925 lines
42 KiB
XML
925 lines
42 KiB
XML
<?xml version='1.0'?> <!--*- Mode: nxml; nxml-child-indent: 2; indent-tabs-mode: nil -*-->
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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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xmlns:xi="http://www.w3.org/2001/XInclude">
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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 run a
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command or OS in a light-weight namespace container. In many ways
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it is similar to
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<citerefentry project='man-pages'><refentrytitle>chroot</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
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but more powerful since it fully virtualizes the file system
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hierarchy, as well as the process tree, the various IPC subsystems
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and the host and domain name.</para>
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<para><command>systemd-nspawn</command> limits access to various
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kernel interfaces in the container to read-only, such as
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<filename>/sys</filename>, <filename>/proc/sys</filename> or
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<filename>/sys/fs/selinux</filename>. Network interfaces and the
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system clock may not be changed from within the container. Device
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nodes may not be created. The host system cannot be rebooted and
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kernel modules may not be loaded from within the container.</para>
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<para>Note that even though these security precautions are taken
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<command>systemd-nspawn</command> is not suitable for fully secure
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container setups. Many of the security features may be
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circumvented and are hence primarily useful to avoid accidental
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changes to the host system from the container.</para>
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<para>In contrast to
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<citerefentry project='man-pages'><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 in a
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container.</para>
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<para>Use a tool like
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<citerefentry project='mankier'><refentrytitle>dnf</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
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<citerefentry project='die-net'><refentrytitle>debootstrap</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
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or
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<citerefentry project='archlinux'><refentrytitle>pacman</refentrytitle><manvolnum>8</manvolnum></citerefentry>
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to set up an OS directory tree suitable as file system hierarchy
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for <command>systemd-nspawn</command> containers.</para>
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<para>Note that <command>systemd-nspawn</command> will mount file
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systems private to the container to <filename>/dev</filename>,
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<filename>/run</filename> and similar. These will not be visible
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outside of the container, and their contents will be lost when the
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container exits.</para>
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<para>Note that running two <command>systemd-nspawn</command>
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containers from the same directory tree will not make processes in
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them see each other. The PID namespace separation of the two
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containers is complete and the containers will share very few
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runtime objects except for the 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 additional login
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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 <command>systemd-nspawn</command> will
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verify the existence of <filename>/usr/lib/os-release</filename>
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or <filename>/etc/os-release</filename> in the container tree
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before starting the container (see
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<citerefentry><refentrytitle>os-release</refentrytitle><manvolnum>5</manvolnum></citerefentry>).
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It might be necessary to add this file to the container tree
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manually if the OS of the container is too old to contain this
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file out-of-the-box.</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 arguments
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are used as arguments for the init binary. Otherwise,
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<replaceable>COMMAND</replaceable> specifies the program to launch
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in the container, and the remaining arguments are used as
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arguments for this program. If <option>-b</option> is not used and
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no arguments are specified, 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>-D</option></term>
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<term><option>--directory=</option></term>
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<listitem><para>Directory to use as file system root for the
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container.</para>
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<para>If neither <option>--directory=</option>, nor
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<option>--image=</option> is specified the directory is
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determined by searching for a directory named the same as the
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machine name specified with <option>--machine=</option>. See
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<citerefentry><refentrytitle>machinectl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
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section "Files and Directories" for the precise search path.</para>
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<para>If neither <option>--directory=</option>,
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<option>--image=</option>, nor <option>--machine=</option>
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are specified, the current directory will
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be used. May not be specified together with
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<option>--image=</option>.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><option>--template=</option></term>
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<listitem><para>Directory or <literal>btrfs</literal>
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subvolume to use as template for the container's root
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directory. If this is specified and the container's root
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directory (as configured by <option>--directory=</option>)
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does not yet exist it is created as <literal>btrfs</literal>
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subvolume and populated from this template tree. Ideally, the
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specified template path refers to the root of a
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<literal>btrfs</literal> subvolume, in which case a simple
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copy-on-write snapshot is taken, and populating the root
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directory is instant. If the specified template path does not
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refer to the root of a <literal>btrfs</literal> subvolume (or
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not even to a <literal>btrfs</literal> file system at all),
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the tree is copied, which can be substantially more
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time-consuming. Note that if this option is used the
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container's root directory (in contrast to the template
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directory!) must be located on a <literal>btrfs</literal> file
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system, so that the <literal>btrfs</literal> subvolume may be
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created. May not be specified together with
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<option>--image=</option> or
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<option>--ephemeral</option>.</para>
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<para>Note that this switch leaves host name, machine ID and
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all other settings that could identify the instance
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unmodified.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><option>-x</option></term>
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<term><option>--ephemeral</option></term>
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<listitem><para>If specified, the container is run with a
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temporary <literal>btrfs</literal> snapshot of its root
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directory (as configured with <option>--directory=</option>),
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that is removed immediately when the container terminates.
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This option is only supported if the root file system is
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<literal>btrfs</literal>. May not be specified together with
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<option>--image=</option> or
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<option>--template=</option>.</para>
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<para>Note that this switch leaves host name, machine ID and
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all other settings that could identify the instance
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unmodified.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><option>-i</option></term>
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<term><option>--image=</option></term>
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<listitem><para>Disk image to mount the root directory for the
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container from. Takes a path to a regular file or to a block
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device node. The file or block device must contain
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either:</para>
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<itemizedlist>
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<listitem><para>An MBR partition table with a single
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partition of type 0x83 that is marked
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bootable.</para></listitem>
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<listitem><para>A GUID partition table (GPT) with a single
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partition of type
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0fc63daf-8483-4772-8e79-3d69d8477de4.</para></listitem>
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<listitem><para>A GUID partition table (GPT) with a marked
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root partition which is mounted as the root directory of the
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container. Optionally, GPT images may contain a home and/or
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a server data partition which are mounted to the appropriate
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places in the container. All these partitions must be
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identified by the partition types defined by the <ulink
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url="http://www.freedesktop.org/wiki/Specifications/DiscoverablePartitionsSpec/">Discoverable
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Partitions Specification</ulink>.</para></listitem>
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</itemizedlist>
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<para>Any other partitions, such as foreign partitions, swap
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partitions or EFI system partitions are not mounted. May not
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be specified together with <option>--directory=</option>,
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<option>--template=</option> or
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<option>--ephemeral</option>.</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 for an init binary and
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invoke it instead of a shell or a user supplied program. If
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this option is used, arguments specified on the command line
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are used as arguments for the init binary. This option may not
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be combined with <option>--share-system</option>.
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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>After transitioning into the container, change
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to the specified user-defined in the container's user
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database. Like all other systemd-nspawn features, this is not
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a security feature and provides protection against accidental
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destructive operations only.</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 for this container. This
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name may be used to identify this container during its runtime
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(for example in tools like
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<citerefentry><refentrytitle>machinectl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
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and similar), and is used to initialize the container's
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hostname (which the container can choose to override,
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however). If not specified, the last component of the root
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directory path of the container is used, possibly suffixed
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with a random identifier in case <option>--ephemeral</option>
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mode is selected. If the root directory selected is the host's
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root directory the host's hostname is used as default
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instead.</para></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 for the container. The
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init system will initialize
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<filename>/etc/machine-id</filename> from this if this file is
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not set yet. </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 part of the specified
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slice, instead of the default
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<filename>machine.slice</filename>. This is only applies if
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the machine is run in its own scope unit, i.e. if
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<option>--keep-unit</option> is not used.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>--property=</option></term>
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<listitem><para>Set a unit property on the scope unit to
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register for the machine. This only applies if the machine is
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run in its own scope unit, i.e. if
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<option>--keep-unit</option> is not used. Takes unit property
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assignments in the same format as <command>systemctl
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set-property</command>. This is useful to set memory limits
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and similar for machines.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>--private-users=</option></term>
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<listitem><para>Enables user namespacing. If enabled, the
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container will run with its own private set of Unix user and
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group ids (UIDs and GIDs). Takes none, one or two
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colon-separated parameters: the first parameter specifies the
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first host UID to assign to the container, the second
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parameter specifies the number of host UIDs to assign to the
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container. If the second parameter is omitted, 65536 UIDs are
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assigned. If the first parameter is also omitted (and hence
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no parameter passed at all), the first UID assigned to the
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container is read from the owner of the root directory of the
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container's directory tree. By default, no user namespacing is
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applied.</para>
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<para>Note that user namespacing currently requires OS trees
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that are prepared for the UID shift that is being applied:
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UIDs and GIDs used for file ownership or in file ACL entries
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must be shifted to the container UID base that is
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used during container runtime.</para>
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<para>It is recommended to assign at least 65536 UIDs to each
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container, so that the usable UID range in the container
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covers 16 bit. For best security, do not assign overlapping UID
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ranges to multiple containers. It is hence a good idea to use
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the upper 16 bit of the host 32-bit UIDs as container
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identifier, while the lower 16 bit encode the container UID
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used.</para>
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<para>When user namespaces are used, the GID range assigned to
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each container is always chosen identical to the UID
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range.</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>Disconnect networking of the container from
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the host. This makes all network interfaces unavailable in the
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container, with the exception of the loopback device and those
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specified with <option>--network-interface=</option> and
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configured with <option>--network-veth</option>. If this
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option is specified, the CAP_NET_ADMIN capability will be
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added to the set of capabilities the container retains. The
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latter may be disabled by using
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<option>--drop-capability=</option>.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><option>--network-interface=</option></term>
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<listitem><para>Assign the specified network interface to the
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container. This will remove the specified interface from the
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||
calling namespace and place it in the container. When the
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container terminates, it is moved back to the host namespace.
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Note that <option>--network-interface=</option> implies
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<option>--private-network</option>. This option may be used
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||
more than once to add multiple network interfaces to the
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||
container.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><option>--network-macvlan=</option></term>
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<listitem><para>Create a <literal>macvlan</literal> interface
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||
of the specified Ethernet network interface and add it to the
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||
container. A <literal>macvlan</literal> interface is a virtual
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||
interface that adds a second MAC address to an existing
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||
physical Ethernet link. The interface in the container will be
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||
named after the interface on the host, prefixed with
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||
<literal>mv-</literal>. Note that
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||
<option>--network-macvlan=</option> implies
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||
<option>--private-network</option>. This option may be used
|
||
more than once to add multiple network interfaces to the
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||
container.</para></listitem>
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||
</varlistentry>
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<varlistentry>
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<term><option>--network-ipvlan=</option></term>
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||
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<listitem><para>Create an <literal>ipvlan</literal> interface
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||
of the specified Ethernet network interface and add it to the
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||
container. An <literal>ipvlan</literal> interface is a virtual
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||
interface, similar to a <literal>macvlan</literal> interface,
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||
which uses the same MAC address as the underlying interface.
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||
The interface in the container will be named after the
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interface on the host, prefixed with <literal>iv-</literal>.
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||
Note that <option>--network-ipvlan=</option> implies
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||
<option>--private-network</option>. This option may be used
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||
more than once to add multiple network interfaces to the
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||
container.</para></listitem>
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||
</varlistentry>
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||
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||
<varlistentry>
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||
<term><option>-n</option></term>
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||
<term><option>--network-veth</option></term>
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||
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||
<listitem><para>Create a virtual Ethernet link
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||
(<literal>veth</literal>) between host and container. The host
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||
side of the Ethernet link will be available as a network
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||
interface named after the container's name (as specified with
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||
<option>--machine=</option>), prefixed with
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||
<literal>ve-</literal>. The container side of the Ethernet
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||
link will be named <literal>host0</literal>. Note that
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<option>--network-veth</option> implies
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||
<option>--private-network</option>.</para></listitem>
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||
</varlistentry>
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||
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||
<varlistentry>
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||
<term><option>--network-bridge=</option></term>
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||
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||
<listitem><para>Adds the host side of the Ethernet link
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||
created with <option>--network-veth</option> to the specified
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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
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<literal>vb-</literal> prefix instead of
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<literal>ve-</literal>.</para></listitem>
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</varlistentry>
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||
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||
<varlistentry>
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||
<term><option>-p</option></term>
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||
<term><option>--port=</option></term>
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<listitem><para>If private networking is enabled, maps an IP
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||
port on the host onto an IP port on the container. Takes a
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protocol specifier (either <literal>tcp</literal> or
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||
<literal>udp</literal>), separated by a colon from a host port
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||
number in the range 1 to 65535, separated by a colon from a
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container port number in the range from 1 to 65535. The
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||
protocol specifier and its separating colon may be omitted, in
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which case <literal>tcp</literal> is assumed. The container
|
||
port number and its colon may be omitted, in which case the
|
||
same port as the host port is implied. This option is only
|
||
supported if private networking is used, such as with
|
||
<option>--network-veth</option> or
|
||
<option>--network-bridge=</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 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>--kill-signal=</option></term>
|
||
|
||
<listitem><para>Specify the process signal to send to the
|
||
container's PID 1 when nspawn itself receives SIGTERM, in
|
||
order to trigger an orderly shutdown of the
|
||
container. Defaults to SIGRTMIN+3 if <option>--boot</option>
|
||
is used (on systemd-compatible init systems SIGRTMIN+3
|
||
triggers an orderly shutdown). Takes a signal name like
|
||
<literal>SIGHUP</literal>, <literal>SIGTERM</literal> or
|
||
similar as argument.</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 persistent 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. Takes one of: 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 —, or a colon-separated triple of source path,
|
||
destination path and mount options. Mount options are
|
||
comma-separated and currently, only "rbind" and "norbind"
|
||
are allowed. Defaults to "rbind". Backslash escapes are interpreted, so
|
||
<literal>\:</literal> may be used to embed colons in either path.
|
||
This option may be specified multiple times for
|
||
creating multiple independent bind mount points. 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>.
|
||
Backslash escapes are interpreted in the path, so
|
||
<literal>\:</literal> may be used to embed colons in the path.
|
||
</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><option>--overlay=</option></term>
|
||
<term><option>--overlay-ro=</option></term>
|
||
|
||
<listitem><para>Combine multiple directory trees into one
|
||
overlay file system and mount it into the container. Takes a
|
||
list of colon-separated paths to the directory trees to
|
||
combine and the destination mount point.</para>
|
||
|
||
<para>Backslash escapes are interpreted in the paths, so
|
||
<literal>\:</literal> may be used to embed colons in the paths.
|
||
</para>
|
||
|
||
<para>If three or more paths are specified, then the last
|
||
specified path is the destination mount point in the
|
||
container, all paths specified before refer to directory trees
|
||
on the host and are combined in the specified order into one
|
||
overlay file system. The left-most path is hence the lowest
|
||
directory tree, the second-to-last path the highest directory
|
||
tree in the stacking order. If <option>--overlay-ro=</option>
|
||
is used instead of <option>--overlay=</option>, a read-only
|
||
overlay file system is created. If a writable overlay file
|
||
system is created, all changes made to it are written to the
|
||
highest directory tree in the stacking order, i.e. the
|
||
second-to-last specified.</para>
|
||
|
||
<para>If only two paths are specified, then the second
|
||
specified path is used both as the top-level directory tree in
|
||
the stacking order as seen from the host, as well as the mount
|
||
point for the overlay file system in the container. At least
|
||
two paths have to be specified.</para>
|
||
|
||
<para>For details about overlay file systems, see <ulink
|
||
url="https://www.kernel.org/doc/Documentation/filesystems/overlayfs.txt">overlayfs.txt</ulink>. Note
|
||
that the semantics of overlay file systems are substantially
|
||
different from normal file systems, in particular regarding
|
||
reported device and inode information. Device and inode
|
||
information may change for a file while it is being written
|
||
to, and processes might see out-of-date versions of files at
|
||
times. Note that this switch automatically derives the
|
||
<literal>workdir=</literal> mount option for the overlay file
|
||
system from the top-level directory tree, making it a sibling
|
||
of it. It is hence essential that the top-level directory tree
|
||
is not a mount point itself (since the working directory must
|
||
be on the same file system as the top-most directory
|
||
tree). Also note that the <literal>lowerdir=</literal> mount
|
||
option receives the paths to stack in the opposite order of
|
||
this switch.</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, which 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 project='man-pages'><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></term>
|
||
<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
|
||
<option>yes</option>, full volatile mode is enabled. This
|
||
means the root directory is mounted as a 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 <option>state</option>, the OS tree is
|
||
mounted read-only, but <filename>/var</filename> is mounted as
|
||
a <literal>tmpfs</literal> instance into it (the system thus
|
||
starts up with read-only OS resources and configuration, but
|
||
pristine state, and any changes to the latter are lost on
|
||
shutdown). When the mode parameter is specified as
|
||
<option>no</option> (the default), the whole OS tree is made
|
||
available writable.</para>
|
||
|
||
<para>Note that setting this to <option>yes</option> or
|
||
<option>state</option> 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>
|
||
|
||
<varlistentry>
|
||
<term><option>--settings=</option><replaceable>MODE</replaceable></term>
|
||
|
||
<listitem><para>Controls whether
|
||
<command>systemd-nspawn</command> shall search for and use
|
||
additional per-container settings from
|
||
<filename>.nspawn</filename> files. Takes a boolean or the
|
||
special values <option>override</option> or
|
||
<option>trusted</option>.</para>
|
||
|
||
<para>If enabled (the default), a settings file named after the
|
||
machine (as specified with the <option>--machine=</option>
|
||
setting, or derived from the directory or image file name)
|
||
with the suffix <filename>.nspawn</filename> is searched in
|
||
<filename>/etc/systemd/nspawn/</filename> and
|
||
<filename>/run/systemd/nspawn/</filename>. If it is found
|
||
there, its settings are read and used. If it is not found
|
||
there, it is subsequently searched in the same directory as the
|
||
image file or in the immediate parent of the root directory of
|
||
the container. In this case, if the file is found, its settings
|
||
will be also read and used, but potentially unsafe settings
|
||
are ignored. Note that in both these cases, settings on the
|
||
command line take precedence over the corresponding settings
|
||
from loaded <filename>.nspawn</filename> files, if both are
|
||
specified. Unsafe settings are considered all settings that
|
||
elevate the container's privileges or grant access to
|
||
additional resources such as files or directories of the
|
||
host. For details about the format and contents of
|
||
<filename>.nspawn</filename> files, consult
|
||
<citerefentry><refentrytitle>systemd.nspawn</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
|
||
|
||
<para>If this option is set to <option>override</option>, the
|
||
file is searched, read and used the same way, however, the order of
|
||
precedence is reversed: settings read from the
|
||
<filename>.nspawn</filename> file will take precedence over
|
||
the corresponding command line options, if both are
|
||
specified.</para>
|
||
|
||
<para>If this option is set to <option>trusted</option>, the
|
||
file is searched, read and used the same way, but regardless
|
||
of being found in <filename>/etc/systemd/nspawn/</filename>,
|
||
<filename>/run/systemd/nspawn/</filename> or next to the image
|
||
file or container root directory, all settings will take
|
||
effect, however, command line arguments still take precedence
|
||
over corresponding settings.</para>
|
||
|
||
<para>If disabled, no <filename>.nspawn</filename> file is read
|
||
and no settings except the ones on the command line are in
|
||
effect.</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>Download a Fedora image and start a shell in it</title>
|
||
|
||
<programlisting># machinectl pull-raw --verify=no http://ftp.halifax.rwth-aachen.de/fedora/linux/releases/21/Cloud/Images/x86_64/Fedora-Cloud-Base-20141203-21.x86_64.raw.xz
|
||
# systemd-nspawn -M Fedora-Cloud-Base-20141203-21</programlisting>
|
||
|
||
<para>This downloads an image using
|
||
<citerefentry><refentrytitle>machinectl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
|
||
and opens a shell in it.</para>
|
||
</example>
|
||
|
||
<example>
|
||
<title>Build and boot a minimal Fedora distribution in a container</title>
|
||
|
||
<programlisting># dnf -y --releasever=23 --installroot=/srv/mycontainer --disablerepo='*' --enablerepo=fedora --enablerepo=updates install systemd passwd dnf 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 minimal 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>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><refentrytitle>systemd.nspawn</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
|
||
<citerefentry project='man-pages'><refentrytitle>chroot</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
|
||
<citerefentry project='mankier'><refentrytitle>dnf</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 project='man-pages'><refentrytitle>btrfs</refentrytitle><manvolnum>8</manvolnum></citerefentry>
|
||
</para>
|
||
</refsect1>
|
||
|
||
</refentry>
|