053d0a7
An embarassing bug introduced in 2018... That made me scratch my head
for way too long, as it made #27135 fail on s390x while it passed
everywhere else.
Follow-up for #26902 and #26971
Let's always calculate the next restart interval
since that's more useful.
For that, we add 1 to s->n_restarts unconditionally,
and change RestartUSecCurrent property to RestartUSecNext.
interval between restarts
RestartSteps= accepts a positive integer as the number of steps
to take to increase the interval between auto-restarts from
RestartSec= to RestartSecMax=, or 0 to disable it.
Closes#6129
This introduces `ExitType=main|cgroup` for services.
Similar to how `Type` specifies the launch of a service, `ExitType` is
concerned with how systemd determines that a service exited.
- If set to `main` (the current behavior), the service manager will consider
the unit stopped when the main process exits.
- The `cgroup` exit type is meant for applications whose forking model is not
known ahead of time and which might not have a specific main process.
The service will stay running as long as at least one process in the cgroup
is running. This is intended for transient or automatically generated
services, such as graphical applications inside of a desktop environment.
Motivation for this is #16805. The original PR (#18782) was reverted (#20073)
after realizing that the exit status of "the last process in the cgroup" can't
reliably be known (#19385)
This version instead uses the main process exit status if there is one and just
listens to the cgroup empty event otherwise.
The advantages of a service with `ExitType=cgroup` over scopes are:
- Integrated logging / stdout redirection
- Avoids the race / synchronisation issue between launch and scope creation
- More extensive use of drop-ins and thus distro-level configuration:
by moving from scopes to services we can have drop ins that will affect
properties that can only be set during service creation,
like `OOMPolicy` and security-related properties
- It makes systemd-xdg-autostart-generator usable by fixing [1], as obviously
only services can be used in the generator, not scopes.
[1] https://bugs.kde.org/show_bug.cgi?id=433299
Michael Vogt
Luca Boccassi
Mike Yuan
Daan De Meyer
Yu Watanabe
Lennart Poettering
Zbigniew Jędrzejewski-Szmek
Ryan Wilson
Luca Boccassi
Richard Phibel
David Tardon
amarjargal
Henri Chain
Albert Brox