path: root/man/systemd-nspawn.xml

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

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

                <authorgroup>
                        <author>
                                <contrib>Developer</contrib>
                                <firstname>Lennart</firstname>
                                <surname>Poettering</surname>
                                <email>lennart@poettering.net</email>
                        </author>
                </authorgroup>
        </refentryinfo>

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

        <refnamediv>
                <refname>systemd-nspawn</refname>
                <refpurpose>Spawn a namespace container for debugging, testing and building</refpurpose>
        </refnamediv>

        <refsynopsisdiv>
                <cmdsynopsis>
                        <command>systemd-nspawn</command>
                        <arg choice="opt" rep="repeat">OPTIONS</arg>
                        <arg choice="opt"><replaceable>COMMAND</replaceable>
                        <arg choice="opt" rep="repeat">ARGS</arg>
                        </arg>
                </cmdsynopsis>
                <cmdsynopsis>
                        <command>systemd-nspawn</command>
                        <arg choice="plain">-b</arg>
                        <arg choice="opt" rep="repeat">OPTIONS</arg>
                        <arg choice="opt" rep="repeat">ARGS</arg>
                </cmdsynopsis>
        </refsynopsisdiv>

        <refsect1>
                <title>Description</title>

                <para><command>systemd-nspawn</command> may be used to
                run a command or OS in a light-weight namespace
                container. In many ways it is similar to
                <citerefentry project='man-pages'><refentrytitle>chroot</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
                but more powerful since it fully virtualizes the file
                system hierarchy, as well as the process tree, the
                various IPC subsystems and the host and domain
                name.</para>

                <para><command>systemd-nspawn</command> limits access
                to various kernel interfaces in the container to
                read-only, such as <filename>/sys</filename>,
                <filename>/proc/sys</filename> or
                <filename>/sys/fs/selinux</filename>. Network
                interfaces and the system clock may not be changed
                from within the container. Device nodes may not be
                created. The host system cannot be rebooted and kernel
                modules may not be loaded from within the
                container.</para>

                <para>Note that even though these security precautions
                are taken <command>systemd-nspawn</command> is not
                suitable for secure container setups. Many of the
                security features may be circumvented and are hence
                primarily useful to avoid accidental changes to the
                host system from the container. The intended use of
                this program is debugging and testing as well as
                building of packages, distributions and software
                involved with boot and systems management.</para>

                <para>In contrast to
                <citerefentry project='man-pages'><refentrytitle>chroot</refentrytitle><manvolnum>1</manvolnum></citerefentry> <command>systemd-nspawn</command>
                may be used to boot full Linux-based operating systems
                in a container.</para>

                <para>Use a tool like
                <citerefentry project='die-net'><refentrytitle>yum</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
                <citerefentry project='die-net'><refentrytitle>debootstrap</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
                or
                <citerefentry project='archlinux'><refentrytitle>pacman</refentrytitle><manvolnum>8</manvolnum></citerefentry>
                to set up an OS directory tree suitable as file system
                hierarchy for <command>systemd-nspawn</command>
                containers.</para>

                <para>Note that <command>systemd-nspawn</command> will
                mount file systems private to the container to
                <filename>/dev</filename>,
                <filename>/run</filename> and similar. These will
                not be visible outside of the container, and their
                contents will be lost when the container exits.</para>

                <para>Note that running two
                <command>systemd-nspawn</command> containers from the
                same directory tree will not make processes in them
                see each other. The PID namespace separation of the
                two containers is complete and the containers will
                share very few runtime objects except for the
                underlying file system. Use
                <citerefentry><refentrytitle>machinectl</refentrytitle><manvolnum>1</manvolnum></citerefentry>'s
                <command>login</command> command to request an
                additional login prompt in a running container.</para>

                <para><command>systemd-nspawn</command> implements the
                <ulink
                url="http://www.freedesktop.org/wiki/Software/systemd/ContainerInterface">Container
                Interface</ulink> specification.</para>

                <para>As a safety check
                <command>systemd-nspawn</command> will verify the
                existence of <filename>/usr/lib/os-release</filename>
                or <filename>/etc/os-release</filename> in the
                container tree before starting the container (see
                <citerefentry><refentrytitle>os-release</refentrytitle><manvolnum>5</manvolnum></citerefentry>). It
                might be necessary to add this file to the container
                tree manually if the OS of the container is too old to
                contain this file out-of-the-box.</para>
        </refsect1>

        <refsect1>
                <title>Options</title>

                <para>If option <option>-b</option> is specified, the
                arguments are used as arguments for the init
                binary. Otherwise, <replaceable>COMMAND</replaceable>
                specifies the program to launch in the container, and
                the remaining arguments are used as arguments for this
                program. If <option>-b</option> is not used and no
                arguments are specifed, a shell is launched in the
                container.</para>

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

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

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

                                <para>If neither
                                <option>--directory=</option>, nor
                                <option>--image=</option> is specified
                                the directory is determined as
                                <filename>/var/lib/container/</filename>
                                suffixed by the machine name as
                                specified with
                                <option>--machine=</option>. If
                                neither <option>--directory=</option>,
                                <option>--image=</option>, nor
                                <option>--machine=</option> are
                                specified, the current directory will
                                be used. May not be specified together
                                with
                                <option>--image=</option>.</para></listitem>
                        </varlistentry>

                        <varlistentry>
                                <term><option>--template=</option></term>

                                <listitem><para>Directory or
                                <literal>btrfs</literal> subvolume to
                                use as template for the container's
                                root directory. If this is specified
                                and the container's root directory (as
                                configured by
                                <option>--directory=</option>) does
                                not yet exist it is created as
                                <literal>btrfs</literal> subvolume and
                                populated from this template
                                tree. Ideally, the specified template
                                path refers to the root of a
                                <literal>btrfs</literal> subvolume, in
                                which case a simple copy-on-write
                                snapshot is taken, and populating the
                                root directory is instant. If the
                                specified template path does not refer
                                to the root of a
                                <literal>btrfs</literal> subvolume (or
                                not even to a <literal>btrfs</literal>
                                file system at all), the tree is
                                copied, which can be substantially
                                more time-consuming. Note that if this
                                option is used the container's root
                                directory (in contrast to the template
                                directory!) must be located on a
                                <literal>btrfs</literal> file system,
                                so that the <literal>btrfs</literal>
                                subvolume may be created. May not be
                                specified together with
                                <option>--image=</option> or
                                <option>--ephemeral</option>.</para></listitem>
                        </varlistentry>

                        <varlistentry>
                                <term><option>-x</option></term>
                                <term><option>--ephemeral</option></term>

                                <listitem><para>If specified, the
                                container is run with a temporary
                                <literal>btrfs</literal> snapshot of
                                its root directory (as configured with
                                <option>--directory=</option>), that
                                is removed immediately when the
                                container terminates. This option is
                                only supported if the root file system
                                is <literal>btrfs</literal>. May not
                                be specified together with
                                <option>--image=</option> or
                                <option>--template=</option>.</para></listitem>
                        </varlistentry>

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

                                <listitem><para>Disk image to mount
                                the root directory for the container
                                from. Takes a path to a regular file
                                or to a block device node. The file or
                                block device must contain a GUID
                                Partition Table with a root partition
                                which is mounted as the root directory
                                of the container. Optionally, it may
                                contain a home and/or a server data
                                partition which are mounted to the
                                appropriate places in the
                                container. All these partitions must
                                be identified by the partition types
                                defined by the <ulink
                                url="http://www.freedesktop.org/wiki/Specifications/DiscoverablePartitionsSpec/">Discoverable
                                Partitions Specification</ulink>. Any
                                other partitions, such as foreign
                                partitions, swap partitions or EFI
                                system partitions are not mounted. May
                                not be specified together with
                                <option>--directory=</option>,
                                <option>--template=</option> or
                                <option>--ephemeral</option>.</para></listitem>
                        </varlistentry>

                        <varlistentry>
                                <term><option>-b</option></term>
                                <term><option>--boot</option></term>

                                <listitem><para>Automatically search
                                for an init binary and invoke it
                                instead of a shell or a user supplied
                                program. If this option is used,
                                arguments specified on the command
                                line are used as arguments for the
                                init binary. This option may not be
                                combined with
                                <option>--share-system</option>.
                                </para></listitem>
                        </varlistentry>

                        <varlistentry>
                                <term><option>-u</option></term>
                                <term><option>--user=</option></term>

                                <listitem><para>After transitioning
                                into the container, change to the
                                specified user-defined in the
                                container's user database. Like all
                                other systemd-nspawn features, this is
                                not a security feature and provides
                                protection against accidental
                                destructive operations
                                only.</para></listitem>
                        </varlistentry>

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

                                <listitem><para>Sets the machine name
                                for this container. This name may be
                                used to identify this container during
                                its runtime (for example in tools like
                                <citerefentry><refentrytitle>machinectl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
                                and similar), and is used to
                                initialize the container's hostname
                                (which the container can choose to
                                override, however). If not specified,
                                the last component of the root
                                directory path of the container is
                                used, possibly suffixed with a random
                                identifier in case
                                <option>--ephemeral</option> mode is
                                selected. If the root directory
                                selected is the host's root directory
                                the host's hostname is used as default
                                instead.</para></listitem>
                        </varlistentry>

                        <varlistentry>
                                <term><option>--uuid=</option></term>

                                <listitem><para>Set the specified UUID
                                for the container. The init system
                                will initialize
                                <filename>/etc/machine-id</filename>
                                from this if this file is not set yet.
                                </para></listitem>
                        </varlistentry>

                        <varlistentry>
                                <term><option>--slice=</option></term>

                                <listitem><para>Make the container
                                part of the specified slice, instead
                                of the default
                                <filename>machine.slice</filename>.</para>
                                </listitem>
                        </varlistentry>

                        <varlistentry>
                                <term><option>--private-network</option></term>

                                <listitem><para>Disconnect networking
                                of the container from the host. This
                                makes all network interfaces
                                unavailable in the container, with the
                                exception of the loopback device and
                                those specified with
                                <option>--network-interface=</option>
                                and configured with
                                <option>--network-veth</option>. If
                                this option is specified, the
                                CAP_NET_ADMIN capability will be added
                                to the set of capabilities the
                                container retains. The latter may be
                                disabled by using
                                <option>--drop-capability=</option>.</para></listitem>
                        </varlistentry>

                        <varlistentry>
                                <term><option>--network-interface=</option></term>

                                <listitem><para>Assign the specified
                                network interface to the
                                container. This will remove the
                                specified interface from the calling
                                namespace and place it in the
                                container. When the container
                                terminates, it is moved back to the
                                host namespace. Note that
                                <option>--network-interface=</option>
                                implies
                                <option>--private-network</option>. This
                                option may be used more than once to
                                add multiple network interfaces to the
                                container.</para></listitem>
                        </varlistentry>

                        <varlistentry>
                                <term><option>--network-macvlan=</option></term>

                                <listitem><para>Create a
                                <literal>macvlan</literal> interface
                                of the specified Ethernet network
                                interface and add it to the
                                container. A
                                <literal>macvlan</literal> interface
                                is a virtual interface that adds a
                                second MAC address to an existing
                                physical Ethernet link. The interface
                                in the container will be named after
                                the interface on the host, prefixed
                                with <literal>mv-</literal>. Note that
                                <option>--network-macvlan=</option>
                                implies
                                <option>--private-network</option>. This
                                option may be used more than once to
                                add multiple network interfaces to the
                                container.</para></listitem>
                        </varlistentry>

                        <varlistentry>
                                <term><option>--network-veth</option></term>

                                <listitem><para>Create a virtual
                                Ethernet link
                                (<literal>veth</literal>) between host
                                and container. The host side of the
                                Ethernet link will be available as a
                                network interface named after the
                                container's name (as specified with
                                <option>--machine=</option>), prefixed
                                with <literal>ve-</literal>. The
                                container side of the Ethernet
                                link will be named
                                <literal>host0</literal>. Note that
                                <option>--network-veth</option>
                                implies
                                <option>--private-network</option>.</para></listitem>
                        </varlistentry>

                        <varlistentry>
                                <term><option>--network-bridge=</option></term>

                                <listitem><para>Adds the host side of
                                the Ethernet link created with
                                <option>--network-veth</option> to the
                                specified bridge. Note that
                                <option>--network-bridge=</option>
                                implies
                                <option>--network-veth</option>. If
                                this option is used, the host side of
                                the Ethernet link will use the
                                <literal>vb-</literal> prefix instead
                                of <literal>ve-</literal>.</para></listitem>
                        </varlistentry>

                        <varlistentry>
                                <term><option>-Z</option></term>
                                <term><option>--selinux-context=</option></term>

                                <listitem><para>Sets the SELinux
                                security context to be used to label
                                processes in the container.</para>
                                </listitem>
                        </varlistentry>

                        <varlistentry>
                                <term><option>-L</option></term>
                                <term><option>--selinux-apifs-context=</option></term>

                                <listitem><para>Sets the SELinux security
                                context to be used to label files in
                                the virtual API file systems in the
                                container.</para>
                                </listitem>
                        </varlistentry>

                        <varlistentry>
                                <term><option>--capability=</option></term>

                                <listitem><para>List one or more
                                additional capabilities to grant the
                                container. Takes a comma-separated
                                list of capability names, see
                                <citerefentry project='man-pages'><refentrytitle>capabilities</refentrytitle><manvolnum>7</manvolnum></citerefentry>
                                for more information. Note that the
                                following capabilities will be granted
                                in any way: CAP_CHOWN,
                                CAP_DAC_OVERRIDE, CAP_DAC_READ_SEARCH,
                                CAP_FOWNER, CAP_FSETID, CAP_IPC_OWNER,
                                CAP_KILL, CAP_LEASE,
                                CAP_LINUX_IMMUTABLE,
                                CAP_NET_BIND_SERVICE,
                                CAP_NET_BROADCAST, CAP_NET_RAW,
                                CAP_SETGID, CAP_SETFCAP, CAP_SETPCAP,
                                CAP_SETUID, CAP_SYS_ADMIN,
                                CAP_SYS_CHROOT, CAP_SYS_NICE,
                                CAP_SYS_PTRACE, CAP_SYS_TTY_CONFIG,
                                CAP_SYS_RESOURCE, CAP_SYS_BOOT,
                                CAP_AUDIT_WRITE,
                                CAP_AUDIT_CONTROL. Also CAP_NET_ADMIN
                                is retained if
                                <option>--private-network</option> is
                                specified. If the special value
                                <literal>all</literal> is passed, all
                                capabilities are
                                retained.</para></listitem>
                        </varlistentry>

                        <varlistentry>
                                <term><option>--drop-capability=</option></term>

                                <listitem><para>Specify one or more
                                additional capabilities to drop for
                                the container. This allows running the
                                container with fewer capabilities than
                                the default (see above).</para></listitem>
                        </varlistentry>

                        <varlistentry>
                                <term><option>--link-journal=</option></term>

                                <listitem><para>Control whether the
                                container's journal shall be made
                                visible to the host system. If enabled,
                                allows viewing the container's journal
                                files from the host (but not vice
                                versa). Takes one of
                                <literal>no</literal>,
                                <literal>host</literal>,
                                <literal>try-host</literal>,
                                <literal>guest</literal>,
                                <literal>try-guest</literal>,
                                <literal>auto</literal>. If
                                <literal>no</literal>, the journal is
                                not linked. If <literal>host</literal>,
                                the journal files are stored on the
                                host file system (beneath
                                <filename>/var/log/journal/<replaceable>machine-id</replaceable></filename>)
                                and the subdirectory is bind-mounted
                                into the container at the same
                                location. If <literal>guest</literal>,
                                the journal files are stored on the
                                guest file system (beneath
                                <filename>/var/log/journal/<replaceable>machine-id</replaceable></filename>)
                                and the subdirectory is symlinked into the host
                                at the same location. <literal>try-host</literal>
                                and <literal>try-guest</literal> do the same
                                but do not fail if the host does not have
                                persistant journalling enabled.
                                If <literal>auto</literal> (the default),
                                and the right subdirectory of
                                <filename>/var/log/journal</filename>
                                exists, it will be bind mounted
                                into the container. If the
                                subdirectory does not exist, no
                                linking is performed. Effectively,
                                booting a container once with
                                <literal>guest</literal> or
                                <literal>host</literal> will link the
                                journal persistently if further on
                                the default of <literal>auto</literal>
                                is used.</para></listitem>
                        </varlistentry>

                        <varlistentry>
                                <term><option>-j</option></term>

                                <listitem><para>Equivalent to
                                <option>--link-journal=try-guest</option>.</para></listitem>
                        </varlistentry>

                        <varlistentry>
                                <term><option>--read-only</option></term>

                                <listitem><para>Mount the root file
                                system read-only for the
                                container.</para></listitem>
                        </varlistentry>

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

                                <listitem><para>Bind mount a file or
                                directory from the host into the
                                container. Either takes a path
                                argument -- in which case the
                                specified path will be mounted from
                                the host to the same path in the
                                container --, 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 container. The
                                <option>--bind-ro=</option> option
                                creates read-only bind
                                mounts.</para></listitem>
                        </varlistentry>

                        <varlistentry>
                                <term><option>--tmpfs=</option></term>

                                <listitem><para>Mount a tmpfs file
                                system into the container. Takes a
                                single absolute path argument that
                                specifies where to mount the tmpfs
                                instance to (in which case the
                                directory access mode will be chosen
                                as 0755, owned by root/root), or
                                optionally a colon-separated pair of
                                path and mount option string, that is
                                used for mounting (in which case the
                                kernel default for access mode and
                                owner will be chosen, unless otherwise
                                specified). This option is
                                particularly useful for mounting
                                directories such as
                                <filename>/var</filename> as tmpfs, to
                                allow state-less systems, in
                                particular when combined with
                                <option>--read-only</option>.</para></listitem>
                        </varlistentry>

                        <varlistentry>
                                <term><option>--setenv=</option></term>

                                <listitem><para>Specifies an
                                environment variable assignment to
                                pass to the init process in the
                                container, in the format
                                <literal>NAME=VALUE</literal>. This
                                may be used to override the default
                                variables or to set additional
                                variables. This parameter may be used
                                more than once.</para></listitem>
                        </varlistentry>

                        <varlistentry>
                                <term><option>--share-system</option></term>

                                <listitem><para>Allows the container
                                to share certain system facilities
                                with the host. More specifically, this
                                turns off PID namespacing, UTS
                                namespacing and IPC namespacing, and
                                thus allows the guest to see and
                                interact more easily with processes
                                outside of the container. Note that
                                using this option makes it impossible
                                to start up a full Operating System in
                                the container, as an init system
                                cannot operate in this mode. It is
                                only useful to run specific programs
                                or applications this way, without
                                involving an init system in the
                                container. This option implies
                                <option>--register=no</option>. This
                                option may not be combined with
                                <option>--boot</option>.</para></listitem>
                        </varlistentry>

                        <varlistentry>
                                <term><option>--register=</option></term>

                                <listitem><para>Controls whether the
                                container is registered with
                                <citerefentry><refentrytitle>systemd-machined</refentrytitle><manvolnum>8</manvolnum></citerefentry>. Takes
                                a boolean argument, defaults to
                                <literal>yes</literal>. This option
                                should be enabled when the container
                                runs a full Operating System (more
                                specifically: an init system), and is
                                useful to ensure that the container is
                                accessible via
                                <citerefentry><refentrytitle>machinectl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
                                and shown by tools such as
                                <citerefentry project='man-pages'><refentrytitle>ps</refentrytitle><manvolnum>1</manvolnum></citerefentry>. If
                                the container does not run an init
                                system, it is recommended to set this
                                option to <literal>no</literal>. Note
                                that <option>--share-system</option>
                                implies
                                <option>--register=no</option>.
                                </para></listitem>
                        </varlistentry>

                        <varlistentry>
                                <term><option>--keep-unit</option></term>

                                <listitem><para>Instead of creating a
                                transient scope unit to run the
                                container in, simply register the
                                service or scope unit
                                <command>systemd-nspawn</command> has
                                been invoked in with
                                <citerefentry><refentrytitle>systemd-machined</refentrytitle><manvolnum>8</manvolnum></citerefentry>. This
                                has no effect if
                                <option>--register=no</option> is
                                used. This switch should be used if
                                <command>systemd-nspawn</command> is
                                invoked from within a service unit,
                                and the service unit's sole purpose
                                is to run a single
                                <command>systemd-nspawn</command>
                                container. This option is not
                                available if run from a user
                                session.</para></listitem>
                        </varlistentry>

                        <varlistentry>
                                <term><option>--personality=</option></term>

                                <listitem><para>Control the
                                architecture ("personality") reported
                                by
                                <citerefentry><refentrytitle>uname</refentrytitle><manvolnum>2</manvolnum></citerefentry>
                                in the container. Currently, only
                                <literal>x86</literal> and
                                <literal>x86-64</literal> are
                                supported. This is useful when running
                                a 32-bit container on a 64-bit
                                host. If this setting is not used,
                                the personality reported in the
                                container is the same as the one
                                reported on the
                                host.</para></listitem>
                        </varlistentry>

                        <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 nspawn will be the console output
                                of the container OS itself.</para></listitem>
                        </varlistentry>

                        <varlistentry>
                                <term><option>--volatile</option><replaceable>=MODE</replaceable></term>

                                <listitem><para>Boots the container in
                                volatile mode. When no mode parameter
                                is passed or when mode is specified as
                                <literal>yes</literal> full volatile
                                mode is enabled. This means the root
                                directory is mounted as mostly
                                unpopulated <literal>tmpfs</literal>
                                instance, and
                                <filename>/usr</filename> from the OS
                                tree is mounted into it, read-only
                                (the system thus starts up with
                                read-only OS resources, but pristine
                                state and configuration, any changes
                                to the either are lost on
                                shutdown). When the mode parameter is
                                specified as <literal>state</literal>
                                the OS tree is mounted read-only, but
                                <filename>/var</filename> is mounted
                                as <literal>tmpfs</literal> instance
                                into it (the system thus starts up
                                with read-only OS resources and
                                configuration, but pristine state, any
                                changes to the latter are lost on
                                shutdown). When the mode parameter is
                                specified as <literal>no</literal>
                                (the default) the whole OS tree is
                                made available writable.</para>

                                <para>Note that setting this to
                                <literal>yes</literal> or
                                <literal>state</literal> will only
                                work correctly with operating systems
                                in the container that can boot up with
                                only <filename>/usr</filename>
                                mounted, and are able to populate
                                <filename>/var</filename>
                                automatically, as
                                needed.</para></listitem>
                        </varlistentry>

                        <xi:include href="standard-options.xml" xpointer="help" />
                        <xi:include href="standard-options.xml" xpointer="version" />
                </variablelist>

        </refsect1>

        <refsect1>
                <title>Examples</title>
                <example>
                        <title>Boot a minimal Fedora distribution in a container</title>

                        <programlisting># yum -y --releasever=19 --nogpg --installroot=/srv/mycontainer --disablerepo='*' --enablerepo=fedora install systemd passwd yum fedora-release vim-minimal
# systemd-nspawn -bD /srv/mycontainer</programlisting>

                        <para>This installs a minimal Fedora distribution into
                        the directory <filename noindex='true'>/srv/mycontainer/</filename> and
                        then boots an OS in a namespace container in
                        it.</para>
                </example>

                <example>
                        <title>Spawn a shell in a container of a minimal Debian unstable distribution</title>

                        <programlisting># debootstrap --arch=amd64 unstable ~/debian-tree/
# systemd-nspawn -D ~/debian-tree/</programlisting>

                        <para>This installs a minimal Debian unstable
                        distribution into the directory
                        <filename>~/debian-tree/</filename> and then spawns a
                        shell in a namespace container in it.</para>
                </example>

                <example>
                        <title>Boot a minimal Arch Linux distribution in a container</title>

                        <programlisting># pacstrap -c -d ~/arch-tree/ base
# systemd-nspawn -bD ~/arch-tree/</programlisting>

                        <para>This installs a mimimal Arch Linux distribution into
                        the directory <filename>~/arch-tree/</filename> and then
                        boots an OS in a namespace container in it.</para>
                </example>

                <example>
                        <title>Enable Arch Linux container on boot</title>

                        <programlisting># mv ~/arch-tree /var/lib/container/arch
# systemctl enable systemd-nspawn@arch.service
# systemctl start systemd-nspawn@arch.service</programlisting>

                        <para>This makes the Arch Linux container part of the
                        <filename>multi-user.target</filename> on the host.
                        </para>
                </example>

                <example>
                        <title>Boot into an ephemeral <literal>btrfs</literal> snapshot of the host system</title>

                        <programlisting># systemd-nspawn -D / -xb</programlisting>

                        <para>This runs a copy of the host system in a
                        <literal>btrfs</literal> snapshot which is
                        removed immediately when the container
                        exits. All file system changes made during
                        runtime will be lost on shutdown,
                        hence.</para>
                </example>

                <example>
                        <title>Run a container with SELinux sandbox security contexts</title>

                        <programlisting># chcon system_u:object_r:svirt_sandbox_file_t:s0:c0,c1 -R /srv/container
# systemd-nspawn -L system_u:object_r:svirt_sandbox_file_t:s0:c0,c1 -Z system_u:system_r:svirt_lxc_net_t:s0:c0,c1 -D /srv/container /bin/sh</programlisting>
                </example>
        </refsect1>

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

                <para>The exit code of the program executed in the
                container is returned.</para>
        </refsect1>

        <refsect1>
                <title>See Also</title>
                <para>
                        <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
                        <citerefentry project='man-pages'><refentrytitle>chroot</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
                        <citerefentry project='die-net'><refentrytitle>yum</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
                        <citerefentry project='die-net'><refentrytitle>debootstrap</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
                        <citerefentry project='archlinux'><refentrytitle>pacman</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
                        <citerefentry><refentrytitle>systemd.slice</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
                        <citerefentry><refentrytitle>machinectl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
                        <citerefentry><refentrytitle>btrfs</refentrytitle><manvolnum>8</manvolnum></citerefentry>
                </para>
        </refsect1>

</refentry>