1135 lines
61 KiB
XML
1135 lines
61 KiB
XML
<?xml version='1.0'?> <!--*- Mode: nxml; nxml-child-indent: 2; indent-tabs-mode: nil -*-->
|
||
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
|
||
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
|
||
|
||
<!--
|
||
This file is part of systemd.
|
||
|
||
Copyright 2010 Lennart Poettering
|
||
|
||
systemd is free software; you can redistribute it and/or modify it
|
||
under the terms of the GNU Lesser General Public License as published by
|
||
the Free Software Foundation; either version 2.1 of the License, or
|
||
(at your option) any later version.
|
||
|
||
systemd is distributed in the hope that it will be useful, but
|
||
WITHOUT ANY WARRANTY; without even the implied warranty of
|
||
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
||
Lesser General Public License for more details.
|
||
|
||
You should have received a copy of the GNU Lesser General Public License
|
||
along with systemd; If not, see <http://www.gnu.org/licenses/>.
|
||
-->
|
||
|
||
<refentry id="systemd-nspawn"
|
||
xmlns:xi="http://www.w3.org/2001/XInclude">
|
||
|
||
<refentryinfo>
|
||
<title>systemd-nspawn</title>
|
||
<productname>systemd</productname>
|
||
|
||
<authorgroup>
|
||
<author>
|
||
<contrib>Developer</contrib>
|
||
<firstname>Lennart</firstname>
|
||
<surname>Poettering</surname>
|
||
<email>lennart@poettering.net</email>
|
||
</author>
|
||
</authorgroup>
|
||
</refentryinfo>
|
||
|
||
<refmeta>
|
||
<refentrytitle>systemd-nspawn</refentrytitle>
|
||
<manvolnum>1</manvolnum>
|
||
</refmeta>
|
||
|
||
<refnamediv>
|
||
<refname>systemd-nspawn</refname>
|
||
<refpurpose>Spawn a namespace container for debugging, testing and building</refpurpose>
|
||
</refnamediv>
|
||
|
||
<refsynopsisdiv>
|
||
<cmdsynopsis>
|
||
<command>systemd-nspawn</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>
|
||
<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
|
||
container. In many ways it is similar to <citerefentry
|
||
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
|
||
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
|
||
tree is automatically searched for in a couple of locations, most importantly in
|
||
<filename>/var/lib/machines</filename>, the suggested directory to place container images installed on the
|
||
system.</para>
|
||
|
||
<para>In contrast to <citerefentry
|
||
project='man-pages'><refentrytitle>chroot</refentrytitle><manvolnum>1</manvolnum></citerefentry> <command>systemd-nspawn</command>
|
||
may be used to boot full Linux-based operating systems in a container.</para>
|
||
|
||
<para><command>systemd-nspawn</command> limits access to various kernel interfaces in the container to read-only,
|
||
such as <filename>/sys</filename>, <filename>/proc/sys</filename> or <filename>/sys/fs/selinux</filename>. The
|
||
host's network interfaces and the system clock may not be changed from within the container. Device nodes may not
|
||
be created. The host system cannot be rebooted and kernel modules may not be loaded from within the
|
||
container.</para>
|
||
|
||
<para>Use a tool like <citerefentry
|
||
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
|
||
set up an OS directory tree suitable as file system hierarchy for <command>systemd-nspawn</command> containers. See
|
||
the Examples section below for details on suitable invocation of these commands.</para>
|
||
|
||
<para>As a safety check <command>systemd-nspawn</command> will verify the existence of
|
||
<filename>/usr/lib/os-release</filename> or <filename>/etc/os-release</filename> in the container tree before
|
||
starting the container (see
|
||
<citerefentry><refentrytitle>os-release</refentrytitle><manvolnum>5</manvolnum></citerefentry>). It might be
|
||
necessary to add this file to the container 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
|
||
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>
|
||
specification.</para>
|
||
|
||
<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
|
||
keeps track of running containers, and provides programming interfaces to interact with them.</para>
|
||
</refsect1>
|
||
|
||
<refsect1>
|
||
<title>Options</title>
|
||
|
||
<para>If option <option>-b</option> is specified, the arguments
|
||
are used as arguments for the init binary. Otherwise,
|
||
<replaceable>COMMAND</replaceable> specifies the program to launch
|
||
in the container, and the remaining arguments are used as
|
||
arguments for this program. If <option>--boot</option> is not used and
|
||
no arguments are specified, a shell is launched in the
|
||
container.</para>
|
||
|
||
<para>The following options are understood:</para>
|
||
|
||
<variablelist>
|
||
<varlistentry>
|
||
<term><option>-D</option></term>
|
||
<term><option>--directory=</option></term>
|
||
|
||
<listitem><para>Directory to use as file system root for the
|
||
container.</para>
|
||
|
||
<para>If neither <option>--directory=</option>, nor
|
||
<option>--image=</option> is specified the directory is
|
||
determined by searching for a directory named the same as the
|
||
machine name specified with <option>--machine=</option>. See
|
||
<citerefentry><refentrytitle>machinectl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
|
||
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
|
||
be used. May not be specified together with
|
||
<option>--image=</option>.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><option>--template=</option></term>
|
||
|
||
<listitem><para>Directory or <literal>btrfs</literal> subvolume to use as template for the container's root
|
||
directory. If this is specified and the container's root directory (as configured by
|
||
<option>--directory=</option>) does not yet exist it is created as <literal>btrfs</literal> snapshot (if
|
||
supported) or plain directory (otherwise) and populated from this template tree. Ideally, the specified
|
||
template path refers to the root of a <literal>btrfs</literal> subvolume, in which case a simple copy-on-write
|
||
snapshot is taken, and populating the root directory is instant. If the specified template path does not refer
|
||
to the root of a <literal>btrfs</literal> subvolume (or not even to a <literal>btrfs</literal> file system at
|
||
all), the tree is copied (though possibly in a copy-on-write scheme — if the file system supports that), which
|
||
can be substantially more time-consuming. May not be specified together with <option>--image=</option> or
|
||
<option>--ephemeral</option>.</para>
|
||
|
||
<para>Note that this switch leaves host name, machine ID and
|
||
all other settings that could identify the instance
|
||
unmodified.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><option>-x</option></term>
|
||
<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
|
||
<option>--template=</option>.</para>
|
||
<para>Note that this switch leaves host name, machine ID and
|
||
all other settings that could identify the instance
|
||
unmodified.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><option>-i</option></term>
|
||
<term><option>--image=</option></term>
|
||
|
||
<listitem><para>Disk image to mount the root directory for the
|
||
container from. Takes a path to a regular file or to a block
|
||
device node. The file or block device must contain
|
||
either:</para>
|
||
|
||
<itemizedlist>
|
||
<listitem><para>An MBR partition table with a single
|
||
partition of type 0x83 that is marked
|
||
bootable.</para></listitem>
|
||
|
||
<listitem><para>A GUID partition table (GPT) with a single
|
||
partition of type
|
||
0fc63daf-8483-4772-8e79-3d69d8477de4.</para></listitem>
|
||
|
||
<listitem><para>A GUID partition table (GPT) with a marked
|
||
root partition which is mounted as the root directory of the
|
||
container. Optionally, GPT images may contain a home and/or
|
||
a server data partition which are mounted to the appropriate
|
||
places in the container. All these partitions must be
|
||
identified by the partition types defined by the <ulink
|
||
url="http://www.freedesktop.org/wiki/Specifications/DiscoverablePartitionsSpec/">Discoverable
|
||
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 256 bits (and hence 64
|
||
formatted hexadecimal characters) long (in case of SHA256 for example). If this option is not specified, but
|
||
the image file carries the <literal>user.verity.roothash</literal> extended file attribute (see <citerefentry
|
||
project='man-pages'><refentrytitle>xattr</refentrytitle><manvolnum>7</manvolnum></citerefentry>), then the root
|
||
hash is read from it, also as formatted hexadecimal characters. If the extended file attribute is not found (or
|
||
is not supported by the underlying file system), 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, also as formatted hexadecimal characters.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><option>-a</option></term>
|
||
<term><option>--as-pid2</option></term>
|
||
|
||
<listitem><para>Invoke the shell or specified program as process ID (PID) 2 instead of PID 1 (init). By
|
||
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
|
||
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
|
||
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>
|
||
<term><option>--boot</option></term>
|
||
|
||
<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>
|