man/systemd.nspawn.xml

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   9   SPDX-License-Identifier: LGPL-2.1+
  10
  11   This file is part of systemd.
  12
  13   Copyright 2015 Lennart Poettering
  14 -->
  15
  16 <refentry id="systemd.nspawn">
  17
  18   <refentryinfo>
  19     <title>systemd.nspawn</title>
  20     <productname>systemd</productname>
  21
  22     <authorgroup>
  23       <author>
  24         <contrib>Developer</contrib>
  25         <firstname>Lennart</firstname>
  26         <surname>Poettering</surname>
  27         <email>lennart@poettering.net</email>
  28       </author>
  29     </authorgroup>
  30   </refentryinfo>
  31
  32   <refmeta>
  33     <refentrytitle>systemd.nspawn</refentrytitle>
  34     <manvolnum>5</manvolnum>
  35   </refmeta>
  36
  37   <refnamediv>
  38     <refname>systemd.nspawn</refname>
  39     <refpurpose>Container settings</refpurpose>
  40   </refnamediv>
  41
  42   <refsynopsisdiv>
  43     <para><filename>/etc/systemd/nspawn/<replaceable>machine</replaceable>.nspawn</filename></para>
  44     <para><filename>/run/systemd/nspawn/<replaceable>machine</replaceable>.nspawn</filename></para>
  45     <para><filename>/var/lib/machines/<replaceable>machine</replaceable>.nspawn</filename></para>
  46   </refsynopsisdiv>
  47
  48   <refsect1>
  49     <title>Description</title>
  50
  51     <para>An nspawn container settings file (suffix
  52     <filename>.nspawn</filename>) encodes additional runtime
  53     information about a local container, and is searched, read and
  54     used by
  55     <citerefentry><refentrytitle>systemd-nspawn</refentrytitle><manvolnum>1</manvolnum></citerefentry>
  56     when starting a container. Files of this type are named after the
  57     containers they define settings for. They are optional, and only
  58     required for containers whose execution environment shall differ
  59     from the defaults. Files of this type mostly contain settings that
  60     may also be set on the <command>systemd-nspawn</command> command
  61     line, and make it easier to persistently attach specific settings
  62     to specific containers. The syntax of these files is inspired by
  63     <filename>.desktop</filename> files following the <ulink
  64     url="http://standards.freedesktop.org/desktop-entry-spec/latest/">XDG
  65     Desktop Entry Specification</ulink>, which in turn are inspired by
  66     Microsoft Windows <filename>.ini</filename> files.</para>
  67
  68     <para>Boolean arguments used in these settings files can be
  69     written in various formats. For positive settings, the strings
  70     <option>1</option>, <option>yes</option>, <option>true</option>
  71     and <option>on</option> are equivalent. For negative settings, the
  72     strings <option>0</option>, <option>no</option>,
  73     <option>false</option> and <option>off</option> are
  74     equivalent.</para>
  75
  76     <para>Empty lines and lines starting with # or ; are
  77     ignored. This may be used for commenting. Lines ending
  78     in a backslash are concatenated with the following
  79     line while reading and the backslash is replaced by a
  80     space character. This may be used to wrap long lines.</para>
  81
  82   </refsect1>
  83
  84   <refsect1>
  85     <title><filename>.nspawn</filename> File Discovery</title>
  86
  87     <para>Files are searched by appending the
  88     <filename>.nspawn</filename> suffix to the machine name of the
  89     container, as specified with the <option>--machine=</option>
  90     switch of <command>systemd-nspawn</command>, or derived from the
  91     directory or image file name. This file is first searched in
  92     <filename>/etc/systemd/nspawn/</filename> and
  93     <filename>/run/systemd/nspawn/</filename>. If found in these
  94     directories, its settings are read and all of them take full effect
  95     (but are possibly overridden by corresponding command line
  96     arguments). If not found, the file will then be searched next to
  97     the image file or in the immediate parent of the root directory of
  98     the container. If the file is found there, only a subset of the
  99     settings will take effect however. All settings that possibly
 100     elevate privileges or grant additional access to resources of the
 101     host (such as files or directories) are ignored. To which options
 102     this applies is documented below.</para>
 103
 104     <para>Persistent settings files created and maintained by the
 105     administrator (and thus trusted) should be placed in
 106     <filename>/etc/systemd/nspawn/</filename>, while automatically
 107     downloaded (and thus potentially untrusted) settings files are
 108     placed in <filename>/var/lib/machines/</filename> instead (next to
 109     the container images), where their security impact is limited. In
 110     order to add privileged settings to <filename>.nspawn</filename>
 111     files acquired from the image vendor, it is recommended to copy the
 112     settings files into <filename>/etc/systemd/nspawn/</filename> and
 113     edit them there, so that the privileged options become
 114     available. The precise algorithm for how the files are searched and
 115     interpreted may be configured with
 116     <command>systemd-nspawn</command>'s <option>--settings=</option>
 117     switch, see
 118     <citerefentry><refentrytitle>systemd-nspawn</refentrytitle><manvolnum>1</manvolnum></citerefentry>
 119     for details.</para>
 120   </refsect1>
 121
 122   <refsect1>
 123     <title>[Exec] Section Options</title>
 124
 125     <para>Settings files may include an <literal>[Exec]</literal>
 126     section, which carries various execution parameters:</para>
 127
 128     <variablelist>
 129
 130       <varlistentry>
 131         <term><varname>Boot=</varname></term>
 132
 133         <listitem><para>Takes a boolean argument, which defaults to off. If enabled, <command>systemd-nspawn</command>
 134         will automatically search for an <filename>init</filename> executable and invoke it. In this case, the
 135         specified parameters using <varname>Parameters=</varname> are passed as additional arguments to the
 136         <filename>init</filename> process. This setting corresponds to the <option>--boot</option> switch on the
 137         <command>systemd-nspawn</command> command line. This option may not be combined with
 138         <varname>ProcessTwo=yes</varname>. This option is the default if the
 139         <filename>systemd-nspawn@.service</filename> template unit file is used.</para></listitem>
 140       </varlistentry>
 141
 142       <varlistentry>
 143         <term><varname>ProcessTwo=</varname></term>
 144
 145         <listitem><para>Takes a boolean argument, which defaults to off. If enabled, the specified program is run as
 146         PID 2. A stub init process is run as PID 1. This setting corresponds to the <option>--as-pid2</option> switch
 147         on the <command>systemd-nspawn</command> command line. This option may not be combined with
 148         <varname>Boot=yes</varname>.</para></listitem>
 149       </varlistentry>
 150
 151       <varlistentry>
 152         <term><varname>Parameters=</varname></term>
 153
 154         <listitem><para>Takes a space-separated list of
 155         arguments. This is either a command line, beginning with the
 156         binary name to execute, or – if <varname>Boot=</varname> is
 157         enabled – the list of arguments to pass to the init
 158         process. This setting corresponds to the command line
 159         parameters passed on the <command>systemd-nspawn</command>
 160         command line.</para></listitem>
 161       </varlistentry>
 162
 163       <varlistentry>
 164         <term><varname>Environment=</varname></term>
 165
 166         <listitem><para>Takes an environment variable assignment
 167         consisting of key and value, separated by
 168         <literal>=</literal>. Sets an environment variable for the
 169         main process invoked in the container. This setting may be
 170         used multiple times to set multiple environment variables. It
 171         corresponds to the <option>--setenv=</option> command line
 172         switch.</para></listitem>
 173       </varlistentry>
 174
 175       <varlistentry>
 176         <term><varname>User=</varname></term>
 177
 178         <listitem><para>Takes a UNIX user name. Specifies the user
 179         name to invoke the main process of the container as. This user
 180         must be known in the container's user database. This
 181         corresponds to the <option>--user=</option> command line
 182         switch.</para></listitem>
 183       </varlistentry>
 184
 185       <varlistentry>
 186         <term><varname>WorkingDirectory=</varname></term>
 187
 188         <listitem><para>Selects the working directory for the process invoked in the container. Expects an absolute
 189         path in the container's file system namespace. This corresponds to the <option>--chdir=</option> command line
 190         switch.</para></listitem>
 191       </varlistentry>
 192
 193       <varlistentry>
 194         <term><varname>PivotRoot=</varname></term>
 195
 196         <listitem><para>Selects a directory to pivot to <filename>/</filename> inside the container when starting up.
 197         Takes a single path, or a pair of two paths separated by a colon. Both paths must be absolute, and are resolved
 198         in the container's file system namespace. This corresponds to the <option>--pivot-root=</option> command line
 199         switch.</para></listitem>
 200       </varlistentry>
 201
 202       <varlistentry>
 203         <term><varname>Capability=</varname></term>
 204         <term><varname>DropCapability=</varname></term>
 205
 206         <listitem><para>Takes a space-separated list of Linux process
 207         capabilities (see
 208         <citerefentry project='man-pages'><refentrytitle>capabilities</refentrytitle><manvolnum>7</manvolnum></citerefentry>
 209         for details). The <varname>Capability=</varname> setting
 210         specifies additional capabilities to pass on top of the
 211         default set of capabilities. The
 212         <varname>DropCapability=</varname> setting specifies
 213         capabilities to drop from the default set. These settings
 214         correspond to the <option>--capability=</option> and
 215         <option>--drop-capability=</option> command line
 216         switches. Note that <varname>Capability=</varname> is a
 217         privileged setting, and only takes effect in
 218         <filename>.nspawn</filename> files in
 219         <filename>/etc/systemd/nspawn/</filename> and
 220         <filename>/run/system/nspawn/</filename> (see above). On the
 221         other hand, <varname>DropCapability=</varname> takes effect in
 222         all cases.</para></listitem>
 223       </varlistentry>
 224
 225       <varlistentry>
 226         <term><varname>KillSignal=</varname></term>
 227
 228         <listitem><para>Specify the process signal to send to the
 229         container's PID 1 when nspawn itself receives SIGTERM, in
 230         order to trigger an orderly shutdown of the container.
 231         Defaults to SIGRTMIN+3 if <option>Boot=</option> is used
 232         (on systemd-compatible init systems SIGRTMIN+3 triggers an
 233         orderly shutdown). For a list of valid signals, see
 234         <citerefentry project='man-pages'><refentrytitle>signal</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para></listitem>
 235       </varlistentry>
 236
 237       <varlistentry>
 238         <term><varname>Personality=</varname></term>
 239
 240         <listitem><para>Configures the kernel personality for the
 241         container. This is equivalent to the
 242         <option>--personality=</option> switch.</para></listitem>
 243       </varlistentry>
 244
 245       <varlistentry>
 246         <term><varname>MachineID=</varname></term>
 247
 248         <listitem><para>Configures the 128-bit machine ID (UUID) to pass to
 249         the container. This is equivalent to the
 250         <option>--uuid=</option> command line switch. This option is
 251         privileged (see above). </para></listitem>
 252       </varlistentry>
 253
 254       <varlistentry>
 255         <term><varname>PrivateUsers=</varname></term>
 256
 257         <listitem><para>Configures support for usernamespacing. This is equivalent to the
 258         <option>--private-users=</option> command line switch, and takes the same options. This option is privileged
 259         (see above). This option is the default if the <filename>systemd-nspawn@.service</filename> template unit file
 260         is used.</para></listitem>
 261       </varlistentry>
 262
 263       <varlistentry>
 264         <term><varname>NotifyReady=</varname></term>
 265
 266         <listitem><para>Configures support for notifications from the container's init process.  This is equivalent to
 267         the <option>--notify-ready=</option> command line switch, and takes the same parameters. See
 268         <citerefentry><refentrytitle>systemd-nspawn</refentrytitle><manvolnum>1</manvolnum></citerefentry> for details
 269         about the specific options supported.</para></listitem>
 270       </varlistentry>
 271
 272       <varlistentry>
 273         <term><varname>SystemCallFilter=</varname></term>
 274
 275         <listitem><para>Configures the system call filter applied to containers. This is equivalent to the
 276         <option>--system-call-filter=</option> command line switch, and takes the same list parameter. See
 277         <citerefentry><refentrytitle>systemd-nspawn</refentrytitle><manvolnum>1</manvolnum></citerefentry> for
 278         details.</para></listitem>
 279       </varlistentry>
 280
 281     </variablelist>
 282   </refsect1>
 283
 284   <refsect1>
 285     <title>[Files] Section Options</title>
 286
 287     <para>Settings files may include a <literal>[Files]</literal>
 288     section, which carries various parameters configuring the file
 289     system of the container:</para>
 290
 291     <variablelist>
 292
 293       <varlistentry>
 294         <term><varname>ReadOnly=</varname></term>
 295
 296         <listitem><para>Takes a boolean argument, which defaults to off. If
 297         specified, the container will be run with a read-only file
 298         system. This setting corresponds to the
 299         <option>--read-only</option> command line
 300         switch.</para></listitem>
 301       </varlistentry>
 302
 303       <varlistentry>
 304         <term><varname>Volatile=</varname></term>
 305
 306         <listitem><para>Takes a boolean argument, or the special value
 307         <literal>state</literal>. This configures whether to run the
 308         container with volatile state and/or configuration. This
 309         option is equivalent to <option>--volatile=</option>, see
 310         <citerefentry><refentrytitle>systemd-nspawn</refentrytitle><manvolnum>1</manvolnum></citerefentry>
 311         for details about the specific options
 312         supported.</para></listitem>
 313       </varlistentry>
 314
 315       <varlistentry>
 316         <term><varname>Bind=</varname></term>
 317         <term><varname>BindReadOnly=</varname></term>
 318
 319         <listitem><para>Adds a bind mount from the host into the
 320         container. Takes a single path, a pair of two paths separated
 321         by a colon, or a triplet of two paths plus an option string
 322         separated by colons. This option may be used multiple times to
 323         configure multiple bind mounts. This option is equivalent to
 324         the command line switches <option>--bind=</option> and
 325         <option>--bind-ro=</option>, see
 326         <citerefentry><refentrytitle>systemd-nspawn</refentrytitle><manvolnum>1</manvolnum></citerefentry>
 327         for details about the specific options supported. This setting
 328         is privileged (see above).</para></listitem>
 329       </varlistentry>
 330
 331       <varlistentry>
 332         <term><varname>TemporaryFileSystem=</varname></term>
 333
 334         <listitem><para>Adds a <literal>tmpfs</literal> mount to the
 335         container. Takes a path or a pair of path and option string,
 336         separated by a colon. This option may be used multiple times to
 337         configure multiple <literal>tmpfs</literal> mounts. This
 338         option is equivalent to the command line switch
 339         <option>--tmpfs=</option>, see
 340         <citerefentry><refentrytitle>systemd-nspawn</refentrytitle><manvolnum>1</manvolnum></citerefentry>
 341         for details about the specific options supported. This setting
 342         is privileged (see above).</para></listitem>
 343       </varlistentry>
 344
 345       <varlistentry>
 346         <term><varname>Overlay=</varname></term>
 347         <term><varname>OverlayReadOnly=</varname></term>
 348
 349         <listitem><para>Adds an overlay mount point. Takes a colon-separated list of paths.  This option may be used
 350         multiple times to configure multiple overlay mounts. This option is equivalent to the command line switches
 351         <option>--overlay=</option> and <option>--overlay-ro=</option>, see
 352         <citerefentry><refentrytitle>systemd-nspawn</refentrytitle><manvolnum>1</manvolnum></citerefentry> for details
 353         about the specific options supported. This setting is privileged (see above).</para></listitem>
 354       </varlistentry>
 355
 356       <varlistentry>
 357         <term><varname>PrivateUsersChown=</varname></term>
 358
 359         <listitem><para>Configures whether the ownership of the files and directories in the container tree shall be
 360         adjusted to the UID/GID range used, if necessary and user namespacing is enabled. This is equivalent to the
 361         <option>--private-users-chown</option> command line switch. This option is privileged (see
 362         above). </para></listitem>
 363       </varlistentry>
 364
 365     </variablelist>
 366   </refsect1>
 367
 368   <refsect1>
 369     <title>[Network] Section Options</title>
 370
 371     <para>Settings files may include a <literal>[Network]</literal>
 372     section, which carries various parameters configuring the network
 373     connectivity of the container:</para>
 374
 375     <variablelist>
 376
 377       <varlistentry>
 378         <term><varname>Private=</varname></term>
 379
 380         <listitem><para>Takes a boolean argument, which defaults to off. If
 381         enabled, the container will run in its own network namespace
 382         and not share network interfaces and configuration with the
 383         host. This setting corresponds to the
 384         <option>--private-network</option> command line
 385         switch.</para></listitem>
 386       </varlistentry>
 387
 388       <varlistentry>
 389         <term><varname>VirtualEthernet=</varname></term>
 390
 391         <listitem><para>Takes a boolean argument. Configures whether to create a virtual Ethernet connection
 392         (<literal>veth</literal>) between host and the container. This setting implies
 393         <varname>Private=yes</varname>. This setting corresponds to the <option>--network-veth</option> command line
 394         switch. This option is privileged (see above). This option is the default if the
 395         <filename>systemd-nspawn@.service</filename> template unit file is used.</para></listitem>
 396       </varlistentry>
 397
 398       <varlistentry>
 399         <term><varname>VirtualEthernetExtra=</varname></term>
 400
 401         <listitem><para>Takes a colon-separated pair of interface
 402         names. Configures an additional virtual Ethernet connection
 403         (<literal>veth</literal>) between host and the container. The
 404         first specified name is the interface name on the host, the
 405         second the interface name in the container. The latter may be
 406         omitted in which case it is set to the same name as the host
 407         side interface. This setting implies
 408         <varname>Private=yes</varname>. This setting corresponds to
 409         the <option>--network-veth-extra=</option> command line
 410         switch, and maybe be used multiple times. It is independent of
 411         <varname>VirtualEthernet=</varname>. This option is privileged
 412         (see above).</para></listitem>
 413       </varlistentry>
 414
 415       <varlistentry>
 416         <term><varname>Interface=</varname></term>
 417
 418         <listitem><para>Takes a space-separated list of interfaces to
 419         add to the container. This option corresponds to the
 420         <option>--network-interface=</option> command line switch and
 421         implies <varname>Private=yes</varname>. This option is
 422         privileged (see above).</para></listitem>
 423       </varlistentry>
 424
 425       <varlistentry>
 426         <term><varname>MACVLAN=</varname></term>
 427         <term><varname>IPVLAN=</varname></term>
 428
 429         <listitem><para>Takes a space-separated list of interfaces to
 430         add MACLVAN or IPVLAN interfaces to, which are then added to
 431         the container. These options correspond to the
 432         <option>--network-macvlan=</option> and
 433         <option>--network-ipvlan=</option> command line switches and
 434         imply <varname>Private=yes</varname>. These options are
 435         privileged (see above).</para></listitem>
 436       </varlistentry>
 437
 438       <varlistentry>
 439         <term><varname>Bridge=</varname></term>
 440
 441         <listitem><para>Takes an interface name. This setting implies
 442         <varname>VirtualEthernet=yes</varname> and
 443         <varname>Private=yes</varname> and has the effect that the
 444         host side of the created virtual Ethernet link is connected to
 445         the specified bridge interface. This option corresponds to the
 446         <option>--network-bridge=</option> command line switch. This
 447         option is privileged (see above).</para></listitem>
 448       </varlistentry>
 449
 450       <varlistentry>
 451         <term><varname>Zone=</varname></term>
 452
 453         <listitem><para>Takes a network zone name. This setting implies <varname>VirtualEthernet=yes</varname> and
 454         <varname>Private=yes</varname> and has the effect that the host side of the created virtual Ethernet link is
 455         connected to an automatically managed bridge interface named after the passed argument, prefixed with
 456         <literal>vz-</literal>. This option corresponds to the <option>--network-zone=</option> command line
 457         switch. This option is privileged (see above).</para></listitem>
 458       </varlistentry>
 459
 460       <varlistentry>
 461         <term><varname>Port=</varname></term>
 462
 463         <listitem><para>Exposes a TCP or UDP port of the container on
 464         the host. This option corresponds to the
 465         <option>--port=</option> command line switch, see
 466         <citerefentry><refentrytitle>systemd-nspawn</refentrytitle><manvolnum>1</manvolnum></citerefentry>
 467         for the precise syntax of the argument this option takes. This
 468         option is privileged (see above).</para></listitem>
 469       </varlistentry>
 470     </variablelist>
 471   </refsect1>
 472
 473   <refsect1>
 474     <title>See Also</title>
 475     <para>
 476       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 477       <citerefentry><refentrytitle>systemd-nspawn</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 478       <citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry>
 479     </para>
 480   </refsect1>
 481
 482 </refentry>