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b53ede699c
Add a new --pivot-root argument to systemd-nspawn, which specifies a directory to pivot to / inside the container; while the original / is pivoted to another specified directory (if provided). This adds support for booting container images which may contain several bootable sysroots, as is common with OSTree disk images. When these disk images are booted on real hardware, ostree-prepare-root is run in conjunction with sysroot.mount in the initramfs to achieve the same results.
1131 lines
61 KiB
XML
1131 lines
61 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">
|
||
|
||
<!--
|
||
This file is part of systemd.
|
||
|
||
Copyright 2010 Lennart Poettering
|
||
|
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systemd is free software; you can redistribute it and/or modify it
|
||
under the terms of the GNU Lesser General Public License as published by
|
||
the Free Software Foundation; either version 2.1 of the License, or
|
||
(at your option) any later version.
|
||
|
||
systemd is distributed in the hope that it will be useful, but
|
||
WITHOUT ANY WARRANTY; without even the implied warranty of
|
||
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
||
Lesser General Public License for more details.
|
||
|
||
You should have received a copy of the GNU Lesser General Public License
|
||
along with systemd; If not, see <http://www.gnu.org/licenses/>.
|
||
-->
|
||
|
||
<refentry id="systemd-nspawn"
|
||
xmlns:xi="http://www.w3.org/2001/XInclude">
|
||
|
||
<refentryinfo>
|
||
<title>systemd-nspawn</title>
|
||
<productname>systemd</productname>
|
||
|
||
<authorgroup>
|
||
<author>
|
||
<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>
|
||
</authorgroup>
|
||
</refentryinfo>
|
||
|
||
<refmeta>
|
||
<refentrytitle>systemd-nspawn</refentrytitle>
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||
<manvolnum>1</manvolnum>
|
||
</refmeta>
|
||
|
||
<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>
|
||
|
||
<refsynopsisdiv>
|
||
<cmdsynopsis>
|
||
<command>systemd-nspawn</command>
|
||
<arg choice="opt" rep="repeat">OPTIONS</arg>
|
||
<arg choice="opt"><replaceable>COMMAND</replaceable>
|
||
<arg choice="opt" rep="repeat">ARGS</arg>
|
||
</arg>
|
||
</cmdsynopsis>
|
||
<cmdsynopsis>
|
||
<command>systemd-nspawn</command>
|
||
<arg choice="plain">--boot</arg>
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||
<arg choice="opt" rep="repeat">OPTIONS</arg>
|
||
<arg choice="opt" rep="repeat">ARGS</arg>
|
||
</cmdsynopsis>
|
||
</refsynopsisdiv>
|
||
|
||
<refsect1>
|
||
<title>Description</title>
|
||
|
||
<para><command>systemd-nspawn</command> may be used to run a command or OS in a light-weight namespace
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||
container. In many ways it is similar to <citerefentry
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||
project='man-pages'><refentrytitle>chroot</refentrytitle><manvolnum>1</manvolnum></citerefentry>, but more powerful
|
||
since it fully virtualizes the file system hierarchy, as well as the process tree, the various IPC subsystems and
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||
the host and domain name.</para>
|
||
|
||
<para><command>systemd-nspawn</command> may be invoked on any directory tree containing an operating system tree,
|
||
using the <option>--directory=</option> command line option. By using the <option>--machine=</option> option an OS
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||
tree is automatically searched for in a couple of locations, most importantly in
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||
<filename>/var/lib/machines</filename>, the suggested directory to place container images installed on the
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||
system.</para>
|
||
|
||
<para>In contrast to <citerefentry
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||
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 container.</para>
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||
|
||
<para><command>systemd-nspawn</command> limits access to various kernel interfaces in the container to read-only,
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||
such as <filename>/sys</filename>, <filename>/proc/sys</filename> or <filename>/sys/fs/selinux</filename>. The
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host's network interfaces and the system clock may not be changed from within the container. Device nodes may not
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||
be created. The host system cannot be rebooted and kernel modules may not be loaded from within the
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||
container.</para>
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||
|
||
<para>Use a tool like <citerefentry
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||
project='mankier'><refentrytitle>dnf</refentrytitle><manvolnum>8</manvolnum></citerefentry>, <citerefentry
|
||
project='die-net'><refentrytitle>debootstrap</refentrytitle><manvolnum>8</manvolnum></citerefentry>, or
|
||
<citerefentry project='archlinux'><refentrytitle>pacman</refentrytitle><manvolnum>8</manvolnum></citerefentry> to
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||
set up an OS directory tree suitable as file system hierarchy for <command>systemd-nspawn</command> containers. See
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||
the Examples section below for details on suitable invocation of these commands.</para>
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||
|
||
<para>As a safety check <command>systemd-nspawn</command> will verify the existence of
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||
<filename>/usr/lib/os-release</filename> or <filename>/etc/os-release</filename> in the container tree before
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||
starting the container (see
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||
<citerefentry><refentrytitle>os-release</refentrytitle><manvolnum>5</manvolnum></citerefentry>). It might be
|
||
necessary to add this file to the container tree manually if the OS of the container is too old to contain this
|
||
file out-of-the-box.</para>
|
||
|
||
<para><command>systemd-nspawn</command> may be invoked directly from the interactive command line or run as system
|
||
service in the background. In this mode each container instance runs as its own service instance; a default
|
||
template unit file <filename>systemd-nspawn@.service</filename> is provided to make this easy, taking the container
|
||
name as instance identifier. Note that different default options apply when <command>systemd-nspawn</command> is
|
||
invoked by the template unit file than interactively on the command line. Most importantly the template unit file
|
||
makes use of the <option>--boot</option> which is not the default in case <command>systemd-nspawn</command> is
|
||
invoked from the interactive command line. Further differences with the defaults are documented along with the
|
||
various supported options below.</para>
|
||
|
||
<para>The <citerefentry><refentrytitle>machinectl</refentrytitle><manvolnum>1</manvolnum></citerefentry> tool may
|
||
be used to execute a number of operations on containers. In particular it provides easy-to-use commands to run
|
||
containers as system services using the <filename>systemd-nspawn@.service</filename> template unit
|
||
file.</para>
|
||
|
||
<para>Along with each container a settings file with the <filename>.nspawn</filename> suffix may exist, containing
|
||
additional settings to apply when running the container. See
|
||
<citerefentry><refentrytitle>systemd.nspawn</refentrytitle><manvolnum>5</manvolnum></citerefentry> for
|
||
details. Settings files override the default options used by the <filename>systemd-nspawn@.service</filename>
|
||
template unit file, making it usually unnecessary to alter this template file directly.</para>
|
||
|
||
<para>Note that <command>systemd-nspawn</command> will mount file systems private to the container to
|
||
<filename>/dev</filename>, <filename>/run</filename> and similar. These will not be visible outside of the
|
||
container, and their contents will be lost when the container exits.</para>
|
||
|
||
<para>Note that running two <command>systemd-nspawn</command> containers from the same directory tree will not make
|
||
processes in them see each other. The PID namespace separation of the two containers is complete and the containers
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||
will share very few runtime objects except for the underlying file system. Use
|
||
<citerefentry><refentrytitle>machinectl</refentrytitle><manvolnum>1</manvolnum></citerefentry>'s
|
||
<command>login</command> or <command>shell</command> commands to request an additional login session in a running
|
||
container.</para>
|
||
|
||
<para><command>systemd-nspawn</command> implements the <ulink
|
||
url="http://www.freedesktop.org/wiki/Software/systemd/ContainerInterface">Container Interface</ulink>
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||
specification.</para>
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||
|
||
<para>While running, containers invoked with <command>systemd-nspawn</command> are registered with the
|
||
<citerefentry><refentrytitle>systemd-machined</refentrytitle><manvolnum>8</manvolnum></citerefentry> service that
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||
keeps track of running containers, and provides programming interfaces to interact with them.</para>
|
||
</refsect1>
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||
|
||
<refsect1>
|
||
<title>Options</title>
|
||
|
||
<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>--boot</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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||
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||
<para>The following options are understood:</para>
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||
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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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||
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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>
|
||
|
||
<para>If neither <option>--directory=</option>,
|
||
<option>--image=</option>, nor <option>--machine=</option>
|
||
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>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
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||
<term><option>--template=</option></term>
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||
|
||
<listitem><para>Directory or <literal>btrfs</literal> subvolume to use as template for the container's root
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||
directory. If this is specified and the container's root directory (as configured by
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||
<option>--directory=</option>) does not yet exist it is created as <literal>btrfs</literal> snapshot (if
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supported) or plain directory (otherwise) and populated from this template tree. Ideally, the specified
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||
template path refers to the root of a <literal>btrfs</literal> subvolume, in which case a simple copy-on-write
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||
snapshot is taken, and populating the root directory is instant. If the specified template path does not refer
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||
to the root of a <literal>btrfs</literal> subvolume (or not even to a <literal>btrfs</literal> file system at
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||
all), the tree is copied (though possibly in a copy-on-write scheme — if the file system supports that), which
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||
can be substantially more time-consuming. May not be specified together with <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
|
||
all other settings that could identify the instance
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||
unmodified.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><option>-x</option></term>
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||
<term><option>--ephemeral</option></term>
|
||
|
||
<listitem><para>If specified, the container is run with a temporary snapshot of its file system that is removed
|
||
immediately when the container terminates. May not be specified together with
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||
<option>--template=</option>.</para>
|
||
<para>Note that this switch leaves host name, machine ID and
|
||
all other settings that could identify the instance
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||
unmodified.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><option>-i</option></term>
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||
<term><option>--image=</option></term>
|
||
|
||
<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
|
||
partition of type
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||
0fc63daf-8483-4772-8e79-3d69d8477de4.</para></listitem>
|
||
|
||
<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
|
||
url="http://www.freedesktop.org/wiki/Specifications/DiscoverablePartitionsSpec/">Discoverable
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||
Partitions Specification</ulink>.</para></listitem>
|
||
|
||
<listitem><para>No partition table, and a single file system spanning the whole image.</para></listitem>
|
||
</itemizedlist>
|
||
|
||
<para>On GPT images, if an EFI System Partition (ESP) is discovered, it is automatically mounted to
|
||
<filename>/efi</filename> (or <filename>/boot</filename> as fallback) in case a directory by this name exists
|
||
and is empty.</para>
|
||
|
||
<para>Partitions encrypted with LUKS are automatically decrypted. Also, on GPT images dm-verity data integrity
|
||
hash partitions are set up if the root hash for them is specified using the <option>--root-hash=</option>
|
||
option.</para>
|
||
|
||
<para>Any other partitions, such as foreign partitions or swap partitions are not mounted. May not be specified
|
||
together with <option>--directory=</option>, <option>--template=</option>.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><option>--root-hash=</option></term>
|
||
|
||
<listitem><para>Takes a data integrity (dm-verity) root hash specified in hexadecimal. This option enables data
|
||
integrity checks using dm-verity, if the used image contains the appropriate integrity data (see above). The
|
||
specified hash must match the root hash of integrity data, and is usually at least 256bits (and hence 64
|
||
hexadecimal characters) long (in case of SHA256 for example). If this option is not specified, but a file with
|
||
the <filename>.roothash</filename> suffix is found next to the image file, bearing otherwise the same name the
|
||
root hash is read from it and automatically used.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><option>-a</option></term>
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||
<term><option>--as-pid2</option></term>
|
||
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||
<listitem><para>Invoke the shell or specified program as process ID (PID) 2 instead of PID 1 (init). By
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||
default, if neither this option nor <option>--boot</option> is used, the selected binary is run as process with
|
||
PID 1, a mode only suitable for programs that are aware of the special semantics that the process with PID 1
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||
has on UNIX. For example, it needs to reap all processes reparented to it, and should implement
|
||
<command>sysvinit</command> compatible signal handling (specifically: it needs to reboot on SIGINT, reexecute
|
||
on SIGTERM, reload configuration on SIGHUP, and so on). With <option>--as-pid2</option> a minimal stub init
|
||
process is run as PID 1 and the selected binary is executed as PID 2 (and hence does not need to implement any
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||
special semantics). The stub init process will reap processes as necessary and react appropriately to
|
||
signals. It is recommended to use this mode to invoke arbitrary commands in containers, unless they have been
|
||
modified to run correctly as PID 1. Or in other words: this switch should be used for pretty much all commands,
|
||
except when the command refers to an init or shell implementation, as these are generally capable of running
|
||
correctly as PID 1. This option may not be combined with <option>--boot</option>.</para>
|
||
</listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<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 invoke it as PID 1, instead of a shell or a user
|
||
supplied program. If this option is used, arguments specified on the command line are used as arguments for the
|
||
init binary. This option may not be combined with <option>--as-pid2</option>.</para>
|
||
|
||
<para>The following table explains the different modes of invocation and relationship to
|
||
<option>--as-pid2</option> (see above):</para>
|
||
|
||
<table>
|
||
<title>Invocation Mode</title>
|
||
<tgroup cols='2' align='left' colsep='1' rowsep='1'>
|
||
<colspec colname="switch" />
|
||
<colspec colname="explanation" />
|
||
<thead>
|
||
<row>
|
||
<entry>Switch</entry>
|
||
<entry>Explanation</entry>
|
||
</row>
|
||
</thead>
|
||
<tbody>
|
||
<row>
|
||
<entry>Neither <option>--as-pid2</option> nor <option>--boot</option> specified</entry>
|
||
<entry>The passed parameters are interpreted as the command line, which is executed as PID 1 in the container.</entry>
|
||
</row>
|
||
|
||
<row>
|
||
<entry><option>--as-pid2</option> specified</entry>
|
||
<entry>The passed parameters are interpreted as the command line, which is executed as PID 2 in the container. A stub init process is run as PID 1.</entry>
|
||
</row>
|
||
|
||
<row>
|
||
<entry><option>--boot</option> specified</entry>
|
||
<entry>An init binary as automatically searched and run as PID 1 in the container. The passed parameters are used as invocation parameters for this process.</entry>
|
||
</row>
|
||
|
||
</tbody>
|
||
</tgroup>
|
||
</table>
|
||
|
||
<para>Note that <option>--boot</option> is the default mode of operation if the
|
||
<filename>systemd-nspawn@.service</filename> template unit file is used.</para>
|
||
</listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><option>--chdir=</option></term>
|
||
|
||
<listitem><para>Change to the specified working directory before invoking the process in the container. Expects
|
||
an absolute path in the container's file system namespace.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><option>--pivot-root=</option></term>
|
||
|
||
<listitem><para>Pivot the specified directory to <filename>/</filename> inside the container, and either unmount the
|
||
container's old root, or pivot it to another specified directory. Takes one of: a path argument — in which case the
|
||
specified path will be pivoted to <filename>/</filename> and the old root will be unmounted; or a colon-separated pair
|
||
of new root path and pivot destination for the old root. The new root path will be pivoted to <filename>/</filename>,
|
||
and the old <filename>/</filename> will be pivoted to the other directory. Both paths must be absolute, and are resolved
|
||
in the container's file system namespace.</para>
|
||
|
||
<para>This is for containers which have several bootable directories in them; for example, several
|
||
<ulink url="https://ostree.readthedocs.io/en/latest/">OSTree</ulink> deployments. It emulates the behavior of the boot
|
||
loader and initial RAM disk which normally select which directory to mount as root and start the container's PID 1 in.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><option>-u</option></term>
|
||
<term><option>--user=</option></term>
|
||
|
||
<listitem><para>After transitioning into the container, change
|
||
to the specified user-defined in the container's user
|
||
database. Like all other systemd-nspawn features, this is not
|
||
a security feature and provides protection against accidental
|
||
destructive operations only.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><option>-M</option></term>
|
||
<term><option>--machine=</option></term>
|
||
|
||
<listitem><para>Sets the machine name for this container. This
|
||
name may be used to identify this container during its runtime
|
||
(for example in tools like
|
||
<citerefentry><refentrytitle>machinectl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
|
||
and similar), and is used to initialize the container's
|
||
hostname (which the container can choose to override,
|
||
however). If not specified, the last component of the root
|
||
directory path of the container is used, possibly suffixed
|
||
with a random identifier in case <option>--ephemeral</option>
|
||
mode is selected. If the root directory selected is the host's
|
||
root directory the host's hostname is used as default
|
||
instead.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><option>--uuid=</option></term>
|
||
|
||
<listitem><para>Set the specified UUID for the container. The
|
||
init system will initialize
|
||
<filename>/etc/machine-id</filename> from this if this file is
|
||
not set yet. Note that this option takes effect only if
|
||
<filename>/etc/machine-id</filename> in the container is
|
||
unpopulated.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><option>--slice=</option></term>
|
||
|
||
<listitem><para>Make the container part of the specified
|
||
slice, instead of the default
|
||
<filename>machine.slice</filename>. This is only applies if
|
||
the machine is run in its own scope unit, i.e. if
|
||
<option>--keep-unit</option> is not used.</para>
|
||
</listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><option>--property=</option></term>
|
||
|
||
<listitem><para>Set a unit property on the scope unit to
|
||
register for the machine. This only applies if the machine is
|
||
run in its own scope unit, i.e. if
|
||
<option>--keep-unit</option> is not used. Takes unit property
|
||
assignments in the same format as <command>systemctl
|
||
set-property</command>. This is useful to set memory limits
|
||
and similar for machines.</para>
|
||
</listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><option>--private-users=</option></term>
|
||
|
||
<listitem><para>Controls user namespacing. If enabled, the container will run with its own private set of UNIX
|
||
user and group ids (UIDs and GIDs). This involves mapping the private UIDs/GIDs used in the container (starting
|
||
with the container's root user 0 and up) to a range of UIDs/GIDs on the host that are not used for other
|
||
purposes (usually in the range beyond the host's UID/GID 65536). The parameter may be specified as follows:</para>
|
||
|
||
<orderedlist>
|
||
<listitem><para>If one or two colon-separated numbers are specified, user namespacing is turned on. The first
|
||
parameter specifies the first host UID/GID to assign to the container, the second parameter specifies the
|
||
number of host UIDs/GIDs to assign to the container. If the second parameter is omitted, 65536 UIDs/GIDs are
|
||
assigned.</para></listitem>
|
||
|
||
<listitem><para>If the parameter is omitted, or true, user namespacing is turned on. The UID/GID range to
|
||
use is determined automatically from the file ownership of the root directory of the container's directory
|
||
tree. To use this option, make sure to prepare the directory tree in advance, and ensure that all files and
|
||
directories in it are owned by UIDs/GIDs in the range you'd like to use. Also, make sure that used file ACLs
|
||
exclusively reference UIDs/GIDs in the appropriate range. If this mode is used the number of UIDs/GIDs
|
||
assigned to the container for use is 65536, and the UID/GID of the root directory must be a multiple of
|
||
65536.</para></listitem>
|
||
|
||
<listitem><para>If the parameter is false, user namespacing is turned off. This is the default.</para>
|
||
</listitem>
|
||
|
||
<listitem><para>The special value <literal>pick</literal> turns on user namespacing. In this case the UID/GID
|
||
range is automatically chosen. As first step, the file owner of the root directory of the container's
|
||
directory tree is read, and it is checked that it is currently not used by the system otherwise (in
|
||
particular, that no other container is using it). If this check is successful, the UID/GID range determined
|
||
this way is used, similar to the behavior if "yes" is specified. If the check is not successful (and thus
|
||
the UID/GID range indicated in the root directory's file owner is already used elsewhere) a new – currently
|
||
unused – UID/GID range of 65536 UIDs/GIDs is randomly chosen between the host UID/GIDs of 524288 and
|
||
1878982656, always starting at a multiple of 65536. This setting implies
|
||
<option>--private-users-chown</option> (see below), which has the effect that the files and directories in
|
||
the container's directory tree will be owned by the appropriate users of the range picked. Using this option
|
||
makes user namespace behavior fully automatic. Note that the first invocation of a previously unused
|
||
container image might result in picking a new UID/GID range for it, and thus in the (possibly expensive) file
|
||
ownership adjustment operation. However, subsequent invocations of the container will be cheap (unless of
|
||
course the picked UID/GID range is assigned to a different use by then).</para></listitem>
|
||
</orderedlist>
|
||
|
||
<para>It is recommended to assign at least 65536 UIDs/GIDs to each container, so that the usable UID/GID range in the
|
||
container covers 16 bit. For best security, do not assign overlapping UID/GID ranges to multiple containers. It is
|
||
hence a good idea to use the upper 16 bit of the host 32-bit UIDs/GIDs as container identifier, while the lower 16
|
||
bit encode the container UID/GID used. This is in fact the behavior enforced by the
|
||
<option>--private-users=pick</option> option.</para>
|
||
|
||
<para>When user namespaces are used, the GID range assigned to each container is always chosen identical to the
|
||
UID range.</para>
|
||
|
||
<para>In most cases, using <option>--private-users=pick</option> is the recommended option as it enhances
|
||
container security massively and operates fully automatically in most cases.</para>
|
||
|
||
<para>Note that the picked UID/GID range is not written to <filename>/etc/passwd</filename> or
|
||
<filename>/etc/group</filename>. In fact, the allocation of the range is not stored persistently anywhere,
|
||
except in the file ownership of the files and directories of the container.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><option>--private-users-chown</option></term>
|
||
|
||
<listitem><para>If specified, all files and directories in the container's directory tree will adjusted so that
|
||
they are owned to the appropriate UIDs/GIDs selected for the container (see above). This operation is
|
||
potentially expensive, as it involves descending and iterating through the full directory tree of the
|
||
container. Besides actual file ownership, file ACLs are adjusted as well.</para>
|
||
|
||
<para>This option is implied if <option>--private-users=pick</option> is used. This option has no effect if
|
||
user namespacing is not used.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><option>-U</option></term>
|
||
|
||
<listitem><para>If the kernel supports the user namespaces feature, equivalent to
|
||
<option>--private-users=pick --private-users-chown</option>, otherwise equivalent to
|
||
<option>--private-users=no</option>.</para>
|
||
|
||
<para>Note that <option>-U</option> is the default if the
|
||
<filename>systemd-nspawn@.service</filename> template unit file is used.</para>
|
||
|
||
<para>Note: it is possible to undo the effect of <option>--private-users-chown</option> (or
|
||
<option>-U</option>) on the file system by redoing the operation with the first UID of 0:</para>
|
||
|
||
<programlisting>systemd-nspawn … --private-users=0 --private-users-chown</programlisting>
|
||
</listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><option>--private-network</option></term>
|
||
|
||
<listitem><para>Disconnect networking of the container from
|
||
the host. This makes all network interfaces unavailable in the
|
||
container, with the exception of the loopback device and those
|
||
specified with <option>--network-interface=</option> and
|
||
configured with <option>--network-veth</option>. If this
|
||
option is specified, the CAP_NET_ADMIN capability will be
|
||
added to the set of capabilities the container retains. The
|
||
latter may be disabled by using
|
||
<option>--drop-capability=</option>.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><option>--network-interface=</option></term>
|
||
|
||
<listitem><para>Assign the specified network interface to the
|
||
container. This will remove the specified interface from the
|
||
calling namespace and place it in the container. When the
|
||
container terminates, it is moved back to the host namespace.
|
||
Note that <option>--network-interface=</option> implies
|
||
<option>--private-network</option>. This option may be used
|
||
more than once to add multiple network interfaces to the
|
||
container.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><option>--network-macvlan=</option></term>
|
||
|
||
<listitem><para>Create a <literal>macvlan</literal> interface
|
||
of the specified Ethernet network interface and add it to the
|
||
container. A <literal>macvlan</literal> interface is a virtual
|
||
interface that adds a second MAC address to an existing
|
||
physical Ethernet link. The interface in the container will be
|
||
named after the interface on the host, prefixed with
|
||
<literal>mv-</literal>. Note that
|
||
<option>--network-macvlan=</option> implies
|
||
<option>--private-network</option>. This option may be used
|
||
more than once to add multiple network interfaces to the
|
||
container.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><option>--network-ipvlan=</option></term>
|
||
|
||
<listitem><para>Create an <literal>ipvlan</literal> interface
|
||
of the specified Ethernet network interface and add it to the
|
||
container. An <literal>ipvlan</literal> interface is a virtual
|
||
interface, similar to a <literal>macvlan</literal> interface,
|
||
which uses the same MAC address as the underlying interface.
|
||
The interface in the container will be named after the
|
||
interface on the host, prefixed with <literal>iv-</literal>.
|
||
Note that <option>--network-ipvlan=</option> implies
|
||
<option>--private-network</option>. This option may be used
|
||
more than once to add multiple network interfaces to the
|
||
container.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><option>-n</option></term>
|
||
<term><option>--network-veth</option></term>
|
||
|
||
<listitem><para>Create a virtual Ethernet link (<literal>veth</literal>) between host and container. The host
|
||
side of the Ethernet link will be available as a network interface named after the container's name (as
|
||
specified with <option>--machine=</option>), prefixed with <literal>ve-</literal>. The container side of the
|
||
Ethernet link will be named <literal>host0</literal>. The <option>--network-veth</option> option implies
|
||
<option>--private-network</option>.</para>
|
||
|
||
<para>Note that
|
||
<citerefentry><refentrytitle>systemd-networkd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
|
||
includes by default a network file <filename>/usr/lib/systemd/network/80-container-ve.network</filename>
|
||
matching the host-side interfaces created this way, which contains settings to enable automatic address
|
||
provisioning on the created virtual link via DHCP, as well as automatic IP routing onto the host's external
|
||
network interfaces. It also contains <filename>/usr/lib/systemd/network/80-container-host0.network</filename>
|
||
matching the container-side interface created this way, containing settings to enable client side address
|
||
assignment via DHCP. In case <filename>systemd-networkd</filename> is running on both the host and inside the
|
||
container, automatic IP communication from the container to the host is thus available, with further
|
||
connectivity to the external network.</para>
|
||
|
||
<para>Note that <option>--network-veth</option> is the default if the
|
||
<filename>systemd-nspawn@.service</filename> template unit file is used.</para>
|
||
</listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><option>--network-veth-extra=</option></term>
|
||
|
||
<listitem><para>Adds an additional virtual Ethernet link
|
||
between host and container. Takes a colon-separated pair of
|
||
host interface name and container interface name. The latter
|
||
may be omitted in which case the container and host sides will
|
||
be assigned the same name. This switch is independent of
|
||
<option>--network-veth</option>, and — in contrast — may be
|
||
used multiple times, and allows configuration of the network
|
||
interface names. Note that <option>--network-bridge=</option>
|
||
has no effect on interfaces created with
|
||
<option>--network-veth-extra=</option>.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><option>--network-bridge=</option></term>
|
||
|
||
<listitem><para>Adds the host side of the Ethernet link created with <option>--network-veth</option> to the
|
||
specified Ethernet bridge interface. Expects a valid network interface name of a bridge device as
|
||
argument. Note that <option>--network-bridge=</option> implies <option>--network-veth</option>. If this option
|
||
is used, the host side of the Ethernet link will use the <literal>vb-</literal> prefix instead of
|
||
<literal>ve-</literal>.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><option>--network-zone=</option></term>
|
||
|
||
<listitem><para>Creates a virtual Ethernet link (<literal>veth</literal>) to the container and adds it to an
|
||
automatically managed Ethernet bridge interface. The bridge interface is named after the passed argument,
|
||
prefixed with <literal>vz-</literal>. The bridge interface is automatically created when the first container
|
||
configured for its name is started, and is automatically removed when the last container configured for its
|
||
name exits. Hence, each bridge interface configured this way exists only as long as there's at least one
|
||
container referencing it running. This option is very similar to <option>--network-bridge=</option>, besides
|
||
this automatic creation/removal of the bridge device.</para>
|
||
|
||
<para>This setting makes it easy to place multiple related containers on a common, virtual Ethernet-based
|
||
broadcast domain, here called a "zone". Each container may only be part of one zone, but each zone may contain
|
||
any number of containers. Each zone is referenced by its name. Names may be chosen freely (as long as they form
|
||
valid network interface names when prefixed with <literal>vz-</literal>), and it is sufficient to pass the same
|
||
name to the <option>--network-zones=</option> switch of the various concurrently running containers to join
|
||
them in one zone.</para>
|
||
|
||
<para>Note that
|
||
<citerefentry><refentrytitle>systemd-networkd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
|
||
includes by default a network file <filename>/usr/lib/systemd/network/80-container-vz.network</filename>
|
||
matching the bridge interfaces created this way, which contains settings to enable automatic address
|
||
provisioning on the created virtual network via DHCP, as well as automatic IP routing onto the host's external
|
||
network interfaces. Using <option>--network-zone=</option> is hence in most cases fully automatic and
|
||
sufficient to connect multiple local containers in a joined broadcast domain to the host, with further
|
||
connectivity to the external network.</para>
|
||
</listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><option>-p</option></term>
|
||
<term><option>--port=</option></term>
|
||
|
||
<listitem><para>If private networking is enabled, maps an IP
|
||
port on the host onto an IP port on the container. Takes a
|
||
protocol specifier (either <literal>tcp</literal> or
|
||
<literal>udp</literal>), separated by a colon from a host port
|
||
number in the range 1 to 65535, separated by a colon from a
|
||
container port number in the range from 1 to 65535. The
|
||
protocol specifier and its separating colon may be omitted, in
|
||
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>, <option>--network-zone=</option>
|
||
<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). For a list of valid signals, see
|
||
<citerefentry project='man-pages'><refentrytitle>signal</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</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 journaling 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>
|
||
|
||
<para>Note that <option>--link-journal=try-guest</option> is the default if the
|
||
<filename>systemd-nspawn@.service</filename> template unit file 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. The source path may optionally be prefixed with a <literal>+</literal> character. If so, the
|
||
source path is taken relative to the image's root directory. This permits setting up bind mounts within the
|
||
container image. The source path may be specified as empty string, in which case a temporary directory below
|
||
the host's <filename>/var/tmp</filename> directory is used. It is automatically removed when the container is
|
||
shut down. Mount options are comma-separated and currently, only <option>rbind</option> and
|
||
<option>norbind</option> are allowed, controlling whether to create a recursive or a regular bind
|
||
mount. 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>The source paths may optionally be prefixed with <literal>+</literal> character. If so they are taken
|
||
relative to the image's root directory. The uppermost source path may also be specified as empty string, in
|
||
which case a temporary directory below the host's <filename>/var/tmp</filename> is used. The directory is
|
||
removed automatically when the container is shut down. This behaviour is useful in order to make read-only
|
||
container directories writable while the container is running. For example, use the
|
||
<literal>--overlay=+/var::/var</literal> option in order to automatically overlay a writable temporary
|
||
directory on a read-only <filename>/var</filename> directory.</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>-E <replaceable>NAME</replaceable>=<replaceable>VALUE</replaceable></option></term>
|
||
<term><option>--setenv=<replaceable>NAME</replaceable>=<replaceable>VALUE</replaceable></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>--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>.</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
|
||
in read-only mode (the system thus starts up with read-only OS
|
||
image, but pristine state and configuration, any changes
|
||
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>This option provides similar functionality for containers as the <literal>systemd.volatile=</literal>
|
||
kernel command line switch provides for host systems. See
|
||
<citerefentry><refentrytitle>kernel-command-line</refentrytitle><manvolnum>7</manvolnum></citerefentry> for
|
||
details.</para>
|
||
|
||
<para>Note that enabling this setting will only work correctly with operating systems in the container that can
|
||
boot up with only <filename>/usr</filename> mounted, and are able to automatically populate
|
||
<filename>/var</filename>, and also <filename>/etc</filename> in case of
|
||
<literal>--volatile=yes</literal>.</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>
|
||
|
||
<varlistentry>
|
||
<term><option>--notify-ready=</option></term>
|
||
|
||
<listitem><para>Configures support for notifications from the container's init process.
|
||
<option>--notify-ready=</option> takes a boolean (<option>no</option> and <option>yes</option>).
|
||
With option <option>no</option> systemd-nspawn notifies systemd
|
||
with a <literal>READY=1</literal> message when the init process is created.
|
||
With option <option>yes</option> systemd-nspawn waits for the
|
||
<literal>READY=1</literal> message from the init process in the container
|
||
before sending its own to systemd. For more details about notifications
|
||
see <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>).</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/24/CloudImages/x86_64/images/Fedora-Cloud-Base-24-1.2.x86_64.raw.xz
|
||
# systemd-nspawn -M Fedora-Cloud-Base-24-1.2.x86_64.raw</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 snapshot of the host system</title>
|
||
|
||
<programlisting># systemd-nspawn -D / -xb</programlisting>
|
||
|
||
<para>This runs a copy of the host system in a 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>
|
||
|
||
<example>
|
||
<title>Run a container with an OSTree deployment</title>
|
||
|
||
<programlisting># systemd-nspawn -b -i ~/image.raw --pivot-root=/ostree/deploy/$OS/deploy/$CHECKSUM:/sysroot --bind=+/sysroot/ostree/deploy/$OS/var:/var</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>
|