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diff --git a/src/systemd-nspawn/systemd-nspawn.xml b/src/systemd-nspawn/systemd-nspawn.xml new file mode 100644 index 0000000000..c449edee89 --- /dev/null +++ b/src/systemd-nspawn/systemd-nspawn.xml @@ -0,0 +1,1088 @@ +<?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> + 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>-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>-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. Mount options are + comma-separated and currently, only "rbind" and "norbind" + are allowed. Defaults to "rbind". Backslash escapes are interpreted, so + <literal>\:</literal> may be used to embed colons in either path. + This option may be specified multiple times for + creating multiple independent bind mount points. The + <option>--bind-ro=</option> option creates read-only bind + mounts.</para></listitem> + </varlistentry> + + <varlistentry> + <term><option>--tmpfs=</option></term> + + <listitem><para>Mount a tmpfs file system into the container. + Takes a single absolute path argument that specifies where to + mount the tmpfs instance to (in which case the directory + access mode will be chosen as 0755, owned by root/root), or + optionally a colon-separated pair of path and mount option + string that is used for mounting (in which case the kernel + default for access mode and owner will be chosen, unless + otherwise specified). This option is particularly useful for + mounting directories such as <filename>/var</filename> as + tmpfs, to allow state-less systems, in particular when + combined with <option>--read-only</option>. + Backslash escapes are interpreted in the path, so + <literal>\:</literal> may be used to embed colons in the path. + </para></listitem> + </varlistentry> + + <varlistentry> + <term><option>--overlay=</option></term> + <term><option>--overlay-ro=</option></term> + + <listitem><para>Combine multiple directory trees into one + overlay file system and mount it into the container. Takes a + list of colon-separated paths to the directory trees to + combine and the destination mount point.</para> + + <para>Backslash escapes are interpreted in the paths, so + <literal>\:</literal> may be used to embed colons in the paths. + </para> + + <para>If three or more paths are specified, then the last + specified path is the destination mount point in the + container, all paths specified before refer to directory trees + on the host and are combined in the specified order into one + overlay file system. The left-most path is hence the lowest + directory tree, the second-to-last path the highest directory + tree in the stacking order. If <option>--overlay-ro=</option> + is used instead of <option>--overlay=</option>, a read-only + overlay file system is created. If a writable overlay file + system is created, all changes made to it are written to the + highest directory tree in the stacking order, i.e. the + second-to-last specified.</para> + + <para>If only two paths are specified, then the second + specified path is used both as the top-level directory tree in + the stacking order as seen from the host, as well as the mount + point for the overlay file system in the container. At least + two paths have to be specified.</para> + + <para>For details about overlay file systems, see <ulink + url="https://www.kernel.org/doc/Documentation/filesystems/overlayfs.txt">overlayfs.txt</ulink>. Note + that the semantics of overlay file systems are substantially + different from normal file systems, in particular regarding + reported device and inode information. Device and inode + information may change for a file while it is being written + to, and processes might see out-of-date versions of files at + times. Note that this switch automatically derives the + <literal>workdir=</literal> mount option for the overlay file + system from the top-level directory tree, making it a sibling + of it. It is hence essential that the top-level directory tree + is not a mount point itself (since the working directory must + be on the same file system as the top-most directory + tree). Also note that the <literal>lowerdir=</literal> mount + option receives the paths to stack in the opposite order of + this switch.</para></listitem> + </varlistentry> + + <varlistentry> + <term><option>-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>Note that setting this to <option>yes</option> or + <option>state</option> will only work correctly with + operating systems in the container that can boot up with only + <filename>/usr</filename> mounted, and are able to populate + <filename>/var</filename> automatically, as + needed.</para></listitem> + </varlistentry> + + <varlistentry> + <term><option>--settings=</option><replaceable>MODE</replaceable></term> + + <listitem><para>Controls whether + <command>systemd-nspawn</command> shall search for and use + additional per-container settings from + <filename>.nspawn</filename> files. Takes a boolean or the + special values <option>override</option> or + <option>trusted</option>.</para> + + <para>If enabled (the default), a settings file named after the + machine (as specified with the <option>--machine=</option> + setting, or derived from the directory or image file name) + with the suffix <filename>.nspawn</filename> is searched in + <filename>/etc/systemd/nspawn/</filename> and + <filename>/run/systemd/nspawn/</filename>. If it is found + there, its settings are read and used. If it is not found + there, it is subsequently searched in the same directory as the + image file or in the immediate parent of the root directory of + the container. In this case, if the file is found, its settings + will be also read and used, but potentially unsafe settings + are ignored. Note that in both these cases, settings on the + command line take precedence over the corresponding settings + from loaded <filename>.nspawn</filename> files, if both are + specified. Unsafe settings are considered all settings that + elevate the container's privileges or grant access to + additional resources such as files or directories of the + host. For details about the format and contents of + <filename>.nspawn</filename> files, consult + <citerefentry><refentrytitle>systemd.nspawn</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para> + + <para>If this option is set to <option>override</option>, the + file is searched, read and used the same way, however, the order of + precedence is reversed: settings read from the + <filename>.nspawn</filename> file will take precedence over + the corresponding command line options, if both are + specified.</para> + + <para>If this option is set to <option>trusted</option>, the + file is searched, read and used the same way, but regardless + of being found in <filename>/etc/systemd/nspawn/</filename>, + <filename>/run/systemd/nspawn/</filename> or next to the image + file or container root directory, all settings will take + effect, however, command line arguments still take precedence + over corresponding settings.</para> + + <para>If disabled, no <filename>.nspawn</filename> file is read + and no settings except the ones on the command line are in + effect.</para></listitem> + </varlistentry> + + <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>Build and boot a minimal BLAG distribution in a container</title> + + <programlisting># dnf -y --releasever=210k --installroot=/srv/mycontainer --disablerepo='*' --enablerepo=blag --enablerepo=updates install systemd passwd dnf blag-release vim-minimal +# systemd-nspawn -bD /srv/mycontainer</programlisting> + + <para>This installs a minimal BLAG 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 gNewSense Ucclia distribution</title> + + <programlisting># debootstrap --arch=amd64 ucclia ~/gnewsense-tree/ +# systemd-nspawn -D ~/gnewsense-tree/</programlisting> + + <para>This installs a minimal gNewSense unstable distribution into + the directory <filename>~/gnewsense-tree/</filename> and then + spawns a shell in a namespace container in it.</para> + </example> + + <example> + <title>Boot a minimal Parabola distribution in a container</title> + + <programlisting># pacstrap -c -d ~/parabola-tree/ base +# systemd-nspawn -bD ~/parabola-tree/</programlisting> + + <para>This installs a minimal Parabola distribution into the + directory <filename>~/parabola-tree/</filename> and then boots an OS + in a namespace container in it.</para> + </example> + + <example> + <title>Boot into an ephemeral <literal>btrfs</literal> snapshot of the host system</title> + + <programlisting># systemd-nspawn -D / -xb</programlisting> + + <para>This runs a copy of the host system in a + <literal>btrfs</literal> snapshot which is removed immediately + when the container exits. All file system changes made during + runtime will be lost on shutdown, hence.</para> + </example> + + <example> + <title>Run a container with SELinux sandbox security contexts</title> + + <programlisting># chcon system_u:object_r:svirt_sandbox_file_t:s0:c0,c1 -R /srv/container +# systemd-nspawn -L system_u:object_r:svirt_sandbox_file_t:s0:c0,c1 -Z system_u:system_r:svirt_lxc_net_t:s0:c0,c1 -D /srv/container /bin/sh</programlisting> + </example> + </refsect1> + + <refsect1> + <title>Exit status</title> + + <para>The exit code of the program executed in the container is + returned.</para> + </refsect1> + + <refsect1> + <title>See Also</title> + <para> + <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, + <citerefentry><refentrytitle>systemd.nspawn</refentrytitle><manvolnum>5</manvolnum></citerefentry>, + <citerefentry project='man-pages'><refentrytitle>chroot</refentrytitle><manvolnum>1</manvolnum></citerefentry>, + <citerefentry project='mankier'><refentrytitle>dnf</refentrytitle><manvolnum>8</manvolnum></citerefentry>, + <citerefentry project='die-net'><refentrytitle>debootstrap</refentrytitle><manvolnum>8</manvolnum></citerefentry>, + <citerefentry project='archlinux'><refentrytitle>pacman</refentrytitle><manvolnum>8</manvolnum></citerefentry>, + <citerefentry><refentrytitle>systemd.slice</refentrytitle><manvolnum>5</manvolnum></citerefentry>, + <citerefentry><refentrytitle>machinectl</refentrytitle><manvolnum>1</manvolnum></citerefentry>, + <citerefentry project='man-pages'><refentrytitle>btrfs</refentrytitle><manvolnum>8</manvolnum></citerefentry> + </para> + </refsect1> + +</refentry> |