diff options
Diffstat (limited to 'man/systemd-nspawn.xml')
| -rw-r--r-- | man/systemd-nspawn.xml | 1303 |
1 files changed, 1303 insertions, 0 deletions
diff --git a/man/systemd-nspawn.xml b/man/systemd-nspawn.xml new file mode 100644 index 0000000..ff6b6a9 --- /dev/null +++ b/man/systemd-nspawn.xml @@ -0,0 +1,1303 @@ +<?xml version='1.0'?> +<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" + "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd" [ +<!ENTITY fedora_latest_version "28"> +<!ENTITY fedora_cloud_release "1.1"> +]> + +<!-- + SPDX-License-Identifier: LGPL-2.1+ +--> + +<refentry id="systemd-nspawn" + xmlns:xi="http://www.w3.org/2001/XInclude"> + + <refentryinfo> + <title>systemd-nspawn</title> + <productname>systemd</productname> + </refentryinfo> + + <refmeta> + <refentrytitle>systemd-nspawn</refentrytitle> + <manvolnum>1</manvolnum> + </refmeta> + + <refnamediv> + <refname>systemd-nspawn</refname> + <refpurpose>Spawn a command or OS in a light-weight container</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 OS 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="https://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 program. 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="https://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 program is run as the 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 program 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 program 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 program. 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 program is automatically searched for 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 the 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>--hostname=</option></term> + + <listitem><para>Controls the hostname to set within the container, if different from the machine name. Expects + a valid hostname as argument. If this option is used, the kernel hostname of the container will be set to this + value, otherwise it will be initialized to the machine name as controlled by the <option>--machine=</option> + option described above. The machine name is used for various aspect of identification of the container from the + outside, the kernel hostname configurable with this option is useful for the container to identify itself from + the inside. It is usually a good idea to keep both forms of identification synchronized, in order to avoid + confusion. It is hence recommended to avoid usage of this option, and use <option>--machine=</option> + exclusively. Note that regardless whether the container's hostname is initialized from the name set with + <option>--hostname=</option> or the one set with <option>--machine=</option>, the container can later override + its kernel hostname freely on its own as well.</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>-S</option></term> + <term><option>--slice=</option></term> + + <listitem><para>Make the container part of the specified slice, instead of the default + <filename>machine.slice</filename>. This applies only if the machine is run in its own scope unit, i.e. if + <option>--keep-unit</option> isn't 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 applies only if the + machine is run in its own scope unit, i.e. if <option>--keep-unit</option> isn't 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 container.</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> + + <para>Note that when user namespacing is used file ownership on disk reflects this, and all of the container's + files and directories are owned by the container's effective user and group IDs. This means that copying files + from and to the container image requires correction of the numeric UID/GID values, according to the UID/GID + shift applied.</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>. + If this option is not specified (or implied by one of the options + listed below), the container will have full access to the host network. + </para></listitem> + </varlistentry> + + <varlistentry> + <term><option>--network-namespace-path=</option></term> + + <listitem><para>Takes the path to a file representing a kernel + network namespace that the container shall run in. The specified path + should refer to a (possibly bind-mounted) network namespace file, as + exposed by the kernel below <filename>/proc/$PID/ns/net</filename>. + This makes the container enter the given network namespace. One of the + typical use cases is to give a network namespace under + <filename>/run/netns</filename> created by <citerefentry + project='man-pages'><refentrytitle>ip-netns</refentrytitle><manvolnum>8</manvolnum></citerefentry>, + for example, <option>--network-namespace-path=/run/netns/foo</option>. + Note that this option cannot be used together with other + network-related options, such as <option>--private-network</option> + or <option>--network-interface=</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-zone=</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_AUDIT_CONTROL, CAP_AUDIT_WRITE, CAP_CHOWN, CAP_DAC_OVERRIDE, CAP_DAC_READ_SEARCH, + CAP_FOWNER, CAP_FSETID, CAP_IPC_OWNER, CAP_KILL, CAP_LEASE, CAP_LINUX_IMMUTABLE, + CAP_MKNOD, CAP_NET_BIND_SERVICE, CAP_NET_BROADCAST, CAP_NET_RAW, CAP_SETFCAP, + CAP_SETGID, CAP_SETPCAP, CAP_SETUID, CAP_SYS_ADMIN, CAP_SYS_BOOT, CAP_SYS_CHROOT, + CAP_SYS_NICE, CAP_SYS_PTRACE, CAP_SYS_RESOURCE, CAP_SYS_TTY_CONFIG. 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>--no-new-privileges=</option></term> + + <listitem><para>Takes a boolean argument. Specifies the value of the <constant>PR_SET_NO_NEW_PRIVS</constant> + flag for the container payload. Defaults to off. When turned on the payload code of the container cannot + acquire new privileges, i.e. the "setuid" file bit as well as file system capabilities will not have an effect + anymore. See <citerefentry + project='man-pages'><refentrytitle>prctl</refentrytitle><manvolnum>2</manvolnum></citerefentry> for details + about this flag. </para></listitem> + </varlistentry> + + <varlistentry> + <term><option>--system-call-filter=</option></term> + + <listitem><para>Alter the system call filter applied to containers. Takes a space-separated list of system call + names or group names (the latter prefixed with <literal>@</literal>, as listed by the + <command>syscall-filter</command> command of + <citerefentry><refentrytitle>systemd-analyze</refentrytitle><manvolnum>1</manvolnum></citerefentry>). Passed + system calls will be permitted. The list may optionally be prefixed by <literal>~</literal>, in which case all + listed system calls are prohibited. If this command line option is used multiple times the configured lists are + combined. If both a positive and a negative list (that is one system call list without and one with the + <literal>~</literal> prefix) are configured, the negative list takes precedence over the positive list. Note + that <command>systemd-nspawn</command> always implements a system call whitelist (as opposed to a blacklist), + and this command line option hence adds or removes entries from the default whitelist, depending on the + <literal>~</literal> prefix. Note that the applied system call filter is also altered implicitly if additional + capabilities are passed using the <command>--capabilities=</command>.</para></listitem> + </varlistentry> + + <varlistentry> + <term><option>--rlimit=</option></term> + + <listitem><para>Sets the specified POSIX resource limit for the container payload. Expects an assignment of the + form + <literal><replaceable>LIMIT</replaceable>=<replaceable>SOFT</replaceable>:<replaceable>HARD</replaceable></literal> + or <literal><replaceable>LIMIT</replaceable>=<replaceable>VALUE</replaceable></literal>, where + <replaceable>LIMIT</replaceable> should refer to a resource limit type, such as + <constant>RLIMIT_NOFILE</constant> or <constant>RLIMIT_NICE</constant>. The <replaceable>SOFT</replaceable> and + <replaceable>HARD</replaceable> fields should refer to the numeric soft and hard resource limit values. If the + second form is used, <replaceable>VALUE</replaceable> may specify a value that is used both as soft and hard + limit. In place of a numeric value the special string <literal>infinity</literal> may be used to turn off + resource limiting for the specific type of resource. This command line option may be used multiple times to + control limits on multiple limit types. If used multiple times for the same limit type, the last use + wins. For details about resource limits see <citerefentry + project='man-pages'><refentrytitle>setrlimit</refentrytitle><manvolnum>2</manvolnum></citerefentry>. By default + resource limits for the container's init process (PID 1) are set to the same values the Linux kernel originally + passed to the host init system. Note that some resource limits are enforced on resources counted per user, in + particular <constant>RLIMIT_NPROC</constant>. This means that unless user namespacing is deployed + (i.e. <option>--private-users=</option> is used, see above), any limits set will be applied to the resource + usage of the same user on all local containers as well as the host. This means particular care needs to be + taken with these limits as they might be triggered by possibly less trusted code. Example: + <literal>--rlimit=RLIMIT_NOFILE=8192:16384</literal>.</para></listitem> + </varlistentry> + + <varlistentry> + <term><option>--oom-score-adjust=</option></term> + + <listitem><para>Changes the OOM ("Out Of Memory") score adjustment value for the container payload. This controls + <filename>/proc/self/oom_score_adj</filename> which influences the preference with which this container is + terminated when memory becomes scarce. For details see <citerefentry + project='man-pages'><refentrytitle>proc</refentrytitle><manvolnum>5</manvolnum></citerefentry>. Takes an + integer in the range -1000…1000.</para></listitem> + </varlistentry> + + <varlistentry> + <term><option>--cpu-affinity=</option></term> + + <listitem><para>Controls the CPU affinity of the container payload. Takes a comma separated list of CPU numbers + or number ranges (the latter's start and end value separated by dashes). See <citerefentry + project='man-pages'><refentrytitle>sched_setaffinity</refentrytitle><manvolnum>2</manvolnum></citerefentry> for + details.</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 + <constant>SIGTERM</constant>, in order to trigger an orderly shutdown of the container. Defaults to + <constant>SIGRTMIN+3</constant> if <option>--boot</option> is used (on systemd-compatible init systems + <constant>SIGRTMIN+3</constant> triggers an orderly shutdown). If <option>--boot</option> is not used and this + option is not specified the container's processes are terminated abrubtly via <constant>SIGKILL</constant>. 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>--resolv-conf=</option></term> + + <listitem><para>Configures how <filename>/etc/resolv.conf</filename> inside of the container (i.e. DNS + configuration synchronization from host to container) shall be handled. Takes one of <literal>off</literal>, + <literal>copy-host</literal>, <literal>copy-static</literal>, <literal>bind-host</literal>, + <literal>bind-static</literal>, <literal>delete</literal> or <literal>auto</literal>. If set to + <literal>off</literal> the <filename>/etc/resolv.conf</filename> file in the container is left as it is + included in the image, and neither modified nor bind mounted over. If set to <literal>copy-host</literal>, the + <filename>/etc/resolv.conf</filename> file from the host is copied into the container. Similar, if + <literal>bind-host</literal> is used, the file is bind mounted from the host into the container. If set to + <literal>copy-static</literal> the static <filename>resolv.conf</filename> file supplied with + <citerefentry><refentrytitle>systemd-resolved.service</refentrytitle><manvolnum>8</manvolnum></citerefentry> is + copied into the container, and correspondingly <literal>bind-static</literal> bind mounts it there. If set to + <literal>delete</literal> the <filename>/etc/resolv.conf</filename> file in the container is deleted if it + exists. Finally, if set to <literal>auto</literal> the file is left as it is if private networking is turned on + (see <option>--private-network</option>). Otherwise, if <filename>systemd-resolved.service</filename> is + connectible its static <filename>resolv.conf</filename> file is used, and if not the host's + <filename>/etc/resolv.conf</filename> file is used. In the latter cases the file is copied if the image is + writable, and bind mounted otherwise. It's recommended to use <literal>copy</literal> if the container shall be + able to make changes to the DNS configuration on its own, deviating from the host's settings. Otherwise + <literal>bind</literal> is preferable, as it means direct changes to <filename>/etc/resolv.conf</filename> in + the container are not allowed, as it is a read-only bind mount (but note that if the container has enough + privileges, it might simply go ahead and unmount the bind mount anyway). Note that both if the file is bind + mounted and if it is copied no further propagation of configuration is generally done after the one-time early + initialization (this is because the file is usually updated through copying and renaming). Defaults to + <literal>auto</literal>.</para></listitem> + </varlistentry> + + <varlistentry> + <term><option>--timezone=</option></term> + + <listitem><para>Configures how <filename>/etc/localtime</filename> inside of the container (i.e. local timezone + synchronization from host to container) shall be handled. Takes one of <literal>off</literal>, + <literal>copy</literal>, <literal>bind</literal>, <literal>symlink</literal>, <literal>delete</literal> or + <literal>auto</literal>. If set to <literal>off</literal> the <filename>/etc/localtime</filename> file in the + container is left as it is included in the image, and neither modified nor bind mounted over. If set to + <literal>copy</literal> the <filename>/etc/localtime</filename> file of the host is copied into the + container. Similar, if <literal>bind</literal> is used, it is bind mounted from the host into the container. If + set to <literal>symlink</literal> a symlink from <filename>/etc/localtime</filename> in the container is + created pointing to the matching the timezone file of the container that matches the timezone setting on the + host. If set to <literal>delete</literal> the file in the container is deleted, should it exist. If set to + <literal>auto</literal> and the <filename>/etc/localtime</filename> file of the host is a symlink, then + <literal>symlink</literal> mode is used, and <literal>copy</literal> otherwise, except if the image is + read-only in which case <literal>bind</literal> is used instead. Defaults to + <literal>auto</literal>.</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> + + <para>Note that when this option is used in combination with <option>--private-users</option>, the resulting + mount points will be owned by the <constant>nobody</constant> user. That's because the mount and its files and + directories continue to be owned by the relevant host users and groups, which do not exist in the container, + and thus show up under the wildcard UID 65534 (nobody). If such bind mounts are created, it is recommended to + make them read-only, using <option>--bind-ro=</option>.</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: a system and service manager as PID 1), 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 a service manager, 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 use the service or + scope unit <command>systemd-nspawn</command> has been invoked in. If <option>--register=yes</option> is set + this unit is registered with + <citerefentry><refentrytitle>systemd-machined</refentrytitle><manvolnum>8</manvolnum></citerefentry>. 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> + <para>Note that passing <option>--keep-unit</option> disables the effect of <option>--slice=</option> and + <option>--property=</option>. Use <option>--keep-unit</option> and <option>--register=no</option> in + combination to disable any kind of unit allocation or registration with + <command>systemd-machined</command>.</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 + <ulink url="https://getfedora.org">Fedora</ulink> image and start a shell in it</title> + + <programlisting># machinectl pull-raw --verify=no \ + https://download.fedoraproject.org/pub/fedora/linux/releases/&fedora_latest_version;/Cloud/x86_64/images/Fedora-Cloud-Base-&fedora_latest_version;-&fedora_cloud_release;.x86_64.raw.xz +# systemd-nspawn -M Fedora-Cloud-Base-&fedora_latest_version;-&fedora_cloud_release;.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=&fedora_latest_version; --installroot=/var/lib/machines/f&fedora_latest_version; \ + --disablerepo='*' --enablerepo=fedora --enablerepo=updates install \ + systemd passwd dnf fedora-release vim-minimal +# systemd-nspawn -bD /var/lib/machines/f&fedora_latest_version;</programlisting> + + <para>This installs a minimal Fedora distribution into the + directory <filename noindex='true'>/var/lib/machines/f&fedora_latest_version;</filename> + and then boots an OS in a namespace container in it. Because the installation + is located underneath the standard <filename>/var/lib/machines/</filename> + directory, it is also possible to start the machine using + <command>systemd-nspawn -M f&fedora_latest_version;</command>.</para> + </example> + + <example> + <title>Spawn a shell in a container of a minimal Debian unstable distribution</title> + + <programlisting># debootstrap 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> + + <para><command>debootstrap</command> supports + <ulink url="https://www.debian.org">Debian</ulink>, + <ulink url="https://www.ubuntu.com">Ubuntu</ulink>, + and <ulink url="https://www.tanglu.org">Tanglu</ulink> + out of the box, so the same command can be used to install any of those. For other + distributions from the Debian family, a mirror has to be specified, see + <citerefentry project='die-net'><refentrytitle>debootstrap</refentrytitle><manvolnum>8</manvolnum></citerefentry>. + </para> + </example> + + <example> + <title>Boot a minimal + <ulink url="https://www.archlinux.org">Arch Linux</ulink> 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>Install the + <ulink url="https://software.opensuse.org/distributions/tumbleweed">OpenSUSE Tumbleweed</ulink> + rolling distribution</title> + + <programlisting># zypper --root=/var/lib/machines/tumbleweed ar -c \ + https://download.opensuse.org/tumbleweed/repo/oss tumbleweed +# zypper --root=/var/lib/machines/tumbleweed refresh +# zypper --root=/var/lib/machines/tumbleweed install --no-recommends \ + systemd shadow zypper openSUSE-release vim +# systemd-nspawn -M tumbleweed passwd root +# systemd-nspawn -M tumbleweed -b</programlisting> + </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 project='mankier'><refentrytitle>zypper</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> |