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7732f92bad
This adds a new switch --as-pid2, which allows running commands as PID 2, while a stub init process is run as PID 1. This is useful in order to run arbitrary commands in a container, as PID1's semantics are different from all other processes regarding reaping of unknown children or signal handling.
415 lines
18 KiB
XML
415 lines
18 KiB
XML
<?xml version='1.0'?> <!--*- Mode: nxml; nxml-child-indent: 2; indent-tabs-mode: nil -*-->
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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
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"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd" [
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<!ENTITY % entities SYSTEM "custom-entities.ent" >
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%entities;
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]>
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<!--
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This file is part of systemd.
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Copyright 2015 Lennart Poettering
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systemd is free software; you can redistribute it and/or modify it
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under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or
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(at your option) any later version.
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systemd is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with systemd; If not, see <http://www.gnu.org/licenses/>.
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-->
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<refentry id="systemd.nspawn">
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<refentryinfo>
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<title>systemd.nspawn</title>
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<productname>systemd</productname>
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<authorgroup>
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<author>
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<contrib>Developer</contrib>
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<firstname>Lennart</firstname>
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<surname>Poettering</surname>
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<email>lennart@poettering.net</email>
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</author>
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</authorgroup>
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</refentryinfo>
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<refmeta>
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<refentrytitle>systemd.nspawn</refentrytitle>
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<manvolnum>5</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>systemd.nspawn</refname>
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<refpurpose>Container settings</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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<para><filename>/etc/systemd/nspawn/<replaceable>machine</replaceable>.nspawn</filename></para>
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<para><filename>/run/systemd/nspawn/<replaceable>machine</replaceable>.nspawn</filename></para>
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<para><filename>/var/lib/machines/<replaceable>machine</replaceable>.nspawn</filename></para>
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</refsynopsisdiv>
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<refsect1>
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<title>Description</title>
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<para>An nspawn container settings file (suffix
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<filename>.nspawn</filename>) encodes additional runtime
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information about a local container, and is searched, read and
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used by
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<citerefentry><refentrytitle>systemd-nspawn</refentrytitle><manvolnum>1</manvolnum></citerefentry>
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when starting a container. Files of this type are named after the
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containers they define settings for. They are optional, and only
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required for containers whose execution environment shall differ
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from the defaults. Files of this type mostly contain settings that
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may also be set on the <command>systemd-nspawn</command> command
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line, and make it easier to persistently attach specific settings
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to specific containers. The syntax of these files is inspired by
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<filename>.desktop</filename> files following the <ulink
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url="http://standards.freedesktop.org/desktop-entry-spec/latest/">XDG
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Desktop Entry Specification</ulink>, which in turn are inspired by
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Microsoft Windows <filename>.ini</filename> files.</para>
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<para>Boolean arguments used in these settings files can be
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written in various formats. For positive settings, the strings
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<option>1</option>, <option>yes</option>, <option>true</option>
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and <option>on</option> are equivalent. For negative settings, the
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strings <option>0</option>, <option>no</option>,
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<option>false</option> and <option>off</option> are
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equivalent.</para>
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<para>Empty lines and lines starting with # or ; are
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ignored. This may be used for commenting. Lines ending
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in a backslash are concatenated with the following
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line while reading and the backslash is replaced by a
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space character. This may be used to wrap long lines.</para>
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</refsect1>
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<refsect1>
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<title><filename>.nspawn</filename> File Discovery</title>
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<para>Files are searched by appending the
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<filename>.nspawn</filename> suffix to the machine name of the
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container, as specified with the <option>--machine=</option>
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switch of <command>systemd-nspawn</command>, or derived from the
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directory or image file name. This file is first searched in
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<filename>/etc/systemd/nspawn/</filename> and
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<filename>/run/systemd/nspawn/</filename>. If found in these
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directories, its settings are read and all of them take full effect
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(but are possibly overridden by corresponding command line
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arguments). If not found, the file will then be searched next to
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the image file or in the immediate parent of the root directory of
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the container. If the file is found there, only a subset of the
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settings will take effect however. All settings that possibly
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elevate privileges or grant additional access to resources of the
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host (such as files or directories) are ignored. To which options
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this applies is documented below.</para>
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<para>Persistent settings files created and maintained by the
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administrator (and thus trusted) should be placed in
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<filename>/etc/systemd/nspawn/</filename>, while automatically
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downloaded (and thus potentially untrusted) settings files are
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placed in <filename>/var/lib/machines/</filename> instead (next to
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the container images), where their security impact is limited. In
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order to add privileged settings to <filename>.nspawn</filename>
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files acquired from the image vendor, it is recommended to copy the
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settings files into <filename>/etc/systemd/nspawn/</filename> and
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edit them there, so that the privileged options become
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available. The precise algorithm for how the files are searched and
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interpreted may be configured with
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<command>systemd-nspawn</command>'s <option>--settings=</option>
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switch, see
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<citerefentry><refentrytitle>systemd-nspawn</refentrytitle><manvolnum>1</manvolnum></citerefentry>
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for details.</para>
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</refsect1>
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<refsect1>
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<title>[Exec] Section Options</title>
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<para>Settings files may include an <literal>[Exec]</literal>
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section, which carries various execution parameters:</para>
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<variablelist>
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<varlistentry>
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<term><varname>Boot=</varname></term>
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<listitem><para>Takes a boolean argument, which defaults to off. If enabled, <command>systemd-nspawn</command>
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will automatically search for an <filename>init</filename> executable and invoke it. In this case, the
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specified parameters using <varname>Parameters=</varname> are passed as additional arguments to the
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<filename>init</filename> process. This setting corresponds to the <option>--boot</option> switch on the
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<command>systemd-nspawn</command> command line. This option may not be combined with
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<varname>ProcessTwo=yes</varname>.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>ProcessTwo=</varname></term>
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<listitem><para>Takes a boolean argument, which defaults to off. If enabled, the specified program is run as
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PID 2. A stub init process is run as PID 1. This setting corresponds to the <option>--as-pid2</option> switch
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on the <command>systemd-nspawn</command> command line. This option may not be combined with
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<varname>Boot=yes</varname>.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>Parameters=</varname></term>
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<listitem><para>Takes a space-separated list of
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arguments. This is either a command line, beginning with the
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binary name to execute, or – if <varname>Boot=</varname> is
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enabled – the list of arguments to pass to the init
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process. This setting corresponds to the command line
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parameters passed on the <command>systemd-nspawn</command>
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command line.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>Environment=</varname></term>
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<listitem><para>Takes an environment variable assignment
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consisting of key and value, separated by
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<literal>=</literal>. Sets an environment variable for the
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main process invoked in the container. This setting may be
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used multiple times to set multiple environment variables. It
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corresponds to the <option>--setenv=</option> command line
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switch.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>User=</varname></term>
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<listitem><para>Takes a UNIX user name. Specifies the user
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name to invoke the main process of the container as. This user
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must be known in the container's user database. This
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corresponds to the <option>--user=</option> command line
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switch.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>WorkingDirectory=</varname></term>
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<listitem><para>Selects the working directory for the process invoked in the container. Expects an absolute
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path in the container's file system namespace. This corresponds to the <option>--chdir=</option> command line
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switch.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>Capability=</varname></term>
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<term><varname>DropCapability=</varname></term>
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<listitem><para>Takes a space-separated list of Linux process
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capabilities (see
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<citerefentry project='man-pages'><refentrytitle>capabilities</refentrytitle><manvolnum>7</manvolnum></citerefentry>
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for details). The <varname>Capability=</varname> setting
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specifies additional capabilities to pass on top of the
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default set of capabilities. The
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<varname>DropCapability=</varname> setting specifies
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capabilities to drop from the default set. These settings
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correspond to the <option>--capability=</option> and
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<option>--drop-capability=</option> command line
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switches. Note that <varname>Capability=</varname> is a
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privileged setting, and only takes effect in
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<filename>.nspawn</filename> files in
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<filename>/etc/systemd/nspawn/</filename> and
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<filename>/run/system/nspawn/</filename> (see above). On the
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other hand, <varname>DropCapability=</varname> takes effect in
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all cases.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>Personality=</varname></term>
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<listitem><para>Configures the kernel personality for the
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container. This is equivalent to the
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<option>--personality=</option> switch.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>MachineID=</varname></term>
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<listitem><para>Configures the 128-bit machine ID (UUID) to pass to
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the container. This is equivalent to the
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<option>--uuid=</option> command line switch. This option is
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privileged (see above). </para></listitem>
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</varlistentry>
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</variablelist>
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</refsect1>
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<refsect1>
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<title>[Files] Section Options</title>
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<para>Settings files may include a <literal>[Files]</literal>
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section, which carries various parameters configuring the file
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system of the container:</para>
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<variablelist>
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<varlistentry>
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<term><varname>ReadOnly=</varname></term>
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<listitem><para>Takes a boolean argument, which defaults to off. If
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specified, the container will be run with a read-only file
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system. This setting corresponds to the
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<option>--read-only</option> command line
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switch.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>Volatile=</varname></term>
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<listitem><para>Takes a boolean argument, or the special value
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<literal>state</literal>. This configures whether to run the
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container with volatile state and/or configuration. This
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option is equivalent to <option>--volatile=</option>, see
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<citerefentry><refentrytitle>systemd-nspawn</refentrytitle><manvolnum>1</manvolnum></citerefentry>
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for details about the specific options
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supported.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>Bind=</varname></term>
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<term><varname>BindReadOnly=</varname></term>
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<listitem><para>Adds a bind mount from the host into the
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container. Takes a single path, a pair of two paths separated
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by a colon, or a triplet of two paths plus an option string
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separated by colons. This option may be used multiple times to
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configure multiple bind mounts. This option is equivalent to
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the command line switches <option>--bind=</option> and
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<option>--bind-ro=</option>, see
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<citerefentry><refentrytitle>systemd-nspawn</refentrytitle><manvolnum>1</manvolnum></citerefentry>
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for details about the specific options supported. This setting
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is privileged (see above).</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>TemporaryFileSystem=</varname></term>
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<listitem><para>Adds a <literal>tmpfs</literal> mount to the
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container. Takes a path or a pair of path and option string,
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separated by a colon. This option may be used multiple times to
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configure multiple <literal>tmpfs</literal> mounts. This
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option is equivalent to the command line switch
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<option>--tmpfs=</option>, see
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<citerefentry><refentrytitle>systemd-nspawn</refentrytitle><manvolnum>1</manvolnum></citerefentry>
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for details about the specific options supported. This setting
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is privileged (see above).</para></listitem>
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</varlistentry>
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</variablelist>
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</refsect1>
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<refsect1>
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<title>[Network] Section Options</title>
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<para>Settings files may include a <literal>[Network]</literal>
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section, which carries various parameters configuring the network
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connectivity of the container:</para>
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<variablelist>
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<varlistentry>
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<term><varname>Private=</varname></term>
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<listitem><para>Takes a boolean argument, which defaults to off. If
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enabled, the container will run in its own network namespace
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and not share network interfaces and configuration with the
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host. This setting corresponds to the
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<option>--private-network</option> command line
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switch.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>VirtualEthernet=</varname></term>
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<listitem><para>Takes a boolean argument. Configures whether
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to create a virtual Ethernet connection
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(<literal>veth</literal>) between host and the container. This
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setting implies <varname>Private=yes</varname>. This setting
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corresponds to the <option>--network-veth</option> command
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line switch. This option is privileged (see
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above).</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>VirtualEthernetExtra=</varname></term>
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<listitem><para>Takes a colon-separated pair of interface
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names. Configures an additional virtual Ethernet connection
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(<literal>veth</literal>) between host and the container. The
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first specified name is the interface name on the host, the
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second the interface name in the container. The latter may be
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omitted in which case it is set to the same name as the host
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side interface. This setting implies
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<varname>Private=yes</varname>. This setting corresponds to
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the <option>--network-veth-extra=</option> command line
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switch, and maybe be used multiple times. It is independent of
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<varname>VirtualEthernet=</varname>. This option is privileged
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(see above).</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>Interface=</varname></term>
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<listitem><para>Takes a space-separated list of interfaces to
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add to the container. This option corresponds to the
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<option>--network-interface=</option> command line switch and
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implies <varname>Private=yes</varname>. This option is
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privileged (see above).</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>MACVLAN=</varname></term>
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<term><varname>IPVLAN=</varname></term>
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<listitem><para>Takes a space-separated list of interfaces to
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add MACLVAN or IPVLAN interfaces to, which are then added to
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the container. These options correspond to the
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<option>--network-macvlan=</option> and
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<option>--network-ipvlan=</option> command line switches and
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imply <varname>Private=yes</varname>. These options are
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privileged (see above).</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>Bridge=</varname></term>
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<listitem><para>Takes an interface name. This setting implies
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<varname>VirtualEthernet=yes</varname> and
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<varname>Private=yes</varname> and has the effect that the
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host side of the created virtual Ethernet link is connected to
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the specified bridge interface. This option corresponds to the
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<option>--network-bridge=</option> command line switch. This
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option is privileged (see above).</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>Port=</varname></term>
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<listitem><para>Exposes a TCP or UDP port of the container on
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the host. This option corresponds to the
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<option>--port=</option> command line switch, see
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<citerefentry><refentrytitle>systemd-nspawn</refentrytitle><manvolnum>1</manvolnum></citerefentry>
|
||
for the precise syntax of the argument this option takes. This
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option is privileged (see above).</para></listitem>
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</varlistentry>
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</variablelist>
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</refsect1>
|
||
|
||
<refsect1>
|
||
<title>See Also</title>
|
||
<para>
|
||
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
|
||
<citerefentry><refentrytitle>systemd-nspawn</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
|
||
<citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry>
|
||
</para>
|
||
</refsect1>
|
||
|
||
</refentry>
|