path: root/man/org.freedesktop.import1.xml

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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
  "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd" >
<!-- SPDX-License-Identifier: LGPL-2.1+ -->

<refentry id="org.freedesktop.import1" conditional='ENABLE_IMPORTD'
    xmlns:xi="http://www.w3.org/2001/XInclude">
  <refentryinfo>
    <title>org.freedesktop.import1</title>
    <productname>systemd</productname>
  </refentryinfo>

  <refmeta>
    <refentrytitle>org.freedesktop.import1</refentrytitle>
    <manvolnum>5</manvolnum>
  </refmeta>

  <refnamediv>
    <refname>org.freedesktop.import1</refname>
    <refpurpose>The D-Bus interface of systemd-importd</refpurpose>
  </refnamediv>

  <refsect1>
    <title>Introduction</title>

    <para>
    <citerefentry><refentrytitle>systemd-importd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
    is a system service which may be used to import, export and download additional system images, for
    running them as local containers using tools such as
    <citerefentry><refentrytitle>systemd-nspawn</refentrytitle><manvolnum>1</manvolnum></citerefentry> The
    service is used as backend for <command>machinectl pull-raw</command> and <command>machinectl
    pull-tar</command> and related commands.
    This page describes the D-Bus interface.</para>

    <para>Note that
    <citerefentry><refentrytitle>systemd-importd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
    is mostly a small companion service for
    <citerefentry><refentrytitle>systemd-machined.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
    Many operations to manipulate local container and VM images are hence available via the <command>systemd-machined</command> bus API, c.f.
    <citerefentry><refentrytitle>org.freedesktop.machine1.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
    </para>
  </refsect1>

  <refsect1>
    <title>The Manager Object</title>

    <para>The service exposes the following interfaces on the Manager object on the bus:</para>

    <programlisting>
$ gdbus introspect --system \
        --dest org.freedesktop.import1 \
        --object-path /org/freedesktop/import1

node /org/freedesktop/import1 {
  interface org.freedesktop.import1.Manager {
    methods:
      ImportTar(in  h fd,
                in  s local_name,
                in  b force,
                in  b read_only,
                out u transfer_id,
                out o transfer_path);
      ImportRaw(in  h fd,
                in  s local_name,
                in  b force,
                in  b read_only,
                out u transfer_id,
                out o transfer_path);
      ExportTar(in  s local_name,
                in  h fd,
                in  s format,
                out u transfer_id,
                out o transfer_path);
      ExportRaw(in  s local_name,
                in  h fd,
                in  s format,
                out u transfer_id,
                out o transfer_path);
      PullTar(in  s url,
              in  s local_name,
              in  s verify_mode,
              in  b force,
              out u transfer_id,
              out o transfer_path);
      PullRaw(in  s url,
              in  s local_name,
              in  s verify_mode,
              in  b force,
              out u transfer_id,
              out o transfer_path);
      ListTransfers(out a(usssdo) list);
      CancelTransfer(in  u transfer_id);
    signals:
      TransferNew(u transfer_id,
                  o transfer_path);
      TransferRemoved(u transfer_id,
                      o transfer_path,
                      s result);
  };
  interface org.freedesktop.DBus.Peer {
  };
  interface org.freedesktop.DBus.Introspectable {
  };
  interface org.freedesktop.DBus.Properties {
  };
};
</programlisting>

    <refsect2>
      <title>Methods</title>

      <para><function>ImportTar()</function> and <function>ImportRaw()</function> import a system image and
      place it into <filename>/var/lib/machines/</filename>. The first argument should be a file descriptor
      (opened for reading) referring to the tar or raw file to import. It should reference either a file on
      disk or a pipe or socket. When <function>ImportTar()</function> is used the file descriptor should
      refer to a tar file, optionally compressed with
      <citerefentry project="die-net"><refentrytitle>gzip</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
      <citerefentry project="die-net"><refentrytitle>bzip2</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
      or
      <citerefentry project="die-net"><refentrytitle>xz</refentrytitle><manvolnum>1</manvolnum></citerefentry>.
      <command>systemd-importd</command> will detect the used compression scheme (if any) automatically. When
      <function>ImportRaw()</function> is used the file descriptor should refer to a raw or qcow2 disk image
      containing an MBR or GPT disk label, also optionally compressed with gzip, bzip2 or xz. In either case,
      if the file is specified as file descriptor on disk, progress information is generated for the import
      operation (since the size on disk is known then), if a socket or pipe is specified this is not
      available. The file descriptor argument is followed by a local name for the image. This should be a
      name suitable as a hostname and will be used to name the imported image below
      <filename>/var/lib/machines</filename>. A tar import is placed as directory tree or
      <citerefentry project="man-pages"><refentrytitle>btrfs</refentrytitle><manvolnum>8</manvolnum></citerefentry>
      subvolume below <filename>/var/lib/machines/</filename>, under the name specified with no suffix
      appended. A raw import is placed as file in <filename>/var/lib/machines/</filename> with the
      <filename>.raw</filename> suffix appended. The <option>force</option> argument controls whether any
      pre-existing image with the same name shall be removed for the operation. If true, it is removed, if
      false the operation fails on a name conflict. Finally, the <option>read_only</option> argument controls
      whether to create a writable or read-only image. The two calls return immediately after invocation,
      with the import transfer ongoing. They return a pair of transfer identifier and object path, which may
      be used to retrieve progress information about the transfer, or cancel it. The transfer identifier is a
      simple numeric identifier, the object path references an
      <interfacename>org.freedesktop.import1.Transfer</interfacename> object, see below. Listen for a
      <function>TransferRemoved</function> signal for the transfer ID it order to detect when a transfer is
      complete. The returned transfer object is useful to determine the current progress or log output of the
      ongoing import operation.</para>

      <para><function>ExportTar()</function> and <function>ExportRaw()</function> implement the reverse
      operation, and may be used to export a system image in order to place it in a tar or raw image. They
      take the machine name to export as first parameter, followed by a file descriptor (opened for writing)
      where the tar or raw file will be written. It may either reference a file on disk or a pipe/socket. The
      third argument specifies in which compression format to write the image. It takes one of
      <literal>uncompressed</literal>, <literal>xz</literal>, <literal>bzip2</literal> or
      <literal>gzip</literal>, depending on which compression scheme is required. The image written to the
      specified file descriptor will be a tar file in case of <function>ExportTar()</function> or a raw disk
      image in case of <function>ExportRaw()</function>. Note that currently raw disk images may not be
      exported as tar files, and vice versa, however this restriction might be lifted eventually. The call
      returns a transfer identifier and object path for canceling or tracking the export operation, similar
      to <function>ImportTar()</function> or <function>ImportRaw()</function> described above.</para>

      <para><function>PullTar()</function> and <function>PullRaw()</function> may be used to download, verify
      and import a system image from a web site. They take an URL argument, that should reference a tar or
      raw file on the <literal>http://</literal> or <literal>https://</literal> protocols, possibly
      compressed with xz, bzip2 or gzip. The second argument is a local name for the image. It should be
      suitable as hostname, similar to the matching argument of the <function>ImportTar()</function> and
      <function>ImportRaw()</function> calls above. The third argument indicates the verification mode for
      the image. It may be one of <literal>no</literal>, <literal>checksum</literal>,
      <literal>signature</literal>. <literal>no</literal> turns of any kind of verification of the image;
      <literal>checksum</literal> looks for a <filename>SHA256SUM</filename> file next to the downloaded
      image, and verifies any SHA256 hash value in that file again the image; <literal>signature</literal>
      does the same but also tries to authenticate the <filename>SHA256SUM</filename> file via
      <citerefentry project="man-pages"><refentrytitle>gpg</refentrytitle><manvolnum>8</manvolnum></citerefentry>
      first. The last argument indicates whether to replace a possibly pre-existing image with the same local
      name (if <literal>true</literal>), or whether to fail (if <literal>false</literal>). Like the import
      and export calls above these calls return a pair of transfer identifier and object path for the ongoing
      download.</para>

      <para><function>ListTransfers()</function> returns a list of ongoing import, export or download
      operations, as created with the six calls described above. It returns an array of structures, which
      consist of the numeric transfer identifier, a string indicating the operation (one of
      <literal>import-tar</literal>, <literal>import-raw</literal>, <literal>export-tar</literal>,
      <literal>export-raw</literal>, <literal>pull-tar</literal> or <literal>pull-raw</literal>), a string
      describing the remote file (in case of download operations this is the source URL, in case of
      import/export operations this is a short string describing the file descriptor passed in), a string
      with the local machine image name, a progress value between 0.0 (for 0%) and 1.0 (for 100%), as well as
      the transfer object path.</para>

      <para><function>CancelTransfer()</function> may be used to cancel an ongoing import, export or download
      operation. Simply specify the transfer identifier to cancel.</para>
    </refsect2>

    <refsect2>
      <title>Signals</title>

      <para>The <function>TransferNew</function> signal is generated each time a new transfer is added with
      the import, export or download calls described above. It carries the transfer ID and object path just
      created.</para>

      <para>The <function>TransferRemoved</function> signal is sent each time a transfer was completed,
      canceled or failed. It also carries the transfer ID and object path, followed by a string indicating
      the result of the operation, which is one of <literal>done</literal> (on success),
      <literal>canceled</literal> or <literal>failed</literal>.</para>
    </refsect2>
  </refsect1>

  <refsect1>
    <title>The Transfer Object</title>

    <programlisting>
$ gdbus introspect --system \
        --dest org.freedesktop.import1 \
        --object-path /org/freedesktop/import1/transfer/_1

node /org/freedesktop/import1/transfer/_1 {
  interface org.freedesktop.import1.Transfer {
    methods:
      Cancel();
    signals:
      LogMessage(u priority,
                 s line);
    properties:
      readonly u Id = 1;
      readonly s Local = 'xenial-server-cloudimg-amd64-root';
      readonly s Remote = 'https://cloud-images.ubuntu.com/xenial/current/xenial-server-cloudimg-amd64-root.tar.gz';
      readonly s Type = 'pull-tar';
      readonly s Verify = 'signature';
      readonly d Progress = 0.253;
  };
  interface org.freedesktop.DBus.Peer {
  };
  interface org.freedesktop.DBus.Introspectable {
  };
  interface org.freedesktop.DBus.Properties {
  };
};
</programlisting>

    <refsect2>
      <title>Methods</title>

      <para>The <function>Cancel()</function> method may be used to cancel the transfer. It takes no
      parameters. This call is pretty much equivalent to the <function>CancelTransfer()</function> call on
      the <structname>Manager</structname> interface (see above), but is exposed on the
      <structname>Transfer</structname> object itself instead of taking a transfer ID.</para>
    </refsect2>

    <refsect2>
      <title>Properties</title>

      <para>The <varname>Id</varname> property exposes the numeric transfer ID of the transfer object.</para>

      <para>The <varname>Local</varname>, <varname>Remote</varname>, <varname>Type</varname> properties
      expose the local container name of this transfer, the remote source (in case of download: the URL, in
      case of import/export a string describing the file descriptor passed in), and the type of operation
      (see the Manager's <function>ListTransfer()</function> call above for an explanation of the possible
      values).</para>

      <para>The <varname>Verify</varname> property exposes the selected verification setting, and is only
      defined for download operations (see above).</para>

      <para>The <varname>Progress</varname> property exposes the current progress of the transfer, as a value
      between 0.0 and 1.0. To show a progress bar on screen it recommend to query this value in regular
      intervals, for example every 500 ms or so.</para>
    </refsect2>
  </refsect1>

  <refsect1>
    <title>Versioning</title>

    <para>These D-Bus interfaces follow <ulink url="http://0pointer.de/blog/projects/versioning-dbus.html">
    the usual interface versioning guidelines</ulink>.</para>
  </refsect1>
</refentry>