1SYSTEMD-NSPAWN(1) systemd-nspawn SYSTEMD-NSPAWN(1)
2
6 systemd-nspawn - Spawn a command or OS in a light-weight container
7
9 systemd-nspawn [OPTIONS...] [COMMAND [ARGS...]]
10 systemd-nspawn --boot [OPTIONS...] [ARGS...]
12
14 systemd-nspawn may be used to run a command or OS in a light-weight
15 namespace container. In many ways it is similar to chroot(1), but more
16 powerful since it fully virtualizes the file system hierarchy, as well
17 as the process tree, the various IPC subsystems and the host and domain
18 name.
19 systemd-nspawn may be invoked on any directory tree containing an
21 operating system tree, using the --directory= command line option. By
22 using the --machine= option an OS tree is automatically searched for in
23 a couple of locations, most importantly in /var/lib/machines, the
24 suggested directory to place OS container images installed on the
25 system.
26 In contrast to chroot(1) systemd-nspawn may be used to boot full
28 Linux-based operating systems in a container.
29 systemd-nspawn limits access to various kernel interfaces in the
31 container to read-only, such as /sys, /proc/sys or /sys/fs/selinux. The
32 host's network interfaces and the system clock may not be changed from
33 within the container. Device nodes may not be created. The host system
34 cannot be rebooted and kernel modules may not be loaded from within the
35 container.
36 Use a tool like dnf(8), debootstrap(8), or pacman(8) to set up an OS
38 directory tree suitable as file system hierarchy for systemd-nspawn
39 containers. See the Examples section below for details on suitable
40 invocation of these commands.
41 As a safety check systemd-nspawn will verify the existence of
43 /usr/lib/os-release or /etc/os-release in the container tree before
44 starting the container (see os-release(5)). It might be necessary to
45 add this file to the container tree manually if the OS of the container
46 is too old to contain this file out-of-the-box.
47 systemd-nspawn may be invoked directly from the interactive command
49 line or run as system service in the background. In this mode each
50 container instance runs as its own service instance; a default template
51 unit file systemd-nspawn@.service is provided to make this easy, taking
52 the container name as instance identifier. Note that different default
53 options apply when systemd-nspawn is invoked by the template unit file
54 than interactively on the command line. Most importantly the template
55 unit file makes use of the --boot which is not the default in case
56 systemd-nspawn is invoked from the interactive command line. Further
57 differences with the defaults are documented along with the various
58 supported options below.
59 The machinectl(1) tool may be used to execute a number of operations on
61 containers. In particular it provides easy-to-use commands to run
62 containers as system services using the systemd-nspawn@.service
63 template unit file.
64 Along with each container a settings file with the .nspawn suffix may
66 exist, containing additional settings to apply when running the
67 container. See systemd.nspawn(5) for details. Settings files override
68 the default options used by the systemd-nspawn@.service template unit
69 file, making it usually unnecessary to alter this template file
70 directly.
71 Note that systemd-nspawn will mount file systems private to the
73 container to /dev, /run and similar. These will not be visible outside
74 of the container, and their contents will be lost when the container
75 exits.
76 Note that running two systemd-nspawn containers from the same directory
78 tree will not make processes in them see each other. The PID namespace
79 separation of the two containers is complete and the containers will
80 share very few runtime objects except for the underlying file system.
81 Use machinectl(1)'s login or shell commands to request an additional
82 login session in a running container.
83 systemd-nspawn implements the Container Interface[1] specification.
85 While running, containers invoked with systemd-nspawn are registered
87 with the systemd-machined(8) service that keeps track of running
88 containers, and provides programming interfaces to interact with them.
89
91 If option -b is specified, the arguments are used as arguments for the
92 init program. Otherwise, COMMAND specifies the program to launch in the
93 container, and the remaining arguments are used as arguments for this
94 program. If --boot is not used and no arguments are specified, a shell
95 is launched in the container.
96 The following options are understood:
98 -q, --quiet
100 Turns off any status output by the tool itself. When this switch is
101 used, the only output from nspawn will be the console output of the
102 container OS itself.
103 --settings=MODE
105 Controls whether systemd-nspawn shall search for and use additional
106 per-container settings from .nspawn files. Takes a boolean or the
107 special values override or trusted.
108 If enabled (the default), a settings file named after the machine
110 (as specified with the --machine= setting, or derived from the
111 directory or image file name) with the suffix .nspawn is searched
112 in /etc/systemd/nspawn/ and /run/systemd/nspawn/. If it is found
113 there, its settings are read and used. If it is not found there, it
114 is subsequently searched in the same directory as the image file or
115 in the immediate parent of the root directory of the container. In
116 this case, if the file is found, its settings will be also read and
117 used, but potentially unsafe settings are ignored. Note that in
118 both these cases, settings on the command line take precedence over
119 the corresponding settings from loaded .nspawn files, if both are
120 specified. Unsafe settings are considered all settings that elevate
121 the container's privileges or grant access to additional resources
122 such as files or directories of the host. For details about the
123 format and contents of .nspawn files, consult systemd.nspawn(5).
124 If this option is set to override, the file is searched, read and
126 used the same way, however, the order of precedence is reversed:
127 settings read from the .nspawn file will take precedence over the
128 corresponding command line options, if both are specified.
129 If this option is set to trusted, the file is searched, read and
131 used the same way, but regardless of being found in
132 /etc/systemd/nspawn/, /run/systemd/nspawn/ or next to the image
133 file or container root directory, all settings will take effect,
134 however, command line arguments still take precedence over
135 corresponding settings.
136 If disabled, no .nspawn file is read and no settings except the
138 ones on the command line are in effect.
139 Image Options
141 -D, --directory=
142 Directory to use as file system root for the container.
143 If neither --directory=, nor --image= is specified the directory is
145 determined by searching for a directory named the same as the
146 machine name specified with --machine=. See machinectl(1) section
147 "Files and Directories" for the precise search path.
148 If neither --directory=, --image=, nor --machine= are specified,
150 the current directory will be used. May not be specified together
151 with --image=.
152 --template=
154 Directory or "btrfs" subvolume to use as template for the
155 container's root directory. If this is specified and the
156 container's root directory (as configured by --directory=) does not
157 yet exist it is created as "btrfs" snapshot (if supported) or plain
158 directory (otherwise) and populated from this template tree.
159 Ideally, the specified template path refers to the root of a
160 "btrfs" subvolume, in which case a simple copy-on-write snapshot is
161 taken, and populating the root directory is instant. If the
162 specified template path does not refer to the root of a "btrfs"
163 subvolume (or not even to a "btrfs" file system at all), the tree
164 is copied (though possibly in a 'reflink' copy-on-write scheme — if
165 the file system supports that), which can be substantially more
166 time-consuming. Note that the snapshot taken is of the specified
167 directory or subvolume, including all subdirectories and subvolumes
168 below it, but excluding any sub-mounts. May not be specified
169 together with --image= or --ephemeral.
170 Note that this switch leaves host name, machine ID and all other
172 settings that could identify the instance unmodified.
173 -x, --ephemeral
175 If specified, the container is run with a temporary snapshot of its
176 file system that is removed immediately when the container
177 terminates. May not be specified together with --template=.
178 Note that this switch leaves host name, machine ID and all other
180 settings that could identify the instance unmodified. Please note
181 that — as with --template= — taking the temporary snapshot is more
182 efficient on file systems that support subvolume snapshots or
183 'reflinks' natively ("btrfs" or new "xfs") than on more traditional
184 file systems that do not ("ext4"). Note that the snapshot taken is
185 of the specified directory or subvolume, including all
186 subdirectories and subvolumes below it, but excluding any
187 sub-mounts.
188 With this option no modifications of the container image are
190 retained. Use --volatile= (described below) for other mechanisms to
191 restrict persistency of container images during runtime.
192 -i, --image=
194 Disk image to mount the root directory for the container from.
195 Takes a path to a regular file or to a block device node. The file
196 or block device must contain either:
197 · An MBR partition table with a single partition of type 0x83
199 that is marked bootable.
200 · A GUID partition table (GPT) with a single partition of type
202 0fc63daf-8483-4772-8e79-3d69d8477de4.
203 · A GUID partition table (GPT) with a marked root partition which
205 is mounted as the root directory of the container. Optionally,
206 GPT images may contain a home and/or a server data partition
207 which are mounted to the appropriate places in the container.
208 All these partitions must be identified by the partition types
209 defined by the Discoverable Partitions Specification[2].
210 · No partition table, and a single file system spanning the whole
212 image.
213 On GPT images, if an EFI System Partition (ESP) is discovered, it
215 is automatically mounted to /efi (or /boot as fallback) in case a
216 directory by this name exists and is empty.
217 Partitions encrypted with LUKS are automatically decrypted. Also,
219 on GPT images dm-verity data integrity hash partitions are set up
220 if the root hash for them is specified using the --root-hash=
221 option.
222 Any other partitions, such as foreign partitions or swap partitions
224 are not mounted. May not be specified together with --directory=,
225 --template=.
226 --oci-bundle=
228 Takes the path to an OCI runtime bundle to invoke, as specified in
229 the OCI Runtime Specification[3]. In this case no .nspawn file is
230 loaded, and the root directory and various settings are read from
231 the OCI runtime JSON data (but data passed on the command line
232 takes precedence).
233 --read-only
235 Mount the container's root file system (and any other file systems
236 container in the container image) read-only. This has no effect on
237 additional mounts made with --bind=, --tmpfs= and similar options.
238 This mode is implied if the container image file or directory is
239 marked read-only itself. It is also implied if --volatile= is used.
240 In this case the container image on disk is strictly read-only,
241 while changes are permitted but kept non-persistently in memory
242 only. For further details, see below.
243 --volatile, --volatile=MODE
245 Boots the container in volatile mode. When no mode parameter is
246 passed or when mode is specified as yes, full volatile mode is
247 enabled. This means the root directory is mounted as a mostly
248 unpopulated "tmpfs" instance, and /usr/ from the OS tree is mounted
249 into it in read-only mode (the system thus starts up with read-only
250 OS image, but pristine state and configuration, any changes are
251 lost on shutdown). When the mode parameter is specified as state,
252 the OS tree is mounted read-only, but /var/ is mounted as a
253 writable "tmpfs" instance into it (the system thus starts up with
254 read-only OS resources and configuration, but pristine state, and
255 any changes to the latter are lost on shutdown). When the mode
256 parameter is specified as overlay the read-only root file system is
257 combined with a writable tmpfs instance through "overlayfs", so
258 that it appears at it normally would, but any changes are applied
259 to the temporary file system only and lost when the container is
260 terminated. When the mode parameter is specified as no (the
261 default), the whole OS tree is made available writable (unless
262 --read-only is specified, see above).
263 Note that if one of the volatile modes is chosen, its effect is
265 limited to the root file system (or /var/ in case of state), and
266 any other mounts placed in the hierarchy are unaffected —
267 regardless if they are established automatically (e.g. the EFI
268 system partition that might be mounted to /efi/ or /boot/) or
269 explicitly (e.g. through an additional command line option such as
270 --bind=, see below). This means, even if --volatile=overlay is used
271 changes to /efi/ or /boot/ are prohibited in case such a partition
272 exists in the container image operated on, and even if
273 --volatile=state is used the hypothetical file /etc/foobar is
274 potentially writable if --bind=/etc/foobar if used to mount it from
275 outside the read-only container /etc directory.
276 The --ephemeral option is closely related to this setting, and
278 provides similar behaviour by making a temporary, ephemeral copy of
279 the whole OS image and executing that. For further details, see
280 above.
281 The --tmpfs= and --overlay= options provide similar functionality,
283 but for specific sub-directories of the OS image only. For details,
284 see below.
285 This option provides similar functionality for containers as the
287 "systemd.volatile=" kernel command line switch provides for host
288 systems. See kernel-command-line(7) for details.
289 Note that setting this option to yes or state will only work
291 correctly with operating systems in the container that can boot up
292 with only /usr/ mounted, and are able to automatically populate
293 /var/ (and /etc/ in case of "--volatile=yes"). Specifically, this
294 means that operating systems that follow the historic split of
295 /bin/ and /lib/ (and related directories) from /usr/ (i.e. where
296 the former are not symlinks into the latter) are not supported by
297 "--volatile=yes" as container payload. The overlay option does not
298 require any particular preparations in the OS, but do note that
299 "overlayfs" behaviour differs from regular file systems in a number
300 of ways, and hence compatibility is limited.
301 --root-hash=
303 Takes a data integrity (dm-verity) root hash specified in
304 hexadecimal. This option enables data integrity checks using
305 dm-verity, if the used image contains the appropriate integrity
306 data (see above). The specified hash must match the root hash of
307 integrity data, and is usually at least 256 bits (and hence 64
308 formatted hexadecimal characters) long (in case of SHA256 for
309 example). If this option is not specified, but the image file
310 carries the "user.verity.roothash" extended file attribute (see
311 xattr(7)), then the root hash is read from it, also as formatted
312 hexadecimal characters. If the extended file attribute is not found
313 (or is not supported by the underlying file system), but a file
314 with the .roothash suffix is found next to the image file, bearing
315 otherwise the same name, the root hash is read from it and
316 automatically used, also as formatted hexadecimal characters.
317 --pivot-root=
319 Pivot the specified directory to / inside the container, and either
320 unmount the container's old root, or pivot it to another specified
321 directory. Takes one of: a path argument — in which case the
322 specified path will be pivoted to / and the old root will be
323 unmounted; or a colon-separated pair of new root path and pivot
324 destination for the old root. The new root path will be pivoted to
325 /, and the old / will be pivoted to the other directory. Both paths
326 must be absolute, and are resolved in the container's file system
327 namespace.
328 This is for containers which have several bootable directories in
330 them; for example, several OSTree[4] deployments. It emulates the
331 behavior of the boot loader and initial RAM disk which normally
332 select which directory to mount as the root and start the
333 container's PID 1 in.
334 Execution Options
336 -a, --as-pid2
337 Invoke the shell or specified program as process ID (PID) 2 instead
338 of PID 1 (init). By default, if neither this option nor --boot is
339 used, the selected program is run as the process with PID 1, a mode
340 only suitable for programs that are aware of the special semantics
341 that the process with PID 1 has on UNIX. For example, it needs to
342 reap all processes reparented to it, and should implement sysvinit
343 compatible signal handling (specifically: it needs to reboot on
344 SIGINT, reexecute on SIGTERM, reload configuration on SIGHUP, and
345 so on). With --as-pid2 a minimal stub init process is run as PID 1
346 and the selected program is executed as PID 2 (and hence does not
347 need to implement any special semantics). The stub init process
348 will reap processes as necessary and react appropriately to
349 signals. It is recommended to use this mode to invoke arbitrary
350 commands in containers, unless they have been modified to run
351 correctly as PID 1. Or in other words: this switch should be used
352 for pretty much all commands, except when the command refers to an
353 init or shell implementation, as these are generally capable of
354 running correctly as PID 1. This option may not be combined with
355 --boot.
356 -b, --boot
358 Automatically search for an init program and invoke it as PID 1,
359 instead of a shell or a user supplied program. If this option is
360 used, arguments specified on the command line are used as arguments
361 for the init program. This option may not be combined with
362 --as-pid2.
363 The following table explains the different modes of invocation and
365 relationship to --as-pid2 (see above):
366 Table 1. Invocation Mode
368 ┌──────────────────────┬────────────────────────────┐
369 │Switch │ Explanation │
370 ├──────────────────────┼────────────────────────────┤
371 │Neither --as-pid2 nor │ The passed parameters are │
372 │--boot specified │ interpreted as the command │
373 │ │ line, which is executed as │
374 │ │ PID 1 in the container. │
375 ├──────────────────────┼────────────────────────────┤
376 │--as-pid2 specified │ The passed parameters are │
377 │ │ interpreted as the command │
378 │ │ line, which is executed as │
379 │ │ PID 2 in the container. A │
380 │ │ stub init process is run │
381 │ │ as PID 1. │
382 ├──────────────────────┼────────────────────────────┤
383 │--boot specified │ An init program is │
384 │ │ automatically searched for │
385 │ │ and run as PID 1 in the │
386 │ │ container. The passed │
387 │ │ parameters are used as │
388 │ │ invocation parameters for │
389 │ │ this process. │
390 └──────────────────────┴────────────────────────────┘
391 Note that --boot is the default mode of operation if the
392 systemd-nspawn@.service template unit file is used.
393 --chdir=
395 Change to the specified working directory before invoking the
396 process in the container. Expects an absolute path in the
397 container's file system namespace.
398 -E NAME=VALUE, --setenv=NAME=VALUE
400 Specifies an environment variable assignment to pass to the init
401 process in the container, in the format "NAME=VALUE". This may be
402 used to override the default variables or to set additional
403 variables. This parameter may be used more than once.
404 -u, --user=
406 After transitioning into the container, change to the specified
407 user-defined in the container's user database. Like all other
408 systemd-nspawn features, this is not a security feature and
409 provides protection against accidental destructive operations only.
410 --kill-signal=
412 Specify the process signal to send to the container's PID 1 when
413 nspawn itself receives SIGTERM, in order to trigger an orderly
414 shutdown of the container. Defaults to SIGRTMIN+3 if --boot is used
415 (on systemd-compatible init systems SIGRTMIN+3 triggers an orderly
416 shutdown). If --boot is not used and this option is not specified
417 the container's processes are terminated abruptly via SIGKILL. For
418 a list of valid signals, see signal(7).
419 --notify-ready=
421 Configures support for notifications from the container's init
422 process. --notify-ready= takes a boolean (no and yes). With option
423 no systemd-nspawn notifies systemd with a "READY=1" message when
424 the init process is created. With option yes systemd-nspawn waits
425 for the "READY=1" message from the init process in the container
426 before sending its own to systemd. For more details about
427 notifications see sd_notify(3)).
428 System Identity Options
430 -M, --machine=
431 Sets the machine name for this container. This name may be used to
432 identify this container during its runtime (for example in tools
433 like machinectl(1) and similar), and is used to initialize the
434 container's hostname (which the container can choose to override,
435 however). If not specified, the last component of the root
436 directory path of the container is used, possibly suffixed with a
437 random identifier in case --ephemeral mode is selected. If the root
438 directory selected is the host's root directory the host's hostname
439 is used as default instead.
440 --hostname=
442 Controls the hostname to set within the container, if different
443 from the machine name. Expects a valid hostname as argument. If
444 this option is used, the kernel hostname of the container will be
445 set to this value, otherwise it will be initialized to the machine
446 name as controlled by the --machine= option described above. The
447 machine name is used for various aspect of identification of the
448 container from the outside, the kernel hostname configurable with
449 this option is useful for the container to identify itself from the
450 inside. It is usually a good idea to keep both forms of
451 identification synchronized, in order to avoid confusion. It is
452 hence recommended to avoid usage of this option, and use --machine=
453 exclusively. Note that regardless whether the container's hostname
454 is initialized from the name set with --hostname= or the one set
455 with --machine=, the container can later override its kernel
456 hostname freely on its own as well.
457 --uuid=
459 Set the specified UUID for the container. The init system will
460 initialize /etc/machine-id from this if this file is not set yet.
461 Note that this option takes effect only if /etc/machine-id in the
462 container is unpopulated.
463 Property Options
465 -S, --slice=
466 Make the container part of the specified slice, instead of the
467 default machine.slice. This applies only if the machine is run in
468 its own scope unit, i.e. if --keep-unit isn't used.
469 --property=
471 Set a unit property on the scope unit to register for the machine.
472 This applies only if the machine is run in its own scope unit, i.e.
473 if --keep-unit isn't used. Takes unit property assignments in the
474 same format as systemctl set-property. This is useful to set memory
475 limits and similar for container.
476 --register=
478 Controls whether the container is registered with systemd-
479 machined(8). Takes a boolean argument, which defaults to "yes".
480 This option should be enabled when the container runs a full
481 Operating System (more specifically: a system and service manager
482 as PID 1), and is useful to ensure that the container is accessible
483 via machinectl(1) and shown by tools such as ps(1). If the
484 container does not run a service manager, it is recommended to set
485 this option to "no".
486 --keep-unit
488 Instead of creating a transient scope unit to run the container in,
489 simply use the service or scope unit systemd-nspawn has been
490 invoked in. If --register=yes is set this unit is registered with
491 systemd-machined(8). This switch should be used if systemd-nspawn
492 is invoked from within a service unit, and the service unit's sole
493 purpose is to run a single systemd-nspawn container. This option is
494 not available if run from a user session.
495 Note that passing --keep-unit disables the effect of --slice= and
497 --property=. Use --keep-unit and --register=no in combination to
498 disable any kind of unit allocation or registration with
499 systemd-machined.
500 User Namespacing Options
502 --private-users=
503 Controls user namespacing. If enabled, the container will run with
504 its own private set of UNIX user and group ids (UIDs and GIDs).
505 This involves mapping the private UIDs/GIDs used in the container
506 (starting with the container's root user 0 and up) to a range of
507 UIDs/GIDs on the host that are not used for other purposes (usually
508 in the range beyond the host's UID/GID 65536). The parameter may be
509 specified as follows:
510 1. If one or two colon-separated numbers are specified, user
512 namespacing is turned on. The first parameter specifies the
513 first host UID/GID to assign to the container, the second
514 parameter specifies the number of host UIDs/GIDs to assign to
515 the container. If the second parameter is omitted, 65536
516 UIDs/GIDs are assigned.
517 2. If the parameter is omitted, or true, user namespacing is
519 turned on. The UID/GID range to use is determined automatically
520 from the file ownership of the root directory of the
521 container's directory tree. To use this option, make sure to
522 prepare the directory tree in advance, and ensure that all
523 files and directories in it are owned by UIDs/GIDs in the range
524 you'd like to use. Also, make sure that used file ACLs
525 exclusively reference UIDs/GIDs in the appropriate range. If
526 this mode is used the number of UIDs/GIDs assigned to the
527 container for use is 65536, and the UID/GID of the root
528 directory must be a multiple of 65536.
529 3. If the parameter is false, user namespacing is turned off. This
531 is the default.
532 4. The special value "pick" turns on user namespacing. In this
534 case the UID/GID range is automatically chosen. As first step,
535 the file owner of the root directory of the container's
536 directory tree is read, and it is checked that it is currently
537 not used by the system otherwise (in particular, that no other
538 container is using it). If this check is successful, the
539 UID/GID range determined this way is used, similar to the
540 behavior if "yes" is specified. If the check is not successful
541 (and thus the UID/GID range indicated in the root directory's
542 file owner is already used elsewhere) a new – currently unused
543 – UID/GID range of 65536 UIDs/GIDs is randomly chosen between
544 the host UID/GIDs of 524288 and 1878982656, always starting at
545 a multiple of 65536. This setting implies --private-users-chown
546 (see below), which has the effect that the files and
547 directories in the container's directory tree will be owned by
548 the appropriate users of the range picked. Using this option
549 makes user namespace behavior fully automatic. Note that the
550 first invocation of a previously unused container image might
551 result in picking a new UID/GID range for it, and thus in the
552 (possibly expensive) file ownership adjustment operation.
553 However, subsequent invocations of the container will be cheap
554 (unless of course the picked UID/GID range is assigned to a
555 different use by then).
556 It is recommended to assign at least 65536 UIDs/GIDs to each
558 container, so that the usable UID/GID range in the container covers
559 16 bit. For best security, do not assign overlapping UID/GID ranges
560 to multiple containers. It is hence a good idea to use the upper 16
561 bit of the host 32-bit UIDs/GIDs as container identifier, while the
562 lower 16 bit encode the container UID/GID used. This is in fact the
563 behavior enforced by the --private-users=pick option.
564 When user namespaces are used, the GID range assigned to each
566 container is always chosen identical to the UID range.
567 In most cases, using --private-users=pick is the recommended option
569 as it enhances container security massively and operates fully
570 automatically in most cases.
571 Note that the picked UID/GID range is not written to /etc/passwd or
573 /etc/group. In fact, the allocation of the range is not stored
574 persistently anywhere, except in the file ownership of the files
575 and directories of the container.
576 Note that when user namespacing is used file ownership on disk
578 reflects this, and all of the container's files and directories are
579 owned by the container's effective user and group IDs. This means
580 that copying files from and to the container image requires
581 correction of the numeric UID/GID values, according to the UID/GID
582 shift applied.
583 --private-users-chown
585 If specified, all files and directories in the container's
586 directory tree will be adjusted so that they are owned by the
587 appropriate UIDs/GIDs selected for the container (see above). This
588 operation is potentially expensive, as it involves iterating
589 through the full directory tree of the container. Besides actual
590 file ownership, file ACLs are adjusted as well.
591 This option is implied if --private-users=pick is used. This option
593 has no effect if user namespacing is not used.
594 -U
596 If the kernel supports the user namespaces feature, equivalent to
597 --private-users=pick --private-users-chown, otherwise equivalent to
598 --private-users=no.
599 Note that -U is the default if the systemd-nspawn@.service template
601 unit file is used.
602 Note: it is possible to undo the effect of --private-users-chown
604 (or -U) on the file system by redoing the operation with the first
605 UID of 0:
606 systemd-nspawn ... --private-users=0 --private-users-chown
608 Networking Options
610 --private-network
611 Disconnect networking of the container from the host. This makes
612 all network interfaces unavailable in the container, with the
613 exception of the loopback device and those specified with
614 --network-interface= and configured with --network-veth. If this
615 option is specified, the CAP_NET_ADMIN capability will be added to
616 the set of capabilities the container retains. The latter may be
617 disabled by using --drop-capability=. If this option is not
618 specified (or implied by one of the options listed below), the
619 container will have full access to the host network.
620 --network-interface=
622 Assign the specified network interface to the container. This will
623 remove the specified interface from the calling namespace and place
624 it in the container. When the container terminates, it is moved
625 back to the host namespace. Note that --network-interface= implies
626 --private-network. This option may be used more than once to add
627 multiple network interfaces to the container.
628 --network-macvlan=
630 Create a "macvlan" interface of the specified Ethernet network
631 interface and add it to the container. A "macvlan" interface is a
632 virtual interface that adds a second MAC address to an existing
633 physical Ethernet link. The interface in the container will be
634 named after the interface on the host, prefixed with "mv-". Note
635 that --network-macvlan= implies --private-network. This option may
636 be used more than once to add multiple network interfaces to the
637 container.
638 --network-ipvlan=
640 Create an "ipvlan" interface of the specified Ethernet network
641 interface and add it to the container. An "ipvlan" interface is a
642 virtual interface, similar to a "macvlan" interface, which uses the
643 same MAC address as the underlying interface. The interface in the
644 container will be named after the interface on the host, prefixed
645 with "iv-". Note that --network-ipvlan= implies --private-network.
646 This option may be used more than once to add multiple network
647 interfaces to the container.
648 -n, --network-veth
650 Create a virtual Ethernet link ("veth") between host and container.
651 The host side of the Ethernet link will be available as a network
652 interface named after the container's name (as specified with
653 --machine=), prefixed with "ve-". The container side of the
654 Ethernet link will be named "host0". The --network-veth option
655 implies --private-network.
656 Note that systemd-networkd.service(8) includes by default a network
658 file /usr/lib/systemd/network/80-container-ve.network matching the
659 host-side interfaces created this way, which contains settings to
660 enable automatic address provisioning on the created virtual link
661 via DHCP, as well as automatic IP routing onto the host's external
662 network interfaces. It also contains
663 /usr/lib/systemd/network/80-container-host0.network matching the
664 container-side interface created this way, containing settings to
665 enable client side address assignment via DHCP. In case
666 systemd-networkd is running on both the host and inside the
667 container, automatic IP communication from the container to the
668 host is thus available, with further connectivity to the external
669 network.
670 Note that --network-veth is the default if the
672 systemd-nspawn@.service template unit file is used.
673 Note that on Linux network interface names may have a length of 15
675 characters at maximum, while container names may have a length up
676 to 64 characters. As this option derives the host-side interface
677 name from the container name the name is possibly truncated. Thus,
678 care needs to be taken to ensure that interface names remain unique
679 in this case, or even better container names are generally not
680 chosen longer than 12 characters, to avoid the truncation.
681 Alternatively, the --network-veth-extra= option may be used, which
682 allows free configuration of the host-side interface name
683 independently of the container name — but might require a bit more
684 additional configuration in case bridging in a fashion similar to
685 --network-bridge= is desired.
686 --network-veth-extra=
688 Adds an additional virtual Ethernet link between host and
689 container. Takes a colon-separated pair of host interface name and
690 container interface name. The latter may be omitted in which case
691 the container and host sides will be assigned the same name. This
692 switch is independent of --network-veth, and — in contrast — may be
693 used multiple times, and allows configuration of the network
694 interface names. Note that --network-bridge= has no effect on
695 interfaces created with --network-veth-extra=.
696 --network-bridge=
698 Adds the host side of the Ethernet link created with --network-veth
699 to the specified Ethernet bridge interface. Expects a valid network
700 interface name of a bridge device as argument. Note that
701 --network-bridge= implies --network-veth. If this option is used,
702 the host side of the Ethernet link will use the "vb-" prefix
703 instead of "ve-". Regardless of the used naming prefix the same
704 network interface name length limits imposed by Linux apply, along
705 with the complications this creates (for details see above).
706 --network-zone=
708 Creates a virtual Ethernet link ("veth") to the container and adds
709 it to an automatically managed Ethernet bridge interface. The
710 bridge interface is named after the passed argument, prefixed with
711 "vz-". The bridge interface is automatically created when the first
712 container configured for its name is started, and is automatically
713 removed when the last container configured for its name exits.
714 Hence, each bridge interface configured this way exists only as
715 long as there's at least one container referencing it running. This
716 option is very similar to --network-bridge=, besides this automatic
717 creation/removal of the bridge device.
718 This setting makes it easy to place multiple related containers on
720 a common, virtual Ethernet-based broadcast domain, here called a
721 "zone". Each container may only be part of one zone, but each zone
722 may contain any number of containers. Each zone is referenced by
723 its name. Names may be chosen freely (as long as they form valid
724 network interface names when prefixed with "vz-"), and it is
725 sufficient to pass the same name to the --network-zone= switch of
726 the various concurrently running containers to join them in one
727 zone.
728 Note that systemd-networkd.service(8) includes by default a network
730 file /usr/lib/systemd/network/80-container-vz.network matching the
731 bridge interfaces created this way, which contains settings to
732 enable automatic address provisioning on the created virtual
733 network via DHCP, as well as automatic IP routing onto the host's
734 external network interfaces. Using --network-zone= is hence in most
735 cases fully automatic and sufficient to connect multiple local
736 containers in a joined broadcast domain to the host, with further
737 connectivity to the external network.
738 --network-namespace-path=
740 Takes the path to a file representing a kernel network namespace
741 that the container shall run in. The specified path should refer to
742 a (possibly bind-mounted) network namespace file, as exposed by the
743 kernel below /proc/$PID/ns/net. This makes the container enter the
744 given network namespace. One of the typical use cases is to give a
745 network namespace under /run/netns created by ip-netns(8), for
746 example, --network-namespace-path=/run/netns/foo. Note that this
747 option cannot be used together with other network-related options,
748 such as --private-network or --network-interface=.
749 -p, --port=
751 If private networking is enabled, maps an IP port on the host onto
752 an IP port on the container. Takes a protocol specifier (either
753 "tcp" or "udp"), separated by a colon from a host port number in
754 the range 1 to 65535, separated by a colon from a container port
755 number in the range from 1 to 65535. The protocol specifier and its
756 separating colon may be omitted, in which case "tcp" is assumed.
757 The container port number and its colon may be omitted, in which
758 case the same port as the host port is implied. This option is only
759 supported if private networking is used, such as with
760 --network-veth, --network-zone= --network-bridge=.
761 Security Options
763 --capability=
764 List one or more additional capabilities to grant the container.
765 Takes a comma-separated list of capability names, see
766 capabilities(7) for more information. Note that the following
767 capabilities will be granted in any way: CAP_AUDIT_CONTROL,
768 CAP_AUDIT_WRITE, CAP_CHOWN, CAP_DAC_OVERRIDE, CAP_DAC_READ_SEARCH,
769 CAP_FOWNER, CAP_FSETID, CAP_IPC_OWNER, CAP_KILL, CAP_LEASE,
770 CAP_LINUX_IMMUTABLE, CAP_MKNOD, CAP_NET_BIND_SERVICE,
771 CAP_NET_BROADCAST, CAP_NET_RAW, CAP_SETFCAP, CAP_SETGID,
772 CAP_SETPCAP, CAP_SETUID, CAP_SYS_ADMIN, CAP_SYS_BOOT,
773 CAP_SYS_CHROOT, CAP_SYS_NICE, CAP_SYS_PTRACE, CAP_SYS_RESOURCE,
774 CAP_SYS_TTY_CONFIG. Also CAP_NET_ADMIN is retained if
775 --private-network is specified. If the special value "all" is
776 passed, all capabilities are retained.
777 --drop-capability=
779 Specify one or more additional capabilities to drop for the
780 container. This allows running the container with fewer
781 capabilities than the default (see above).
782 --no-new-privileges=
784 Takes a boolean argument. Specifies the value of the
785 PR_SET_NO_NEW_PRIVS flag for the container payload. Defaults to
786 off. When turned on the payload code of the container cannot
787 acquire new privileges, i.e. the "setuid" file bit as well as file
788 system capabilities will not have an effect anymore. See prctl(2)
789 for details about this flag.
790 --system-call-filter=
792 Alter the system call filter applied to containers. Takes a
793 space-separated list of system call names or group names (the
794 latter prefixed with "@", as listed by the syscall-filter command
795 of systemd-analyze(1)). Passed system calls will be permitted. The
796 list may optionally be prefixed by "~", in which case all listed
797 system calls are prohibited. If this command line option is used
798 multiple times the configured lists are combined. If both a
799 positive and a negative list (that is one system call list without
800 and one with the "~" prefix) are configured, the negative list
801 takes precedence over the positive list. Note that systemd-nspawn
802 always implements a system call whitelist (as opposed to a
803 blacklist), and this command line option hence adds or removes
804 entries from the default whitelist, depending on the "~" prefix.
805 Note that the applied system call filter is also altered implicitly
806 if additional capabilities are passed using the --capabilities=.
807 -Z, --selinux-context=
809 Sets the SELinux security context to be used to label processes in
810 the container.
811 -L, --selinux-apifs-context=
813 Sets the SELinux security context to be used to label files in the
814 virtual API file systems in the container.
815 Resource Options
817 --rlimit=
818 Sets the specified POSIX resource limit for the container payload.
819 Expects an assignment of the form "LIMIT=SOFT:HARD" or
820 "LIMIT=VALUE", where LIMIT should refer to a resource limit type,
821 such as RLIMIT_NOFILE or RLIMIT_NICE. The SOFT and HARD fields
822 should refer to the numeric soft and hard resource limit values. If
823 the second form is used, VALUE may specify a value that is used
824 both as soft and hard limit. In place of a numeric value the
825 special string "infinity" may be used to turn off resource limiting
826 for the specific type of resource. This command line option may be
827 used multiple times to control limits on multiple limit types. If
828 used multiple times for the same limit type, the last use wins. For
829 details about resource limits see setrlimit(2). By default resource
830 limits for the container's init process (PID 1) are set to the same
831 values the Linux kernel originally passed to the host init system.
832 Note that some resource limits are enforced on resources counted
833 per user, in particular RLIMIT_NPROC. This means that unless user
834 namespacing is deployed (i.e. --private-users= is used, see
835 above), any limits set will be applied to the resource usage of the
836 same user on all local containers as well as the host. This means
837 particular care needs to be taken with these limits as they might
838 be triggered by possibly less trusted code. Example:
839 "--rlimit=RLIMIT_NOFILE=8192:16384".
840 --oom-score-adjust=
842 Changes the OOM ("Out Of Memory") score adjustment value for the
843 container payload. This controls /proc/self/oom_score_adj which
844 influences the preference with which this container is terminated
845 when memory becomes scarce. For details see proc(5). Takes an
846 integer in the range -1000...1000.
847 --cpu-affinity=
849 Controls the CPU affinity of the container payload. Takes a comma
850 separated list of CPU numbers or number ranges (the latter's start
851 and end value separated by dashes). See sched_setaffinity(2) for
852 details.
853 --personality=
855 Control the architecture ("personality") reported by uname(2) in
856 the container. Currently, only "x86" and "x86-64" are supported.
857 This is useful when running a 32-bit container on a 64-bit host. If
858 this setting is not used, the personality reported in the container
859 is the same as the one reported on the host.
860 Integration Options
862 --resolv-conf=
863 Configures how /etc/resolv.conf inside of the container (i.e. DNS
864 configuration synchronization from host to container) shall be
865 handled. Takes one of "off", "copy-host", "copy-static",
866 "bind-host", "bind-static", "delete" or "auto". If set to "off" the
867 /etc/resolv.conf file in the container is left as it is included in
868 the image, and neither modified nor bind mounted over. If set to
869 "copy-host", the /etc/resolv.conf file from the host is copied into
870 the container. Similar, if "bind-host" is used, the file is bind
871 mounted from the host into the container. If set to "copy-static"
872 the static resolv.conf file supplied with systemd-
873 resolved.service(8) is copied into the container, and
874 correspondingly "bind-static" bind mounts it there. If set to
875 "delete" the /etc/resolv.conf file in the container is deleted if
876 it exists. Finally, if set to "auto" the file is left as it is if
877 private networking is turned on (see --private-network). Otherwise,
878 if systemd-resolved.service is connectible its static resolv.conf
879 file is used, and if not the host's /etc/resolv.conf file is used.
880 In the latter cases the file is copied if the image is writable,
881 and bind mounted otherwise. It's recommended to use "copy" if the
882 container shall be able to make changes to the DNS configuration on
883 its own, deviating from the host's settings. Otherwise "bind" is
884 preferable, as it means direct changes to /etc/resolv.conf in the
885 container are not allowed, as it is a read-only bind mount (but
886 note that if the container has enough privileges, it might simply
887 go ahead and unmount the bind mount anyway). Note that both if the
888 file is bind mounted and if it is copied no further propagation of
889 configuration is generally done after the one-time early
890 initialization (this is because the file is usually updated through
891 copying and renaming). Defaults to "auto".
892 --timezone=
894 Configures how /etc/localtime inside of the container (i.e. local
895 timezone synchronization from host to container) shall be handled.
896 Takes one of "off", "copy", "bind", "symlink", "delete" or "auto".
897 If set to "off" the /etc/localtime file in the container is left as
898 it is included in the image, and neither modified nor bind mounted
899 over. If set to "copy" the /etc/localtime file of the host is
900 copied into the container. Similar, if "bind" is used, it is bind
901 mounted from the host into the container. If set to "symlink" a
902 symlink from /etc/localtime in the container is created pointing to
903 the matching the timezone file of the container that matches the
904 timezone setting on the host. If set to "delete" the file in the
905 container is deleted, should it exist. If set to "auto" and the
906 /etc/localtime file of the host is a symlink, then "symlink" mode
907 is used, and "copy" otherwise, except if the image is read-only in
908 which case "bind" is used instead. Defaults to "auto".
909 --link-journal=
911 Control whether the container's journal shall be made visible to
912 the host system. If enabled, allows viewing the container's journal
913 files from the host (but not vice versa). Takes one of "no",
914 "host", "try-host", "guest", "try-guest", "auto". If "no", the
915 journal is not linked. If "host", the journal files are stored on
916 the host file system (beneath /var/log/journal/machine-id) and the
917 subdirectory is bind-mounted into the container at the same
918 location. If "guest", the journal files are stored on the guest
919 file system (beneath /var/log/journal/machine-id) and the
920 subdirectory is symlinked into the host at the same location.
921 "try-host" and "try-guest" do the same but do not fail if the host
922 does not have persistent journaling enabled. If "auto" (the
923 default), and the right subdirectory of /var/log/journal exists, it
924 will be bind mounted into the container. If the subdirectory does
925 not exist, no linking is performed. Effectively, booting a
926 container once with "guest" or "host" will link the journal
927 persistently if further on the default of "auto" is used.
928 Note that --link-journal=try-guest is the default if the
930 systemd-nspawn@.service template unit file is used.
931 -j
933 Equivalent to --link-journal=try-guest.
934 Mount Options
936 --bind=, --bind-ro=
937 Bind mount a file or directory from the host into the container.
938 Takes one of: a path argument — in which case the specified path
939 will be mounted from the host to the same path in the container, or
940 a colon-separated pair of paths — in which case the first specified
941 path is the source in the host, and the second path is the
942 destination in the container, or a colon-separated triple of source
943 path, destination path and mount options. The source path may
944 optionally be prefixed with a "+" character. If so, the source path
945 is taken relative to the image's root directory. This permits
946 setting up bind mounts within the container image. The source path
947 may be specified as empty string, in which case a temporary
948 directory below the host's /var/tmp directory is used. It is
949 automatically removed when the container is shut down. Mount
950 options are comma-separated and currently, only rbind and norbind
951 are allowed, controlling whether to create a recursive or a regular
952 bind mount. Defaults to "rbind". Backslash escapes are interpreted,
953 so "\:" may be used to embed colons in either path. This option may
954 be specified multiple times for creating multiple independent bind
955 mount points. The --bind-ro= option creates read-only bind mounts.
956 Note that when this option is used in combination with
958 --private-users, the resulting mount points will be owned by the
959 nobody user. That's because the mount and its files and directories
960 continue to be owned by the relevant host users and groups, which
961 do not exist in the container, and thus show up under the wildcard
962 UID 65534 (nobody). If such bind mounts are created, it is
963 recommended to make them read-only, using --bind-ro=.
964 --inaccessible=
966 Make the specified path inaccessible in the container. This
967 over-mounts the specified path (which must exist in the container)
968 with a file node of the same type that is empty and has the most
969 restrictive access mode supported. This is an effective way to mask
970 files, directories and other file system objects from the container
971 payload. This option may be used more than once in case all
972 specified paths are masked.
973 --tmpfs=
975 Mount a tmpfs file system into the container. Takes a single
976 absolute path argument that specifies where to mount the tmpfs
977 instance to (in which case the directory access mode will be chosen
978 as 0755, owned by root/root), or optionally a colon-separated pair
979 of path and mount option string that is used for mounting (in which
980 case the kernel default for access mode and owner will be chosen,
981 unless otherwise specified). Backslash escapes are interpreted in
982 the path, so "\:" may be used to embed colons in the path.
983 Note that this option cannot be used to replace the root file
985 system of the container with a temporary file system. However, the
986 --volatile= option described below provides similar functionality,
987 with a focus on implementing stateless operating system images.
988 --overlay=, --overlay-ro=
990 Combine multiple directory trees into one overlay file system and
991 mount it into the container. Takes a list of colon-separated paths
992 to the directory trees to combine and the destination mount point.
993 Backslash escapes are interpreted in the paths, so "\:" may be used
995 to embed colons in the paths.
996 If three or more paths are specified, then the last specified path
998 is the destination mount point in the container, all paths
999 specified before refer to directory trees on the host and are
1000 combined in the specified order into one overlay file system. The
1001 left-most path is hence the lowest directory tree, the
1002 second-to-last path the highest directory tree in the stacking
1003 order. If --overlay-ro= is used instead of --overlay=, a read-only
1004 overlay file system is created. If a writable overlay file system
1005 is created, all changes made to it are written to the highest
1006 directory tree in the stacking order, i.e. the second-to-last
1007 specified.
1008 If only two paths are specified, then the second specified path is
1010 used both as the top-level directory tree in the stacking order as
1011 seen from the host, as well as the mount point for the overlay file
1012 system in the container. At least two paths have to be specified.
1013 The source paths may optionally be prefixed with "+" character. If
1015 so they are taken relative to the image's root directory. The
1016 uppermost source path may also be specified as empty string, in
1017 which case a temporary directory below the host's /var/tmp is used.
1018 The directory is removed automatically when the container is shut
1019 down. This behaviour is useful in order to make read-only container
1020 directories writable while the container is running. For example,
1021 use the "--overlay=+/var::/var" option in order to automatically
1022 overlay a writable temporary directory on a read-only /var
1023 directory.
1024 For details about overlay file systems, see overlayfs.txt[5]. Note
1026 that the semantics of overlay file systems are substantially
1027 different from normal file systems, in particular regarding
1028 reported device and inode information. Device and inode information
1029 may change for a file while it is being written to, and processes
1030 might see out-of-date versions of files at times. Note that this
1031 switch automatically derives the "workdir=" mount option for the
1032 overlay file system from the top-level directory tree, making it a
1033 sibling of it. It is hence essential that the top-level directory
1034 tree is not a mount point itself (since the working directory must
1035 be on the same file system as the top-most directory tree). Also
1036 note that the "lowerdir=" mount option receives the paths to stack
1037 in the opposite order of this switch.
1038 Note that this option cannot be used to replace the root file
1040 system of the container with an overlay file system. However, the
1041 --volatile= option described above provides similar functionality,
1042 with a focus on implementing stateless operating system images.
1043 Input/Output Options
1045 --console=MODE
1046 Configures how to set up standard input, output and error output
1047 for the container payload, as well as the /dev/console device for
1048 the container. Takes one of interactive, read-only, passive or
1049 pipe. If interactive a pseudo-TTY is allocated and made available
1050 as /dev/console in the container. It is then bi-directionally
1051 connected to the standard input and output passed to
1052 systemd-nspawn. read-only is similar but only the output of the
1053 container is propagated and no input from the caller is read. In
1054 passive mode a pseudo TTY is allocated, but it is not connected
1055 anywhere. Finally, in pipe mode no pseudo TTY is allocated, but the
1056 passed standard input, output and error output file descriptors are
1057 passed on — as they are — to the container payload. In this mode
1058 /dev/console will not exist in the container. Note that in this
1059 mode the container payload generally cannot be a full init system
1060 as init systems tend to require /dev/console to be available. On
1061 the other hand, in this mode container invocations can be used
1062 within shell pipelines. This is because intermediary pseudo TTYs do
1063 not permit independent bidirectional propagation of the end-of-file
1064 (EOF) condition, which is necessary for shell pipelines to work
1065 correctly.
1066 Note that the pipe mode should be used carefully, as passing
1068 arbitrary file descriptors to less trusted container payloads might
1069 open up unwanted interfaces for access by the container payload.
1070 For example, if a passed file descriptor refers to a TTY of some
1071 form, APIs such as TIOCSTI may be used to synthesize input that
1072 might be used for escaping the container. Hence pipe mode should
1073 only be used if the payload is sufficiently trusted or when the
1074 standard input/output/error output file descriptors are known safe,
1075 for example pipes. Defaults to interactive if systemd-nspawn is
1076 invoked from a terminal, and read-only otherwise.
1077 --pipe, -P
1079 Equivalent to --console=pipe.
1080 --no-pager
1082 Do not pipe output into a pager.
1083 -h, --help
1085 Print a short help text and exit.
1086 --version
1088 Print a short version string and exit.
1089
1091 $SYSTEMD_PAGER
1092 Pager to use when --no-pager is not given; overrides $PAGER. If
1093 neither $SYSTEMD_PAGER nor $PAGER are set, a set of well-known
1094 pager implementations are tried in turn, including less(1) and
1095 more(1), until one is found. If no pager implementation is
1096 discovered no pager is invoked. Setting this environment variable
1097 to an empty string or the value "cat" is equivalent to passing
1098 --no-pager.
1099 $SYSTEMD_LESS
1101 Override the options passed to less (by default "FRSXMK").
1102 Users might want to change two options in particular:
1104 K
1106 This option instructs the pager to exit immediately when Ctrl+C
1107 is pressed. To allow less to handle Ctrl+C itself to switch
1108 back to the pager command prompt, unset this option.
1109 If the value of $SYSTEMD_LESS does not include "K", and the
1111 pager that is invoked is less, Ctrl+C will be ignored by the
1112 executable, and needs to be handled by the pager.
1113 X
1115 This option instructs the pager to not send termcap
1116 initialization and deinitialization strings to the terminal. It
1117 is set by default to allow command output to remain visible in
1118 the terminal even after the pager exits. Nevertheless, this
1119 prevents some pager functionality from working, in particular
1120 paged output cannot be scrolled with the mouse.
1121 See less(1) for more discussion.
1123 $SYSTEMD_LESSCHARSET
1125 Override the charset passed to less (by default "utf-8", if the
1126 invoking terminal is determined to be UTF-8 compatible).
1127 $SYSTEMD_COLORS
1129 The value must be a boolean. Controls whether colorized output
1130 should be generated. This can be specified to override the decision
1131 that systemd makes based on $TERM and what the console is connected
1132 to.
1133 $SYSTEMD_URLIFY
1135 The value must be a boolean. Controls whether clickable links
1136 should be generated in the output for terminal emulators supporting
1137 this. This can be specified to override the decision that systemd
1138 makes based on $TERM and other conditions.
1139
1141 Example 1. Download a Fedora image and start a shell in it
1142 # machinectl pull-raw --verify=no \
1144 https://download.fedoraproject.org/pub/fedora/linux/releases/30/Cloud/x86_64/images/Fedora-Cloud-Base-30-1.2.x86_64.raw.xz \
1145 Fedora-Cloud-Base-30-1.2.x86-64
1146 # systemd-nspawn -M Fedora-Cloud-Base-30-1.2.x86-64
1147 This downloads an image using machinectl(1) and opens a shell in it.
1149 Example 2. Build and boot a minimal Fedora distribution in a container
1151 # dnf -y --releasever=30 --installroot=/var/lib/machines/f30 \
1153 --disablerepo='*' --enablerepo=fedora --enablerepo=updates install \
1154 systemd passwd dnf fedora-release vim-minimal
1155 # systemd-nspawn -bD /var/lib/machines/f30
1156 This installs a minimal Fedora distribution into the directory
1158 /var/lib/machines/f30 and then boots an OS in a namespace container in
1159 it. Because the installation is located underneath the standard
1160 /var/lib/machines/ directory, it is also possible to start the machine
1161 using systemd-nspawn -M f30.
1162 Example 3. Spawn a shell in a container of a minimal Debian unstable
1164 distribution
1165 # debootstrap unstable ~/debian-tree/
1167 # systemd-nspawn -D ~/debian-tree/
1168 This installs a minimal Debian unstable distribution into the directory
1170 ~/debian-tree/ and then spawns a shell in a namespace container in it.
1171 debootstrap supports Debian[7], Ubuntu[8], and Tanglu[9] out of the
1173 box, so the same command can be used to install any of those. For other
1174 distributions from the Debian family, a mirror has to be specified, see
1175 debootstrap(8).
1176 Example 4. Boot a minimal Arch Linux distribution in a container
1178 # pacstrap -c ~/arch-tree/ base
1180 # systemd-nspawn -bD ~/arch-tree/
1181 This installs a minimal Arch Linux distribution into the directory
1183 ~/arch-tree/ and then boots an OS in a namespace container in it.
1184 Example 5. Install the OpenSUSE Tumbleweed rolling distribution
1186 # zypper --root=/var/lib/machines/tumbleweed ar -c \
1188 https://download.opensuse.org/tumbleweed/repo/oss tumbleweed
1189 # zypper --root=/var/lib/machines/tumbleweed refresh
1190 # zypper --root=/var/lib/machines/tumbleweed install --no-recommends \
1191 systemd shadow zypper openSUSE-release vim
1192 # systemd-nspawn -M tumbleweed passwd root
1193 # systemd-nspawn -M tumbleweed -b
1194 Example 6. Boot into an ephemeral snapshot of the host system
1196 # systemd-nspawn -D / -xb
1198 This runs a copy of the host system in a snapshot which is removed
1200 immediately when the container exits. All file system changes made
1201 during runtime will be lost on shutdown, hence.
1202 Example 7. Run a container with SELinux sandbox security contexts
1204 # chcon system_u:object_r:svirt_sandbox_file_t:s0:c0,c1 -R /srv/container
1206 # systemd-nspawn -L system_u:object_r:svirt_sandbox_file_t:s0:c0,c1 \
1207 -Z system_u:system_r:svirt_lxc_net_t:s0:c0,c1 -D /srv/container /bin/sh
1208 Example 8. Run a container with an OSTree deployment
1210 # systemd-nspawn -b -i ~/image.raw \
1212 --pivot-root=/ostree/deploy/$OS/deploy/$CHECKSUM:/sysroot \
1213 --bind=+/sysroot/ostree/deploy/$OS/var:/var
1214
1216 The exit code of the program executed in the container is returned.
1217
1219 systemd(1), systemd.nspawn(5), chroot(1), dnf(8), debootstrap(8),
1220 pacman(8), zypper(8), systemd.slice(5), machinectl(1), btrfs(8)
1221
1223 1. Container Interface
1224 https://www.freedesktop.org/wiki/Software/systemd/ContainerInterface
1225 2. Discoverable Partitions Specification
1227 https://www.freedesktop.org/wiki/Specifications/DiscoverablePartitionsSpec/
1228 3. OCI Runtime Specification
1230 https://github.com/opencontainers/runtime-spec/blob/master/spec.md
1231 4. OSTree
1233 https://ostree.readthedocs.io/en/latest/
1234 5. overlayfs.txt
1236 https://www.kernel.org/doc/Documentation/filesystems/overlayfs.txt
1237 6. Fedora
1239 https://getfedora.org
1240 7. Debian
1242 https://www.debian.org
1243 8. Ubuntu
1245 https://www.ubuntu.com
1246 9. Tanglu
1248 https://www.tanglu.org
1249 10. Arch Linux
1251 https://www.archlinux.org
1252 11. OpenSUSE Tumbleweed
1254 https://software.opensuse.org/distributions/tumbleweed
1255systemd 243 SYSTEMD-NSPAWN(1)