mirror of
https://github.com/systemd/systemd-stable.git
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82adf6af7c
Let's always call the security labels the same way: SMACK: "Smack Label" SELINUX: "SELinux Security Context" And the low-level encapsulation is called "seclabel". Now let's hope we stick to this vocabulary in future, too, and don't mix "label"s and "security contexts" and so on wildly.
522 lines
25 KiB
XML
522 lines
25 KiB
XML
<?xml version='1.0'?> <!--*-nxml-*-->
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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
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"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
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<!--
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This file is part of systemd.
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Copyright 2010 Lennart Poettering
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systemd is free software; you can redistribute it and/or modify it
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under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or
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(at your option) any later version.
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systemd is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with systemd; If not, see <http://www.gnu.org/licenses/>.
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-->
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<refentry id="systemd-nspawn">
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<refentryinfo>
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<title>systemd-nspawn</title>
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<productname>systemd</productname>
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<authorgroup>
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<author>
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<contrib>Developer</contrib>
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<firstname>Lennart</firstname>
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<surname>Poettering</surname>
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<email>lennart@poettering.net</email>
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</author>
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</authorgroup>
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</refentryinfo>
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<refmeta>
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<refentrytitle>systemd-nspawn</refentrytitle>
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<manvolnum>1</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>systemd-nspawn</refname>
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<refpurpose>Spawn a namespace container for debugging, testing and building</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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<cmdsynopsis>
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<command>systemd-nspawn</command>
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<arg choice="opt" rep="repeat">OPTIONS</arg>
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<arg choice="opt"><replaceable>COMMAND</replaceable>
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<arg choice="opt" rep="repeat">ARGS</arg>
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</arg>
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</cmdsynopsis>
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<cmdsynopsis>
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<command>systemd-nspawn</command>
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<arg choice="plain">-b</arg>
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<arg choice="opt" rep="repeat">OPTIONS</arg>
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<arg choice="opt" rep="repeat">ARGS</arg>
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</cmdsynopsis>
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</refsynopsisdiv>
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<refsect1>
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<title>Description</title>
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<para><command>systemd-nspawn</command> may be used to
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run a command or OS in a light-weight namespace
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container. In many ways it is similar to
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<citerefentry><refentrytitle>chroot</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
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but more powerful since it fully virtualizes the file
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system hierarchy, as well as the process tree, the
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various IPC subsystems and the host and domain
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name.</para>
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<para><command>systemd-nspawn</command> limits access
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to various kernel interfaces in the container to
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read-only, such as <filename>/sys</filename>,
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<filename>/proc/sys</filename> or
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<filename>/sys/fs/selinux</filename>. Network
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interfaces and the system clock may not be changed
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from within the container. Device nodes may not be
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created. The host system cannot be rebooted and kernel
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modules may not be loaded from within the
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container.</para>
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<para>Note that even though these security precautions
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are taken <command>systemd-nspawn</command> is not
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suitable for secure container setups. Many of the
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security features may be circumvented and are hence
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primarily useful to avoid accidental changes to the
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host system from the container. The intended use of
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this program is debugging and testing as well as
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building of packages, distributions and software
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involved with boot and systems management.</para>
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<para>In contrast to
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<citerefentry><refentrytitle>chroot</refentrytitle><manvolnum>1</manvolnum></citerefentry> <command>systemd-nspawn</command>
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may be used to boot full Linux-based operating systems
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in a container.</para>
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<para>Use a tool like
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<citerefentry><refentrytitle>yum</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>debootstrap</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
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or
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<citerefentry><refentrytitle>pacman</refentrytitle><manvolnum>8</manvolnum></citerefentry>
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to set up an OS directory tree suitable as file system
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hierarchy for <command>systemd-nspawn</command>
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containers.</para>
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<para>Note that <command>systemd-nspawn</command> will
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mount file systems private to the container to
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<filename>/dev</filename>,
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<filename>/run</filename> and similar. These will
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not be visible outside of the container, and their
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contents will be lost when the container exits.</para>
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<para>Note that running two
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<command>systemd-nspawn</command> containers from the
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same directory tree will not make processes in them
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see each other. The PID namespace separation of the
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two containers is complete and the containers will
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share very few runtime objects except for the
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underlying file system. Use
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<citerefentry><refentrytitle>machinectl</refentrytitle><manvolnum>1</manvolnum></citerefentry>'s
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<command>login</command> command to request an
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additional login prompt in a running container.</para>
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<para><command>systemd-nspawn</command> implements the
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<ulink
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url="http://www.freedesktop.org/wiki/Software/systemd/ContainerInterface">Container
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Interface</ulink> specification.</para>
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<para>As a safety check
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<command>systemd-nspawn</command> will verify the
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existence of <filename>/etc/os-release</filename> in
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the container tree before starting the container (see
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<citerefentry><refentrytitle>os-release</refentrytitle><manvolnum>5</manvolnum></citerefentry>). It
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might be necessary to add this file to the container
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tree manually if the OS of the container is too old to
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contain this file out-of-the-box.</para>
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</refsect1>
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<refsect1>
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<title>Incompatibility with Auditing</title>
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<para>Note that the kernel auditing subsystem is
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currently broken when used together with
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containers. We hence recommend turning it off entirely
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by booting with <literal>audit=0</literal> on the
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kernel command line, or by turning it off at kernel
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build time. If auditing is enabled in the kernel,
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operating systems booted in an nspawn container might
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refuse log-in attempts.</para>
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</refsect1>
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<refsect1>
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<title>Options</title>
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<para>If option <option>-b</option> is specified, the
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arguments are used as arguments for the init
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binary. Otherwise, <replaceable>COMMAND</replaceable>
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specifies the program to launch in the container, and
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the remaining arguments are used as arguments for this
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program. If <option>-b</option> is not used and no
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arguments are specifed, a shell is launched in the
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container.</para>
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<para>The following options are understood:</para>
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<variablelist>
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<varlistentry>
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<term><option>-h</option></term>
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<term><option>--help</option></term>
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<listitem><para>Prints a short help
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text and exits.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><option>--version</option></term>
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<listitem><para>Prints a version string
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and exits.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><option>-D</option></term>
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<term><option>--directory=</option></term>
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<listitem><para>Directory to use as
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file system root for the namespace
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container. If omitted, the current
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directory will be
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used.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><option>-b</option></term>
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<term><option>--boot</option></term>
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<listitem><para>Automatically search
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for an init binary and invoke it
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instead of a shell or a user supplied
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program. If this option is used, arguments
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specified on the command line are used
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as arguments for the init binary.
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</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><option>-u</option></term>
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<term><option>--user=</option></term>
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<listitem><para>Run the command
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under specified user, create home
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directory and cd into it. As rest
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of systemd-nspawn, this is not
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the security feature and limits
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against accidental changes only.
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</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><option>-M</option></term>
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<term><option>--machine=</option></term>
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<listitem><para>Sets the machine name
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for this container. This name may be
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used to identify this container on the
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host, and is used to initialize the
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container's hostname (which the
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container can choose to override,
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however). If not specified, the last
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component of the root directory of the
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container is used.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><option>--slice=</option></term>
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<listitem><para>Make the container
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part of the specified slice, instead
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of the
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<filename>machine.slice</filename>.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>-Z</option></term>
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<term><option>--selinux-context=</option></term>
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<listitem><para>Sets the SELinux
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security context to be used to label
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processes in the container.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>-L</option></term>
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<term><option>--selinux-apifs-context=</option></term>
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<listitem><para>Sets the SELinux security
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context to be used to label files in
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the virtual API file systems in the
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container.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>--uuid=</option></term>
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<listitem><para>Set the specified UUID
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for the container. The init system
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will initialize
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<filename>/etc/machine-id</filename>
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from this if this file is not set yet.
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</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><option>--private-network</option></term>
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<listitem><para>Turn off networking in
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the container. This makes all network
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interfaces unavailable in the
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container, with the exception of the
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loopback device.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><option>--read-only</option></term>
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<listitem><para>Mount the root file
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system read-only for the
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container.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><option>--capability=</option></term>
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<listitem><para>List one or more
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additional capabilities to grant the
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container. Takes a comma-separated
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list of capability names, see
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<citerefentry><refentrytitle>capabilities</refentrytitle><manvolnum>7</manvolnum></citerefentry>
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for more information. Note that the
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following capabilities will be granted
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in any way: CAP_CHOWN,
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CAP_DAC_OVERRIDE, CAP_DAC_READ_SEARCH,
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CAP_FOWNER, CAP_FSETID, CAP_IPC_OWNER,
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CAP_KILL, CAP_LEASE,
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CAP_LINUX_IMMUTABLE,
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CAP_NET_BIND_SERVICE,
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CAP_NET_BROADCAST, CAP_NET_RAW,
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CAP_SETGID, CAP_SETFCAP, CAP_SETPCAP,
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CAP_SETUID, CAP_SYS_ADMIN,
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CAP_SYS_CHROOT, CAP_SYS_NICE,
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CAP_SYS_PTRACE, CAP_SYS_TTY_CONFIG,
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CAP_SYS_RESOURCE, CAP_SYS_BOOT,
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CAP_AUDIT_WRITE,
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CAP_AUDIT_CONTROL.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><option>--drop-capability=</option></term>
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<listitem><para>Specify one or more
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additional capabilities to drop for
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the container. This allows running the
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container with fewer capabilities than
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the default (see above).</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><option>--link-journal=</option></term>
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<listitem><para>Control whether the
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container's journal shall be made
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visible to the host system. If enabled,
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allows viewing the container's journal
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files from the host (but not vice
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versa). Takes one of
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<literal>no</literal>,
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<literal>host</literal>,
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<literal>guest</literal>,
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<literal>auto</literal>. If
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<literal>no</literal>, the journal is
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not linked. If <literal>host</literal>,
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the journal files are stored on the
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host file system (beneath
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<filename>/var/log/journal/<replaceable>machine-id</replaceable></filename>)
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and the subdirectory is bind-mounted
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into the container at the same
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location. If <literal>guest</literal>,
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the journal files are stored on the
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guest file system (beneath
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<filename>/var/log/journal/<replaceable>machine-id</replaceable></filename>)
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and the subdirectory is symlinked into the host
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at the same location. If
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<literal>auto</literal> (the default),
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and the right subdirectory of
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<filename>/var/log/journal</filename>
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exists, it will be bind mounted
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into the container. If the
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subdirectory does not exist, no
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linking is performed. Effectively,
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booting a container once with
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<literal>guest</literal> or
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<literal>host</literal> will link the
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journal persistently if further on
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the default of <literal>auto</literal>
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is used.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><option>-j</option></term>
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<listitem><para>Equivalent to
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<option>--link-journal=guest</option>.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><option>--bind=</option></term>
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<term><option>--bind-ro=</option></term>
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<listitem><para>Bind mount a file or
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directory from the host into the
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container. Either takes a path
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argument -- in which case the
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specified path will be mounted from
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the host to the same path in the
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container --, or a colon-separated
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pair of paths -- in which case the
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first specified path is the source in
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the host, and the second path is the
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destination in the container. The
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<option>--bind-ro=</option> option
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creates read-only bind
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mount.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><option>--setenv=</option></term>
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<listitem><para>Specifies an
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environment variable assignment to
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pass to the init process in the
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container, in the format
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<literal>NAME=VALUE</literal>. This
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may be used to override the default
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variables or to set additional
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variables. This parameter may be used
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more than once.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><option>-q</option></term>
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<term><option>--quiet</option></term>
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<listitem><para>Turns off any status
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output by the tool itself. When this
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switch is used, then the only output
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by nspawn will be the console output
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of the container OS
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itself.</para></listitem>
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</varlistentry>
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</variablelist>
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</refsect1>
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<refsect1>
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<title>Example 1</title>
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<programlisting># yum -y --releasever=19 --nogpg --installroot=/srv/mycontainer --disablerepo='*' --enablerepo=fedora install systemd passwd yum fedora-release vim-minimal
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# systemd-nspawn -bD /srv/mycontainer</programlisting>
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<para>This installs a minimal Fedora distribution into
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the directory <filename noindex='true'>/srv/mycontainer/</filename> and
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||
then boots an OS in a namespace container in
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||
it.</para>
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||
</refsect1>
|
||
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||
<refsect1>
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<title>Example 2</title>
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||
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<programlisting># debootstrap --arch=amd64 unstable ~/debian-tree/
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# systemd-nspawn -D ~/debian-tree/</programlisting>
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<para>This installs a minimal Debian unstable
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distribution into the directory
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<filename>~/debian-tree/</filename> and then spawns a
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shell in a namespace container in it.</para>
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||
</refsect1>
|
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<refsect1>
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<title>Example 3</title>
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||
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<programlisting># pacstrap -c -d ~/arch-tree/ base
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# systemd-nspawn -bD ~/arch-tree/</programlisting>
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||
<para>This installs a mimimal Arch Linux distribution into
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the directory <filename>~/arch-tree/</filename> and then
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||
boots an OS in a namespace container in it.</para>
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||
</refsect1>
|
||
|
||
<refsect1>
|
||
<title>Example 4</title>
|
||
|
||
<programlisting># mv ~/arch-tree /var/lib/container/arch
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||
# systemctl enable systemd-nspawn@arch.service
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||
# 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>
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||
</refsect1>
|
||
|
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<refsect1>
|
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<title>Example 5</title>
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||
|
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<programlisting># btrfs subvolume snapshot / /.tmp
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# systemd-nspawn --private-network -D /.tmp -b</programlisting>
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|
||
<para>This runs a copy of the host system in a
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btrfs snapshot.</para>
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||
</refsect1>
|
||
|
||
<refsect1>
|
||
<title>Example 6</title>
|
||
|
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<programlisting># chcon system_u:object_r:svirt_sandbox_file_t:s0:c0,c1 -R /srv/container
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# 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>
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||
|
||
<para>This runs a container with SELinux sandbox security contexts.</para>
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||
</refsect1>
|
||
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||
<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>,
|
||
<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>
|
||
|
||
</refentry>
|