1SYSTEMD.NSPAWN(5) systemd.nspawn SYSTEMD.NSPAWN(5)
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6 systemd.nspawn - Container settings
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9 /etc/systemd/nspawn/machine.nspawn
10 /run/systemd/nspawn/machine.nspawn
12 /var/lib/machines/machine.nspawn
14
16 An nspawn container settings file (suffix .nspawn) contains runtime
17 configuration for a local container, and is used by systemd-nspawn(1).
18 Files of this type are named after the containers they define settings
19 for. They are optional, and only required for containers whose
20 execution environment shall differ from the defaults. Files of this
21 type mostly contain settings that may also be set on the systemd-nspawn
22 command line, and make it easier to persistently attach specific
23 settings to specific containers. The syntax of these files is inspired
24 by .desktop files, similarly to other configuration files supported by
25 the systemd project. See systemd.syntax(7) for an overview.
26
28 Files are searched for by appending the .nspawn suffix to the machine
29 name of the container, as specified with the --machine= switch of
30 systemd-nspawn, or derived from the directory or image file name. This
31 file is first searched for in /etc/systemd/nspawn/ and
32 /run/systemd/nspawn/. If found there, the settings are read and all of
33 them take full effect (but may still be overridden by corresponding
34 command line arguments). Otherwise, the file will then be searched for
35 next to the image file or in the immediate parent of the root directory
36 of the container. If the file is found there, only a subset of the
37 settings will take effect however. All settings that possibly elevate
38 privileges or grant additional access to resources of the host (such as
39 files or directories) are ignored. To which options this applies is
40 documented below.
41 Persistent settings files created and maintained by the administrator
43 (and thus trusted) should be placed in /etc/systemd/nspawn/, while
44 automatically downloaded (and thus potentially untrusted) settings
45 files are placed in /var/lib/machines/ instead (next to the container
46 images), where their security impact is limited. In order to add
47 privileged settings to .nspawn files acquired from the image vendor, it
48 is recommended to copy the settings files into /etc/systemd/nspawn/ and
49 edit them there, so that the privileged options become available. The
50 precise algorithm for how the files are searched and interpreted may be
51 configured with systemd-nspawn's --settings= switch, see systemd-
52 nspawn(1) for details.
53
55 Settings files may include an [Exec] section, which carries various
56 execution parameters:
57 Boot=
59 Takes a boolean argument, which defaults to off. If enabled,
60 systemd-nspawn will automatically search for an init executable and
61 invoke it. In this case, the specified parameters using Parameters=
62 are passed as additional arguments to the init process. This
63 setting corresponds to the --boot switch on the systemd-nspawn
64 command line. This option may not be combined with ProcessTwo=yes.
65 This option is specified by default in the systemd-nspawn@.service
66 template unit.
67 Ephemeral=
69 Takes a boolean argument, which defaults to off, If enabled, the
70 container is run with a temporary snapshot of its file system that
71 is removed immediately when the container terminates. This is
72 equivalent to the --ephemeral command line switch. See systemd-
73 nspawn(1) for details about the specific options supported.
74 ProcessTwo=
76 Takes a boolean argument, which defaults to off. If enabled, the
77 specified program is run as PID 2. A stub init process is run as
78 PID 1. This setting corresponds to the --as-pid2 switch on the
79 systemd-nspawn command line. This option may not be combined with
80 Boot=yes.
81 Parameters=
83 Takes a whitespace-separated list of arguments. Single ("'") and
84 double (""") quotes may be used around arguments with whitespace.
85 This is either a command line, beginning with the binary name to
86 execute, or – if Boot= is enabled – the list of arguments to pass
87 to the init process. This setting corresponds to the command line
88 parameters passed on the systemd-nspawn command line.
89 Note: Boot=no, Parameters=a b "c c" is the same as systemd-nspawn a
91 b "c c", and Boot=yes, Parameters=b 'c c' is the same as
92 systemd-nspawn --boot b 'c c'.
93 Environment=
95 Takes an environment variable assignment consisting of key and
96 value, separated by "=". Sets an environment variable for the main
97 process invoked in the container. This setting may be used multiple
98 times to set multiple environment variables. It corresponds to the
99 --setenv= command line switch.
100 User=
102 Takes a UNIX user name. Specifies the user name to invoke the main
103 process of the container as. This user must be known in the
104 container's user database. This corresponds to the --user= command
105 line switch.
106 WorkingDirectory=
108 Selects the working directory for the process invoked in the
109 container. Expects an absolute path in the container's file system
110 namespace. This corresponds to the --chdir= command line switch.
111 PivotRoot=
113 Selects a directory to pivot to / inside the container when
114 starting up. Takes a single path, or a pair of two paths separated
115 by a colon. Both paths must be absolute, and are resolved in the
116 container's file system namespace. This corresponds to the
117 --pivot-root= command line switch.
118 Capability=, DropCapability=
120 Takes a space-separated list of Linux process capabilities (see
121 capabilities(7) for details). The Capability= setting specifies
122 additional capabilities to pass on top of the default set of
123 capabilities. The DropCapability= setting specifies capabilities to
124 drop from the default set. These settings correspond to the
125 --capability= and --drop-capability= command line switches. Note
126 that Capability= is a privileged setting, and only takes effect in
127 .nspawn files in /etc/systemd/nspawn/ and /run/system/nspawn/ (see
128 above). On the other hand, DropCapability= takes effect in all
129 cases. If the special value "all" is passed, all capabilities are
130 retained (or dropped).
131 These settings change the bounding set of capabilities which also
133 limits the ambient capabilities as given with the
134 AmbientCapability=.
135 AmbientCapability=
137 Takes a space-separated list of Linux process capabilities (see
138 capabilities(7) for details). The AmbientCapability= setting
139 specifies capabilities which will be passed to the started program
140 in the inheritable and ambient capability sets. This will grant
141 these capabilities to this process. This setting correspond to the
142 --ambient-capability= command line switch.
143 The value "all" is not supported for this setting.
145 The setting of AmbientCapability= must be covered by the bounding
147 set settings which were established by Capability= and
148 DropCapability=.
149 Note that AmbientCapability= is a privileged setting (see above).
151 NoNewPrivileges=
153 Takes a boolean argument that controls the PR_SET_NO_NEW_PRIVS flag
154 for the container payload. This is equivalent to the
155 --no-new-privileges= command line switch. See systemd-nspawn(1) for
156 details.
157 KillSignal=
159 Specify the process signal to send to the container's PID 1 when
160 nspawn itself receives SIGTERM, in order to trigger an orderly
161 shutdown of the container. Defaults to SIGRTMIN+3 if Boot= is used
162 (on systemd-compatible init systems SIGRTMIN+3 triggers an orderly
163 shutdown). For a list of valid signals, see signal(7).
164 Personality=
166 Configures the kernel personality for the container. This is
167 equivalent to the --personality= switch.
168 MachineID=
170 Configures the 128-bit machine ID (UUID) to pass to the container.
171 This is equivalent to the --uuid= command line switch. This option
172 is privileged (see above).
173 PrivateUsers=
175 Configures support for usernamespacing. This is equivalent to the
176 --private-users= command line switch, and takes the same options.
177 This option is privileged (see above). This option is the default
178 if the systemd-nspawn@.service template unit file is used.
179 NotifyReady=
181 Configures support for notifications from the container's init
182 process. This is equivalent to the --notify-ready= command line
183 switch, and takes the same parameters. See systemd-nspawn(1) for
184 details about the specific options supported.
185 SystemCallFilter=
187 Configures the system call filter applied to containers. This is
188 equivalent to the --system-call-filter= command line switch, and
189 takes the same list parameter. See systemd-nspawn(1) for details.
190 LimitCPU=, LimitFSIZE=, LimitDATA=, LimitSTACK=, LimitCORE=, LimitRSS=,
192 LimitNOFILE=, LimitAS=, LimitNPROC=, LimitMEMLOCK=, LimitLOCKS=,
193 LimitSIGPENDING=, LimitMSGQUEUE=, LimitNICE=, LimitRTPRIO=,
194 LimitRTTIME=
195 Configures various types of resource limits applied to containers.
196 This is equivalent to the --rlimit= command line switch, and takes
197 the same arguments. See systemd-nspawn(1) for details.
198 OOMScoreAdjust=
200 Configures the OOM score adjustment value. This is equivalent to
201 the --oom-score-adjust= command line switch, and takes the same
202 argument. See systemd-nspawn(1) for details.
203 CPUAffinity=
205 Configures the CPU affinity. This is equivalent to the
206 --cpu-affinity= command line switch, and takes the same argument.
207 See systemd-nspawn(1) for details.
208 Hostname=
210 Configures the kernel hostname set for the container. This is
211 equivalent to the --hostname= command line switch, and takes the
212 same argument. See systemd-nspawn(1) for details.
213 ResolvConf=
215 Configures how /etc/resolv.conf in the container shall be handled.
216 This is equivalent to the --resolv-conf= command line switch, and
217 takes the same argument. See systemd-nspawn(1) for details.
218 Timezone=
220 Configures how /etc/localtime in the container shall be handled.
221 This is equivalent to the --timezone= command line switch, and
222 takes the same argument. See systemd-nspawn(1) for details.
223 LinkJournal=
225 Configures how to link host and container journal setups. This is
226 equivalent to the --link-journal= command line switch, and takes
227 the same parameter. See systemd-nspawn(1) for details.
228 SuppressSync=
230 Configures whether to suppress disk synchronization for the
231 container payload. This is equivalent to the --suppress-sync=
232 command line switch, and takes the same parameter. See systemd-
233 nspawn(1) for details.
234
236 Settings files may include a [Files] section, which carries various
237 parameters configuring the file system of the container:
238 ReadOnly=
240 Takes a boolean argument, which defaults to off. If specified, the
241 container will be run with a read-only file system. This setting
242 corresponds to the --read-only command line switch.
243 Volatile=
245 Takes a boolean argument, or the special value "state". This
246 configures whether to run the container with volatile state and/or
247 configuration. This option is equivalent to --volatile=, see
248 systemd-nspawn(1) for details about the specific options supported.
249 Bind=, BindReadOnly=
251 Adds a bind mount from the host into the container. Takes a single
252 path, a pair of two paths separated by a colon, or a triplet of two
253 paths plus an option string separated by colons. This option may be
254 used multiple times to configure multiple bind mounts. This option
255 is equivalent to the command line switches --bind= and --bind-ro=,
256 see systemd-nspawn(1) for details about the specific options
257 supported. This setting is privileged (see above).
258 BindUser=
260 Binds a user from the host into the container. This option is
261 equivalent to the command line switch --bind-user=, see systemd-
262 nspawn(1) for details about the specific options supported. This
263 setting is privileged (see above).
264 TemporaryFileSystem=
266 Adds a "tmpfs" mount to the container. Takes a path or a pair of
267 path and option string, separated by a colon. This option may be
268 used multiple times to configure multiple "tmpfs" mounts. This
269 option is equivalent to the command line switch --tmpfs=, see
270 systemd-nspawn(1) for details about the specific options supported.
271 This setting is privileged (see above).
272 Inaccessible=
274 Masks the specified file or directory in the container, by
275 over-mounting it with an empty file node of the same type with the
276 most restrictive access mode. Takes a file system path as argument.
277 This option may be used multiple times to mask multiple files or
278 directories. This option is equivalent to the command line switch
279 --inaccessible=, see systemd-nspawn(1) for details about the
280 specific options supported. This setting is privileged (see above).
281 Overlay=, OverlayReadOnly=
283 Adds an overlay mount point. Takes a colon-separated list of paths.
284 This option may be used multiple times to configure multiple
285 overlay mounts. This option is equivalent to the command line
286 switches --overlay= and --overlay-ro=, see systemd-nspawn(1) for
287 details about the specific options supported. This setting is
288 privileged (see above).
289 PrivateUsersOwnership=
291 Configures whether the ownership of the files and directories in
292 the container tree shall be adjusted to the UID/GID range used, if
293 necessary and user namespacing is enabled. This is equivalent to
294 the --private-users-ownership= command line switch. This option is
295 privileged (see above).
296
298 Settings files may include a [Network] section, which carries various
299 parameters configuring the network connectivity of the container:
300 Private=
302 Takes a boolean argument, which defaults to off. If enabled, the
303 container will run in its own network namespace and not share
304 network interfaces and configuration with the host. This setting
305 corresponds to the --private-network command line switch.
306 VirtualEthernet=
308 Takes a boolean argument. Configures whether to create a virtual
309 Ethernet connection ("veth") between host and the container. This
310 setting implies Private=yes. This setting corresponds to the
311 --network-veth command line switch. This option is privileged (see
312 above). This option is the default if the systemd-nspawn@.service
313 template unit file is used.
314 VirtualEthernetExtra=
316 Takes a colon-separated pair of interface names. Configures an
317 additional virtual Ethernet connection ("veth") between host and
318 the container. The first specified name is the interface name on
319 the host, the second the interface name in the container. The
320 latter may be omitted in which case it is set to the same name as
321 the host side interface. This setting implies Private=yes. This
322 setting corresponds to the --network-veth-extra= command line
323 switch, and maybe be used multiple times. It is independent of
324 VirtualEthernet=. Note that this option is unrelated to the Bridge=
325 setting below, and thus any connections created this way are not
326 automatically added to any bridge device on the host side. This
327 option is privileged (see above).
328 Interface=
330 Takes a space-separated list of interfaces to add to the container.
331 This option corresponds to the --network-interface= command line
332 switch and implies Private=yes. This option is privileged (see
333 above).
334 MACVLAN=, IPVLAN=
336 Takes a space-separated list of interfaces to add MACLVAN or IPVLAN
337 interfaces to, which are then added to the container. These options
338 correspond to the --network-macvlan= and --network-ipvlan= command
339 line switches and imply Private=yes. These options are privileged
340 (see above).
341 Bridge=
343 Takes an interface name. This setting implies VirtualEthernet=yes
344 and Private=yes and has the effect that the host side of the
345 created virtual Ethernet link is connected to the specified bridge
346 interface. This option corresponds to the --network-bridge= command
347 line switch. This option is privileged (see above).
348 Zone=
350 Takes a network zone name. This setting implies VirtualEthernet=yes
351 and Private=yes and has the effect that the host side of the
352 created virtual Ethernet link is connected to an automatically
353 managed bridge interface named after the passed argument, prefixed
354 with "vz-". This option corresponds to the --network-zone= command
355 line switch. This option is privileged (see above).
356 Port=
358 Exposes a TCP or UDP port of the container on the host. This option
359 corresponds to the --port= command line switch, see systemd-
360 nspawn(1) for the precise syntax of the argument this option takes.
361 This option is privileged (see above).
362
364 systemd(1), systemd-nspawn(1), systemd.directives(7)
365systemd 251 SYSTEMD.NSPAWN(5)