2 <!DOCTYPE refentry PUBLIC
"-//OASIS//DTD DocBook XML V4.5//EN"
3 "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd" [
4 <!ENTITY % entities SYSTEM
"custom-entities.ent" >
7 <!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
9 <refentry id=
"systemd-nspawn"
10 xmlns:
xi=
"http://www.w3.org/2001/XInclude">
13 <title>systemd-nspawn
</title>
14 <productname>systemd
</productname>
18 <refentrytitle>systemd-nspawn
</refentrytitle>
19 <manvolnum>1</manvolnum>
23 <refname>systemd-nspawn
</refname>
24 <refpurpose>Spawn a command or OS in a light-weight container
</refpurpose>
29 <command>systemd-nspawn
</command>
30 <arg choice=
"opt" rep=
"repeat">OPTIONS
</arg>
31 <arg choice=
"opt"><replaceable>COMMAND
</replaceable>
32 <arg choice=
"opt" rep=
"repeat">ARGS
</arg>
36 <command>systemd-nspawn
</command>
37 <arg choice=
"plain">--boot
</arg>
38 <arg choice=
"opt" rep=
"repeat">OPTIONS
</arg>
39 <arg choice=
"opt" rep=
"repeat">ARGS
</arg>
44 <title>Description
</title>
46 <para><command>systemd-nspawn
</command> may be used to run a command or OS in a light-weight namespace
47 container. In many ways it is similar to
<citerefentry
48 project='man-pages'
><refentrytitle>chroot
</refentrytitle><manvolnum>1</manvolnum></citerefentry>, but more powerful
49 since it fully virtualizes the file system hierarchy, as well as the process tree, the various IPC subsystems and
50 the host and domain name.
</para>
52 <para><command>systemd-nspawn
</command> may be invoked on any directory tree containing an operating system tree,
53 using the
<option>--directory=
</option> command line option. By using the
<option>--machine=
</option> option an OS
54 tree is automatically searched for in a couple of locations, most importantly in
55 <filename>/var/lib/machines/
</filename>, the suggested directory to place OS container images installed on the
58 <para>In contrast to
<citerefentry
59 project='man-pages'
><refentrytitle>chroot
</refentrytitle><manvolnum>1</manvolnum></citerefentry> <command>systemd-nspawn
</command>
60 may be used to boot full Linux-based operating systems in a container.
</para>
62 <para><command>systemd-nspawn
</command> limits access to various kernel interfaces in the container to read-only,
63 such as
<filename>/sys/
</filename>,
<filename>/proc/sys/
</filename> or
<filename>/sys/fs/selinux/
</filename>. The
64 host's network interfaces and the system clock may not be changed from within the container. Device nodes may not
65 be created. The host system cannot be rebooted and kernel modules may not be loaded from within the
68 <para>Use a tool like
<citerefentry
69 project='mankier'
><refentrytitle>dnf
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
<citerefentry
70 project='die-net'
><refentrytitle>debootstrap
</refentrytitle><manvolnum>8</manvolnum></citerefentry>, or
71 <citerefentry project='archlinux'
><refentrytitle>pacman
</refentrytitle><manvolnum>8</manvolnum></citerefentry> to
72 set up an OS directory tree suitable as file system hierarchy for
<command>systemd-nspawn
</command> containers. See
73 the Examples section below for details on suitable invocation of these commands.
</para>
75 <para>As a safety check
<command>systemd-nspawn
</command> will verify the existence of
76 <filename>/usr/lib/os-release
</filename> or
<filename>/etc/os-release
</filename> in the container tree before
77 starting the container (see
78 <citerefentry><refentrytitle>os-release
</refentrytitle><manvolnum>5</manvolnum></citerefentry>). It might be
79 necessary to add this file to the container tree manually if the OS of the container is too old to contain this
80 file out-of-the-box.
</para>
82 <para><command>systemd-nspawn
</command> may be invoked directly from the interactive command line or run as system
83 service in the background. In this mode each container instance runs as its own service instance; a default
84 template unit file
<filename>systemd-nspawn@.service
</filename> is provided to make this easy, taking the container
85 name as instance identifier. Note that different default options apply when
<command>systemd-nspawn
</command> is
86 invoked by the template unit file than interactively on the command line. Most importantly the template unit file
87 makes use of the
<option>--boot
</option> which is not the default in case
<command>systemd-nspawn
</command> is
88 invoked from the interactive command line. Further differences with the defaults are documented along with the
89 various supported options below.
</para>
91 <para>The
<citerefentry><refentrytitle>machinectl
</refentrytitle><manvolnum>1</manvolnum></citerefentry> tool may
92 be used to execute a number of operations on containers. In particular it provides easy-to-use commands to run
93 containers as system services using the
<filename>systemd-nspawn@.service
</filename> template unit
96 <para>Along with each container a settings file with the
<filename>.nspawn
</filename> suffix may exist, containing
97 additional settings to apply when running the container. See
98 <citerefentry><refentrytitle>systemd.nspawn
</refentrytitle><manvolnum>5</manvolnum></citerefentry> for
99 details. Settings files override the default options used by the
<filename>systemd-nspawn@.service
</filename>
100 template unit file, making it usually unnecessary to alter this template file directly.
</para>
102 <para>Note that
<command>systemd-nspawn
</command> will mount file systems private to the container to
103 <filename>/dev/
</filename>,
<filename>/run/
</filename> and similar. These will not be visible outside of the
104 container, and their contents will be lost when the container exits.
</para>
106 <para>Note that running two
<command>systemd-nspawn
</command> containers from the same directory tree will not make
107 processes in them see each other. The PID namespace separation of the two containers is complete and the containers
108 will share very few runtime objects except for the underlying file system. Use
109 <citerefentry><refentrytitle>machinectl
</refentrytitle><manvolnum>1</manvolnum></citerefentry>'s
110 <command>login
</command> or
<command>shell
</command> commands to request an additional login session in a running
113 <para><command>systemd-nspawn
</command> implements the
<ulink
114 url=
"https://systemd.io/CONTAINER_INTERFACE">Container Interface
</ulink> specification.
</para>
116 <para>While running, containers invoked with
<command>systemd-nspawn
</command> are registered with the
117 <citerefentry><refentrytitle>systemd-machined
</refentrytitle><manvolnum>8</manvolnum></citerefentry> service that
118 keeps track of running containers, and provides programming interfaces to interact with them.
</para>
122 <title>Options
</title>
124 <para>If option
<option>-b
</option> is specified, the arguments
125 are used as arguments for the init program. Otherwise,
126 <replaceable>COMMAND
</replaceable> specifies the program to launch
127 in the container, and the remaining arguments are used as
128 arguments for this program. If
<option>--boot
</option> is not used and
129 no arguments are specified, a shell is launched in the
132 <para>The following options are understood:
</para>
137 <term><option>-q
</option></term>
138 <term><option>--quiet
</option></term>
140 <listitem><para>Turns off any status output by the tool
141 itself. When this switch is used, the only output from nspawn
142 will be the console output of the container OS
143 itself.
</para></listitem>
147 <term><option>--settings=
</option><replaceable>MODE
</replaceable></term>
149 <listitem><para>Controls whether
150 <command>systemd-nspawn
</command> shall search for and use
151 additional per-container settings from
152 <filename>.nspawn
</filename> files. Takes a boolean or the
153 special values
<option>override
</option> or
154 <option>trusted
</option>.
</para>
156 <para>If enabled (the default), a settings file named after the
157 machine (as specified with the
<option>--machine=
</option>
158 setting, or derived from the directory or image file name)
159 with the suffix
<filename>.nspawn
</filename> is searched in
160 <filename>/etc/systemd/nspawn/
</filename> and
161 <filename>/run/systemd/nspawn/
</filename>. If it is found
162 there, its settings are read and used. If it is not found
163 there, it is subsequently searched in the same directory as the
164 image file or in the immediate parent of the root directory of
165 the container. In this case, if the file is found, its settings
166 will be also read and used, but potentially unsafe settings
167 are ignored. Note that in both these cases, settings on the
168 command line take precedence over the corresponding settings
169 from loaded
<filename>.nspawn
</filename> files, if both are
170 specified. Unsafe settings are considered all settings that
171 elevate the container's privileges or grant access to
172 additional resources such as files or directories of the
173 host. For details about the format and contents of
174 <filename>.nspawn
</filename> files, consult
175 <citerefentry><refentrytitle>systemd.nspawn
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
177 <para>If this option is set to
<option>override
</option>, the
178 file is searched, read and used the same way, however, the order of
179 precedence is reversed: settings read from the
180 <filename>.nspawn
</filename> file will take precedence over
181 the corresponding command line options, if both are
184 <para>If this option is set to
<option>trusted
</option>, the
185 file is searched, read and used the same way, but regardless
186 of being found in
<filename>/etc/systemd/nspawn/
</filename>,
187 <filename>/run/systemd/nspawn/
</filename> or next to the image
188 file or container root directory, all settings will take
189 effect, however, command line arguments still take precedence
190 over corresponding settings.
</para>
192 <para>If disabled, no
<filename>.nspawn
</filename> file is read
193 and no settings except the ones on the command line are in
194 effect.
</para></listitem>
200 <title>Image Options
</title>
205 <term><option>-D
</option></term>
206 <term><option>--directory=
</option></term>
208 <listitem><para>Directory to use as file system root for the
211 <para>If neither
<option>--directory=
</option>, nor
212 <option>--image=
</option> is specified the directory is
213 determined by searching for a directory named the same as the
214 machine name specified with
<option>--machine=
</option>. See
215 <citerefentry><refentrytitle>machinectl
</refentrytitle><manvolnum>1</manvolnum></citerefentry>
216 section
"Files and Directories" for the precise search path.
</para>
218 <para>If neither
<option>--directory=
</option>,
219 <option>--image=
</option>, nor
<option>--machine=
</option>
220 are specified, the current directory will
221 be used. May not be specified together with
222 <option>--image=
</option>.
</para></listitem>
226 <term><option>--template=
</option></term>
228 <listitem><para>Directory or
<literal>btrfs
</literal> subvolume to use as template for the
229 container's root directory. If this is specified and the container's root directory (as configured by
230 <option>--directory=
</option>) does not yet exist it is created as
<literal>btrfs
</literal> snapshot
231 (if supported) or plain directory (otherwise) and populated from this template tree. Ideally, the
232 specified template path refers to the root of a
<literal>btrfs
</literal> subvolume, in which case a
233 simple copy-on-write snapshot is taken, and populating the root directory is instant. If the
234 specified template path does not refer to the root of a
<literal>btrfs
</literal> subvolume (or not
235 even to a
<literal>btrfs
</literal> file system at all), the tree is copied (though possibly in a
236 'reflink' copy-on-write scheme — if the file system supports that), which can be substantially more
237 time-consuming. Note that the snapshot taken is of the specified directory or subvolume, including
238 all subdirectories and subvolumes below it, but excluding any sub-mounts. May not be specified
239 together with
<option>--image=
</option> or
<option>--ephemeral
</option>.
</para>
241 <para>Note that this switch leaves hostname, machine ID and
242 all other settings that could identify the instance
243 unmodified.
</para></listitem>
247 <term><option>-x
</option></term>
248 <term><option>--ephemeral
</option></term>
250 <listitem><para>If specified, the container is run with a temporary snapshot of its file system that is removed
251 immediately when the container terminates. May not be specified together with
252 <option>--template=
</option>.
</para>
253 <para>Note that this switch leaves hostname, machine ID and all other settings that could identify
254 the instance unmodified. Please note that — as with
<option>--template=
</option> — taking the
255 temporary snapshot is more efficient on file systems that support subvolume snapshots or 'reflinks'
256 natively (
<literal>btrfs
</literal> or new
<literal>xfs
</literal>) than on more traditional file
257 systems that do not (
<literal>ext4
</literal>). Note that the snapshot taken is of the specified
258 directory or subvolume, including all subdirectories and subvolumes below it, but excluding any
261 <para>With this option no modifications of the container image are retained. Use
262 <option>--volatile=
</option> (described below) for other mechanisms to restrict persistency of
263 container images during runtime.
</para>
268 <term><option>-i
</option></term>
269 <term><option>--image=
</option></term>
271 <listitem><para>Disk image to mount the root directory for the
272 container from. Takes a path to a regular file or to a block
273 device node. The file or block device must contain
277 <listitem><para>An MBR partition table with a single
278 partition of type
0x83 that is marked
279 bootable.
</para></listitem>
281 <listitem><para>A GUID partition table (GPT) with a single
283 0fc63daf-
8483-
4772-
8e79-
3d69d8477de4.
</para></listitem>
285 <listitem><para>A GUID partition table (GPT) with a marked
286 root partition which is mounted as the root directory of the
287 container. Optionally, GPT images may contain a home and/or
288 a server data partition which are mounted to the appropriate
289 places in the container. All these partitions must be
290 identified by the partition types defined by the
<ulink
291 url=
"https://systemd.io/DISCOVERABLE_PARTITIONS">Discoverable
292 Partitions Specification
</ulink>.
</para></listitem>
294 <listitem><para>No partition table, and a single file system spanning the whole image.
</para></listitem>
297 <para>On GPT images, if an EFI System Partition (ESP) is discovered, it is automatically mounted to
298 <filename>/efi
</filename> (or
<filename>/boot
</filename> as fallback) in case a directory by this name exists
301 <para>Partitions encrypted with LUKS are automatically decrypted. Also, on GPT images dm-verity data integrity
302 hash partitions are set up if the root hash for them is specified using the
<option>--root-hash=
</option>
305 <para>Single file system images (i.e. file systems without a surrounding partition table) can be opened using
306 dm-verity if the integrity data is passed using the
<option>--root-hash=
</option> and
307 <option>--verity-data=
</option> (and optionally
<option>--root-hash-sig=
</option>) options.
</para>
309 <para>Any other partitions, such as foreign partitions or swap partitions are not mounted. May not be specified
310 together with
<option>--directory=
</option>,
<option>--template=
</option>.
</para></listitem>
314 <term><option>--oci-bundle=
</option></term>
316 <listitem><para>Takes the path to an OCI runtime bundle to invoke, as specified in the
<ulink
317 url=
"https://github.com/opencontainers/runtime-spec/blob/master/spec.md">OCI Runtime Specification
</ulink>. In
318 this case no
<filename>.nspawn
</filename> file is loaded, and the root directory and various settings are read
319 from the OCI runtime JSON data (but data passed on the command line takes precedence).
</para></listitem>
323 <term><option>--read-only
</option></term>
325 <listitem><para>Mount the container's root file system (and any other file systems container in the container
326 image) read-only. This has no effect on additional mounts made with
<option>--bind=
</option>,
327 <option>--tmpfs=
</option> and similar options. This mode is implied if the container image file or directory is
328 marked read-only itself. It is also implied if
<option>--volatile=
</option> is used. In this case the container
329 image on disk is strictly read-only, while changes are permitted but kept non-persistently in memory only. For
330 further details, see below.
</para></listitem>
334 <term><option>--volatile
</option></term>
335 <term><option>--volatile=
</option><replaceable>MODE
</replaceable></term>
337 <listitem><para>Boots the container in volatile mode. When no mode parameter is passed or when mode is
338 specified as
<option>yes
</option>, full volatile mode is enabled. This means the root directory is mounted as a
339 mostly unpopulated
<literal>tmpfs
</literal> instance, and
<filename>/usr/
</filename> from the OS tree is
340 mounted into it in read-only mode (the system thus starts up with read-only OS image, but pristine state and
341 configuration, any changes are lost on shutdown). When the mode parameter is specified as
342 <option>state
</option>, the OS tree is mounted read-only, but
<filename>/var/
</filename> is mounted as a
343 writable
<literal>tmpfs
</literal> instance into it (the system thus starts up with read-only OS resources and
344 configuration, but pristine state, and any changes to the latter are lost on shutdown). When the mode parameter
345 is specified as
<option>overlay
</option> the read-only root file system is combined with a writable
346 <filename>tmpfs
</filename> instance through
<literal>overlayfs
</literal>, so that it appears at it normally
347 would, but any changes are applied to the temporary file system only and lost when the container is
348 terminated. When the mode parameter is specified as
<option>no
</option> (the default), the whole OS tree is
349 made available writable (unless
<option>--read-only
</option> is specified, see above).
</para>
351 <para>Note that if one of the volatile modes is chosen, its effect is limited to the root file system
352 (or
<filename>/var/
</filename> in case of
<option>state
</option>), and any other mounts placed in the
353 hierarchy are unaffected — regardless if they are established automatically (e.g. the EFI system
354 partition that might be mounted to
<filename>/efi/
</filename> or
<filename>/boot/
</filename>) or
355 explicitly (e.g. through an additional command line option such as
<option>--bind=
</option>, see
356 below). This means, even if
<option>--volatile=overlay
</option> is used changes to
357 <filename>/efi/
</filename> or
<filename>/boot/
</filename> are prohibited in case such a partition
358 exists in the container image operated on, and even if
<option>--volatile=state
</option> is used the
359 hypothetical file
<filename index=
"false">/etc/foobar
</filename> is potentially writable if
360 <option>--bind=/etc/foobar
</option> if used to mount it from outside the read-only container
361 <filename>/etc/
</filename> directory.
</para>
363 <para>The
<option>--ephemeral
</option> option is closely related to this setting, and provides similar
364 behaviour by making a temporary, ephemeral copy of the whole OS image and executing that. For further details,
367 <para>The
<option>--tmpfs=
</option> and
<option>--overlay=
</option> options provide similar functionality, but
368 for specific sub-directories of the OS image only. For details, see below.
</para>
370 <para>This option provides similar functionality for containers as the
<literal>systemd.volatile=
</literal>
371 kernel command line switch provides for host systems. See
372 <citerefentry><refentrytitle>kernel-command-line
</refentrytitle><manvolnum>7</manvolnum></citerefentry> for
375 <para>Note that setting this option to
<option>yes
</option> or
<option>state
</option> will only work
376 correctly with operating systems in the container that can boot up with only
377 <filename>/usr/
</filename> mounted, and are able to automatically populate
<filename>/var/
</filename>
378 (and
<filename>/etc/
</filename> in case of
<literal>--volatile=yes
</literal>). Specifically, this
379 means that operating systems that follow the historic split of
<filename>/bin/
</filename> and
380 <filename>/lib/
</filename> (and related directories) from
<filename>/usr/
</filename> (i.e. where the
381 former are not symlinks into the latter) are not supported by
<literal>--volatile=yes
</literal> as
382 container payload. The
<option>overlay
</option> option does not require any particular preparations
383 in the OS, but do note that
<literal>overlayfs
</literal> behaviour differs from regular file systems
384 in a number of ways, and hence compatibility is limited.
</para></listitem>
388 <term><option>--root-hash=
</option></term>
390 <listitem><para>Takes a data integrity (dm-verity) root hash specified in hexadecimal. This option enables data
391 integrity checks using dm-verity, if the used image contains the appropriate integrity data (see above). The
392 specified hash must match the root hash of integrity data, and is usually at least
256 bits (and hence
64
393 formatted hexadecimal characters) long (in case of SHA256 for example). If this option is not specified, but
394 the image file carries the
<literal>user.verity.roothash
</literal> extended file attribute (see
<citerefentry
395 project='man-pages'
><refentrytitle>xattr
</refentrytitle><manvolnum>7</manvolnum></citerefentry>), then the root
396 hash is read from it, also as formatted hexadecimal characters. If the extended file attribute is not found (or
397 is not supported by the underlying file system), but a file with the
<filename>.roothash
</filename> suffix is
398 found next to the image file, bearing otherwise the same name (except if the image has the
399 <filename>.raw
</filename> suffix, in which case the root hash file must not have it in its name), the root hash
400 is read from it and automatically used, also as formatted hexadecimal characters.
</para>
402 <para>Note that this configures the root hash for the root file system. Disk images may also contain
403 separate file systems for the
<filename>/usr/
</filename> hierarchy, which may be Verity protected as
404 well. The root hash for this protection may be configured via the
405 <literal>user.verity.usrhash
</literal> extended file attribute or via a
<filename>.usrhash
</filename>
406 file adjacent to the disk image, following the same format and logic as for the root hash for the
407 root file system described here. Note that there's currently no switch to configure the root hash for
408 the
<filename>/usr/
</filename> from the command line.
</para>
410 <para>Also see the
<varname>RootHash=
</varname> option in
411 <citerefentry><refentrytitle>systemd.exec
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
416 <term><option>--root-hash-sig=
</option></term>
418 <listitem><para>Takes a PKCS7 signature of the
<option>--root-hash=
</option> option.
419 The semantics are the same as for the
<varname>RootHashSignature=
</varname> option, see
420 <citerefentry><refentrytitle>systemd.exec
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
425 <term><option>--verity-data=
</option></term>
427 <listitem><para>Takes the path to a data integrity (dm-verity) file. This option enables data integrity checks
428 using dm-verity, if a root-hash is passed and if the used image itself does not contains the integrity data.
429 The integrity data must be matched by the root hash. If this option is not specified, but a file with the
430 <filename>.verity
</filename> suffix is found next to the image file, bearing otherwise the same name (except if
431 the image has the
<filename>.raw
</filename> suffix, in which case the verity data file must not have it in its name),
432 the verity data is read from it and automatically used.
</para></listitem>
436 <term><option>--pivot-root=
</option></term>
438 <listitem><para>Pivot the specified directory to
<filename>/
</filename> inside the container, and either unmount the
439 container's old root, or pivot it to another specified directory. Takes one of: a path argument — in which case the
440 specified path will be pivoted to
<filename>/
</filename> and the old root will be unmounted; or a colon-separated pair
441 of new root path and pivot destination for the old root. The new root path will be pivoted to
<filename>/
</filename>,
442 and the old
<filename>/
</filename> will be pivoted to the other directory. Both paths must be absolute, and are resolved
443 in the container's file system namespace.
</para>
445 <para>This is for containers which have several bootable directories in them; for example, several
446 <ulink url=
"https://ostree.readthedocs.io/en/latest/">OSTree
</ulink> deployments. It emulates the behavior of
447 the boot loader and initial RAM disk which normally select which directory to mount as the root and start the
448 container's PID
1 in.
</para></listitem>
452 </refsect2><refsect2>
453 <title>Execution Options
</title>
457 <term><option>-a
</option></term>
458 <term><option>--as-pid2
</option></term>
460 <listitem><para>Invoke the shell or specified program as process ID (PID)
2 instead of PID
1 (init). By
461 default, if neither this option nor
<option>--boot
</option> is used, the selected program is run as the process
462 with PID
1, a mode only suitable for programs that are aware of the special semantics that the process with
463 PID
1 has on UNIX. For example, it needs to reap all processes reparented to it, and should implement
464 <command>sysvinit
</command> compatible signal handling (specifically: it needs to reboot on SIGINT, reexecute
465 on SIGTERM, reload configuration on SIGHUP, and so on). With
<option>--as-pid2
</option> a minimal stub init
466 process is run as PID
1 and the selected program is executed as PID
2 (and hence does not need to implement any
467 special semantics). The stub init process will reap processes as necessary and react appropriately to
468 signals. It is recommended to use this mode to invoke arbitrary commands in containers, unless they have been
469 modified to run correctly as PID
1. Or in other words: this switch should be used for pretty much all commands,
470 except when the command refers to an init or shell implementation, as these are generally capable of running
471 correctly as PID
1. This option may not be combined with
<option>--boot
</option>.
</para>
476 <term><option>-b
</option></term>
477 <term><option>--boot
</option></term>
479 <listitem><para>Automatically search for an init program and invoke it as PID
1, instead of a shell or a user
480 supplied program. If this option is used, arguments specified on the command line are used as arguments for the
481 init program. This option may not be combined with
<option>--as-pid2
</option>.
</para>
483 <para>The following table explains the different modes of invocation and relationship to
484 <option>--as-pid2
</option> (see above):
</para>
487 <title>Invocation Mode
</title>
488 <tgroup cols='
2' align='left' colsep='
1' rowsep='
1'
>
489 <colspec colname=
"switch" />
490 <colspec colname=
"explanation" />
493 <entry>Switch
</entry>
494 <entry>Explanation
</entry>
499 <entry>Neither
<option>--as-pid2
</option> nor
<option>--boot
</option> specified
</entry>
500 <entry>The passed parameters are interpreted as the command line, which is executed as PID
1 in the container.
</entry>
504 <entry><option>--as-pid2
</option> specified
</entry>
505 <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>
509 <entry><option>--boot
</option> specified
</entry>
510 <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>
517 <para>Note that
<option>--boot
</option> is the default mode of operation if the
518 <filename>systemd-nspawn@.service
</filename> template unit file is used.
</para>
523 <term><option>--chdir=
</option></term>
525 <listitem><para>Change to the specified working directory before invoking the process in the container. Expects
526 an absolute path in the container's file system namespace.
</para></listitem>
530 <term><option>-E
<replaceable>NAME
</replaceable>=
<replaceable>VALUE
</replaceable></option></term>
531 <term><option>--setenv=
<replaceable>NAME
</replaceable>=
<replaceable>VALUE
</replaceable></option></term>
533 <listitem><para>Specifies an environment variable assignment
534 to pass to the init process in the container, in the format
535 <literal>NAME=VALUE
</literal>. This may be used to override
536 the default variables or to set additional variables. This
537 parameter may be used more than once.
</para></listitem>
541 <term><option>-u
</option></term>
542 <term><option>--user=
</option></term>
544 <listitem><para>After transitioning into the container, change to the specified user defined in the
545 container's user database. Like all other systemd-nspawn features, this is not a security feature and
546 provides protection against accidental destructive operations only.
</para></listitem>
550 <term><option>--kill-signal=
</option></term>
552 <listitem><para>Specify the process signal to send to the container's PID
1 when nspawn itself receives
553 <constant>SIGTERM
</constant>, in order to trigger an orderly shutdown of the container. Defaults to
554 <constant>SIGRTMIN+
3</constant> if
<option>--boot
</option> is used (on systemd-compatible init systems
555 <constant>SIGRTMIN+
3</constant> triggers an orderly shutdown). If
<option>--boot
</option> is not used and this
556 option is not specified the container's processes are terminated abruptly via
<constant>SIGKILL
</constant>. For
557 a list of valid signals, see
<citerefentry
558 project='man-pages'
><refentrytitle>signal
</refentrytitle><manvolnum>7</manvolnum></citerefentry>.
</para></listitem>
562 <term><option>--notify-ready=
</option></term>
564 <listitem><para>Configures support for notifications from the container's init process.
565 <option>--notify-ready=
</option> takes a boolean (
<option>no
</option> and
<option>yes
</option>).
566 With option
<option>no
</option> systemd-nspawn notifies systemd
567 with a
<literal>READY=
1</literal> message when the init process is created.
568 With option
<option>yes
</option> systemd-nspawn waits for the
569 <literal>READY=
1</literal> message from the init process in the container
570 before sending its own to systemd. For more details about notifications
571 see
<citerefentry><refentrytitle>sd_notify
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
</para></listitem>
575 </refsect2><refsect2>
576 <title>System Identity Options
</title>
580 <term><option>-M
</option></term>
581 <term><option>--machine=
</option></term>
583 <listitem><para>Sets the machine name for this container. This
584 name may be used to identify this container during its runtime
585 (for example in tools like
586 <citerefentry><refentrytitle>machinectl
</refentrytitle><manvolnum>1</manvolnum></citerefentry>
587 and similar), and is used to initialize the container's
588 hostname (which the container can choose to override,
589 however). If not specified, the last component of the root
590 directory path of the container is used, possibly suffixed
591 with a random identifier in case
<option>--ephemeral
</option>
592 mode is selected. If the root directory selected is the host's
593 root directory the host's hostname is used as default
594 instead.
</para></listitem>
598 <term><option>--hostname=
</option></term>
600 <listitem><para>Controls the hostname to set within the container, if different from the machine name. Expects
601 a valid hostname as argument. If this option is used, the kernel hostname of the container will be set to this
602 value, otherwise it will be initialized to the machine name as controlled by the
<option>--machine=
</option>
603 option described above. The machine name is used for various aspect of identification of the container from the
604 outside, the kernel hostname configurable with this option is useful for the container to identify itself from
605 the inside. It is usually a good idea to keep both forms of identification synchronized, in order to avoid
606 confusion. It is hence recommended to avoid usage of this option, and use
<option>--machine=
</option>
607 exclusively. Note that regardless whether the container's hostname is initialized from the name set with
608 <option>--hostname=
</option> or the one set with
<option>--machine=
</option>, the container can later override
609 its kernel hostname freely on its own as well.
</para>
614 <term><option>--uuid=
</option></term>
616 <listitem><para>Set the specified UUID for the container. The
617 init system will initialize
618 <filename>/etc/machine-id
</filename> from this if this file is
619 not set yet. Note that this option takes effect only if
620 <filename>/etc/machine-id
</filename> in the container is
621 unpopulated.
</para></listitem>
625 </refsect2><refsect2>
626 <title>Property Options
</title>
630 <term><option>-S
</option></term>
631 <term><option>--slice=
</option></term>
633 <listitem><para>Make the container part of the specified slice, instead of the default
634 <filename>machine.slice
</filename>. This applies only if the machine is run in its own scope unit, i.e. if
635 <option>--keep-unit
</option> isn't used.
</para>
640 <term><option>--property=
</option></term>
642 <listitem><para>Set a unit property on the scope unit to register for the machine. This applies only if the
643 machine is run in its own scope unit, i.e. if
<option>--keep-unit
</option> isn't used. Takes unit property
644 assignments in the same format as
<command>systemctl set-property
</command>. This is useful to set memory
645 limits and similar for container.
</para>
650 <term><option>--register=
</option></term>
652 <listitem><para>Controls whether the container is registered with
653 <citerefentry><refentrytitle>systemd-machined
</refentrytitle><manvolnum>8</manvolnum></citerefentry>. Takes a
654 boolean argument, which defaults to
<literal>yes
</literal>. This option should be enabled when the container
655 runs a full Operating System (more specifically: a system and service manager as PID
1), and is useful to
656 ensure that the container is accessible via
657 <citerefentry><refentrytitle>machinectl
</refentrytitle><manvolnum>1</manvolnum></citerefentry> and shown by
658 tools such as
<citerefentry
659 project='man-pages'
><refentrytitle>ps
</refentrytitle><manvolnum>1</manvolnum></citerefentry>. If the container
660 does not run a service manager, it is recommended to set this option to
661 <literal>no
</literal>.
</para></listitem>
665 <term><option>--keep-unit
</option></term>
667 <listitem><para>Instead of creating a transient scope unit to run the container in, simply use the service or
668 scope unit
<command>systemd-nspawn
</command> has been invoked in. If
<option>--register=yes
</option> is set
669 this unit is registered with
670 <citerefentry><refentrytitle>systemd-machined
</refentrytitle><manvolnum>8</manvolnum></citerefentry>. This
671 switch should be used if
<command>systemd-nspawn
</command> is invoked from within a service unit, and the
672 service unit's sole purpose is to run a single
<command>systemd-nspawn
</command> container. This option is not
673 available if run from a user session.
</para>
674 <para>Note that passing
<option>--keep-unit
</option> disables the effect of
<option>--slice=
</option> and
675 <option>--property=
</option>. Use
<option>--keep-unit
</option> and
<option>--register=no
</option> in
676 combination to disable any kind of unit allocation or registration with
677 <command>systemd-machined
</command>.
</para></listitem>
681 </refsect2><refsect2>
682 <title>User Namespacing Options
</title>
686 <term><option>--private-users=
</option></term>
688 <listitem><para>Controls user namespacing. If enabled, the container will run with its own private set of UNIX
689 user and group ids (UIDs and GIDs). This involves mapping the private UIDs/GIDs used in the container (starting
690 with the container's root user
0 and up) to a range of UIDs/GIDs on the host that are not used for other
691 purposes (usually in the range beyond the host's UID/GID
65536). The parameter may be specified as follows:
</para>
694 <listitem><para>If one or two colon-separated numbers are specified, user namespacing is turned on. The first
695 parameter specifies the first host UID/GID to assign to the container, the second parameter specifies the
696 number of host UIDs/GIDs to assign to the container. If the second parameter is omitted,
65536 UIDs/GIDs are
697 assigned.
</para></listitem>
699 <listitem><para>If the parameter is omitted, or true, user namespacing is turned on. The UID/GID range to
700 use is determined automatically from the file ownership of the root directory of the container's directory
701 tree. To use this option, make sure to prepare the directory tree in advance, and ensure that all files and
702 directories in it are owned by UIDs/GIDs in the range you'd like to use. Also, make sure that used file ACLs
703 exclusively reference UIDs/GIDs in the appropriate range. If this mode is used the number of UIDs/GIDs
704 assigned to the container for use is
65536, and the UID/GID of the root directory must be a multiple of
705 65536.
</para></listitem>
707 <listitem><para>If the parameter is false, user namespacing is turned off. This is the default.
</para>
710 <listitem><para>The special value
<literal>pick
</literal> turns on user namespacing. In this case the UID/GID
711 range is automatically chosen. As first step, the file owner of the root directory of the container's
712 directory tree is read, and it is checked that it is currently not used by the system otherwise (in
713 particular, that no other container is using it). If this check is successful, the UID/GID range determined
714 this way is used, similar to the behavior if
"yes" is specified. If the check is not successful (and thus
715 the UID/GID range indicated in the root directory's file owner is already used elsewhere) a new – currently
716 unused – UID/GID range of
65536 UIDs/GIDs is randomly chosen between the host UID/GIDs of
524288 and
717 1878982656, always starting at a multiple of
65536, and, if possible, consistently hashed from the machine
718 name. This setting implies
719 <option>--private-users-chown
</option> (see below), which has the effect that the files and directories in
720 the container's directory tree will be owned by the appropriate users of the range picked. Using this option
721 makes user namespace behavior fully automatic. Note that the first invocation of a previously unused
722 container image might result in picking a new UID/GID range for it, and thus in the (possibly expensive) file
723 ownership adjustment operation. However, subsequent invocations of the container will be cheap (unless of
724 course the picked UID/GID range is assigned to a different use by then).
</para></listitem>
727 <para>It is recommended to assign at least
65536 UIDs/GIDs to each container, so that the usable UID/GID range in the
728 container covers
16 bit. For best security, do not assign overlapping UID/GID ranges to multiple containers. It is
729 hence a good idea to use the upper
16 bit of the host
32-bit UIDs/GIDs as container identifier, while the lower
16
730 bit encode the container UID/GID used. This is in fact the behavior enforced by the
731 <option>--private-users=pick
</option> option.
</para>
733 <para>When user namespaces are used, the GID range assigned to each container is always chosen identical to the
736 <para>In most cases, using
<option>--private-users=pick
</option> is the recommended option as it enhances
737 container security massively and operates fully automatically in most cases.
</para>
739 <para>Note that the picked UID/GID range is not written to
<filename>/etc/passwd
</filename> or
740 <filename>/etc/group
</filename>. In fact, the allocation of the range is not stored persistently anywhere,
741 except in the file ownership of the files and directories of the container.
</para>
743 <para>Note that when user namespacing is used file ownership on disk reflects this, and all of the container's
744 files and directories are owned by the container's effective user and group IDs. This means that copying files
745 from and to the container image requires correction of the numeric UID/GID values, according to the UID/GID
746 shift applied.
</para></listitem>
750 <term><option>--private-users-chown
</option></term>
752 <listitem><para>If specified, all files and directories in the container's directory tree will be
753 adjusted so that they are owned by the appropriate UIDs/GIDs selected for the container (see above).
754 This operation is potentially expensive, as it involves iterating through the full directory tree of
755 the container. Besides actual file ownership, file ACLs are adjusted as well.
</para>
757 <para>This option is implied if
<option>--private-users=pick
</option> is used. This option has no effect if
758 user namespacing is not used.
</para></listitem>
762 <term><option>-U
</option></term>
764 <listitem><para>If the kernel supports the user namespaces feature, equivalent to
765 <option>--private-users=pick --private-users-chown
</option>, otherwise equivalent to
766 <option>--private-users=no
</option>.
</para>
768 <para>Note that
<option>-U
</option> is the default if the
769 <filename>systemd-nspawn@.service
</filename> template unit file is used.
</para>
771 <para>Note: it is possible to undo the effect of
<option>--private-users-chown
</option> (or
772 <option>-U
</option>) on the file system by redoing the operation with the first UID of
0:
</para>
774 <programlisting>systemd-nspawn … --private-users=
0 --private-users-chown
</programlisting>
780 </refsect2><refsect2>
781 <title>Networking Options
</title>
786 <term><option>--private-network
</option></term>
788 <listitem><para>Disconnect networking of the container from
789 the host. This makes all network interfaces unavailable in the
790 container, with the exception of the loopback device and those
791 specified with
<option>--network-interface=
</option> and
792 configured with
<option>--network-veth
</option>. If this
793 option is specified, the
<constant>CAP_NET_ADMIN
</constant> capability will be
794 added to the set of capabilities the container retains. The
795 latter may be disabled by using
<option>--drop-capability=
</option>.
796 If this option is not specified (or implied by one of the options
797 listed below), the container will have full access to the host network.
802 <term><option>--network-interface=
</option></term>
804 <listitem><para>Assign the specified network interface to the container. This will remove the
805 specified interface from the calling namespace and place it in the container. When the container
806 terminates, it is moved back to the calling namespace. Note that
807 <option>--network-interface=
</option> implies
<option>--private-network
</option>. This option may be
808 used more than once to add multiple network interfaces to the container.
</para>
810 <para>Note that any network interface specified this way must already exist at the time the container
811 is started. If the container shall be started automatically at boot via a
812 <filename>systemd-nspawn@.service
</filename> unit file instance, it might hence make sense to add a
813 unit file drop-in to the service instance
814 (e.g.
<filename>/etc/systemd/system/systemd-nspawn@foobar.service.d/
50-network.conf
</filename>) with
815 contents like the following:
</para>
817 <programlisting>[Unit]
818 Wants=sys-subsystem-net-devices-ens1.device
819 After=sys-subsystem-net-devices-ens1.device
</programlisting>
821 <para>This will make sure that activation of the container service will be delayed until the
822 <literal>ens1
</literal> network interface has shown up. This is required since hardware probing is
823 fully asynchronous, and network interfaces might be discovered only later during the boot process,
824 after the container would normally be started without these explicit dependencies.
</para>
829 <term><option>--network-macvlan=
</option></term>
831 <listitem><para>Create a
<literal>macvlan
</literal> interface of the specified Ethernet network
832 interface and add it to the container. A
<literal>macvlan
</literal> interface is a virtual interface
833 that adds a second MAC address to an existing physical Ethernet link. The interface in the container
834 will be named after the interface on the host, prefixed with
<literal>mv-
</literal>. Note that
835 <option>--network-macvlan=
</option> implies
<option>--private-network
</option>. This option may be
836 used more than once to add multiple network interfaces to the container.
</para>
838 <para>As with
<option>--network-interface=
</option>, the underlying Ethernet network interface must
839 already exist at the time the container is started, and thus similar unit file drop-ins as described
840 above might be useful.
</para></listitem>
844 <term><option>--network-ipvlan=
</option></term>
846 <listitem><para>Create an
<literal>ipvlan
</literal> interface of the specified Ethernet network
847 interface and add it to the container. An
<literal>ipvlan
</literal> interface is a virtual interface,
848 similar to a
<literal>macvlan
</literal> interface, which uses the same MAC address as the underlying
849 interface. The interface in the container will be named after the interface on the host, prefixed
850 with
<literal>iv-
</literal>. Note that
<option>--network-ipvlan=
</option> implies
851 <option>--private-network
</option>. This option may be used more than once to add multiple network
852 interfaces to the container.
</para>
854 <para>As with
<option>--network-interface=
</option>, the underlying Ethernet network interface must
855 already exist at the time the container is started, and thus similar unit file drop-ins as described
856 above might be useful.
</para></listitem>
860 <term><option>-n
</option></term>
861 <term><option>--network-veth
</option></term>
863 <listitem><para>Create a virtual Ethernet link (
<literal>veth
</literal>) between host and container. The host
864 side of the Ethernet link will be available as a network interface named after the container's name (as
865 specified with
<option>--machine=
</option>), prefixed with
<literal>ve-
</literal>. The container side of the
866 Ethernet link will be named
<literal>host0
</literal>. The
<option>--network-veth
</option> option implies
867 <option>--private-network
</option>.
</para>
870 <citerefentry><refentrytitle>systemd-networkd.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>
871 includes by default a network file
<filename>/usr/lib/systemd/network/
80-container-ve.network
</filename>
872 matching the host-side interfaces created this way, which contains settings to enable automatic address
873 provisioning on the created virtual link via DHCP, as well as automatic IP routing onto the host's external
874 network interfaces. It also contains
<filename>/usr/lib/systemd/network/
80-container-host0.network
</filename>
875 matching the container-side interface created this way, containing settings to enable client side address
876 assignment via DHCP. In case
<filename>systemd-networkd
</filename> is running on both the host and inside the
877 container, automatic IP communication from the container to the host is thus available, with further
878 connectivity to the external network.
</para>
880 <para>Note that
<option>--network-veth
</option> is the default if the
881 <filename>systemd-nspawn@.service
</filename> template unit file is used.
</para>
883 <para>Note that on Linux network interface names may have a length of
15 characters at maximum, while
884 container names may have a length up to
64 characters. As this option derives the host-side interface
885 name from the container name the name is possibly truncated. Thus, care needs to be taken to ensure
886 that interface names remain unique in this case, or even better container names are generally not
887 chosen longer than
12 characters, to avoid the truncation. If the name is truncated,
888 <command>systemd-nspawn
</command> will automatically append a
4-digit hash value to the name to
889 reduce the chance of collisions. However, the hash algorithm is not collision-free. (See
890 <citerefentry><refentrytitle>systemd.net-naming-scheme
</refentrytitle><manvolnum>7</manvolnum></citerefentry>
891 for details on older naming algorithms for this interface). Alternatively, the
892 <option>--network-veth-extra=
</option> option may be used, which allows free configuration of the
893 host-side interface name independently of the container name — but might require a bit more
894 additional configuration in case bridging in a fashion similar to
<option>--network-bridge=
</option>
900 <term><option>--network-veth-extra=
</option></term>
902 <listitem><para>Adds an additional virtual Ethernet link
903 between host and container. Takes a colon-separated pair of
904 host interface name and container interface name. The latter
905 may be omitted in which case the container and host sides will
906 be assigned the same name. This switch is independent of
907 <option>--network-veth
</option>, and — in contrast — may be
908 used multiple times, and allows configuration of the network
909 interface names. Note that
<option>--network-bridge=
</option>
910 has no effect on interfaces created with
911 <option>--network-veth-extra=
</option>.
</para></listitem>
915 <term><option>--network-bridge=
</option></term>
917 <listitem><para>Adds the host side of the Ethernet link created with
<option>--network-veth
</option>
918 to the specified Ethernet bridge interface. Expects a valid network interface name of a bridge device
919 as argument. Note that
<option>--network-bridge=
</option> implies
<option>--network-veth
</option>. If
920 this option is used, the host side of the Ethernet link will use the
<literal>vb-
</literal> prefix
921 instead of
<literal>ve-
</literal>. Regardless of the used naming prefix the same network interface
922 name length limits imposed by Linux apply, along with the complications this creates (for details see
925 <para>As with
<option>--network-interface=
</option>, the underlying bridge network interface must
926 already exist at the time the container is started, and thus similar unit file drop-ins as described
927 above might be useful.
</para></listitem>
931 <term><option>--network-zone=
</option></term>
933 <listitem><para>Creates a virtual Ethernet link (
<literal>veth
</literal>) to the container and adds it to an
934 automatically managed Ethernet bridge interface. The bridge interface is named after the passed argument,
935 prefixed with
<literal>vz-
</literal>. The bridge interface is automatically created when the first container
936 configured for its name is started, and is automatically removed when the last container configured for its
937 name exits. Hence, each bridge interface configured this way exists only as long as there's at least one
938 container referencing it running. This option is very similar to
<option>--network-bridge=
</option>, besides
939 this automatic creation/removal of the bridge device.
</para>
941 <para>This setting makes it easy to place multiple related containers on a common, virtual Ethernet-based
942 broadcast domain, here called a
"zone". Each container may only be part of one zone, but each zone may contain
943 any number of containers. Each zone is referenced by its name. Names may be chosen freely (as long as they form
944 valid network interface names when prefixed with
<literal>vz-
</literal>), and it is sufficient to pass the same
945 name to the
<option>--network-zone=
</option> switch of the various concurrently running containers to join
946 them in one zone.
</para>
949 <citerefentry><refentrytitle>systemd-networkd.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>
950 includes by default a network file
<filename>/usr/lib/systemd/network/
80-container-vz.network
</filename>
951 matching the bridge interfaces created this way, which contains settings to enable automatic address
952 provisioning on the created virtual network via DHCP, as well as automatic IP routing onto the host's external
953 network interfaces. Using
<option>--network-zone=
</option> is hence in most cases fully automatic and
954 sufficient to connect multiple local containers in a joined broadcast domain to the host, with further
955 connectivity to the external network.
</para>
960 <term><option>--network-namespace-path=
</option></term>
962 <listitem><para>Takes the path to a file representing a kernel
963 network namespace that the container shall run in. The specified path
964 should refer to a (possibly bind-mounted) network namespace file, as
965 exposed by the kernel below
<filename>/proc/$PID/ns/net
</filename>.
966 This makes the container enter the given network namespace. One of the
967 typical use cases is to give a network namespace under
968 <filename>/run/netns
</filename> created by
<citerefentry
969 project='man-pages'
><refentrytitle>ip-netns
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
970 for example,
<option>--network-namespace-path=/run/netns/foo
</option>.
971 Note that this option cannot be used together with other
972 network-related options, such as
<option>--private-network
</option>
973 or
<option>--network-interface=
</option>.
</para></listitem>
977 <term><option>-p
</option></term>
978 <term><option>--port=
</option></term>
980 <listitem><para>If private networking is enabled, maps an IP
981 port on the host onto an IP port on the container. Takes a
982 protocol specifier (either
<literal>tcp
</literal> or
983 <literal>udp
</literal>), separated by a colon from a host port
984 number in the range
1 to
65535, separated by a colon from a
985 container port number in the range from
1 to
65535. The
986 protocol specifier and its separating colon may be omitted, in
987 which case
<literal>tcp
</literal> is assumed. The container
988 port number and its colon may be omitted, in which case the
989 same port as the host port is implied. This option is only
990 supported if private networking is used, such as with
991 <option>--network-veth
</option>,
<option>--network-zone=
</option>
992 <option>--network-bridge=
</option>.
</para></listitem>
996 </refsect2><refsect2>
997 <title>Security Options
</title>
1001 <term><option>--capability=
</option></term>
1003 <listitem><para>List one or more additional capabilities to grant the container. Takes a
1004 comma-separated list of capability names, see
<citerefentry
1005 project='man-pages'
><refentrytitle>capabilities
</refentrytitle><manvolnum>7</manvolnum></citerefentry>
1006 for more information. Note that the following capabilities will be granted in any way:
1007 <constant>CAP_AUDIT_CONTROL
</constant>,
<constant>CAP_AUDIT_WRITE
</constant>,
1008 <constant>CAP_CHOWN
</constant>,
<constant>CAP_DAC_OVERRIDE
</constant>,
1009 <constant>CAP_DAC_READ_SEARCH
</constant>,
<constant>CAP_FOWNER
</constant>,
1010 <constant>CAP_FSETID
</constant>,
<constant>CAP_IPC_OWNER
</constant>,
<constant>CAP_KILL
</constant>,
1011 <constant>CAP_LEASE
</constant>,
<constant>CAP_LINUX_IMMUTABLE
</constant>,
1012 <constant>CAP_MKNOD
</constant>,
<constant>CAP_NET_BIND_SERVICE
</constant>,
1013 <constant>CAP_NET_BROADCAST
</constant>,
<constant>CAP_NET_RAW
</constant>,
1014 <constant>CAP_SETFCAP
</constant>,
<constant>CAP_SETGID
</constant>,
<constant>CAP_SETPCAP
</constant>,
1015 <constant>CAP_SETUID
</constant>,
<constant>CAP_SYS_ADMIN
</constant>,
1016 <constant>CAP_SYS_BOOT
</constant>,
<constant>CAP_SYS_CHROOT
</constant>,
1017 <constant>CAP_SYS_NICE
</constant>,
<constant>CAP_SYS_PTRACE
</constant>,
1018 <constant>CAP_SYS_RESOURCE
</constant>,
<constant>CAP_SYS_TTY_CONFIG
</constant>. Also
1019 <constant>CAP_NET_ADMIN
</constant> is retained if
<option>--private-network
</option> is specified.
1020 If the special value
<literal>all
</literal> is passed, all capabilities are retained.
</para>
1022 <para>If the special value of
<literal>help
</literal> is passed, the program will print known
1023 capability names and exit.
</para>
1025 <para>This option sets the bounding set of capabilities which
1026 also limits the ambient capabilities as given with the
1027 <option>--ambient-capability=
</option>.
</para></listitem>
1031 <term><option>--drop-capability=
</option></term>
1033 <listitem><para>Specify one or more additional capabilities to
1034 drop for the container. This allows running the container with
1035 fewer capabilities than the default (see
1038 <para>If the special value of
<literal>help
</literal> is passed, the program will print known
1039 capability names and exit.
</para>
1041 <para>This option sets the bounding set of capabilities which
1042 also limits the ambient capabilities as given with the
1043 <option>--ambient-capability=
</option>.
</para></listitem>
1047 <term><option>--ambient-capability=
</option></term>
1049 <listitem><para>Specify one or more additional capabilities to
1050 pass in the inheritable and ambient set to the program started
1051 within the container. The value
<literal>all
</literal> is not
1052 supported for this setting.
</para>
1054 <para>All capabilities specified here must be in the set
1055 allowed with the
<option>--capability=
</option> and
1056 <option>--drop-capability=
</option> options. Otherwise, an
1057 error message will be shown.
</para>
1059 <para>This option cannot be combined with the boot mode of the
1060 container (as requested via
<option>--boot
</option>).
</para>
1062 <para>If the special value of
<literal>help
</literal> is
1063 passed, the program will print known capability names and
1064 exit.
</para></listitem>
1068 <term><option>--no-new-privileges=
</option></term>
1070 <listitem><para>Takes a boolean argument. Specifies the value of the
1071 <constant>PR_SET_NO_NEW_PRIVS
</constant> flag for the container payload. Defaults to off. When turned
1072 on the payload code of the container cannot acquire new privileges, i.e. the
"setuid" file bit as
1073 well as file system capabilities will not have an effect anymore. See
<citerefentry
1074 project='man-pages'
><refentrytitle>prctl
</refentrytitle><manvolnum>2</manvolnum></citerefentry> for
1075 details about this flag.
</para></listitem>
1079 <term><option>--system-call-filter=
</option></term> <listitem><para>Alter the system call filter
1080 applied to containers. Takes a space-separated list of system call names or group names (the latter
1081 prefixed with
<literal>@
</literal>, as listed by the
<command>syscall-filter
</command> command of
1082 <citerefentry><refentrytitle>systemd-analyze
</refentrytitle><manvolnum>1</manvolnum></citerefentry>). Passed
1083 system calls will be permitted. The list may optionally be prefixed by
<literal>~
</literal>, in which
1084 case all listed system calls are prohibited. If this command line option is used multiple times the
1085 configured lists are combined. If both a positive and a negative list (that is one system call list
1086 without and one with the
<literal>~
</literal> prefix) are configured, the negative list takes
1087 precedence over the positive list. Note that
<command>systemd-nspawn
</command> always implements a
1088 system call allow list (as opposed to a deny list!), and this command line option hence adds or
1089 removes entries from the default allow list, depending on the
<literal>~
</literal> prefix. Note that
1090 the applied system call filter is also altered implicitly if additional capabilities are passed using
1091 the
<command>--capabilities=
</command>.
</para></listitem>
1095 <term><option>-Z
</option></term>
1096 <term><option>--selinux-context=
</option></term>
1098 <listitem><para>Sets the SELinux security context to be used
1099 to label processes in the container.
</para>
1104 <term><option>-L
</option></term>
1105 <term><option>--selinux-apifs-context=
</option></term>
1107 <listitem><para>Sets the SELinux security context to be used
1108 to label files in the virtual API file systems in the
1114 </refsect2><refsect2>
1115 <title>Resource Options
</title>
1120 <term><option>--rlimit=
</option></term>
1122 <listitem><para>Sets the specified POSIX resource limit for the container payload. Expects an assignment of the
1124 <literal><replaceable>LIMIT
</replaceable>=
<replaceable>SOFT
</replaceable>:
<replaceable>HARD
</replaceable></literal>
1125 or
<literal><replaceable>LIMIT
</replaceable>=
<replaceable>VALUE
</replaceable></literal>, where
1126 <replaceable>LIMIT
</replaceable> should refer to a resource limit type, such as
1127 <constant>RLIMIT_NOFILE
</constant> or
<constant>RLIMIT_NICE
</constant>. The
<replaceable>SOFT
</replaceable> and
1128 <replaceable>HARD
</replaceable> fields should refer to the numeric soft and hard resource limit values. If the
1129 second form is used,
<replaceable>VALUE
</replaceable> may specify a value that is used both as soft and hard
1130 limit. In place of a numeric value the special string
<literal>infinity
</literal> may be used to turn off
1131 resource limiting for the specific type of resource. This command line option may be used multiple times to
1132 control limits on multiple limit types. If used multiple times for the same limit type, the last use
1133 wins. For details about resource limits see
<citerefentry
1134 project='man-pages'
><refentrytitle>setrlimit
</refentrytitle><manvolnum>2</manvolnum></citerefentry>. By default
1135 resource limits for the container's init process (PID
1) are set to the same values the Linux kernel originally
1136 passed to the host init system. Note that some resource limits are enforced on resources counted per user, in
1137 particular
<constant>RLIMIT_NPROC
</constant>. This means that unless user namespacing is deployed
1138 (i.e.
<option>--private-users=
</option> is used, see above), any limits set will be applied to the resource
1139 usage of the same user on all local containers as well as the host. This means particular care needs to be
1140 taken with these limits as they might be triggered by possibly less trusted code. Example:
1141 <literal>--rlimit=RLIMIT_NOFILE=
8192:
16384</literal>.
</para></listitem>
1145 <term><option>--oom-score-adjust=
</option></term>
1147 <listitem><para>Changes the OOM (
"Out Of Memory") score adjustment value for the container payload. This controls
1148 <filename>/proc/self/oom_score_adj
</filename> which influences the preference with which this container is
1149 terminated when memory becomes scarce. For details see
<citerefentry
1150 project='man-pages'
><refentrytitle>proc
</refentrytitle><manvolnum>5</manvolnum></citerefentry>. Takes an
1151 integer in the range -
1000…
1000.
</para></listitem>
1155 <term><option>--cpu-affinity=
</option></term>
1157 <listitem><para>Controls the CPU affinity of the container payload. Takes a comma separated list of CPU numbers
1158 or number ranges (the latter's start and end value separated by dashes). See
<citerefentry
1159 project='man-pages'
><refentrytitle>sched_setaffinity
</refentrytitle><manvolnum>2</manvolnum></citerefentry> for
1160 details.
</para></listitem>
1164 <term><option>--personality=
</option></term>
1166 <listitem><para>Control the architecture (
"personality")
1168 <citerefentry project='man-pages'
><refentrytitle>uname
</refentrytitle><manvolnum>2</manvolnum></citerefentry>
1169 in the container. Currently, only
<literal>x86
</literal> and
1170 <literal>x86-
64</literal> are supported. This is useful when
1171 running a
32-bit container on a
64-bit host. If this setting
1172 is not used, the personality reported in the container is the
1173 same as the one reported on the host.
</para></listitem>
1177 </refsect2><refsect2>
1178 <title>Integration Options
</title>
1182 <term><option>--resolv-conf=
</option></term>
1184 <listitem><para>Configures how
<filename>/etc/resolv.conf
</filename> inside of the container shall be
1185 handled (i.e. DNS configuration synchronization from host to container). Takes one of
1186 <literal>off
</literal>,
<literal>copy-host
</literal>,
<literal>copy-static
</literal>,
1187 <literal>copy-uplink
</literal>,
<literal>copy-stub
</literal>,
<literal>replace-host
</literal>,
1188 <literal>replace-static
</literal>,
<literal>replace-uplink
</literal>,
1189 <literal>replace-stub
</literal>,
<literal>bind-host
</literal>,
<literal>bind-static
</literal>,
1190 <literal>bind-uplink
</literal>,
<literal>bind-stub
</literal>,
<literal>delete
</literal> or
1191 <literal>auto
</literal>.
</para>
1193 <para>If set to
<literal>off
</literal> the
<filename>/etc/resolv.conf
</filename> file in the
1194 container is left as it is included in the image, and neither modified nor bind mounted over.
</para>
1196 <para>If set to
<literal>copy-host
</literal>, the
<filename>/etc/resolv.conf
</filename> file from the
1197 host is copied into the container, unless the file exists already and is not a regular file (e.g. a
1198 symlink). Similar, if
<literal>replace-host
</literal> is used the file is copied, replacing any
1199 existing inode, including symlinks. Similar, if
<literal>bind-host
</literal> is used, the file is
1200 bind mounted from the host into the container.
</para>
1202 <para>If set to
<literal>copy-static
</literal>,
<literal>replace-static
</literal> or
1203 <literal>bind-static
</literal> the static
<filename>resolv.conf
</filename> file supplied with
1204 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>
1205 (specifically:
<filename>/usr/lib/systemd/resolv.conf
</filename>) is copied or bind mounted into the
1208 <para>If set to
<literal>copy-uplink
</literal>,
<literal>replace-uplink
</literal> or
1209 <literal>bind-uplink
</literal> the uplink
<filename>resolv.conf
</filename> file managed by
1210 <filename>systemd-resolved.service
</filename> (specifically:
1211 <filename>/run/systemd/resolve/resolv.conf
</filename>) is copied or bind mounted into the
1214 <para>If set to
<literal>copy-stub
</literal>,
<literal>replace-stub
</literal> or
1215 <literal>bind-stub
</literal> the stub
<filename>resolv.conf
</filename> file managed by
1216 <filename>systemd-resolved.service
</filename> (specifically:
1217 <filename>/run/systemd/resolve/stub-resolv.conf
</filename>) is copied or bind mounted into the
1220 <para>If set to
<literal>delete
</literal> the
<filename>/etc/resolv.conf
</filename> file in the
1221 container is deleted if it exists.
</para>
1223 <para>Finally, if set to
<literal>auto
</literal> the file is left as it is if private networking is
1224 turned on (see
<option>--private-network
</option>). Otherwise, if
1225 <filename>systemd-resolved.service
</filename> is running its stub
<filename>resolv.conf
</filename>
1226 file is used, and if not the host's
<filename>/etc/resolv.conf
</filename> file. In the latter cases
1227 the file is copied if the image is writable, and bind mounted otherwise.
</para>
1229 <para>It's recommended to use
<literal>copy-…
</literal> or
<literal>replace-…
</literal> if the
1230 container shall be able to make changes to the DNS configuration on its own, deviating from the
1231 host's settings. Otherwise
<literal>bind
</literal> is preferable, as it means direct changes to
1232 <filename>/etc/resolv.conf
</filename> in the container are not allowed, as it is a read-only bind
1233 mount (but note that if the container has enough privileges, it might simply go ahead and unmount the
1234 bind mount anyway). Note that both if the file is bind mounted and if it is copied no further
1235 propagation of configuration is generally done after the one-time early initialization (this is
1236 because the file is usually updated through copying and renaming). Defaults to
1237 <literal>auto
</literal>.
</para></listitem>
1241 <term><option>--timezone=
</option></term>
1243 <listitem><para>Configures how
<filename>/etc/localtime
</filename> inside of the container
1244 (i.e. local timezone synchronization from host to container) shall be handled. Takes one of
1245 <literal>off
</literal>,
<literal>copy
</literal>,
<literal>bind
</literal>,
<literal>symlink
</literal>,
1246 <literal>delete
</literal> or
<literal>auto
</literal>. If set to
<literal>off
</literal> the
1247 <filename>/etc/localtime
</filename> file in the container is left as it is included in the image, and
1248 neither modified nor bind mounted over. If set to
<literal>copy
</literal> the
1249 <filename>/etc/localtime
</filename> file of the host is copied into the container. Similarly, if
1250 <literal>bind
</literal> is used, the file is bind mounted from the host into the container. If set to
1251 <literal>symlink
</literal>, a symlink is created pointing from
<filename>/etc/localtime
</filename> in
1252 the container to the timezone file in the container that matches the timezone setting on the host. If
1253 set to
<literal>delete
</literal>, the file in the container is deleted, should it exist. If set to
1254 <literal>auto
</literal> and the
<filename>/etc/localtime
</filename> file of the host is a symlink,
1255 then
<literal>symlink
</literal> mode is used, and
<literal>copy
</literal> otherwise, except if the
1256 image is read-only in which case
<literal>bind
</literal> is used instead. Defaults to
1257 <literal>auto
</literal>.
</para></listitem>
1261 <term><option>--link-journal=
</option></term>
1263 <listitem><para>Control whether the container's journal shall
1264 be made visible to the host system. If enabled, allows viewing
1265 the container's journal files from the host (but not vice
1266 versa). Takes one of
<literal>no
</literal>,
1267 <literal>host
</literal>,
<literal>try-host
</literal>,
1268 <literal>guest
</literal>,
<literal>try-guest
</literal>,
1269 <literal>auto
</literal>. If
<literal>no
</literal>, the journal
1270 is not linked. If
<literal>host
</literal>, the journal files
1271 are stored on the host file system (beneath
1272 <filename>/var/log/journal/
<replaceable>machine-id
</replaceable></filename>)
1273 and the subdirectory is bind-mounted into the container at the
1274 same location. If
<literal>guest
</literal>, the journal files
1275 are stored on the guest file system (beneath
1276 <filename>/var/log/journal/
<replaceable>machine-id
</replaceable></filename>)
1277 and the subdirectory is symlinked into the host at the same
1278 location.
<literal>try-host
</literal> and
1279 <literal>try-guest
</literal> do the same but do not fail if
1280 the host does not have persistent journaling enabled. If
1281 <literal>auto
</literal> (the default), and the right
1282 subdirectory of
<filename>/var/log/journal
</filename> exists,
1283 it will be bind mounted into the container. If the
1284 subdirectory does not exist, no linking is performed.
1285 Effectively, booting a container once with
1286 <literal>guest
</literal> or
<literal>host
</literal> will link
1287 the journal persistently if further on the default of
1288 <literal>auto
</literal> is used.
</para>
1290 <para>Note that
<option>--link-journal=try-guest
</option> is the default if the
1291 <filename>systemd-nspawn@.service
</filename> template unit file is used.
</para></listitem>
1295 <term><option>-j
</option></term>
1297 <listitem><para>Equivalent to
1298 <option>--link-journal=try-guest
</option>.
</para></listitem>
1303 </refsect2><refsect2>
1304 <title>Mount Options
</title>
1309 <term><option>--bind=
</option></term>
1310 <term><option>--bind-ro=
</option></term>
1312 <listitem><para>Bind mount a file or directory from the host into the container. Takes one of: a path
1313 argument — in which case the specified path will be mounted from the host to the same path in the container, or
1314 a colon-separated pair of paths — in which case the first specified path is the source in the host, and the
1315 second path is the destination in the container, or a colon-separated triple of source path, destination path
1316 and mount options. The source path may optionally be prefixed with a
<literal>+
</literal> character. If so, the
1317 source path is taken relative to the image's root directory. This permits setting up bind mounts within the
1318 container image. The source path may be specified as empty string, in which case a temporary directory below
1319 the host's
<filename>/var/tmp/
</filename> directory is used. It is automatically removed when the container is
1320 shut down. Mount options are comma-separated and currently, only
<option>rbind
</option> and
1321 <option>norbind
</option> are allowed, controlling whether to create a recursive or a regular bind
1322 mount. Defaults to
"rbind". Backslash escapes are interpreted, so
<literal>\:
</literal> may be used to embed
1323 colons in either path. This option may be specified multiple times for creating multiple independent bind
1324 mount points. The
<option>--bind-ro=
</option> option creates read-only bind mounts.
</para>
1326 <para>Note that when this option is used in combination with
<option>--private-users
</option>, the resulting
1327 mount points will be owned by the
<constant>nobody
</constant> user. That's because the mount and its files and
1328 directories continue to be owned by the relevant host users and groups, which do not exist in the container,
1329 and thus show up under the wildcard UID
65534 (nobody). If such bind mounts are created, it is recommended to
1330 make them read-only, using
<option>--bind-ro=
</option>.
</para></listitem>
1334 <term><option>--inaccessible=
</option></term>
1336 <listitem><para>Make the specified path inaccessible in the container. This over-mounts the specified path
1337 (which must exist in the container) with a file node of the same type that is empty and has the most
1338 restrictive access mode supported. This is an effective way to mask files, directories and other file system
1339 objects from the container payload. This option may be used more than once in case all specified paths are
1340 masked.
</para></listitem>
1344 <term><option>--tmpfs=
</option></term>
1346 <listitem><para>Mount a tmpfs file system into the container. Takes a single absolute path argument that
1347 specifies where to mount the tmpfs instance to (in which case the directory access mode will be chosen as
0755,
1348 owned by root/root), or optionally a colon-separated pair of path and mount option string that is used for
1349 mounting (in which case the kernel default for access mode and owner will be chosen, unless otherwise
1350 specified). Backslash escapes are interpreted in the path, so
<literal>\:
</literal> may be used to embed colons
1353 <para>Note that this option cannot be used to replace the root file system of the container with a temporary
1354 file system. However, the
<option>--volatile=
</option> option described below provides similar
1355 functionality, with a focus on implementing stateless operating system images.
</para></listitem>
1359 <term><option>--overlay=
</option></term>
1360 <term><option>--overlay-ro=
</option></term>
1362 <listitem><para>Combine multiple directory trees into one
1363 overlay file system and mount it into the container. Takes a
1364 list of colon-separated paths to the directory trees to
1365 combine and the destination mount point.
</para>
1367 <para>Backslash escapes are interpreted in the paths, so
1368 <literal>\:
</literal> may be used to embed colons in the paths.
1371 <para>If three or more paths are specified, then the last
1372 specified path is the destination mount point in the
1373 container, all paths specified before refer to directory trees
1374 on the host and are combined in the specified order into one
1375 overlay file system. The left-most path is hence the lowest
1376 directory tree, the second-to-last path the highest directory
1377 tree in the stacking order. If
<option>--overlay-ro=
</option>
1378 is used instead of
<option>--overlay=
</option>, a read-only
1379 overlay file system is created. If a writable overlay file
1380 system is created, all changes made to it are written to the
1381 highest directory tree in the stacking order, i.e. the
1382 second-to-last specified.
</para>
1384 <para>If only two paths are specified, then the second
1385 specified path is used both as the top-level directory tree in
1386 the stacking order as seen from the host, as well as the mount
1387 point for the overlay file system in the container. At least
1388 two paths have to be specified.
</para>
1390 <para>The source paths may optionally be prefixed with
<literal>+
</literal> character. If so they are
1391 taken relative to the image's root directory. The uppermost source path may also be specified as an
1392 empty string, in which case a temporary directory below the host's
<filename>/var/tmp/
</filename> is
1393 used. The directory is removed automatically when the container is shut down. This behaviour is
1394 useful in order to make read-only container directories writable while the container is running. For
1395 example, use
<literal>--overlay=+/var::/var
</literal> in order to automatically overlay a writable
1396 temporary directory on a read-only
<filename>/var/
</filename> directory.
</para>
1398 <para>For details about overlay file systems, see
<ulink
1399 url=
"https://www.kernel.org/doc/Documentation/filesystems/overlayfs.txt">overlayfs.txt
</ulink>. Note
1400 that the semantics of overlay file systems are substantially
1401 different from normal file systems, in particular regarding
1402 reported device and inode information. Device and inode
1403 information may change for a file while it is being written
1404 to, and processes might see out-of-date versions of files at
1405 times. Note that this switch automatically derives the
1406 <literal>workdir=
</literal> mount option for the overlay file
1407 system from the top-level directory tree, making it a sibling
1408 of it. It is hence essential that the top-level directory tree
1409 is not a mount point itself (since the working directory must
1410 be on the same file system as the top-most directory
1411 tree). Also note that the
<literal>lowerdir=
</literal> mount
1412 option receives the paths to stack in the opposite order of
1415 <para>Note that this option cannot be used to replace the root file system of the container with an overlay
1416 file system. However, the
<option>--volatile=
</option> option described above provides similar functionality,
1417 with a focus on implementing stateless operating system images.
</para></listitem>
1421 </refsect2><refsect2>
1422 <title>Input/Output Options
</title>
1426 <term><option>--console=
</option><replaceable>MODE
</replaceable></term>
1428 <listitem><para>Configures how to set up standard input, output and error output for the container
1429 payload, as well as the
<filename>/dev/console
</filename> device for the container. Takes one of
1430 <option>interactive
</option>,
<option>read-only
</option>,
<option>passive
</option>,
1431 <option>pipe
</option> or
<option>autopipe
</option>. If
<option>interactive
</option>, a pseudo-TTY is
1432 allocated and made available as
<filename>/dev/console
</filename> in the container. It is then
1433 bi-directionally connected to the standard input and output passed to
1434 <command>systemd-nspawn
</command>.
<option>read-only
</option> is similar but only the output of the
1435 container is propagated and no input from the caller is read. If
<option>passive
</option>, a pseudo
1436 TTY is allocated, but it is not connected anywhere. In
<option>pipe
</option> mode no pseudo TTY is
1437 allocated, but the standard input, output and error output file descriptors passed to
1438 <command>systemd-nspawn
</command> are passed on — as they are — to the container payload, see the
1439 following paragraph. Finally,
<option>autopipe
</option> mode operates like
1440 <option>interactive
</option> when
<command>systemd-nspawn
</command> is invoked on a terminal, and
1441 like
<option>pipe
</option> otherwise. Defaults to
<option>interactive
</option> if
1442 <command>systemd-nspawn
</command> is invoked from a terminal, and
<option>read-only
</option>
1445 <para>In
<option>pipe
</option> mode,
<filename>/dev/console
</filename> will not exist in the
1446 container. This means that the container payload generally cannot be a full init system as init
1447 systems tend to require
<filename>/dev/console
</filename> to be available. On the other hand, in this
1448 mode container invocations can be used within shell pipelines. This is because intermediary pseudo
1449 TTYs do not permit independent bidirectional propagation of the end-of-file (EOF) condition, which is
1450 necessary for shell pipelines to work correctly.
<emphasis>Note that the
<option>pipe
</option> mode
1451 should be used carefully
</emphasis>, as passing arbitrary file descriptors to less trusted container
1452 payloads might open up unwanted interfaces for access by the container payload. For example, if a
1453 passed file descriptor refers to a TTY of some form, APIs such as
<constant>TIOCSTI
</constant> may be
1454 used to synthesize input that might be used for escaping the container. Hence
<option>pipe
</option>
1455 mode should only be used if the payload is sufficiently trusted or when the standard
1456 input/output/error output file descriptors are known safe, for example pipes.
</para></listitem>
1460 <term><option>--pipe
</option></term>
1461 <term><option>-P
</option></term>
1463 <listitem><para>Equivalent to
<option>--console=pipe
</option>.
</para></listitem>
1467 </refsect2><refsect2>
1468 <title>Credentials
</title>
1472 <term><option>--load-credential=
</option><replaceable>ID
</replaceable>:
<replaceable>PATH
</replaceable></term>
1473 <term><option>--set-credential=
</option><replaceable>ID
</replaceable>:
<replaceable>VALUE
</replaceable></term>
1475 <listitem><para>Pass a credential to the container. These two options correspond to the
1476 <varname>LoadCredential=
</varname> and
<varname>SetCredential=
</varname> settings in unit files. See
1477 <citerefentry><refentrytitle>systemd.exec
</refentrytitle><manvolnum>5</manvolnum></citerefentry> for
1478 details about these concepts, as well as the syntax of the option's arguments.
</para>
1480 <para>Note: when
<command>systemd-nspawn
</command> runs as systemd system service it can propagate
1481 the credentials it received via
<varname>LoadCredential=
</varname>/
<varname>SetCredential=
</varname>
1482 to the container payload. A systemd service manager running as PID
1 in the container can further
1483 propagate them to the services it itself starts. It is thus possible to easily propagate credentials
1484 from a parent service manager to a container manager service and from there into its payload. This
1485 can even be done recursively.
</para>
1487 <para>In order to embed binary data into the credential data for
<option>--set-credential=
</option>
1488 use C-style escaping (i.e.
<literal>\n
</literal> to embed a newline, or
<literal>\x00
</literal> to
1489 embed a
<constant>NUL
</constant> byte. Note that the invoking shell might already apply unescaping
1490 once, hence this might require double escaping!).
</para></listitem>
1495 </refsect2><refsect2>
1496 <title>Other
</title>
1499 <xi:include href=
"standard-options.xml" xpointer=
"no-pager" />
1500 <xi:include href=
"standard-options.xml" xpointer=
"help" />
1501 <xi:include href=
"standard-options.xml" xpointer=
"version" />
1506 <xi:include href=
"common-variables.xml" />
1509 <title>Examples
</title>
1513 <ulink url=
"https://getfedora.org">Fedora
</ulink> image and start a shell in it
</title>
1515 <programlisting># machinectl pull-raw --verify=no \
1516 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 \
1517 Fedora-Cloud-Base-
&fedora_latest_version;-
&fedora_cloud_release;.x86-
64
1518 # systemd-nspawn -M Fedora-Cloud-Base-
&fedora_latest_version;-
&fedora_cloud_release;.x86-
64</programlisting>
1520 <para>This downloads an image using
1521 <citerefentry><refentrytitle>machinectl
</refentrytitle><manvolnum>1</manvolnum></citerefentry>
1522 and opens a shell in it.
</para>
1526 <title>Build and boot a minimal Fedora distribution in a container
</title>
1528 <programlisting># dnf -y --releasever=
&fedora_latest_version; --installroot=/var/lib/machines/f
&fedora_latest_version; \
1529 --disablerepo='*' --enablerepo=fedora --enablerepo=updates install \
1530 systemd passwd dnf fedora-release vim-minimal glibc-minimal-langpack
1531 # systemd-nspawn -bD /var/lib/machines/f
&fedora_latest_version;</programlisting>
1533 <para>This installs a minimal Fedora distribution into the
1534 directory
<filename index=
"false">/var/lib/machines/f
&fedora_latest_version;</filename>
1535 and then boots that OS in a namespace container. Because the installation
1536 is located underneath the standard
<filename>/var/lib/machines/
</filename>
1537 directory, it is also possible to start the machine using
1538 <command>systemd-nspawn -M f
&fedora_latest_version;</command>.
</para>
1542 <title>Spawn a shell in a container of a minimal Debian unstable distribution
</title>
1544 <programlisting># debootstrap unstable ~/debian-tree/
1545 # systemd-nspawn -D ~/debian-tree/
</programlisting>
1547 <para>This installs a minimal Debian unstable distribution into
1548 the directory
<filename>~/debian-tree/
</filename> and then
1549 spawns a shell from this image in a namespace container.
</para>
1551 <para><command>debootstrap
</command> supports
1552 <ulink url=
"https://www.debian.org">Debian
</ulink>,
1553 <ulink url=
"https://www.ubuntu.com">Ubuntu
</ulink>,
1554 and
<ulink url=
"https://www.tanglu.org">Tanglu
</ulink>
1555 out of the box, so the same command can be used to install any of those. For other
1556 distributions from the Debian family, a mirror has to be specified, see
1557 <citerefentry project='die-net'
><refentrytitle>debootstrap
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
1562 <title>Boot a minimal
1563 <ulink url=
"https://www.archlinux.org">Arch Linux
</ulink> distribution in a container
</title>
1565 <programlisting># pacstrap -c ~/arch-tree/ base
1566 # systemd-nspawn -bD ~/arch-tree/
</programlisting>
1568 <para>This installs a minimal Arch Linux distribution into the
1569 directory
<filename>~/arch-tree/
</filename> and then boots an OS
1570 in a namespace container in it.
</para>
1575 <ulink url=
"https://software.opensuse.org/distributions/tumbleweed">OpenSUSE Tumbleweed
</ulink>
1576 rolling distribution
</title>
1578 <programlisting># zypper --root=/var/lib/machines/tumbleweed ar -c \
1579 https://download.opensuse.org/tumbleweed/repo/oss tumbleweed
1580 # zypper --root=/var/lib/machines/tumbleweed refresh
1581 # zypper --root=/var/lib/machines/tumbleweed install --no-recommends \
1582 systemd shadow zypper openSUSE-release vim
1583 # systemd-nspawn -M tumbleweed passwd root
1584 # systemd-nspawn -M tumbleweed -b
</programlisting>
1588 <title>Boot into an ephemeral snapshot of the host system
</title>
1590 <programlisting># systemd-nspawn -D / -xb
</programlisting>
1592 <para>This runs a copy of the host system in a snapshot which is removed immediately when the container
1593 exits. All file system changes made during runtime will be lost on shutdown, hence.
</para>
1597 <title>Run a container with SELinux sandbox security contexts
</title>
1599 <programlisting># chcon system_u:object_r:svirt_sandbox_file_t:s0:c0,c1 -R /srv/container
1600 # systemd-nspawn -L system_u:object_r:svirt_sandbox_file_t:s0:c0,c1 \
1601 -Z system_u:system_r:svirt_lxc_net_t:s0:c0,c1 -D /srv/container /bin/sh
</programlisting>
1605 <title>Run a container with an OSTree deployment
</title>
1607 <programlisting># systemd-nspawn -b -i ~/image.raw \
1608 --pivot-root=/ostree/deploy/$OS/deploy/$CHECKSUM:/sysroot \
1609 --bind=+/sysroot/ostree/deploy/$OS/var:/var
</programlisting>
1614 <title>Exit status
</title>
1616 <para>The exit code of the program executed in the container is
1621 <title>See Also
</title>
1623 <citerefentry><refentrytitle>systemd
</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
1624 <citerefentry><refentrytitle>systemd.nspawn
</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1625 <citerefentry project='man-pages'
><refentrytitle>chroot
</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
1626 <citerefentry project='mankier'
><refentrytitle>dnf
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
1627 <citerefentry project='die-net'
><refentrytitle>debootstrap
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
1628 <citerefentry project='archlinux'
><refentrytitle>pacman
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
1629 <citerefentry project='mankier'
><refentrytitle>zypper
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
1630 <citerefentry><refentrytitle>systemd.slice
</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1631 <citerefentry><refentrytitle>machinectl
</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
1632 <citerefentry project='man-pages'
><refentrytitle>btrfs
</refentrytitle><manvolnum>8</manvolnum></citerefentry>
projects / thirdparty / systemd.git / blob