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.attached/ directory (or
/run/systemd/system.attached/ — depending whether
--runtime is specified, see above), which is included in
the built-in unit search path of the system service
manager.
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 an 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.
If --now and/or --enable are passed, the portable service(s)
are immediately started (blocking operation unless --no-block
is passed) and/or enabled after attaching the image.
detach IMAGE [PREFIX...]
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 convenience feature to allow all arguments passed as
attach also to detach.
If --now and/or --enable are passed, the portable service(s)
are immediately stopped (blocking operation) and/or disabled
before detaching the image. Prefix(es) are also accepted, to
be used in case the unit names do not match the image name as
described in the attach.
reattach IMAGE [PREFIX...]
Detaches an existing portable service image from the host,
and immediately attaches it again. This is useful in case the
image was replaced. Running units are not stopped during the
process. Partial matching, to allow for different versions in
the image name, is allowed: only the part before the first
"_" character has to match. If the new image doesn't exist,
the existing one will not be detached. The parameters follow
the same syntax as the attach command.
If --now and/or --enable are passed, the portable service(s)
are immediately stopped if removed, started and/or enabled if
added, or restarted if updated. Prefixes are also accepted,
in the same way as described in the attach case.
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 │
│ │ 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.
