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+<?xml version='1.0'?> <!--*-nxml-*-->
+<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
+ "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
+
+<!--
+ This file is part of systemd.
+
+ Copyright 2010 Lennart Poettering
+
+ systemd is free software; you can redistribute it and/or modify it
+ under the terms of the GNU Lesser General Public License as published by
+ the Free Software Foundation; either version 2.1 of the License, or
+ (at your option) any later version.
+
+ systemd is distributed in the hope that it will be useful, but
+ WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public License
+ along with systemd; If not, see <http://www.gnu.org/licenses/>.
+-->
+
+<refentry id="systemd-nspawn">
+
+ <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 <arg choice="opt" rep="repeat">OPTIONS</arg> <arg choice="opt">COMMAND</arg> <arg choice="opt" rep="repeat">ARGS</arg></command>
+ </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><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><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>
+ or
+ <citerefentry><refentrytitle>debootstrap</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.</para>
+
+ <para><command>systemd-nspawn</command> implements the
+ <ulink
+ url="http://www.freedesktop.org/wiki/Software/systemd/ContainerInterface">Container
+ Interface</ulink> specification.</para>
+ </refsect1>
+
+ <refsect1>
+ <title>Options</title>
+
+ <para>If no arguments are passed the container is set
+ up and a shell started in it, otherwise the passed
+ command and arguments are executed in it. The
+ following options are understood:</para>
+
+ <variablelist>
+ <varlistentry>
+ <term><option>--help</option></term>
+ <term><option>-h</option></term>
+
+ <listitem><para>Prints a short help
+ text and exits.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><option>--directory=</option></term>
+ <term><option>-D</option></term>
+
+ <listitem><para>Directory to use as
+ file system root for the namespace
+ container. If omitted the current
+ directory will be
+ used.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><option>--boot</option></term>
+ <term><option>-b</option></term>
+
+ <listitem><para>Automatically search
+ for an init binary and invoke it
+ instead of a shell or a user supplied
+ program.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><option>--user=</option></term>
+ <term><option>-u</option></term>
+
+ <listitem><para>Run the command
+ under specified user, create home
+ directory and cd into it. As rest
+ of systemd-nspawn, this is not
+ the security feature and limits
+ against accidental changes only.
+ </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>--controllers=</option></term>
+ <term><option>-C</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>
+ </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>
+ </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>--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><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.</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>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/&lt;machine-id&gt;</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/&lt;machine-id&gt;</filename>)
+ and the subdirectory is symlinked into the host
+ at the same location. 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 doesn't 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=guest</option>.</para></listitem>
+ </varlistentry>
+ </variablelist>
+
+ </refsect1>
+
+ <refsect1>
+ <title>Example 1</title>
+
+ <programlisting># yum --releasever=17 --nogpgcheck --installroot ~/fedora-tree/ install yum passwd vim-minimal rootfiles systemd
+# systemd-nspawn -D ~/fedora-tree /usr/lib/systemd/systemd</programlisting>
+
+ <para>This installs a minimal Fedora distribution into
+ the directory <filename>~/fedora-tree/</filename>
+ and then boots an OS in a namespace container in it,
+ with systemd as init system.</para>
+ </refsect1>
+
+ <refsect1>
+ <title>Example 2</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>
+
+ </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><refentrytitle>chroot</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>yum</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>debootstrap</refentrytitle><manvolnum>8</manvolnum></citerefentry>
+ </para>
+ </refsect1>
+
+</refentry>