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It's useful to be able to combine a regular /usr/ file system with a
tmpfs as root, for an OS that boots up in volatile mode on every single
boot. Let's add explicit support for this via root=tmpfs.
Note the relationship to the existing systemd.volatile= option:
1. The kernel command line "root=/dev/… systemd.volatile=yes" will mount
the specified root fs, and then hide everything at the top by
overmounting it with a tmpfs, except for the /usr subtree.
2. The kernel command line "root=tmpfs mount.usr=/dev/…" otoh will mount
a toot fs at the top (just like the case above), but will then mount
the top-level dir of the fs specified in mount.usr= directly below
it.
Or to say this differently: in the first case /usr/ from the physical
storage fs is going to become /usr/ of the hierarchy ultimately booted,
while in the second case / from the physical storage fs is going to
become /usr of the hierarchy booted.
Philosophically I figure systemd.volatile= is more an option for
"one-off" boots, while root=tmpfs is something to have as default mode
of operation for suitable images.
This is currently hard to test reasonably, since Dracut refuses to
accept root=tmpfs. This needs to be addressed separately though.
This got moved under the systemd umbrella a long time ago.
Github redirects from the old path, so the link worked, but it's
nicer to use the real location.
Fixes#17910: we didn't clearly explain that coredumps may exist without
journal entries, and vice versa.
Also, make the examples more concrete, and use '$' instead of '#' to avoid
suggesting that running as root is required. The text is extended a bit in
various places. In the description of systemd-coredump, the details of executor
separation are split out to a separate subsection, since they are rather
detailed and not necessary to understand for normal use.
systemd.unit(5) is a wall of text. And this particular feature can be very useful
in the context of resource control. Let's avertise this cool feature a bit more.
Fixes#17900.
Before, we only allowed conditionalizing on controllers, not the hierarchy.
This commit extends this to allow a simple check for v1 (i.e. classic or hybrid),
and v2 (full unified).
An alternative approach would be to add a separate Condition for this, but I'm
not too keen on that, considering that v1 is already being deprecrecated
(c.f. 82f3063218).
This follows the addition of DEFAULT_HOSTNAME= in os-release.
The distinction between the value from os-release or the env var and
the compile-time setting is not made in the api: HostnameSource is
"default" is all cases. I think that this level of detail is not needed,
because the users of this mostly care whether the hostname was set by
user configuration or not.
The motivation is that variants of the same distro that share the same compiled
rpm want to customize various aspects of the system, in particular the
hostname. In some sense the default hostname is part of the identity of the
system, so setting it through os-release makes sense. In particular, instead of
setting a default value in /etc/hostname, the appropriate default can be baked
into the image, leaving /etc/hostname for local overrides only.
Why make this a separate field instead of e.g. using NAME from os-release?
NAME is already used for other purposes, and it seems likely that people want
to set those independently.
e3820eeaf1 did that replacement XDG_CONFIG_HOME, in one
of two places. Let's use ~/.config everywhere.
Quoting https://github.com/systemd/systemd/pull/18704#discussion_r579465254:
> I'd really drop XDG_CONFIG_HOME from the docs. It's confusing enough as it
> is. Where we don't need the indirections we should not confuse people with
> it, in particular as people might then think it's actually a good idea to use
> that env var and redirect things. I'd just show the literal path everywhere,
> even if we internally use the env var.
This is useful for various variables that modify process behaviour. This makes
it easy to set it for pid1 without touching the kernel command line. Even for
the *user manager* this also can be convenient for the unprivileged user, who
cannot modify user@.service definition.
Variables that could be set like this include $SD_EVENT_PROFILE_DELAYS,
$SYSTEMD_FALLBACK_HOSTNAME, $SYSTEMD_MEMPOOL, $SYSTMED_RDRAND, etc.
This changes the paths we read user manager config from in two ways:
- split-usr-root paths are dropped. The user manager is a poster boy for
non-early-boot, so reading dropins only from /usr is appropriate.
- we look at ~/.config/systemd/user.conf. Users should be allowed to override
their own config.
As user managers become more and more used, it becomes more important for users
to customize their own daemon. By reading from ~/.config, this is possible
without privileges.
Commit 83f72cd65f ("man,docs: document the new unit file directory for
attached images") updated the docs and man page with the new unit file
directory for attached images but included a system.attached ->
systemd.attached typo in the man page portion of the change. Fix the
typo to document the correct path.
sd_bus_get_fd() and related calls are useful for integrating a bus
connection into arbitrary event loops. But sd_bus_set_fd() is quite a
different beast, it's for using D-Bus over pre-initialized sockets or
pairs of fifos or stuff, i.e. very advanced stuff.
Let's split this man page in two, in order not to confuse things
needlessly.
And while we are at it, let's slightly extend the documentation.
Previously, any positive boolean string for IPMasquerade= enables only IPv4
masquerade. The commit 48ed276647 adds
IPv6 masquerade support. However, only "yes" is handled as "ipv4", and other
positive boolean strings are handled as "both".
This makes all positive boolean strings considered as "ipv4", warn that they
are deprecated, and suggest to use "ipv4" or "both".
Follow-up for 48ed276647.
oomd.conf has two parameters with fractionals: SwapUsedLimit= and
DefaultMemoryPressureLimit=, but one accepts permyriads, the other only
percentages, for no apparent reason. One carries the "Percent" in the
name, the other doesn't.
Let's clean this up: always accept permyriads, and drop the suffix,
given that it is misleading.
I figure we should internally try to focus on scaling everything
relative to UINT32_MAX, and if that isn't in the cards at least 10000,
but never permille nor percent unless there's a really really good
reason for it (e.g. interface defined by someone else).
So far OOMD limits used permyriads, as an upgrade from the original
percent.
The rest of our codebase typically scales stuff relative to UINT32_MAX.
Let's clean this up, an make sure this happens here too. This is
particularly relevant, as this is exposed in unit files and API, and
before we mark this stable we should get the APIs right.
A "Credentials" section name in systemd.exec man page was used
both for User/Group and for actual credentials support in systemd.
Rename the first instance to "User/Group Identity"
This was changed in commit 482efedc08,
which was released in v243, to only enable and never disable IPv6.
Signed-off-by: Richard Laager <rlaager@wiktel.com>
--no-legend is replaced by --legend=no.
--quiet now implies --legend=no, but --legend=yes may be used to override that.
--quiet controls hints and warnings and such, and --legend controls just the
legends. I think it makes sense to allow both to controlled independently, in
particular --quiet --legend makes sense when using systemctl in a script to
provide some user-visible output.
Fixes#18560.
Taking a stab at implementing #14479.
Add {Condition,Assert}CPUFeature to `systemd-analyze` & friends. Implement it
by executing the CPUID instruction. Add tables for common x86/i386
features.
Tested via unit tests + checked that commands such as:
```bash
systemd-analyze condition 'AssertCPUFeature = rdrand'
```
Succeed as expected and that commands such as
```bash
systemd-analyze condition 'AssertCPUFeature = foobar'
```
Fail as expected. Finally, I have amended the `systemd.unit` manual page
with the new condition and the list of all currently supported flags.
When low-level RR resolution is requested from "resolvectl query" via
"--type=" or "--class=" no search domain logic is applied and no IDNA
translation.
Explain this in detail in the documentation, and also mentions this when
users attempt to resolve single-label names or names with international
characters in the output.
I believe the current behaviour is correct, but it is indeed surprising.
Hence the documentation and output improvement.
Fixes: #11325#10737
This is almost equivalent to 'busctl call-method org.freedesktop.systemd1
/org/freedesktop/systemd1 org.freedesktop.systemd1.Manager EnqueueMarkedJobs',
but waits for the jobs to finish.
We support two return types for methods that start jobs. EnqueueJob support the
full-monty mode with affected jobs. I didn't do this here, since it seems
unlikely to be used. In the common case there'd be a huge list of jobs and
affected jobs. EnqueueMarkedJobs() just returns a list of jobs that we can wait
upon.
The name of the method is generic in case we decide to add something other than
just reload/restart later on.
When errors occur, resource errors are treated as fatal, but for other error
types we queue up other jobs, and only return an error at the end. The
assumption is that the caller will ignore the result error anyway, so it's
better to try to reload/restart as much as possible.
The property is never set by systemd, only reset after a stop or restart or
reload. It may externally be set to mark the unit for a later restart/reload.
I wasn't sure whether to configure the property only for the types where this
makes sense (Service, Swap, etc). But Restart() method is defined on the unit,
and also having this always under the same property name is more convenient.
This lists numerical signal values:
$ systemctl --signal list
SIGNAL NAME
1 SIGHUP
2 SIGINT
3 SIGQUIT
...
62 SIGRTMIN+28
63 SIGRTMIN+29
64 SIGRTMIN+30
This is useful when trying to kill e.g. systemd with a specific signal number
using kill. kill doesn't accept our fancy signal names like RTMIN+4, so one
would have to calculate that value somehow. Doing
systemctl --signal list | grep -F RTMIN+4
is a nice way of doing that.
It's rather convenient to be able to read all three types with this function.
Strictly speaking this change is not fully compatible, in case someone was
relying on sd_bus_message_read_strv() returning an error for anything except
"as", but I hope nobody was doing that.
Similar to DHCPv4's UseHostname option, add a UseFQDN config option in
[DHCPv6] to set the system's transient hostname if the FQDN option is
set in the DHCPv6 response from the server.
Add 'reattach' verb to portablectl, and corresponding DBUS interface
to systemd-portabled.
Takes the same parameters as 'attach', but it will do a 'detach' (and
it will refuse to proceed if it cannot be done) first, matching on
the unversioned prefix of the new image. Eg:
portablectl reattach /tmp/foo_2.raw
will cause foo_1.raw to be detached, and foo_2.raw to be attached.
The key difference with a manual 'detach old' plus 'attach new' is that
the running units are not disturbed until after the attach completed,
and if --now is passed they are then restarted.
A 'detach' is not allowed normally if the units are running.
By using a restart-after-deploy method, 'reattach' allows for minimal
interruption of service and also for features that only work on restart
(eg: file descriptor store) to work as intended.
The DBUS interface returns two lists: first the removals from the detach
that were not immediately re-added in the attach, so that the caller
can stop the relevant units, and then the list of additions that are
either new or updates, so that the caller can restart/enable the
relevant units. portablectl already implements this with the existing
--now/--enable switches.
As we usually (unfortunately not always though) do not use abbreviations.
Tx may be standard abbreviation, but we already have e.g.
TransmitChecksumOffload=. So, let's use Transmit instead of Tx.
Follow-up for ef4a91a7e8.
The wiki was slightly stale, and almost all the information there
was already present in the man page. I moved the remaing part (discussion)
into the man page and adjusted all links to point to the man page instead.
daemon(7) has a some examples of packaging scriptlets… I don't think it fits
there very well. Most likely they should be moved to systemd.preset(5) or maybe
even removed, but I'm leaving that for later.
GetMulticastHosts() returns an array of hostnames/addresses discovered via
LLMNR or Multicast DNS. It does not trigger any discovery on its own.
Instead, it simply returns whatever is already in resolved's cache.
Actually, systemd takes the minimum of
* a) the maximum tasks value the kernel allows on this architecture
* b) the cgroups pids_max attribute for the system
* c) the kernel's configured maximum PID value
to calculate the DefaultTasksMax. Here, kernel.thread-max should also be methioned.
Implement directives `NoExecPaths=` and `ExecPaths=` to control `MS_NOEXEC`
mount flag for the file system tree. This can be used to implement file system
W^X policies, and for example with allow-listing mode (NoExecPaths=/) a
compromised service would not be able to execute a shell, if that was not
explicitly allowed.
Example:
[Service]
NoExecPaths=/
ExecPaths=/usr/bin/daemon /usr/lib64 /usr/lib
Closes: #17942.
Very old versions of meson did not include the subdirectory name in the
target name, so we started adding various "top-level" custom targets in
subdirectories. This was nice because the main meson.build file wasn't
as cluttered. But then meson started including the subdir name in the
target name. So let's move the definition to the root so we can have all
targets named uniformly.
While sd-bus already provides sd_bus_call() for calling a method
from a complete bus message object, We don't have an equivalent
function for replying from a method with a complete bus message
object.
Currently, we use sd_bus_send(call->bus, m, NULL) instead. Let's
add a shorthand for this pattern and name it sd_bus_reply().
Until now, update-man-rules assumed that the build directory was
a subdirectory of the project directory. When using mkosi, this is
not the case. We use find instead of git ls-files because git ls-files
does not seem to support outputting absolute paths.
Also, this makes update-man-rules a bit more user-friendly as new manpages
don't have to be added to the git staging area before they are processed by
update-man-rules.py.
This doesn't actually port systemd-dissect to table_print_with_pager()
but at least rearranges things so that similar behaviour is exposed. The
reason it's not ported over 1:1 is that systemd-dissect actually adjusts
the JSON output of the table with additional info, and doesn't print the
table 1:1 as JSON.
This parameter allows configuring the activation policy for an interface,
meaning how it manages the interface's administrative state (IFF_UP flag).
The policy can be configured to bring the interface either up or down when
the interface is (re)configured, to always force the interface either up or
down, or to never change the interface administrative state.
If the interface is bound with BindCarrier=, its administrative state is
controlled by the interface(s) it's bound to, and this parameter is forced
to 'bound'.
This changes the default behavior of how systemd-networkd sets the IFF_UP
flag; previously, it was set up (if not already up) every time the
link_joined() function was called. Now, with the default ActivationPolicy=
setting of 'up', it will only set the IFF_UP flag once, the first time
link_joined() is called, during an interface's configuration; and on
the first link_joined() call each time the interface is reconfigured.
Fixes: #3031Fixes: #17437
Extend IPMasquerade to also cover ipv6.
For compatibility reasons with earlier releases IPMasquerade=yes
is identical to IPMasquerade=ipv4.
Use IPMasquerade=both to cover ipv6 as well as ipv4.
IPForward will now also enable ipv6 forwarding if IPMasquerade for ipv6 is enabled.
So far, we would allow certain control characters (NL since
b4346b9a77, TAB since 6294aa76d8), but not others. Having
other control characters in environment variable *value* is expected and widely
used, for various prompts like $LESS, $LESS_TERMCAP_*, and other similar
variables. The typical environment exported by bash already contains a dozen or
so such variables, so programs need to handle them.
We handle then correctly too, for example in 'systemctl show-environment',
since 804ee07c13. But we would still disallow setting such variables
by the user, in unit file Environment= and in set-environment/import-environment
operations. This is unexpected and confusing and doesn't help with anything
because such variables are present in the environment through other means.
When printing such variables, 'show-environment' escapes all special
characters, so variables with control characters are plainly visible.
In other uses, e.g. 'cat -v' can be used in similar fashion. This would already
need to be done to suppress color codes starting with \[.
Note that we still forbid invalid utf-8 with this patch. (Control characters
are valid, since they are valid 7-bit ascii.) I'm not sure if we should do
that, but since people haven't been actually asking for invalid utf-8, and only
for control characters, and invalid utf-8 causes other issues, I think it's OK
to leave this unchanged.
Fixes#4446, https://gitlab.gnome.org/GNOME/gnome-session/-/issues/45.
Allow to setup new bind mounts for a service at runtime (via either
DBUS or a new 'systemctl bind' verb) with a new helper that forks into
the unit's mount namespace.
Add a new integration test to cover this.
Useful for zero-downtime addition to services that are running inside
mount namespaces, especially when using RootImage/RootDirectory.
If a service runs with a read-only root, a tmpfs is added on /run
to ensure we can create the airlock directory for incoming mounts
under /run/host/incoming.
We need a writable /run for most operations, but in case a read-only
RootImage (or similar) is used, by default there's no additional
tmpfs mount on /run. Change this behaviour and document it.
This adds the support for veritytab.
The veritytab file contains at most five fields, the first four are
mandatory, the last one is optional:
- The first field contains the name of the resulting verity volume; its
block device is set up /dev/mapper/</filename>.
- The second field contains a path to the underlying block data device,
or a specification of a block device via UUID= followed by the UUID.
- The third field contains a path to the underlying block hash device,
or a specification of a block device via UUID= followed by the UUID.
- The fourth field is the roothash in hexadecimal.
- The fifth field, if present, is a comma-delimited list of options.
The following options are recognized only: ignore-corruption,
restart-on-corruption, panic-on-corruption, ignore-zero-blocks,
check-at-most-once and root-hash-signature. The others options will
be implemented later.
Also, this adds support for the new kernel verity command line boolean
option "veritytab" which enables the read for veritytab, and the new
environment variable SYSTEMD_VERITYTAB which sets the path to the file
veritytab to read.
This adds the ability to specify truncate:PATH for StandardOutput= and
StandardError=, similar to the existing append:PATH. The code is mostly
copied from the related append: code. Fixes#8983.
This adds support for a new kernel root verity command line option
"verity_root_options=" which controls the behaviour of dm-verity by
forwarding options directly to systemd-veritysetup.
See `veritysetup(8)` for more details.
As described in #2680, systemctl did ignore inhibitors if it is not
attached to a tty to allow scripts to ignore inhibitors automatically.
This pull request preserves this behavior but allows scripts to
explicit check inhibitors if required.
The new parameter '--check-inhibitors=yes' enables this feature.
The old parameter '-i'/'--ignore-inhibitors' was deprecated in favor
of '--check-inhibitors=no', the default behaviour can be specified
with '--check-inhibitors=auto'.
The new parameter is also described in the documentations and shell
completions found here.
Enable udev to set the transmit queue length of a device via a new directive to
be used in link files. The kernel stores this parameter as an unsigned 32 bit
integer. As typical values currently range in the order of 10 to a few 10,000
packets reduce the domain of valid values for this directive to 0..4294967294
and take the excluded 4294967295 == UINT32_MAX to indicate that the directive
is unset.
This adjust the documentation to match the code, addressing #17740.
I actually think that not making the "argument" field accept quotes was
a mistake, but I also understand why this choice was made. Given that we
shipped this forever like this though I don't think it's worth changing
the behaviour now. Supporting quotes for this is not that important I
guess. Hence document the current behaviour.
Fixes: #17740
When suspend-then-hibernate is called, hooks have no ability to determine which
stage of the request is being handled; they only see 'pre' and 'post' with the
verb 'suspend-then-hibernate'. This change introduces an environment variable
called SYSTEMD_SLEEP_ACTION that contains the name of the action that is
processing: 'suspend', 'hibernate', 'hybrid-sleep', or
'suspend-after-failed-hibernate'.
Enhance systemd-networkd to be able to control a CAN device's berr-reporting
flag via the new boolean directive BusErrorReporting= to be used in network
files.
Importing the full environment is convenient, but it doesn't work too well in
practice, because we get a metric ton of shell-specific crap that should never
end up in the global environment block:
$ systemctl --user show-environment
...
SHELL=/bin/zsh
AUTOJUMP_ERROR_PATH=/home/zbyszek/.local/share/autojump/errors.log
AUTOJUMP_SOURCED=1
CONDA_SHLVL=0
CVS_RSH=ssh
DBUS_SESSION_BUS_ADDRESS=unix:path=/run/user/1000/bus
DESKTOP_SESSION=gnome
DISPLAY=:0
FPATH=/usr/share/Modules/init/zsh-functions:/usr/local/share/zsh/site-functions:/usr/share/zsh/site-functions:/usr/share/zsh/5.8/functions
GDMSESSION=gnome
GDM_LANG=en_US.UTF-8
GNOME_SETUP_DISPLAY=:1
GUESTFISH_INIT=$'\\e[1;34m'
GUESTFISH_OUTPUT=$'\\e[0m'
GUESTFISH_PS1=$'\\[\\e[1;32m\\]><fs>\\[\\e[0;31m\\] '
GUESTFISH_RESTORE=$'\\e[0m'
HISTCONTROL=ignoredups
HISTSIZE=1000
LOADEDMODULES=
OLDPWD=/home/zbyszek
PWD=/home/zbyszek
QTDIR=/usr/lib64/qt-3.3
QTINC=/usr/lib64/qt-3.3/include
QTLIB=/usr/lib64/qt-3.3/lib
QT_IM_MODULE=ibus
SDL_VIDEO_MINIMIZE_ON_FOCUS_LOSS=0
SESSION_MANAGER=local/unix:@/tmp/.ICE-unix/2612,unix/unix:/tmp/.ICE-unix/2612
SHLVL=0
STEAM_FRAME_FORCE_CLOSE=1
TERM=xterm-256color
USERNAME=zbyszek
WISECONFIGDIR=/usr/share/wise2/
...
Plenty of shell-specific and terminal-specific stuff that have no global
significance.
Let's start warning when this is used to push people towards importing only
specific variables.
Putative NEWS entry:
* systemctl import-environment will now emit a warning when called without
any arguments (i.e. to import the full environment block of the called
program). This command will usually be invoked from a shell, which means
that it'll inherit a bunch of variables which are specific to that shell,
and usually to the tty the shell is connected to, and don't have any
meaning in the global context of the system or user service manager.
Instead, only specific variables should be imported into the manager
environment block.
Similarly, programs which update the manager environment block by directly
calling the D-Bus API of the manager, should also push specific variables,
and not the full inherited environment.
This adds a general description of "philosphy" of keeping the environemnt
block small and hints about systemd-run -P env.
The list of generated variables is split out to a subsection. Viewing
the patch with ignoring whitespace changes is recommended.
We don't ignore invalid assignments (except in import-environment to some
extent), previous description was wrong.
For https://bugzilla.redhat.com/show_bug.cgi?id=1912046#c17.
A minor tweak, that hopefully makes things a bit clearer, given that we
previously used "requirement dependency" when referring to Wants=, which
might be confusing given that we have Requires=
Document that systemd-sysusers doesn’t create the specified home
directory, and point to systemd-tmpfiles as the service that can create
the home directory instead. (systemd-tmpfiles-setup.service is ordered
After=systemd-sysusers.service, so by the time systemd-tmpfiles would
create the home directory, sysusers would have created the owning user
already, and it should all work out.)
The unit files are located at path /usr/lib/systemd/system.
This fixes the path reference to the unit file by adding the missing
path component system.
Let's link the three man pages together more tightly and explain what
the two targets are about, emphasizing local/quick/reliable/approximate
vs remote/slow/unreliable/accurate synchronization.
Follow-up for: 1431b2f701fe934b42e4
This commit adds support for disabling the read and write
workqueues with the new crypttab options no-read-workqueue
and no-write-workqueue. These correspond to the cryptsetup
options --perf-no_read_workqueue and --perf-no_write_workqueue
respectively.
Explicitly document the behavior introduced in #7437: when picking a new
UID shift base with "-U", a hash of the machine name will be tried
before falling back to fully random UID base candidates.
`AllowedIPs=` only affects "routing inside the network interface
itself", as in, which wireguard peer packets with a specific destination
address are sent to, and what source addresses are accepted from which
peer.
To cause packets to be sent via wireguard in first place, a route via
that interface needs to be added - either in the `[Routes]` section on
the `.network` matching the wireguard interface, or outside of networkd.
This is a common cause of misunderstanding, because tools like wg-quick
also add routes to the interface. However, those tools are meant as a
"extremely simple script for easily bringing up a WireGuard interface,
suitable for a few common use cases (from their manpage).
Networkd also should support other usecases - like setting AllowedIPs to
0.0.0.0/0 and ::/0 and having a dynamic routing protocol setting more
specific routes (or the user manually setting them).
Reported-In: https://github.com/systemd/systemd/issues/14176
* man: Advertise systemd-time-wait-sync.service more
The description of time-sync.target says that NTP services *should* pull
that target, but doesn't mention that e.g. systemd-timesyncd.service
doesn't actually do that. As a result, time-sync.target is reached way
earlier than people expect; see #5097, #8861, #11008.
systemd provides systemd-time-wait-sync.service to ameliorate this
problem, but doesn't feature it prominently in relevant manpages. In
fact, it's only mentioned in passing in systemd-timesyncd.service(8). As
a result, I ended up re-implementing that service, and I'm not the first
one: https://github.com/NixOS/nixpkgs/pull/51338
This patch adds a mention right in the description of time-sync.target,
which will hopefully raise awareness of this helper service.
Allow configuration for IPv6 discovered routes to be ignored instead of
adding them as a route. This can be used to block unwanted routes, for
example, you may wish to not receive some set of routes on an interface
if they are causing issues.
In hostnamed this is exposed as a dbus property, and in the logs in both
places.
This is of interest to network management software and such: if the fallback
hostname is used, it's not as useful as the real configured thing. Right now
various programs try to guess the source of hostname by looking at the string.
E.g. "localhost" is assumed to be not the real hostname, but "fedora" is. Any
such attempts are bound to fail, because we cannot distinguish "fedora" (a
fallback value set by a distro), from "fedora" (received from reverse dns),
from "fedora" read from /etc/hostname.
/run/systemd/fallback-hostname is written with the fallback hostname when
either pid1 or hostnamed sets the kernel hostname to the fallback value. Why
remember the fallback value and not the transient hostname in /run/hostname
instead?
We have three hostname types: "static", "transient", fallback".
– Distinguishing "static" is easy: the hostname that is set matches what
is in /etc/hostname.
– Distingiushing "transient" and "fallback" is not easy. And the
"transient" hostname may be set outside of pid1+hostnamed. In particular,
it may be set by container manager, some non-systemd tool in the initramfs,
or even by a direct call. All those mechanisms count as "transient". Trying
to get those cases to write /run/hostname is futile. It is much easier to
isolate the "fallback" case which is mostly under our control.
And since the file is only used as a flag to mark the hostname as fallback,
it can be hidden inside of our /run/systemd directory.
For https://bugzilla.redhat.com/show_bug.cgi?id=1892235.
We would sometimes ignore localhost-style names in /etc/hostname. That is
brittle. If the user configured some hostname, it's most likely because they
want to use that as the hostname. If they don't want to use such a hostname,
they should just not create the config. Everything becomes simples if we just
use the configured hostname as-is.
This behaviour seems to have been a workaround for Anaconda installer and other
tools writing out /etc/hostname with the default of "localhost.localdomain".
Anaconda PR to stop doing that: https://github.com/rhinstaller/anaconda/pull/3040.
That might have been useful as a work-around for other programs misbehaving if
/etc/hostname was not present, but nowadays it's not useful because systemd
mostly controls the hostname and it is perfectly happy without that file.
Apart from making things simpler, this allows users to set a hostname like
"localhost" and have it honoured, if such a whim strikes them.
The semantics were significantly changed in c779a44222
("hostnamed: Fix the way that static and transient host names interact", Feb. 2014),
but when the dbus api documentation was imported much later, it wasn't properly
adjusted to describe those new semantics.
34293dfafd which added systemd.hostname= also
added new behaviour.
Let's ove various bits and pieces around so that they are in more appropriate
places. Drop recommendations to set the hostname for DHCP or mDNS purposes.
Nowadays we expect tools that want to expose some different hostname to the
outside to manage that internally without affecting visible state. Also drop
mentions of DHCP or mDNS directly setting the hostname, since nowadays network
management software is expected to (and does) go through hostnamed.
Also, add a high-level description of semantics. It glosses over the details of
handling of localhost-style names. Later commits will remove this special handling
anyway.
This commit extends $SYSTEMD_COLORS to an enum variable (compared to
a simple boolean) which specifies the "colors mode". This means that, in
addition to disabling colors altogether, it's now possible to restrict
the console output to 16 or 256 colors only.
```
❯ ssh sus@xx.xx.xx.xx
Last login: Sat Nov 14 17:32:08 2020 from 10.104.45.138
17:36:19 up 0 min, 0 users, load average: 0.00, 0.00, 0.00
> systemd-analyze blame
Bootup is not yet finished (org.freedesktop.systemd1.Manager.FinishTimestampMonotonic=0).
Please try again later.
Hint: Use 'systemctl list-jobs' to see active jobs
> systemd-analyze blame
43.954s systemd-time-wait-sync.service
1.969s systemd-networkd-wait-online.service
1.559s cloud-init-local.service
1.039s cloud-init.service
414ms cloud-final.service
387ms dracut-initqueue.service
382ms initrd-switch-root.service
380ms cloud-config.service
198ms systemd-journal-flush.service
136ms systemd-udev-trigger.service
115ms initrd-parse-etc.service
97ms systemd-timesyncd.service
84ms systemd-journald.service
```
After made it configurable and set to 5s
```
❯ ssh sus@xx.xx.xx.xx
Last login: Sat Nov 14 18:41:42 2020 from 10.104.45.138
18:42:36 up 0 min, 0 users, load average: 0.16, 0.03, 0.01
> systemd-analyze blame
10.450s systemd-time-wait-sync.service
8.303s systemd-networkd-wait-online.service
1.621s cloud-init-local.service
1.068s cloud-init.service
```
The old code was only able to pass the value 0 for the inheritable
and ambient capability set when a non-root user was specified.
However, sometimes it is useful to run a program in its own container
with a user specification and some capabilities set. This is needed
when the capabilities cannot be provided by file capabilities (because
the file system is mounted with MS_NOSUID for additional security).
This commit introduces the option --ambient-capability and the config
file option AmbientCapability=. Both are used in a similar way to the
existing Capability= setting. It changes the inheritable and ambient
set (which is 0 by default). The code also checks that the settings
for the bounding set (as defined by Capability= and DropCapability=)
and the setting for the ambient set (as defined by AmbientCapability=)
are compatible. Otherwise, the operation would fail in any way.
Due to the current use of -1 to indicate no support for ambient
capability set the special value "all" cannot be supported.
Also, the setting of ambient capability is restricted to running a
single program in the container payload.
