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 used by systemd-
18 nspawn(1). Files of this type are named after the containers they
19 define settings for. They are optional, and only required for
20 containers whose execution environment shall differ from the defaults.
21 Files of this type mostly contain settings that may also be set on the
22 systemd-nspawn command line, and make it easier to persistently attach
23 specific settings to specific containers. The syntax of these files is
24 inspired by .desktop files, similarly to other configuration files
25 supported by the systemd project. See systemd.syntax(7) for an
26 overview.
27
29 Files are searched for by appending the .nspawn suffix to the machine
30 name of the container, as specified with the --machine= switch of
31 systemd-nspawn, or derived from the directory or image file name. This
32 file is first searched for in /etc/systemd/nspawn/ and
33 /run/systemd/nspawn/. If found there, the settings are read and all of
34 them take full effect (but may still be overridden by corresponding
35 command line arguments). Otherwise, the file will then be searched for
36 next to the image file or in the immediate parent of the root directory
37 of the container. If the file is found there, only a subset of the
38 settings will take effect however. All settings that possibly elevate
39 privileges or grant additional access to resources of the host (such as
40 files or directories) are ignored. To which options this applies is
41 documented below.
42 Persistent settings files created and maintained by the administrator
44 (and thus trusted) should be placed in /etc/systemd/nspawn/, while
45 automatically downloaded (and thus potentially untrusted) settings
46 files are placed in /var/lib/machines/ instead (next to the container
47 images), where their security impact is limited. In order to add
48 privileged settings to .nspawn files acquired from the image vendor, it
49 is recommended to copy the settings files into /etc/systemd/nspawn/ and
50 edit them there, so that the privileged options become available. The
51 precise algorithm for how the files are searched and interpreted may be
52 configured with systemd-nspawn's --settings= switch, see systemd-
53 nspawn(1) for details.
54
56 Settings files may include an [Exec] section, which carries various
57 execution parameters:
58 Boot=
60 Takes a boolean argument, which defaults to off. If enabled,
61 systemd-nspawn will automatically search for an init executable and
62 invoke it. In this case, the specified parameters using Parameters=
63 are passed as additional arguments to the init process. This
64 setting corresponds to the --boot switch on the systemd-nspawn
65 command line. This option may not be combined with ProcessTwo=yes.
66 This option is specified by default in the systemd-nspawn@.service
67 template unit.
68 Ephemeral=
70 Takes a boolean argument, which defaults to off, If enabled, the
71 container is run with a temporary snapshot of its file system that
72 is removed immediately when the container terminates. This is
73 equivalent to the --ephemeral command line switch. See systemd-
74 nspawn(1) for details about the specific options supported.
75 ProcessTwo=
77 Takes a boolean argument, which defaults to off. If enabled, the
78 specified program is run as PID 2. A stub init process is run as
79 PID 1. This setting corresponds to the --as-pid2 switch on the
80 systemd-nspawn command line. This option may not be combined with
81 Boot=yes.
82 Parameters=
84 Takes a whitespace-separated list of arguments. Single ("'") and
85 double (""") quotes may be used around arguments with whitespace.
86 This is either a command line, beginning with the binary name to
87 execute, or – if Boot= is enabled – the list of arguments to pass
88 to the init process. This setting corresponds to the command line
89 parameters passed on the systemd-nspawn command line.
90 Note: Boot=no, Parameters=a b "c c" is the same as systemd-nspawn a
92 b "c c", and Boot=yes, Parameters=b 'c c' is the same as
93 systemd-nspawn --boot b 'c c'.
94 Environment=
96 Takes an environment variable assignment consisting of key and
97 value, separated by "=". Sets an environment variable for the main
98 process invoked in the container. This setting may be used multiple
99 times to set multiple environment variables. It corresponds to the
100 --setenv= command line switch.
101 User=
103 Takes a UNIX user name. Specifies the user name to invoke the main
104 process of the container as. This user must be known in the
105 container's user database. This corresponds to the --user= command
106 line switch.
107 WorkingDirectory=
109 Selects the working directory for the process invoked in the
110 container. Expects an absolute path in the container's file system
111 namespace. This corresponds to the --chdir= command line switch.
112 PivotRoot=
114 Selects a directory to pivot to / inside the container when
115 starting up. Takes a single path, or a pair of two paths separated
116 by a colon. Both paths must be absolute, and are resolved in the
117 container's file system namespace. This corresponds to the
118 --pivot-root= command line switch.
119 Capability=, DropCapability=
121 Takes a space-separated list of Linux process capabilities (see
122 capabilities(7) for details). The Capability= setting specifies
123 additional capabilities to pass on top of the default set of
124 capabilities. The DropCapability= setting specifies capabilities to
125 drop from the default set. These settings correspond to the
126 --capability= and --drop-capability= command line switches. Note
127 that Capability= is a privileged setting, and only takes effect in
128 .nspawn files in /etc/systemd/nspawn/ and /run/system/nspawn/ (see
129 above). On the other hand, DropCapability= takes effect in all
130 cases. If the special value "all" is passed, all capabilities are
131 retained (or dropped).
132 These settings change the bounding set of capabilities which also
134 limits the ambient capabilities as given with the
135 AmbientCapability=.
136 AmbientCapability=
138 Takes a space-separated list of Linux process capabilities (see
139 capabilities(7) for details). The AmbientCapability= setting
140 specifies capability which will be passed to to started program in
141 the inheritable and ambient capability sets. This will grant these
142 capabilities to this process. This setting correspond to the
143 --ambient-capability= command line switch.
144 The value "all" is not supported for this setting.
146 The setting of AmbientCapability= must be covered by the bounding
148 set settings which were established by Capability= and
149 DropCapability=.
150 Note that AmbientCapability= is a privileged setting (see above).
152 NoNewPrivileges=
154 Takes a boolean argument that controls the PR_SET_NO_NEW_PRIVS flag
155 for the container payload. This is equivalent to the
156 --no-new-privileges= command line switch. See systemd-nspawn(1) for
157 details.
158 KillSignal=
160 Specify the process signal to send to the container's PID 1 when
161 nspawn itself receives SIGTERM, in order to trigger an orderly
162 shutdown of the container. Defaults to SIGRTMIN+3 if Boot= is used
163 (on systemd-compatible init systems SIGRTMIN+3 triggers an orderly
164 shutdown). For a list of valid signals, see signal(7).
165 Personality=
167 Configures the kernel personality for the container. This is
168 equivalent to the --personality= switch.
169 MachineID=
171 Configures the 128-bit machine ID (UUID) to pass to the container.
172 This is equivalent to the --uuid= command line switch. This option
173 is privileged (see above).
174 PrivateUsers=
176 Configures support for usernamespacing. This is equivalent to the
177 --private-users= command line switch, and takes the same options.
178 This option is privileged (see above). This option is the default
179 if the systemd-nspawn@.service template unit file is used.
180 NotifyReady=
182 Configures support for notifications from the container's init
183 process. This is equivalent to the --notify-ready= command line
184 switch, and takes the same parameters. See systemd-nspawn(1) for
185 details about the specific options supported.
186 SystemCallFilter=
188 Configures the system call filter applied to containers. This is
189 equivalent to the --system-call-filter= command line switch, and
190 takes the same list parameter. See systemd-nspawn(1) for details.
191 LimitCPU=, LimitFSIZE=, LimitDATA=, LimitSTACK=, LimitCORE=, LimitRSS=,
193 LimitNOFILE=, LimitAS=, LimitNPROC=, LimitMEMLOCK=, LimitLOCKS=,
194 LimitSIGPENDING=, LimitMSGQUEUE=, LimitNICE=, LimitRTPRIO=,
195 LimitRTTIME=
196 Configures various types of resource limits applied to containers.
197 This is equivalent to the --rlimit= command line switch, and takes
198 the same arguments. See systemd-nspawn(1) for details.
199 OOMScoreAdjust=
201 Configures the OOM score adjustment value. This is equivalent to
202 the --oom-score-adjust= command line switch, and takes the same
203 argument. See systemd-nspawn(1) for details.
204 CPUAffinity=
206 Configures the CPU affinity. This is equivalent to the
207 --cpu-affinity= command line switch, and takes the same argument.
208 See systemd-nspawn(1) for details.
209 Hostname=
211 Configures the kernel hostname set for the container. This is
212 equivalent to the --hostname= command line switch, and takes the
213 same argument. See systemd-nspawn(1) for details.
214 ResolvConf=
216 Configures how /etc/resolv.conf in the container shall be handled.
217 This is equivalent to the --resolv-conf= command line switch, and
218 takes the same argument. See systemd-nspawn(1) for details.
219 Timezone=
221 Configures how /etc/localtime in the container shall be handled.
222 This is equivalent to the --timezone= command line switch, and
223 takes the same argument. See systemd-nspawn(1) for details.
224 LinkJournal=
226 Configures how to link host and container journal setups. This is
227 equivalent to the --link-journal= command line switch, and takes
228 the same parameter. See systemd-nspawn(1) for details.
229
231 Settings files may include a [Files] section, which carries various
232 parameters configuring the file system of the container:
233 ReadOnly=
235 Takes a boolean argument, which defaults to off. If specified, the
236 container will be run with a read-only file system. This setting
237 corresponds to the --read-only command line switch.
238 Volatile=
240 Takes a boolean argument, or the special value "state". This
241 configures whether to run the container with volatile state and/or
242 configuration. This option is equivalent to --volatile=, see
243 systemd-nspawn(1) for details about the specific options supported.
244 Bind=, BindReadOnly=
246 Adds a bind mount from the host into the container. Takes a single
247 path, a pair of two paths separated by a colon, or a triplet of two
248 paths plus an option string separated by colons. This option may be
249 used multiple times to configure multiple bind mounts. This option
250 is equivalent to the command line switches --bind= and --bind-ro=,
251 see systemd-nspawn(1) for details about the specific options
252 supported. This setting is privileged (see above).
253 TemporaryFileSystem=
255 Adds a "tmpfs" mount to the container. Takes a path or a pair of
256 path and option string, separated by a colon. This option may be
257 used multiple times to configure multiple "tmpfs" mounts. This
258 option is equivalent to the command line switch --tmpfs=, see
259 systemd-nspawn(1) for details about the specific options supported.
260 This setting is privileged (see above).
261 Inaccessible=
263 Masks the specified file or directory in the container, by
264 over-mounting it with an empty file node of the same type with the
265 most restrictive access mode. Takes a file system path as argument.
266 This option may be used multiple times to mask multiple files or
267 directories. This option is equivalent to the command line switch
268 --inaccessible=, see systemd-nspawn(1) for details about the
269 specific options supported. This setting is privileged (see above).
270 Overlay=, OverlayReadOnly=
272 Adds an overlay mount point. Takes a colon-separated list of paths.
273 This option may be used multiple times to configure multiple
274 overlay mounts. This option is equivalent to the command line
275 switches --overlay= and --overlay-ro=, see systemd-nspawn(1) for
276 details about the specific options supported. This setting is
277 privileged (see above).
278 PrivateUsersChown=
280 Configures whether the ownership of the files and directories in
281 the container tree shall be adjusted to the UID/GID range used, if
282 necessary and user namespacing is enabled. This is equivalent to
283 the --private-users-chown command line switch. This option is
284 privileged (see above).
285
287 Settings files may include a [Network] section, which carries various
288 parameters configuring the network connectivity of the container:
289 Private=
291 Takes a boolean argument, which defaults to off. If enabled, the
292 container will run in its own network namespace and not share
293 network interfaces and configuration with the host. This setting
294 corresponds to the --private-network command line switch.
295 VirtualEthernet=
297 Takes a boolean argument. Configures whether to create a virtual
298 Ethernet connection ("veth") between host and the container. This
299 setting implies Private=yes. This setting corresponds to the
300 --network-veth command line switch. This option is privileged (see
301 above). This option is the default if the systemd-nspawn@.service
302 template unit file is used.
303 VirtualEthernetExtra=
305 Takes a colon-separated pair of interface names. Configures an
306 additional virtual Ethernet connection ("veth") between host and
307 the container. The first specified name is the interface name on
308 the host, the second the interface name in the container. The
309 latter may be omitted in which case it is set to the same name as
310 the host side interface. This setting implies Private=yes. This
311 setting corresponds to the --network-veth-extra= command line
312 switch, and maybe be used multiple times. It is independent of
313 VirtualEthernet=. Note that this option is unrelated to the Bridge=
314 setting below, and thus any connections created this way are not
315 automatically added to any bridge device on the host side. This
316 option is privileged (see above).
317 Interface=
319 Takes a space-separated list of interfaces to add to the container.
320 This option corresponds to the --network-interface= command line
321 switch and implies Private=yes. This option is privileged (see
322 above).
323 MACVLAN=, IPVLAN=
325 Takes a space-separated list of interfaces to add MACLVAN or IPVLAN
326 interfaces to, which are then added to the container. These options
327 correspond to the --network-macvlan= and --network-ipvlan= command
328 line switches and imply Private=yes. These options are privileged
329 (see above).
330 Bridge=
332 Takes an interface name. This setting implies VirtualEthernet=yes
333 and Private=yes and has the effect that the host side of the
334 created virtual Ethernet link is connected to the specified bridge
335 interface. This option corresponds to the --network-bridge= command
336 line switch. This option is privileged (see above).
337 Zone=
339 Takes a network zone name. This setting implies VirtualEthernet=yes
340 and Private=yes and has the effect that the host side of the
341 created virtual Ethernet link is connected to an automatically
342 managed bridge interface named after the passed argument, prefixed
343 with "vz-". This option corresponds to the --network-zone= command
344 line switch. This option is privileged (see above).
345 Port=
347 Exposes a TCP or UDP port of the container on the host. This option
348 corresponds to the --port= command line switch, see systemd-
349 nspawn(1) for the precise syntax of the argument this option takes.
350 This option is privileged (see above).
351
353 systemd(1), systemd-nspawn(1), systemd.directives(7)
354systemd 248 SYSTEMD.NSPAWN(5)