This is useful for debugging client-side ref counting of units: for each
ref taken on a unit the client's sender name is listed. If a client has
multiple refs on the same unit it is listed multiple times.
"killing" is very UNIX terminology, and not really what this is about.
Let's be more correct and say "send a UNIX signal" for the operation.
Otherwise things are really weird if users call "journalctl --rotate"
from the command line, which internally asks systemd to send SIGUSR2 to
to journald: when german locale is selected this asks the user — roughly
transliterated — whether they want to "eliminate" journald, which is
definitely not the intended meaning.
We would accept e.g. FailureAction=reboot-force in user units and then do an
exit in the user manager. Let's be stricter, and define "exit"/"exit-force" as
the only supported actions in user units.
v2:
- rename 'exit' to 'exit-force' and add new 'exit'
- add test for the parsing function
These lines are generally out-of-date, incomplete and unnecessary. With
SPDX and git repository much more accurate and fine grained information
about licensing and authorship is available, hence let's drop the
per-file copyright notice. Of course, removing copyright lines of others
is problematic, hence this commit only removes my own lines and leaves
all others untouched. It might be nicer if sooner or later those could
go away too, making git the only and accurate source of authorship
information.
This part of the copyright blurb stems from the GPL use recommendations:
https://www.gnu.org/licenses/gpl-howto.en.html
The concept appears to originate in times where version control was per
file, instead of per tree, and was a way to glue the files together.
Ultimately, we nowadays don't live in that world anymore, and this
information is entirely useless anyway, as people are very welcome to
copy these files into any projects they like, and they shouldn't have to
change bits that are part of our copyright header for that.
hence, let's just get rid of this old cruft, and shorten our codebase a
bit.
Since bb28e68477 parsing failures of
certain unit file settings will result in load failures of units. This
introduces a new load state "bad-setting" that is entered in precisely
this case.
With this addition error messages on bad settings should be a lot more
explicit, as we don't have to show some generic "errno" error in that
case, but can explicitly say that a bad setting is at fault.
Internally this unit load state is entered as soon as any configuration
loader call returns ENOEXEC. Hence: config parser calls should return
ENOEXEC now for such essential unit file settings. Turns out, they
generally already do.
Fixes: #9107
The load_error is only valid in some load_state cases, lets generate
prettier messages for other cases too, by reusing the
bus_unit_validate_load_state() call which does jus that.
Clients (such as systemctl) ignored LoadError unles LoadState was
"error" before. With this change they could even show LoadError in other
cases and it would show a useful name.
Let's use a switch() statement, cover more cases with pretty messages.
Also let's rename it to "validate", as that's more specific that
"check", as it implies checking for a "valid"/"good" state, which is
what this function does.
Files which are installed as-is (any .service and other unit files, .conf
files, .policy files, etc), are left as is. My assumption is that SPDX
identifiers are not yet that well known, so it's better to retain the
extended header to avoid any doubt.
I also kept any copyright lines. We can probably remove them, but it'd nice to
obtain explicit acks from all involved authors before doing that.
This adds a new bus call to service and scope units called
AttachProcesses() that moves arbitrary processes into the cgroup of the
unit. The primary user for this new API is systemd itself: the systemd
--user instance uses this call of the systemd --system instance to
migrate processes if itself gets the request to migrate processes and
the kernel refuses this due to access restrictions.
The primary use-case of this is to make "systemd-run --scope --user …"
invoked from user session scopes work correctly on pure cgroupsv2
environments. There, the kernel refuses to migrate processes between two
unprivileged-owned cgroups unless the requestor as well as the ownership
of the closest parent cgroup all match. This however is not the case
between the session-XYZ.scope unit of a login session and the
user@ABC.service of the systemd --user instance.
The new logic always tries to move the processes on its own, but if
that doesn't work when being the user manager, then the system manager
is asked to do it instead.
The new operation is relatively restrictive: it will only allow to move
the processes like this if the caller is root, or the UID of the target
unit, caller and process all match. Note that this means that
unprivileged users cannot attach processes to scope units, as those do
not have "owning" users (i.e. they have now User= field).
Fixes: #3388
StartLimitIntervalSec= and DefaultStartLimitIntervalSec= are the
last options whose suffix is 'Sec' instead of 'USec'.
All the other option has suffix 'USec'. So, let's rename them.
This majorly refactors the transient unit file and drop-in writing
logic, so that we properly C-escape and specifier-escape (% → %%)
everything we write out, so that when we read it back again, specifiers
are parsed that aren't supposed to be parsed.
This renames unit_write_drop_in() and friends by unit_write_setting().
The name change is supposed to clarify that the functions are not only
used to write drop-in files, but also transient unit files.
The previous "mode" parameter to this function is replaced by a more
generic "flags", which knows additional flags for implicit C-style and
specifier escaping before writing things out. This can cover most
properties where either form of escaping is defined. For the cases where
this isn't sufficient, we add helpers unit_escape_setting() and
unit_concat_strv() for escaping individual strings or strvs properly.
While we are at it, we also prettify generation of transient unit files:
we try to reduce the number of section headers written out: previously
we'd write the right section header our for each setting. With this
change we do so only if the setting lives in a different section than
the one before.
(This should also be considered preparation for when we add proper APIs
to systemd to write normal, persistant unit files through the bus API)
SuccessAction= is similar to FailureAction= but declares what to do on
success of a unit, rather than on failure. This is useful for running
commands in qemu/nspawn images, that shall power down on completion. We
frequently see "ExecStopPost=/usr/bin/systemctl poweroff" or so in unit
files like this. Offer a simple, more declarative alternative for this.
While we are at it, hook up failure action with unit_dump() and
transient units too.
Right now, the option only takes one of two possible values "inactive"
or "inactive-or-failed", the former being the default, and exposing same
behaviour as the status quo ante. If set to "inactive-or-failed" units
may be collected by the GC logic when in the "failed" state too.
This logic should be a nicer alternative to using the "-" modifier for
ExecStart= and friends, as the exit data is collected and logged about
and only removed when the GC comes along. This should be useful in
particular for per-connection socket-activated services, as well as
"systemd-run" command lines that shall leave no artifacts in the
system.
I was thinking about whether to expose this as a boolean, but opted for
an enum instead, as I have the suspicion other tweaks like this might be
a added later on, in which case we extend this setting instead of having
to add yet another one.
Also, let's add some documentation for the GC logic.
PR #7186 changes requires_mounts_for from strv to Hashmap.
So, it is necessary to implement a function for getting the property RequiresMountsFor=.
This introduces property_get_requires_mounts_for() which reads the Hashmap
and sends messages to bus.
Fixes#7321.
This replaces the dependencies Set* objects by Hashmap* objects, where
the key is the depending Unit, and the value is a bitmask encoding why
the specific dependency was created.
The bitmask contains a number of different, defined bits, that indicate
why dependencies exist, for example whether they are created due to
explicitly configured deps in files, by udev rules or implicitly.
Note that memory usage is not increased by this change, even though we
store more information, as we manage to encode the bit mask inside the
value pointer each Hashmap entry contains.
Why this all? When we know how a dependency came to be, we can update
dependencies correctly when a configuration source changes but others
are left unaltered. Specifically:
1. We can fix UDEV_WANTS dependency generation: so far we kept adding
dependencies configured that way, but if a device lost such a
dependency we couldn't them again as there was no scheme for removing
of dependencies in place.
2. We can implement "pin-pointed" reload of unit files. If we know what
dependencies were created as result of configuration in a unit file,
then we know what to flush out when we want to reload it.
3. It's useful for debugging: "systemd-analyze dump" now shows
this information, helping substantially with understanding how
systemd's dependency tree came to be the way it came to be.
Unit.JobTimeoutSec starts when a job is enqueued in a transaction. The
introduced distinct Unit.JobRunningTimeoutSec starts only when the job starts
running (e.g. it groups all Exec* commands of a service or spans waiting for a
device period.)
Unit.JobRunningTimeoutSec is intended to be used by default instead of
Unit.JobTimeoutSec for device units where such behavior causes less confusion
(consider a job for a _netdev mount device, with this change the timeout will
start ticking only after the network is ready).
If a client pins a unit, then it makes sense to also implicitly make it
a subscriber. This is useful for clients that just want to watch one
specific unit: they can pin it and receive its messages.
In contrast to all other unit types device units when queued just track
external state, they cannot effect state changes on their own. Hence unless a
client or other job waits for them there's no reason to keep them in the job
queue. This adds a concept of GC'ing jobs of this type as soon as no client or
other job waits for them anymore.
To ensure this works correctly we need to track which clients actually
reference a job (i.e. which ones enqueued it). Unfortunately that's pretty
nasty to do for direct connections, as sd_bus_track doesn't work for
them. For now, work around this, by simply remembering in a boolean that a job
was requested by a direct connection, and reset it when we notice the direct
connection is gone. This means the GC logic works fine, except that jobs are
not immediately removed when direct connections disconnect.
In the longer term, a rework of the bus logic should fix this properly. For now
this should be good enough, as GC works for fine all cases except this one, and
thus is a clear improvement over the previous behaviour.
Fixes: #1921
Let's make semantics of this field more similar to the same functionality in
the Unit object, in particular as we add new functionality to it later on.
So far "no_gc" was set on -.slice and init.scope, to units that are always
running, cannot be stopped and never exist in an "inactive" state. Since these
units are the only users of this flag, let's remodel it and rename it
"perpetual" and let's derive more funcitonality off it. Specifically, refuse
enqueing stop jobs for these units, and report that they are "unstoppable" in
the CanStop bus property.
This adds a new invocation ID concept to the service manager. The invocation ID
identifies each runtime cycle of a unit uniquely. A new randomized 128bit ID is
generated each time a unit moves from and inactive to an activating or active
state.
The primary usecase for this concept is to connect the runtime data PID 1
maintains about a service with the offline data the journal stores about it.
Previously we'd use the unit name plus start/stop times, which however is
highly racy since the journal will generally process log data after the service
already ended.
The "invocation ID" kinda matches the "boot ID" concept of the Linux kernel,
except that it applies to an individual unit instead of the whole system.
The invocation ID is passed to the activated processes as environment variable.
It is additionally stored as extended attribute on the cgroup of the unit. The
latter is used by journald to automatically retrieve it for each log logged
message and attach it to the log entry. The environment variable is very easily
accessible, even for unprivileged services. OTOH the extended attribute is only
accessible to privileged processes (this is because cgroupfs only supports the
"trusted." xattr namespace, not "user."). The environment variable may be
altered by services, the extended attribute may not be, hence is the better
choice for the journal.
Note that reading the invocation ID off the extended attribute from journald is
racy, similar to the way reading the unit name for a logging process is.
This patch adds APIs to read the invocation ID to sd-id128:
sd_id128_get_invocation() may be used in a similar fashion to
sd_id128_get_boot().
PID1's own logging is updated to always include the invocation ID when it logs
information about a unit.
A new bus call GetUnitByInvocationID() is added that allows retrieving a bus
path to a unit by its invocation ID. The bus path is built using the invocation
ID, thus providing a path for referring to a unit that is valid only for the
current runtime cycleof it.
Outlook for the future: should the kernel eventually allow passing of cgroup
information along AF_UNIX/SOCK_DGRAM messages via a unique cgroup id, then we
can alter the invocation ID to be generated as hash from that rather than
entirely randomly. This way we can derive the invocation race-freely from the
messages.
If the unit is in the dbus queue when it is removed then the last change
signal is never sent. Fix this by checking the dbus queue and explicitly
send the change signal before sending the remove signal.
This adds two (privileged) bus calls Ref() and Unref() to the Unit interface.
The two calls may be used by clients to pin a unit into memory, so that various
runtime properties aren't flushed out by the automatic GC. This is necessary
to permit clients to race-freely acquire runtime results (such as process exit
status/code or accumulated CPU time) on successful service termination.
Ref() and Unref() are fully recursive, hence act like the usual reference
counting concept in C. Taking a reference is a privileged operation, as this
allows pinning units into memory which consumes resources.
Transient units may also gain a reference at the time of creation, via the new
AddRef property (that is only defined for transient units at the time of
creation).
Lennart Poettering