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5a8af538ae
Previously all bind mount mounts were applied in the order specified, followed by all tmpfs mounts in the order specified. This is problematic, if bind mounts shall be placed within tmpfs mounts. This patch hence reworks the custom mount point logic, and alwas applies them in strict prefix-first order. This means the order of mounts specified on the command line becomes irrelevant, the right operation will always be executed. While we are at it this commit also adds native support for overlayfs mounts, as supported by recent kernels.
823 lines
37 KiB
XML
823 lines
37 KiB
XML
<?xml version='1.0'?> <!--*-nxml-*-->
|
||
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
|
||
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
|
||
|
||
<!--
|
||
This file is part of systemd.
|
||
|
||
Copyright 2010 Lennart Poettering
|
||
|
||
systemd is free software; you can redistribute it and/or modify it
|
||
under the terms of the GNU Lesser General Public License as published by
|
||
the Free Software Foundation; either version 2.1 of the License, or
|
||
(at your option) any later version.
|
||
|
||
systemd is distributed in the hope that it will be useful, but
|
||
WITHOUT ANY WARRANTY; without even the implied warranty of
|
||
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
||
Lesser General Public License for more details.
|
||
|
||
You should have received a copy of the GNU Lesser General Public License
|
||
along with systemd; If not, see <http://www.gnu.org/licenses/>.
|
||
-->
|
||
|
||
<refentry id="systemd-nspawn"
|
||
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">-b</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> limits access to various
|
||
kernel interfaces in the container to read-only, such as
|
||
<filename>/sys</filename>, <filename>/proc/sys</filename> or
|
||
<filename>/sys/fs/selinux</filename>. Network interfaces and the
|
||
system clock may not be changed from within the container. Device
|
||
nodes may not be created. The host system cannot be rebooted and
|
||
kernel modules may not be loaded from within the container.</para>
|
||
|
||
<para>Note that even though these security precautions are taken
|
||
<command>systemd-nspawn</command> is not suitable for fully secure
|
||
container setups. Many of the security features may be
|
||
circumvented and are hence primarily useful to avoid accidental
|
||
changes to the host system from the container.</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>Use a tool like
|
||
<citerefentry project='mankier'><refentrytitle>dnf</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
|
||
<citerefentry project='die-net'><refentrytitle>yum</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.</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> command to request an additional login
|
||
prompt 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>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>
|
||
</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>-b</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 as <filename>/var/lib/machines/</filename> suffixed
|
||
by the machine name as specified with
|
||
<option>--machine=</option>. 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>
|
||
subvolume 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, which can be substantially more
|
||
time-consuming. Note that if this option is used the
|
||
container's root directory (in contrast to the template
|
||
directory!) must be located on a <literal>btrfs</literal> file
|
||
system, so that the <literal>btrfs</literal> subvolume may be
|
||
created. 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 <literal>btrfs</literal> snapshot of its root
|
||
directory (as configured with <option>--directory=</option>),
|
||
that is removed immediately when the container terminates.
|
||
This option is only supported if the root file system is
|
||
<literal>btrfs</literal>. May not be specified together with
|
||
<option>--image=</option> or
|
||
<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>
|
||
</itemizedlist>
|
||
|
||
<para>Any other partitions, such as foreign partitions, swap
|
||
partitions or EFI system partitions are not mounted. May not
|
||
be specified together with <option>--directory=</option>,
|
||
<option>--template=</option> or
|
||
<option>--ephemeral</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 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>--share-system</option>.
|
||
</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. </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-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>. Note that
|
||
<option>--network-veth</option> implies
|
||
<option>--private-network</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
|
||
bridge. Note that <option>--network-bridge=</option> implies
|
||
<option>--network-veth</option>. If this option is used, the
|
||
host side of the Ethernet link will use the
|
||
<literal>vb-</literal> prefix instead of
|
||
<literal>ve-</literal>.</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 ommitted, in which case the
|
||
same port as the host port is implied. This option is only
|
||
supported if private networking is used, such as
|
||
<option>--network-veth</option> or
|
||
<option>--network-bridge=</option>.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><option>-Z</option></term>
|
||
<term><option>--selinux-context=</option></term>
|
||
|
||
<listitem><para>Sets the SELinux security context to be used
|
||
to label processes in the container.</para>
|
||
</listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><option>-L</option></term>
|
||
<term><option>--selinux-apifs-context=</option></term>
|
||
|
||
<listitem><para>Sets the SELinux security context to be used
|
||
to label files in the virtual API file systems in the
|
||
container.</para>
|
||
</listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><option>--capability=</option></term>
|
||
|
||
<listitem><para>List one or more additional capabilities to
|
||
grant the container. Takes a comma-separated list of
|
||
capability names, see
|
||
<citerefentry project='man-pages'><refentrytitle>capabilities</refentrytitle><manvolnum>7</manvolnum></citerefentry>
|
||
for more information. Note that the following capabilities
|
||
will be granted in any way: CAP_CHOWN, CAP_DAC_OVERRIDE,
|
||
CAP_DAC_READ_SEARCH, CAP_FOWNER, CAP_FSETID, CAP_IPC_OWNER,
|
||
CAP_KILL, CAP_LEASE, CAP_LINUX_IMMUTABLE,
|
||
CAP_NET_BIND_SERVICE, CAP_NET_BROADCAST, CAP_NET_RAW,
|
||
CAP_SETGID, CAP_SETFCAP, CAP_SETPCAP, CAP_SETUID,
|
||
CAP_SYS_ADMIN, CAP_SYS_CHROOT, CAP_SYS_NICE, CAP_SYS_PTRACE,
|
||
CAP_SYS_TTY_CONFIG, CAP_SYS_RESOURCE, CAP_SYS_BOOT,
|
||
CAP_AUDIT_WRITE, CAP_AUDIT_CONTROL. Also CAP_NET_ADMIN is
|
||
retained if <option>--private-network</option> is specified.
|
||
If the special value <literal>all</literal> is passed, all
|
||
capabilities are retained.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><option>--drop-capability=</option></term>
|
||
|
||
<listitem><para>Specify one or more additional capabilities to
|
||
drop for the container. This allows running the container with
|
||
fewer capabilities than the default (see
|
||
above).</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><option>--kill-signal=</option></term>
|
||
|
||
<listitem><para>Specify the process signal to send to the
|
||
container's PID 1 when nspawn itself receives SIGTERM, in
|
||
order to trigger an orderly shutdown of the
|
||
container. Defaults to SIGRTMIN+3 if <option>--boot</option>
|
||
is used (on systemd-compatible init systems SIGRTMIN+3
|
||
triggers an orderly shutdown). Takes a signal name like
|
||
<literal>SIGHUP</literal>, <literal>SIGTERM</literal> or
|
||
similar as argument.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><option>--link-journal=</option></term>
|
||
|
||
<listitem><para>Control whether the container's journal shall
|
||
be made visible to the host system. If enabled, allows viewing
|
||
the container's journal files from the host (but not vice
|
||
versa). Takes one of <literal>no</literal>,
|
||
<literal>host</literal>, <literal>try-host</literal>,
|
||
<literal>guest</literal>, <literal>try-guest</literal>,
|
||
<literal>auto</literal>. If <literal>no</literal>, the journal
|
||
is not linked. If <literal>host</literal>, the journal files
|
||
are stored on the host file system (beneath
|
||
<filename>/var/log/journal/<replaceable>machine-id</replaceable></filename>)
|
||
and the subdirectory is bind-mounted into the container at the
|
||
same location. If <literal>guest</literal>, the journal files
|
||
are stored on the guest file system (beneath
|
||
<filename>/var/log/journal/<replaceable>machine-id</replaceable></filename>)
|
||
and the subdirectory is symlinked into the host at the same
|
||
location. <literal>try-host</literal> and
|
||
<literal>try-guest</literal> do the same but do not fail if
|
||
the host does not have persistent journalling enabled. If
|
||
<literal>auto</literal> (the default), and the right
|
||
subdirectory of <filename>/var/log/journal</filename> exists,
|
||
it will be bind mounted into the container. If the
|
||
subdirectory does not exist, no linking is performed.
|
||
Effectively, booting a container once with
|
||
<literal>guest</literal> or <literal>host</literal> will link
|
||
the journal persistently if further on the default of
|
||
<literal>auto</literal> is used.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><option>-j</option></term>
|
||
|
||
<listitem><para>Equivalent to
|
||
<option>--link-journal=try-guest</option>.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><option>--read-only</option></term>
|
||
|
||
<listitem><para>Mount the root file system read-only for the
|
||
container.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><option>--bind=</option></term>
|
||
<term><option>--bind-ro=</option></term>
|
||
|
||
<listitem><para>Bind mount a file or directory from the host
|
||
into the container. Either takes 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. 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>.</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>If three or more paths are specified, then the last
|
||
specified path is the destination mount point in the
|
||
container, all paths specified before refer to directory trees
|
||
on the host and are combined in the specified order into one
|
||
overlay file system. The left-most path is hence the lowest
|
||
directory tree, the second-to-last path the highest directory
|
||
tree in the stacking order. If <option>--overlay-ro=</option>
|
||
is used instead of <option>--overlay=</option> a read-only
|
||
overlay file system is created. If a writable overlay file
|
||
system is created all changes made to it are written to the
|
||
highest directory tree in the stacking order, i.e. the
|
||
second-to-last specified.</para>
|
||
|
||
<para>If only two paths are specified, then the second
|
||
specified path is used both as the top-level directory tree in
|
||
the stacking order as seen from the host, as well as the mount
|
||
point for the overlay file system in the container. At least
|
||
two paths have to be specified.</para>
|
||
|
||
<para>For details about overlay file systems, see <ulink
|
||
url="https://www.kernel.org/doc/Documentation/filesystems/overlayfs.txt">overlayfs.txt</ulink>. Note
|
||
that the semantics of overlay file systems are substantially
|
||
different from normal file systems, in particular regarding
|
||
reported device and inode information. Device and inode
|
||
information may change for a file while it is being written
|
||
to, and processes might see out-of-date versions of files at
|
||
times. Note that this switch automatically derives the
|
||
<literal>workdir=</literal> mount option for the overlay file
|
||
system from the top-level directory tree, making it a sibling
|
||
of it. It is hence essential that the top-level directory tree
|
||
is not a mount point itself (since the working directory must
|
||
be on the same file system as the top-most directory
|
||
tree). Also note that the <literal>lowerdir=</literal> mount
|
||
option receives the paths to stack in the opposite order of
|
||
this switch.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><option>--setenv=</option></term>
|
||
|
||
<listitem><para>Specifies an environment variable assignment
|
||
to pass to the init process in the container, in the format
|
||
<literal>NAME=VALUE</literal>. This may be used to override
|
||
the default variables or to set additional variables. This
|
||
parameter may be used more than once.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><option>--share-system</option></term>
|
||
|
||
<listitem><para>Allows the container to share certain system
|
||
facilities with the host. More specifically, this turns off
|
||
PID namespacing, UTS namespacing and IPC namespacing, and thus
|
||
allows the guest to see and interact more easily with
|
||
processes outside of the container. Note that using this
|
||
option makes it impossible to start up a full Operating System
|
||
in the container, as an init system cannot operate in this
|
||
mode. It is only useful to run specific programs or
|
||
applications this way, without involving an init system in the
|
||
container. This option implies <option>--register=no</option>.
|
||
This option may not be combined with
|
||
<option>--boot</option>.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><option>--register=</option></term>
|
||
|
||
<listitem><para>Controls whether the container is registered
|
||
with
|
||
<citerefentry><refentrytitle>systemd-machined</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
|
||
Takes a boolean argument, defaults to <literal>yes</literal>.
|
||
This option should be enabled when the container runs a full
|
||
Operating System (more specifically: an init system), and is
|
||
useful to ensure that the container is accessible via
|
||
<citerefentry><refentrytitle>machinectl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
|
||
and shown by tools such as
|
||
<citerefentry project='man-pages'><refentrytitle>ps</refentrytitle><manvolnum>1</manvolnum></citerefentry>.
|
||
If the container does not run an init system, it is
|
||
recommended to set this option to <literal>no</literal>. Note
|
||
that <option>--share-system</option> implies
|
||
<option>--register=no</option>. </para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><option>--keep-unit</option></term>
|
||
|
||
<listitem><para>Instead of creating a transient scope unit to
|
||
run the container in, simply register the service or scope
|
||
unit <command>systemd-nspawn</command> has been invoked in
|
||
with
|
||
<citerefentry><refentrytitle>systemd-machined</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
|
||
This has no effect if <option>--register=no</option> is used.
|
||
This switch should be used if
|
||
<command>systemd-nspawn</command> is invoked from within a
|
||
service unit, and the service unit's sole purpose is to run a
|
||
single <command>systemd-nspawn</command> container. This
|
||
option is not available if run from a user
|
||
session.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><option>--personality=</option></term>
|
||
|
||
<listitem><para>Control the architecture ("personality")
|
||
reported by
|
||
<citerefentry project='man-pages'><refentrytitle>uname</refentrytitle><manvolnum>2</manvolnum></citerefentry>
|
||
in the container. Currently, only <literal>x86</literal> and
|
||
<literal>x86-64</literal> are supported. This is useful when
|
||
running a 32-bit container on a 64-bit host. If this setting
|
||
is not used, the personality reported in the container is the
|
||
same as the one reported on the host.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><option>-q</option></term>
|
||
<term><option>--quiet</option></term>
|
||
|
||
<listitem><para>Turns off any status output by the tool
|
||
itself. When this switch is used, the only output from nspawn
|
||
will be the console output of the container OS
|
||
itself.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><option>--volatile</option><replaceable>=MODE</replaceable></term>
|
||
|
||
<listitem><para>Boots the container in volatile mode. When no
|
||
mode parameter is passed or when mode is specified as
|
||
<literal>yes</literal> full volatile mode is enabled. This
|
||
means the root directory is mounted as mostly unpopulated
|
||
<literal>tmpfs</literal> instance, and
|
||
<filename>/usr</filename> from the OS tree is mounted into it,
|
||
read-only (the system thus starts up with read-only OS
|
||
resources, but pristine state and configuration, any changes
|
||
to the either are lost on shutdown). When the mode parameter
|
||
is specified as <literal>state</literal> the OS tree is
|
||
mounted read-only, but <filename>/var</filename> is mounted as
|
||
<literal>tmpfs</literal> instance into it (the system thus
|
||
starts up with read-only OS resources and configuration, but
|
||
pristine state, any changes to the latter are lost on
|
||
shutdown). When the mode parameter is specified as
|
||
<literal>no</literal> (the default) the whole OS tree is made
|
||
available writable.</para>
|
||
|
||
<para>Note that setting this to <literal>yes</literal> or
|
||
<literal>state</literal> will only work correctly with
|
||
operating systems in the container that can boot up with only
|
||
<filename>/usr</filename> mounted, and are able to populate
|
||
<filename>/var</filename> automatically, as
|
||
needed.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<xi:include href="standard-options.xml" xpointer="help" />
|
||
<xi:include href="standard-options.xml" xpointer="version" />
|
||
</variablelist>
|
||
|
||
</refsect1>
|
||
|
||
<refsect1>
|
||
<title>Examples</title>
|
||
|
||
<example>
|
||
<title>Download a Fedora image and start a shell in it</title>
|
||
|
||
<programlisting># machinectl pull-raw --verify=no http://ftp.halifax.rwth-aachen.de/fedora/linux/releases/21/Cloud/Images/x86_64/Fedora-Cloud-Base-20141203-21.x86_64.raw.xz
|
||
# systemd-nspawn -M Fedora-Cloud-Base-20141203-21</programlisting>
|
||
|
||
<para>This downloads an image using
|
||
<citerefentry><refentrytitle>machinectl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
|
||
and opens a shell in it.</para>
|
||
</example>
|
||
|
||
<example>
|
||
<title>Build and boot a minimal Fedora distribution in a container</title>
|
||
|
||
<programlisting># dnf -y --releasever=21 --nogpg --installroot=/srv/mycontainer --disablerepo='*' --enablerepo=fedora install systemd passwd dnf fedora-release vim-minimal
|
||
# systemd-nspawn -bD /srv/mycontainer</programlisting>
|
||
|
||
<para>This installs a minimal Fedora distribution into the
|
||
directory <filename noindex='true'>/srv/mycontainer/</filename>
|
||
and then boots an OS in a namespace container in it.</para>
|
||
</example>
|
||
|
||
<example>
|
||
<title>Spawn a shell in a container of a minimal Debian unstable distribution</title>
|
||
|
||
<programlisting># debootstrap --arch=amd64 unstable ~/debian-tree/
|
||
# systemd-nspawn -D ~/debian-tree/</programlisting>
|
||
|
||
<para>This installs a minimal Debian unstable distribution into
|
||
the directory <filename>~/debian-tree/</filename> and then
|
||
spawns a shell in a namespace container in it.</para>
|
||
</example>
|
||
|
||
<example>
|
||
<title>Boot a minimal Arch Linux distribution in a container</title>
|
||
|
||
<programlisting># pacstrap -c -d ~/arch-tree/ base
|
||
# systemd-nspawn -bD ~/arch-tree/</programlisting>
|
||
|
||
<para>This installs a minimal Arch Linux distribution into the
|
||
directory <filename>~/arch-tree/</filename> and then boots an OS
|
||
in a namespace container in it.</para>
|
||
</example>
|
||
|
||
<example>
|
||
<title>Boot into an ephemeral <literal>btrfs</literal> snapshot of the host system</title>
|
||
|
||
<programlisting># systemd-nspawn -D / -xb</programlisting>
|
||
|
||
<para>This runs a copy of the host system in a
|
||
<literal>btrfs</literal> snapshot which is removed immediately
|
||
when the container exits. All file system changes made during
|
||
runtime will be lost on shutdown, hence.</para>
|
||
</example>
|
||
|
||
<example>
|
||
<title>Run a container with SELinux sandbox security contexts</title>
|
||
|
||
<programlisting># chcon system_u:object_r:svirt_sandbox_file_t:s0:c0,c1 -R /srv/container
|
||
# systemd-nspawn -L system_u:object_r:svirt_sandbox_file_t:s0:c0,c1 -Z system_u:system_r:svirt_lxc_net_t:s0:c0,c1 -D /srv/container /bin/sh</programlisting>
|
||
</example>
|
||
</refsect1>
|
||
|
||
<refsect1>
|
||
<title>Exit status</title>
|
||
|
||
<para>The exit code of the program executed in the container is
|
||
returned.</para>
|
||
</refsect1>
|
||
|
||
<refsect1>
|
||
<title>See Also</title>
|
||
<para>
|
||
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
|
||
<citerefentry 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>yum</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>
|