IMPORTCTL(1)

NAME
importctl - Download, import or export disk images

SYNOPSIS

importctl [OPTIONS...] {COMMAND} [NAME...]

DESCRIPTION

importctl may be used to download, import, and export disk images via systemd-importd.service(8).

importctl operates both on block-level disk images (such as DDIs) as well as file-system-level images (tarballs). It supports disk images in one of the four following classes:

    • VM images or full OS container images, that may be run via systemd-vmspawn(1) or systemd-nspawn(1), and managed via machinectl(1).

    • Portable service images, that may be attached and managed via portablectl(1).

    • System extension (sysext) images, that may be activated via systemd-sysext(8).

    • Configuration extension (confext) images, that may be activated via systemd-confext(8).

When images are downloaded or imported they are placed in the following directories, depending on the --class= parameter:

Table 1. Classes and Directories
Class | Directory
"machine" | /var/lib/machines/
"portable" | /var/lib/portables/
"sysext" | /var/lib/extensions/
"confext" | /var/lib/confexts/

COMMANDS

The following commands are understood:

pull-tar URL [NAME]
    Downloads a .tar image from the specified URL, and makes it available under the specified local name in the image directory for the selected --class=. The URL must be of type "http://" or "https://", and must refer to a .tar, .tar.gz, .tar.xz or .tar.bz2 archive file. If the local image name is omitted, it is automatically derived from the last component of the URL, with its suffix removed.

    The image is verified before it is made available, unless --verify=no is specified. Verification is done either via an inline signed file with the name of the image and the suffix .sha256 or via separate SHA256SUMS and SHA256SUMS.gpg files. The signature files need to be made available on the same web server, under the same URL as the .tar file. With --verify=checksum, only the SHA256 checksum for the file is verified, based on the .sha256 suffixed file or the SHA256SUMS file. With --verify=signature, the sha checksum file is first verified with the inline signature in the .sha256 file or the detached GPG signature file SHA256SUMS.gpg. The public key for this verification step needs to be available in /usr/lib/systemd/import-pubring.gpg or /etc/systemd/import-pubring.gpg.

    If -keep-download=yes is specified the image will be downloaded and stored in a read-only subvolume/directory in the image directory that is named after the specified URL and its HTTP etag (see HTTP ETag[1] for more information). A writable snapshot is then taken from this subvolume, and named after the specified local name. This behavior ensures that creating multiple instances of the same URL is efficient, as multiple downloads are not necessary. In order to create only the read-only image, and avoid creating its writable snapshot, specify "-" as local name.

    Note that pressing Control-c during execution of this command will not abort the download. Use cancel-transfer, described below.

    Added in version 256.

pull-raw URL [NAME]
    Downloads a .raw disk image from the specified URL, and makes it available under the specified local name in the image directory for the selected --class=. The URL must be of type "http://" or "https://". The image must either be a qcow2 or raw disk image, optionally compressed as .gz, .xz, or .bz2. If the local name is omitted, it is automatically derived from the last component of the URL, with its suffix removed.

    Image verification is identical for raw and tar images (see above).

    If the downloaded image is in qcow2 format it is converted into a raw image file before it is made available.

    If -keep-download=yes is specified the image will be downloaded and stored in a read-only file in the image directory that is named after the specified URL and its HTTP etag. A writable copy is then made from this file, and named after the specified local name. This behavior ensures that creating multiple instances of the same URL is efficient, as multiple downloads are not necessary. In order to create only the read-only image, and avoid creating its writable copy, specify "-" as local name.

    Note that pressing Control-c during execution of this command will not abort the download. Use cancel-transfer, described below.

    Added in version 256.

import-tar FILE [NAME], import-raw FILE [NAME]
    Imports a TAR or RAW image, and places it under the specified name in the image directory for the image class selected via --class=. When import-tar is used, the file specified as the first argument should be a tar(1) archive, possibly compressed with xz(1), gzip(1), or bzip2(1). It will then be unpacked into its own subvolume/directory. When import-raw is used, the file should be a qcow2 or raw disk image, possibly compressed with xz, gzip or bzip2. If the second argument (the resulting image name) is not specified, it is automatically derived from the file name. If the filename is passed as "-", the image is read from standard input, in which case the second argument is mandatory.

    No cryptographic validation is done when importing the images.

    Much like image downloads, ongoing imports may be listed with list and aborted with cancel-transfer.

    Added in version 256.

import-fs DIRECTORY [NAME]
    Imports an image stored in a local directory into the image directory for the image class selected via --class= and operates similarly to import-tar or import-raw, but the first argument is the source directory. If supported, this command will create a btrfs(8) snapshot or subvolume for the new image.

    Added in version 256.

export-tar NAME [FILE], export-raw NAME [FILE]
    Exports a TAR or RAW image and stores it in the specified file. The first parameter should be an image name. The second parameter should be a file path the TAR or RAW image is written to. If the path ends in ".gz", the file is compressed with gzip(1), if it ends in ".xz", with xz(1), and if it ends in ".bz2", with bzip2(1). If the path ends in neither, the file is left uncompressed. If the second argument is missing, the image is written to standard output. The compression may also be explicitly selected with the --format= switch. This is in particular useful if the second parameter is left unspecified.

    Much like image downloads and imports, ongoing exports may be listed with list and aborted with cancel-transfer.

    Note that, currently, only directory and subvolume images may be exported as TAR images, and only raw disk images as RAW images.

    Added in version 256.

list-transfer
    Shows a list of image downloads, imports and exports that are currently in progress.

    Added in version 256.

cancel-transfer ID...
    Aborts a download, import or export of the image with the specified ID. To list ongoing transfers and their IDs, use list.

    Added in version 256.

list-images
    Shows a list of already downloaded/imported images.

    Added in version 256.

OPTIONS

The following options are understood:

--read-only
    When used with pull-raw, pull-tar, import-raw, import-tar or import-fs a read-only image is created.

    Added in version 256.

--verify=
    When downloading an image, specify whether the image shall be verified before it is made available. Takes one of "no", "checksum" and "signature". If "no", no verification is done. If "checksum" is specified, the download is checked for integrity after the transfer is complete, but no signatures are verified. If "signature" is specified, the checksum is verified and the image's signature is checked against a local keyring of trustable vendors. It is strongly recommended to set this option to "signature" if the server and protocol support this. Defaults to "signature".

    Added in version 256.

--force
    When downloading an image, and a local copy by the specified local name already exists, delete it first and replace it by the newly downloaded image.

    Added in version 256.

--format=
    When used with the export-tar or export-raw commands, specifies the compression format to use for the resulting file. Takes one of "uncompressed", "xz", "gzip", "bzip2". By default, the format is determined automatically from the output image file name passed.

    Added in version 256.

-q, --quiet
    Suppresses additional informational output while running.

    Added in version 256.

-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 port ssh is listening on, separated by ":", and then 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. Put IPv6 addresses in brackets.

-M, --machine=
    Connect to systemd-importd.service(8) running in a local container, to perform the specified operation within the container.

    Added in version 256.

--class=, -m, -P, -S, -C
    Selects the image class for the downloaded images. This primarily selects the directory to download into. The --class= switch takes "machine", "portable", "sysext" or "confext" as argument. The short options -m, -P, -S, -C are shortcuts for --class=machine, --class=portable, --class=sysext, --class=confext.

    Note that --keep-download= defaults to true for --class=machine and false otherwise, see below.

    Added in version 256.

--keep-download=, -N
    Takes a boolean argument. When specified with pull-raw or pull-tar, selects whether to download directly into the specified local image name, or whether to download into a read-only copy first of which to make a writable copy after the download is completed. Defaults to true for --class=machine, false otherwise.

    The -N switch is a shortcut for --keep-download=no.

    Added in version 256.

--json=MODE
    Shows output formatted as JSON. Expects one of "short" (for the shortest possible output without any redundant whitespace or line breaks), "pretty" (for a pretty version of the same, with indentation and line breaks) or "off" (to turn off JSON output, the default).

-j
    Equivalent to --json=pretty if running on a terminal, and --json=short otherwise.

--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.

EXAMPLES

Example 1. Download an Ubuntu TAR image and open a shell in it

    # importctl pull-tar -mN https://cloud-images.ubuntu.com/jammy/current/jammy-server-cloudimg-amd64-root.tar.xz
    # systemd-nspawn -M jammy-server-cloudimg-amd64-root

This downloads and verifies the specified .tar image, and then uses systemd-nspawn(1) to open a shell in it.

Example 2. Download an Ubuntu RAW image, set a root password in it, start it as a service

    # importctl pull-raw -mN \
          https://cloud-images.ubuntu.com/jammy/current/jammy-server-cloudimg-amd64-disk-kvm.img \
          jammy
    # systemd-firstboot --image=/var/lib/machines/jammy.raw --prompt-root-password --force
    # machinectl start jammy
    # machinectl login jammy

This downloads the specified .raw image and makes it available under the local name "jammy". Then, a root password is set with systemd-firstboot(1). Afterwards the machine is started as system service. With the last command a login prompt into the container is requested.

Example 3. Exports a container image as tar file

    # importctl export-tar -m fedora myfedora.tar.xz

Exports the container "fedora" as an xz-compressed tar file myfedora.tar.xz into the current directory.

EXIT STATUS

On success, 0 is returned, a non-zero failure code otherwise.

ENVIRONMENT

$SYSTEMD_LOG_LEVEL
    The maximum log level of emitted messages (messages with a higher log level, i.e. less important ones, will be suppressed). Takes a comma-separated list of values. A value may be either one of (in order of decreasing importance) emerg, alert, crit, err, warning, notice, info, debug, or an integer in the range 0...7. See syslog(3) for more information. Each value may optionally be prefixed with one of console, syslog, kmsg or journal followed by a colon to set the maximum log level for that specific log target (e.g. SYSTEMD_LOG_LEVEL=debug,console:info specifies to log at debug level except when logging to the console which should be at info level). Note that the global maximum log level takes priority over any per target maximum log levels.

$SYSTEMD_LOG_COLOR
    A boolean. If true, messages written to the tty will be colored according to priority.

    This setting is only useful when messages are written directly to the terminal, because journalctl(1) and other tools that display logs will color messages based on the log level on their own.

$SYSTEMD_LOG_TIME
    A boolean. If true, console log messages will be prefixed with a timestamp.

    This setting is only useful when messages are written directly to the terminal or a file, because journalctl(1) and other tools that display logs will attach timestamps based on the entry metadata on their own.

$SYSTEMD_LOG_LOCATION
    A boolean. If true, messages will be prefixed with a filename and line number in the source code where the message originates.

    Note that the log location is often attached as metadata to journal entries anyway. Including it directly in the message text can nevertheless be convenient when debugging programs.

$SYSTEMD_LOG_TID
    A boolean. If true, messages will be prefixed with the current numerical thread ID (TID).

    Note that the this information is attached as metadata to journal entries anyway. Including it directly in the message text can nevertheless be convenient when debugging programs.

$SYSTEMD_LOG_TARGET
    The destination for log messages. One of console (log to the attached tty), console-prefixed (log to the attached tty but with prefixes encoding the log level and "facility", see syslog(3), kmsg (log to the kernel circular log buffer), journal (log to the journal), journal-or-kmsg (log to the journal if available, and to kmsg otherwise), auto (determine the appropriate log target automatically, the default), null (disable log output).

$SYSTEMD_LOG_RATELIMIT_KMSG
    Whether to ratelimit kmsg or not. Takes a boolean. Defaults to "true". If disabled, systemd will not ratelimit messages written to kmsg.

$SYSTEMD_PAGER, $PAGER
    Pager to use when --no-pager is not given. $SYSTEMD_PAGER is used if set; otherwise $PAGER is used. If neither $SYSTEMD_PAGER nor $PAGER are set, a set of well-known pager implementations is tried in turn, including less(1) and more(1), until one is found. If no pager implementation is discovered, no pager is invoked. Setting those environment variables to an empty string or the value "cat" is equivalent to passing --no-pager.

    Note: if $SYSTEMD_PAGERSECURE is not set, $SYSTEMD_PAGER and $PAGER can only be used to disable the pager (with "cat" or ""), and are otherwise ignored.

$SYSTEMD_LESS
    Override the options passed to less (by default "FRSXMK").

    Users might want to change two options in particular:

    K
        This option instructs the pager to exit immediately when Ctrl+C is pressed. To allow less to handle Ctrl+C itself to switch back to the pager command prompt, unset this option.

        If the value of $SYSTEMD_LESS does not include "K", and the pager that is invoked is less, Ctrl+C will be ignored by the executable, and needs to be handled by the pager.

    X
        This option instructs the pager to not send termcap initialization and deinitialization strings to the terminal. It is set by default to allow command output to remain visible in the terminal even after the pager exits. Nevertheless, this prevents some pager functionality from working, in particular paged output cannot be scrolled with the mouse.

    Note that setting the regular $LESS environment variable has no effect for less invocations by systemd tools.

    See less(1) for more discussion.

$SYSTEMD_LESSCHARSET
    Override the charset passed to less (by default "utf-8", if the invoking terminal is determined to be UTF-8 compatible).

    Note that setting the regular $LESSCHARSET environment variable has no effect for less invocations by systemd tools.

$SYSTEMD_PAGERSECURE
    Common pager commands like less(1), in addition to "paging", i.e. scrolling through the output, support opening of or writing to other files and running arbitrary shell commands. When commands are invoked with elevated privileges, for example under sudo(8) or pkexec(1), the pager becomes a security boundary. Care must be taken that only programs with strictly limited functionality are used as pagers, and unintended interactive features like opening or creation of new files or starting of subprocesses are not allowed. "Secure mode" for the pager may be enabled as described below, if the pager supports that (most pagers are not written in a way that takes this into consideration). It is recommended to either explicitly enable "secure mode" or to completely disable the pager using --no-pager or PAGER=cat when allowing untrusted users to execute commands with elevated privileges.

    This option takes a boolean argument. When set to true, the "secure mode" of the pager is enabled. In "secure mode", LESSSECURE=1 will be set when invoking the pager, which instructs the pager to disable commands that open or create new files or start new subprocesses. Currently only less(1) is known to understand this variable and implement "secure mode".

    When set to false, no limitation is placed on the pager. Setting SYSTEMD_PAGERSECURE=0 or not removing it from the inherited environment may allow the user to invoke arbitrary commands.

    When $SYSTEMD_PAGERSECURE is not set, systemd tools attempt to automatically figure out if "secure mode" should be enabled and whether the pager supports it. "Secure mode" is enabled if the effective UID is not the same as the owner of the login session, see geteuid(2) and sd_pid_get_owner_uid(3), or when running under sudo(8) or similar tools ($SUDO_UID is set [2]). In those cases, SYSTEMD_PAGERSECURE=1 will be set and pagers which are not known to implement "secure mode" will not be used at all. Note that this autodetection only covers the most common mechanisms to elevate privileges and is intended as convenience. It is recommended to explicitly set $SYSTEMD_PAGERSECURE or disable the pager.

    Note that if the $SYSTEMD_PAGER or $PAGER variables are to be honoured, other than to disable the pager, $SYSTEMD_PAGERSECURE must be set too.

$SYSTEMD_COLORS
    Takes a boolean argument. When true, systemd and related utilities will use colors in their output, otherwise the output will be monochrome. Additionally, the variable can take one of the following special values: "16", "256" to restrict the use of colors to the base 16 or 256 ANSI colors, respectively. This can be specified to override the automatic decision based on $TERM and what the console is connected to.

$SYSTEMD_URLIFY
    The value must be a boolean. Controls whether clickable links should be generated in the output for terminal emulators supporting this. This can be specified to override the decision that systemd makes based on $TERM and other conditions.

SEE ALSO

systemd(1), systemd-importd.service(8), systemd-nspawn(1), systemd-vmspawn(1), machinectl(1), portablectl(1), systemd-sysext(8), systemd-confext(8), tar(1), xz(1), gzip(1), bzip2(1)

NOTES

1.  HTTP ETag
    https://en.wikipedia.org/wiki/HTTP_ETag

2.  It is recommended for other tools to set and check $SUDO_UID as appropriate, treating it is a common interface.