path: root/man/systemd-vmspawn.xml

<?xml version='1.0'?>
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
  "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd">
<!-- SPDX-License-Identifier: LGPL-2.1-or-later -->

<refentry id="systemd-vmspawn" conditional="ENABLE_VMSPAWN"
    xmlns:xi="http://www.w3.org/2001/XInclude">

  <refentryinfo>
    <title>systemd-vmspawn</title>
    <productname>systemd</productname>
  </refentryinfo>

  <refmeta>
    <refentrytitle>systemd-vmspawn</refentrytitle>
    <manvolnum>1</manvolnum>
  </refmeta>

  <refnamediv>
    <refname>systemd-vmspawn</refname>
    <refpurpose>Spawn an OS in a virtual machine.</refpurpose>
  </refnamediv>

  <refsynopsisdiv>
    <cmdsynopsis>
      <command>systemd-vmspawn</command>
      <arg choice="opt" rep="repeat">OPTIONS</arg>
      <arg choice="opt" rep="repeat">ARGS</arg>
    </cmdsynopsis>
  </refsynopsisdiv>

  <refsect1>
    <title>Description</title>
    <para><command>systemd-vmspawn</command> may be used to start a virtual machine from an OS image. In many ways it is similar to <citerefentry
    project='man-pages'><refentrytitle>systemd-nspawn</refentrytitle><manvolnum>1</manvolnum></citerefentry>, but it
    launches a full virtual machine instead of using namespaces.</para>

    <para>File descriptors for <filename>/dev/kvm</filename> and <filename>/dev/vhost-vsock</filename> can be
    passed to <command>systemd-vmspawn</command> via systemd's native socket passing interface (see
    <citerefentry><refentrytitle>sd_listen_fds</refentrytitle><manvolnum>3</manvolnum></citerefentry> for
    details about the precise protocol used and the order in which the file descriptors are passed), these
    fds must be passed with the names <literal>kvm</literal> and <literal>vhost-vsock</literal> respectively.</para>

    <para>Note: on Ubuntu/Debian derivatives systemd-vmspawn requires the user to be in the <literal>kvm</literal> group to use the VSock options.</para>
  </refsect1>

  <refsect1>
    <title>Options</title>

    <para>The excess arguments are passed as extra kernel command line arguments using SMBIOS.</para>

    <para>The following options are understood:</para>

    <variablelist>

      <varlistentry>
        <term><option>-q</option></term>
        <term><option>--quiet</option></term>

        <listitem><para>Turns off any status output by the tool
        itself. When this switch is used, the only output from vmspawn
        will be the console output of the Virtual Machine OS itself.</para>

        <xi:include href="version-info.xml" xpointer="v256"/></listitem>
      </varlistentry>

    </variablelist>

    <refsect2>
      <title>Image Options</title>

      <varlistentry>
        <term><option>-D</option></term>
        <term><option>--directory=</option></term>

        <listitem><para>Directory to use as file system root for the virtual machine.</para>

        <para>One of either <option>--directory=</option> or <option>--image=</option> must be specified.</para>
        <para>Note: If mounting a non-root owned directory you may require <option>--private-users=</option>
              to map into the user's subuid namespace.</para>

        <xi:include href="version-info.xml" xpointer="v256"/>
        </listitem>
      </varlistentry>

      <variablelist>
        <varlistentry>
          <term><option>-i</option></term>
          <term><option>--image=</option></term>

          <listitem><para>Root file system disk image (or device node) for the virtual machine.</para>

          <xi:include href="version-info.xml" xpointer="v255"/>
          </listitem>
        </varlistentry>
      </variablelist>
    </refsect2>

    <refsect2>
      <title>Host Configuration</title>

      <variablelist>
        <varlistentry>
          <term><option>--qemu-smp=</option><replaceable>SMP</replaceable></term>

          <listitem><para>Configures the number of CPUs to start the virtual machine with.
          Defaults to 1.</para>

          <xi:include href="version-info.xml" xpointer="v255"/>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term><option>--qemu-mem=</option><replaceable>MEM</replaceable></term>

          <listitem><para>Configures the amount of memory to start the virtual machine with.
          Defaults to 2G.</para>

          <xi:include href="version-info.xml" xpointer="v255"/>
          </listitem>
        </varlistentry>

      <varlistentry>
        <term><option>--qemu-kvm=</option><replaceable>BOOL</replaceable></term>

        <listitem><para>Configures whether to use KVM. If the option is not specified KVM support will be
        detected automatically. If true, KVM is always used, and if false, KVM is never used.</para>

        <xi:include href="version-info.xml" xpointer="v255"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--qemu-vsock=</option><replaceable>BOOL</replaceable></term>

        <listitem>
          <para>Configure whether to use VSock networking.</para>
          <para>If the option is not specified VSock support will be detected automatically.
          If yes is specified VSocks are always used, and vice versa if no is set VSocks are never used.</para>
          <xi:include href="version-info.xml" xpointer="v255"/>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--vsock-cid=</option><replaceable>CID</replaceable></term>

        <listitem>
          <para>Configure vmspawn to use a specific CID for the guest.</para>
          <para>If the option is not specified or an empty argument is supplied the guest will be assigned a random CID.</para>
          <para>Valid CIDs are in the range <constant>3</constant> to <constant>4294967294</constant> (<constant>0xFFFF_FFFE</constant>).
          CIDs outside of this range are reserved.</para>
          <xi:include href="version-info.xml" xpointer="v255"/>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--tpm=</option><replaceable>BOOL</replaceable></term>

        <listitem>
          <para>Configure whether to use qemu with a virtual TPM or not.</para>
          <para>If the option is not specified vmspawn will detect the presence of <citerefentry project='man-pages'>
          <refentrytitle>swtpm</refentrytitle><manvolnum>8</manvolnum></citerefentry> and use it if available.
          If yes is specified <citerefentry project='man-pages'><refentrytitle>swtpm</refentrytitle><manvolnum>8</manvolnum></citerefentry>
          is always used, and vice versa if no is set <citerefentry project='man-pages'><refentrytitle>swtpm</refentrytitle>
          <manvolnum>8</manvolnum></citerefentry> is never used.</para>
          <para>Note: the virtual TPM used may change in future.</para>
          <xi:include href="version-info.xml" xpointer="v256"/>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--linux=</option><replaceable>PATH</replaceable></term>

        <listitem>
          <para>Set the linux kernel image to use for direct kernel boot.</para>
          <para>If no kernel was installed into the image then the image will fail to boot.</para>
          <xi:include href="version-info.xml" xpointer="v256"/>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--initrd=</option><replaceable>PATH</replaceable></term>

        <listitem>
          <para>Set the initrd to use for direct kernel boot.</para>
          <para>If the linux kernel supplied is a UKI then this argument is not required.</para>
          <para>If the option is specified multiple times vmspawn will merge the initrds together.</para>
          <para>If no initrd was installed into the image then the image will fail to boot.</para>
          <xi:include href="version-info.xml" xpointer="v256"/>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--qemu-gui</option></term>

        <listitem><para>Start QEMU in graphical mode.</para>

        <xi:include href="version-info.xml" xpointer="v255"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>-n</option></term>
        <term><option>--network-tap</option></term>

        <listitem>
          <para>Create a TAP device to network with the virtual machine.</para>
          <para>
            Note: root privileges are required to use TAP networking.
            Additionally requires a correctly setup
            <citerefentry><refentrytitle>systemd-networkd</refentrytitle><manvolnum>8</manvolnum></citerefentry>
            to be running on the host to ensure the host interface is correctly configured.
            The relevant <literal>.network</literal> file can be found at <filename>/usr/lib/systemd/network/80-vm-vt.network</filename>.
          </para>
          <xi:include href="version-info.xml" xpointer="v255"/>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--network-user-mode</option></term>

        <listitem><para>Use user mode networking with QEMU.</para>

        <xi:include href="version-info.xml" xpointer="v255"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--firmware=</option><replaceable>PATH</replaceable></term>

        <listitem><para>Takes an absolute path, or a relative path beginning with
        <filename>./</filename>. Specifies a JSON firmware definition file, which allows selecting the
        firmware to boot in the VM. If not specified a suitable firmware is automatically discovered. If the
        special string <literal>list</literal> is specified lists all discovered firmwares.</para>

        <xi:include href="version-info.xml" xpointer="v256"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--secure-boot=</option><replaceable>BOOL</replaceable></term>

        <listitem><para>Configure whether to search for firmware which supports Secure Boot.</para>
        <para>If the option is not specified the first firmware which is detected will be used.
        If the option is set to yes then the first firmware with Secure Boot support will be selected.
        If no is specified then the first firmware without Secure Boot will be selected.</para>

        <xi:include href="version-info.xml" xpointer="v255"/></listitem>
      </varlistentry>
      </variablelist>
    </refsect2>

    <refsect2>
      <title>System Identity Options</title>

      <variablelist>
        <varlistentry>
          <term><option>-M</option></term>
          <term><option>--machine=</option></term>

          <listitem><para>Sets the machine name for this virtual machine. This
          name may be used to identify this virtual machine during its runtime
          (for example in tools like
          <citerefentry><refentrytitle>machinectl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
          and similar).</para>
          <xi:include href="version-info.xml" xpointer="v255"/>
          </listitem>
        </varlistentry>
      </variablelist>
    </refsect2>

    <refsect2>
      <title>User Namespacing Options</title>

      <variablelist>
        <varlistentry>
          <term><option>--private-users=</option><replaceable>UID_SHIFT[:UID_RANGE]</replaceable></term>

          <listitem><para>Controls user namespacing under <option>--directory=</option>.
          If enabled, <citerefentry project='man-pages'><refentrytitle>virtiofsd</refentrytitle><manvolnum>1</manvolnum></citerefentry>
          is instructed to map user and group ids (UIDs and GIDs). This involves mapping the private UIDs/GIDs used in the virtual machine
          (starting with the virtual machine's root user 0 and up) to a range of UIDs/GIDs on the host that are not used for other
          purposes (usually in the range beyond the host's UID/GID 65536).</para>

          <para>If one or two colon-separated numbers are specified, user namespacing is turned on. <replaceable>UID_SHIFT</replaceable>
          specifies the first host UID/GID to map, <replaceable>UID_RANGE</replaceable> is optional and specifies number of host
          UIDs/GIDs to assign to the virtual machine. If <replaceable>UID_RANGE</replaceable> is omitted, 65536 UIDs/GIDs are assigned.</para>

          <para>When user namespaces are used, the GID range assigned to each virtual machine is always chosen identical to the
          UID range.</para>

          <xi:include href="version-info.xml" xpointer="v256"/></listitem>
        </varlistentry>
      </variablelist>
    </refsect2>

    <refsect2>
      <title>Mount Options</title>

      <variablelist>

        <varlistentry>
          <term><option>--bind=</option><replaceable>PATH</replaceable></term>
          <term><option>--bind-ro=</option><replaceable>PATH</replaceable></term>

          <listitem><para>Mount a directory from the host into the virtual machine. Takes one of: a path
          argument — in which case the specified path will be mounted from the host to the same path in the virtual machine, or
          a colon-separated pair of paths — in which case the first specified path is the source in the host, and the
          second path is the destination in the virtual machine. If the source path is not absolute, it is resolved
          relative to the current working directory. The <option>--bind-ro=</option> option creates read-only bind mounts.
          Backslash escapes are interpreted, so <literal>\:</literal> may be used to embed colons in either path.
          This option may be specified multiple times for creating multiple independent bind mount points.</para>

          <xi:include href="version-info.xml" xpointer="v256"/></listitem>
        </varlistentry>
      </variablelist>
    </refsect2>

    <refsect2>
      <title>Integration Options</title>

      <variablelist>
        <varlistentry>
          <term><option>--forward-journal=</option><replaceable>FILE|DIR</replaceable></term>

          <listitem><para>Forward the virtual machine's journal entries to the host.</para>
          <para><citerefentry><refentrytitle>systemd-journal-remote</refentrytitle><manvolnum>8</manvolnum></citerefentry>
          Is currently used to receive the guest VM's forwarded journal entries. For more information on the semantics
          of supplying a file vs a directory here see <option>-o</option>/<option>--output</option> in
          <citerefentry><refentrytitle>systemd-journal-remote</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>

          <xi:include href="version-info.xml" xpointer="v256"/>
          </listitem>
        </varlistentry>
      </variablelist>
    </refsect2>

    <refsect2>
      <title>Credentials</title>

      <variablelist>
        <varlistentry>
          <term><option>--load-credential=</option><replaceable>ID</replaceable>:<replaceable>PATH</replaceable></term>
          <term><option>--set-credential=</option><replaceable>ID</replaceable>:<replaceable>VALUE</replaceable></term>

          <listitem><para>Pass a credential to the virtual machine. These two options correspond to the
          <varname>LoadCredential=</varname> and <varname>SetCredential=</varname> settings in unit files. See
          <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry> for
          details about these concepts, as well as the syntax of the option's arguments.</para>

          <para>In order to embed binary data into the credential data for <option>--set-credential=</option>,
          use C-style escaping (i.e. <literal>\n</literal> to embed a newline, or <literal>\x00</literal> to
          embed a <constant>NUL</constant> byte). Note that the invoking shell might already apply unescaping
          once, hence this might require double escaping!.</para>

          <xi:include href="version-info.xml" xpointer="v255"/></listitem>
        </varlistentry>
      </variablelist>

    </refsect2><refsect2>
      <title>Other</title>

      <variablelist>
        <xi:include href="standard-options.xml" xpointer="no-pager" />
        <xi:include href="standard-options.xml" xpointer="help" />
        <xi:include href="standard-options.xml" xpointer="version" />
      </variablelist>
    </refsect2>
  </refsect1>

  <xi:include href="common-variables.xml" />

  <refsect1>
    <title>Examples</title>

    <example>
      <title>Run an Arch Linux VM image generated by mkosi</title>

      <programlisting>
$ mkosi -d arch -p systemd -p linux --autologin -o image.raw -f build
$ systemd-vmspawn --image=image.raw
      </programlisting>
    </example>
  </refsect1>

  <refsect1>
    <title>Exit status</title>

    <para>If an error occurred the value errno is propagated to the return code.
    If EXIT_STATUS is supplied by the running image that is returned.
    Otherwise EXIT_SUCCESS is returned.</para>
  </refsect1>

  <refsect1>
    <title>See Also</title>
    <para><simplelist type="inline">
      <member><citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
      <member><citerefentry><refentrytitle>mkosi</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
    </simplelist></para>
  </refsect1>
</refentry>