NAME¶
portablectl - Attach, detach or inspect portable service
images
SYNOPSIS¶
portablectl [OPTIONS...] {COMMAND} [NAME...]
DESCRIPTION¶
portablectl may be used to attach, detach or inspect
portable service images. It's primarily a command interfacing with
systemd-portabled.service(8).
Portable service images contain an OS file system tree along with
systemd(1) unit file information. A service image may be
"attached" to the local system. If attached, a set of unit files
are copied from the image to the host, and extended with
RootDirectory= or RootImage= assignments (in case of service
units) pointing to the image file or directory, ensuring the services will
run within the file system context of the image.
Portable service images are an efficient way to bundle multiple
related services and other units together, and transfer them as a whole
between systems. When these images are attached the local system the
contained units may run in most ways like regular system-provided units,
either with full privileges or inside strict sandboxing, depending on the
selected configuration.
Specifically portable service images may be of the following
kind:
•Directory trees containing an OS, including the
top-level directories /usr/, /etc/, and so on.
•btrfs subvolumes containing OS trees, similar to
normal directory trees.
•Binary "raw" disk images containing MBR
or GPT partition tables and Linux file system partitions.
OPTIONS¶
The following options are understood:
-q, --quiet
Suppresses additional informational output while
running.
-p PROFILE, --profile=PROFILE
When attaching an image, select the profile to use. By
default the "default" profile is used. For details about profiles,
see below.
--copy=
When attaching an image, select whether to prefer copying
or symlinking of files installed into the host system. Takes one of
"copy" (to prefer copying of files), "symlink" (to prefer
creation of symbolic links) or "auto" for an intermediary mode where
security profile drop-ins are symlinked while unit files are copied. Note that
this option expresses a preference only, in cases where symbolic links cannot
be created — for example when the image operated on is a raw disk
image, and hence not directly referentiable from the host file system —
copying of files is used unconditionally.
--runtime
When specified the unit and drop-in files are placed in
/run/systemd/system/ instead of /etc/systemd/system/. Images attached with
this option set hence remain attached only until the next reboot, while they
are normally attached persistently.
--no-reload
Don't reload the service manager after attaching or
detaching a portable service image. Normally the service manager is reloaded
to ensure it is aware of added or removed unit files.
--cat
When inspecting portable service images, show the
(unprocessed) contents of the metadata files pulled from the image, instead of
brief summaries. Specifically, this will show the
os-release(5) and
unit file contents of the image.
-H, --host=
Execute the operation remotely. Specify a hostname, or a
username and hostname separated by "@", to connect to. The hostname
may optionally be suffixed by a container name, separated by ":",
which connects directly to a specific container on the specified host. This
will use SSH to talk to the remote machine manager instance. Container names
may be enumerated with machinectl -H HOST.
-M, --machine=
Execute operation on a local container. Specify a
container name to connect to.
--no-pager
Do not pipe output into a pager.
--no-legend
Do not print the legend, i.e. column headers and the
footer with hints.
--no-ask-password
Do not query the user for authentication for privileged
operations.
-h, --help
Print a short help text and exit.
--version
Print a short version string and exit.
COMMANDS¶
The following commands are understood:
list
List available portable service images. This will list
all portable service images discovered in the portable image search paths (see
below), along with brief metadata and state information. Note that many of the
commands below may both operate on images inside and outside of the search
paths. This command is hence mostly a convenience option, the commands are
generally not restricted to what this list shows.
attach IMAGE [PREFIX...]
Attach a portable service image to the host system.
Expects a file system path to a portable service image file or directory as
first argument. If the specified path contains no slash character
("/") it is understood as image filename that is searched for in the
portable service image search paths (see below). To reference a file in the
current working directory prefix the filename with "./" to avoid
this search path logic.
When a portable service is attached four operations are
executed:
1.All unit files of types .service, .socket, .target,
.timer and .path which match the indicated unit file name prefix are copied
from the image to the host's /etc/systemd/system/ directory (or
/run/systemd/system/ — depending whether --runtime is specified,
see above).
2.For unit files of type .service a drop-in is added to
these copies that adds
RootDirectory= or
RootImage= settings
(see
systemd.unit(5) for details), that ensures these services are run
within the file system of the originating portable service image.
3.A second drop-in is created: the "profile"
drop-in, that may contain additional security settings (and other settings). A
number of profiles are available by default but administrators may define
their own ones. See below.
4.If the portable service image file is not already in
the search path (see below), a symbolic link to it is created in
/etc/portables/ or /run/portables/, to make sure it is included in it.
By default all unit files whose names start with a prefix
generated from the image's file name are copied out. Specifically, the
prefix is determined from the image file name with any suffix such as .raw
removed, truncated at the first occurrence of and underscore character
("_"), if there is one. The underscore logic is supposed to be
used to versioning so that the an image file foobar_47.11.raw will result in
a unit file matching prefix of foobar. This prefix is then compared with all
unit files names contained in the image in the usual directories, but only
unit file names where the prefix is followed by "-", "."
or "@" are considered. Example: if a portable service image file
is named foobar_47.11.raw then by default all its unit files with names such
as foobar-quux-waldi.service, foobar.service or foobar@.service will be
considered. It's possible to override the matching prefix: all strings
listed on the command line after the image file name are considered
prefixes, overriding the implicit logic where the prefix is derived from the
image file name.
By default, after the unit files are attached the service
manager's configuration is reloaded, except when --no-reload is
specified (see above). This ensures that the new units made available to the
service manager are seen by it.
detach IMAGE
Detaches a portable service image from the host. This
undoes the operations executed by the attach command above, and removes
the unit file copies, drop-ins and image symlink again. This command expects
an image name or path as parameter. Note that if a path is specified only the
last component of it (i.e. the file or directory name itself, not the path to
it) is used for finding matching unit files. This is a convencience feature to
allow all arguments passed as attach also to detach.
inspect IMAGE [PREFIX...]
Extracts various metadata from a portable service image
and presents it to the caller. Specifically, the
os-release(5) file of
the image is retrieved as well as all matching unit files. By default a short
summary showing the most relevant metadata in combination with a list of
matching unit files is shown (that is the unit files
attach would
install to the host system). If combined with
--cat (see above), the
os-release data and the units files' contents is displayed unprocessed. This
command is useful to determine whether an image qualifies as portable service
image, and which unit files are included. This command expects the path to the
image as parameter, optionally followed by a list of unit file prefixes to
consider, similar to the
attach command described above.
is-attached IMAGE
Determines whether the specified image is currently
attached or not. Unless combined with the
--quiet switch this will show
a short state identifier for the image. Specifically:
Table 1. Image attachment states
| State |
Description |
| detached |
The image is currently not attached. |
| attached |
The image is currently attached, i.e. its unit files have been made
available to the host system. |
| attached-runtime |
Like attached, but the unit files have been made available
transiently only, i.e. the attach command has been invoked with the
--runtime option. |
| enabled |
The image is currently attached, and at least one unit file associated
with it has been enabled. |
| enabled-runtime |
Like enabled, but the the unit files have been made available
transiently only, i.e. the attach command has been invoked with the
--runtime option. |
| running |
The image is currently attached, and at least one unit file associated
with it is running. |
| running-runtime |
The image is currently attached transiently, and at least one unit file
associated with it is running. |
read-only IMAGE [BOOL]
Marks or (unmarks) a portable service image read-only.
Takes an image name, followed by a boolean as arguments. If the boolean is
omitted, positive is implied, i.e. the image is marked read-only.
remove IMAGE...
Removes one or more portable service images. Note that
this command will only remove the specified image path itself — it
refers to a symbolic link then the symbolic link is removed and not the image
it points to.
set-limit [IMAGE] BYTES
Sets the maximum size in bytes that a specific portable
service image, or all images, may grow up to on disk (disk quota). Takes
either one or two parameters. The first, optional parameter refers to a
portable service image name. If specified, the size limit of the specified
image is changed. If omitted, the overall size limit of the sum of all images
stored locally is changed. The final argument specifies the size limit in
bytes, possibly suffixed by the usual K, M, G, T units. If the size limit
shall be disabled, specify "-" as size.
Note that per-image size limits are only supported on btrfs file
systems. Also, depending on BindPaths= settings in the portable
service's unit files directories from the host might be visible in the image
environment during runtime which are not affected by this setting, as only
the image itself is counted against this limit.
FILES AND DIRECTORIES¶
Portable service images are preferably stored in
/var/lib/portables/, but are also searched for in /etc/portables/,
/run/systemd/portables/, /usr/local/lib/portables/ and /usr/lib/portables/.
It's recommended not to place image files directly in /etc/portables/ or
/run/systemd/portables/ (as these are generally not suitable for storing
large or non-textual data), but use these directories only for linking
images located elsewhere into the image search path.
PROFILES¶
When portable service images are attached a "profile"
drop-in is linked in, which may be used to enforce additional security (and
other) restrictions locally. Four profile drop-ins are defined by default,
and shipped in /usr/lib/systemd/portable/profile/. Additional, local
profiles may be defined by placing them in /etc/systemd/portable/profile/.
The default profiles are:
Table 2. Profiles
| Name |
Description |
| default |
This is the default profile if no other profile name is set via the
--profile= (see above). It's fairly restrictive, but should be
useful for common, unprivileged system workloads. This includes write
access to the logging framework, as well as IPC access to the D-Bus
system. |
| nonetwork |
Very similar to default, but networking is turned off for any services
of the portable service image. |
| strict |
A profile with very strict settings. This profile excludes IPC (D-Bus)
and network access. |
| trusted |
A profile with very relaxed settings. In this profile the services run
with full privileges. |
For details on this profiles, and their effects please have a look
at their precise definitions, e.g.
/usr/lib/systemd/portable/profile/default/service.conf and similar.
EXIT STATUS¶
On success, 0 is returned, a non-zero failure code otherwise.
ENVIRONMENT¶
$SYSTEMD_PAGER
Pager to use when
--no-pager is not given;
overrides
$PAGER. If neither
$SYSTEMD_PAGER nor
$PAGER
are set, a set of well-known pager implementations are tried in turn,
including
less(1) and
more(1), until one is found. If no pager
implementation is discovered no pager is invoked. Setting this environment
variable to an empty string or the value "cat" is equivalent to
passing
--no-pager.
$SYSTEMD_LESS
Override the options passed to less (by default
"FRSXMK").
$SYSTEMD_LESSCHARSET
Override the charset passed to less (by default
"utf-8", if the invoking terminal is determined to be UTF-8
compatible).
$SYSTEMD_PAGERSECURE
Takes a boolean argument. When true, the
"secure" mode of the pager is enabled; if false, disabled. If
$SYSTEMD_PAGERSECURE is not set at all, secure mode is enabled if the
effective UID is not the same as the owner of the login session, see
geteuid(2) and
sd_pid_get_owner_uid(3). In secure mode,
LESSSECURE=1 will be set when invoking the pager, and the pager shall
disable commands that open or create new files or start new subprocesses. When
$SYSTEMD_PAGERSECURE is not set at all, pagers which are not known to
implement secure mode will not be used. (Currently only
less(1)
implements secure mode.)
Note: when commands are invoked with elevated privileges, for
example under sudo(8) or pkexec(1), care must be taken to
ensure that unintended interactive features are not enabled.
"Secure" mode for the pager may be enabled automatically as
describe above. Setting SYSTEMD_PAGERSECURE=0 or not removing it from
the inherited environment allows the user to invoke arbitrary commands. Note
that if the $SYSTEMD_PAGER or $PAGER variables are to be
honoured, $SYSTEMD_PAGERSECURE must be set too. It might be
reasonable to completly disable the pager using --no-pager
instead.