involved with boot and systems management.</para>
<para>In contrast to
- <citerefentry><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>
+ <citerefentry><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><refentrytitle>yum</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
- <citerefentry><refentrytitle>debootstrap</refentrytitle><manvolnum>8</manvolnum></citerefentry>
+ <citerefentry><refentrytitle>debootstrap</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
or
<citerefentry><refentrytitle>pacman</refentrytitle><manvolnum>8</manvolnum></citerefentry>
to set up an OS directory tree suitable as file system
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. It is however possible to
- enter an existing container, see
- <link linkend='example-nsenter'>Example 4</link> below.
- </para>
+ 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
<para>As a safety check
<command>systemd-nspawn</command> will verify the
- existance of <filename>/etc/os-release</filename> in
+ existence of <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
contain this file out-of-the-box.</para>
</refsect1>
- <refsect1>
- <title>Incompatibility with Auditing</title>
-
- <para>Note that the kernel auditing subsystem is
- currently broken when used together with
- containers. We hence recommend turning it off entirely
- by booting with <literal>audit=0</literal> on the
- kernel command line, or by turning it off at kernel
- build time. If auditing is enabled in the kernel
- operating systems booted in an nspawn container might
- refuse log-in attempts.</para>
- </refsect1>
-
<refsect1>
<title>Options</title>
and exits.</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>-D</option></term>
<term><option>--directory=</option></term>
<listitem><para>Directory to use as
file system root for the namespace
- container. If omitted the current
+ container. If omitted, the current
directory will be
used.</para></listitem>
</varlistentry>
<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.
+ 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>
host, and is used to initialize the
container's hostname (which the
container can choose to override,
- however). If not specified the last
+ however). If not specified, the last
component of the root directory of the
container is used.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>--uuid=</option></term>
- <listitem><para>Set the specified uuid
+ <listitem><para>Set the specified UUID
for the container. The init system
will initialize
<filename>/etc/machine-id</filename>
</varlistentry>
<varlistentry>
- <term><option>-C</option></term>
- <term><option>--controllers=</option></term>
+ <term><option>--slice=</option></term>
- <listitem><para>Makes the container appear in
- other hierarchies than the name=systemd:/ one.
- Takes a comma-separated list of controllers.
- </para></listitem>
+ <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>Turn off networking in
- the container. This makes all network
- interfaces unavailable in the
- container, with the exception of the
- loopback device.</para></listitem>
+ <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>--read-only</option></term>
-
- <listitem><para>Mount the root file
- system read only for the
+ <term><option>--network-interface=</option></term>
+
+ <listitem><para>Assign the specified
+ network interface to the
+ container. This will move 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-veth</option></term>
+
+ <listitem><para>Create a virtual
+ Ethernet link 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 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>.</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
+ container. Takes a comma-separated
list of capability names, see
<citerefentry><refentrytitle>capabilities</refentrytitle><manvolnum>7</manvolnum></citerefentry>
for more information. Note that the
CAP_SYS_PTRACE, CAP_SYS_TTY_CONFIG,
CAP_SYS_RESOURCE, CAP_SYS_BOOT,
CAP_AUDIT_WRITE,
- CAP_AUDIT_CONTROL.</para></listitem>
+ 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>
<listitem><para>Control whether the
container's journal shall be made
- visible to the host system. If enabled
+ visible to the host system. If enabled,
allows viewing the container's journal
files from the host (but not vice
versa). Takes one of
<filename>/var/log/journal</filename>
exists, it will be bind mounted
into the container. If the
- subdirectory doesn't exist, no
+ subdirectory does not exist, no
linking is performed. Effectively,
booting a container once with
<literal>guest</literal> or
<option>--link-journal=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>
creates read-only bind
mount.</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><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 32bit container on a 64bit
+ 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>
</variablelist>
</refsect1>
boots an OS in a namespace container in it.</para>
</refsect1>
- <refsect1 id='example-nsenter'>
+ <refsect1>
<title>Example 4</title>
- <para>To enter the container, PID of one of the
- processes sharing the new namespaces must be used.
- <command>systemd-nspawn</command> prints the PID
- (as viewed from the outside) of the launched process,
- and it can be used to enter the container.</para>
+ <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>
+ </refsect1>
+
+ <refsect1>
+ <title>Example 5</title>
+
+ <programlisting># btrfs subvolume snapshot / /.tmp
+# systemd-nspawn --private-network -D /.tmp -b</programlisting>
+
+ <para>This runs a copy of the host system in a
+ btrfs snapshot.</para>
+ </refsect1>
+
+ <refsect1>
+ <title>Example 6</title>
- <programlisting># nsenter -m -u -i -n -p -t $PID</programlisting>
+ <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>
- <para><citerefentry><refentrytitle>nsenter</refentrytitle><manvolnum>1</manvolnum></citerefentry>
- is part of
- <ulink url="https://github.com/karelzak/util-linux">util-linux</ulink>.
- Kernel support for entering namespaces was added in
- Linux 3.8.</para>
+ <para>This runs a container with SELinux sandbox security contexts.</para>
</refsect1>
<refsect1>
<para>
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>chroot</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
- <citerefentry><refentrytitle>unshare</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>yum</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
<citerefentry><refentrytitle>debootstrap</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
- <citerefentry><refentrytitle>pacman</refentrytitle><manvolnum>8</manvolnum></citerefentry>
+ <citerefentry><refentrytitle>pacman</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>systemd.slice</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>machinectl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
</para>
</refsect1>
~ianmdlvl / elogind.git / blobdiff