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 NoNewPrivileges=
134 Takes a boolean argument that controls the PR_SET_NO_NEW_PRIVS flag
135 for the container payload. This is equivalent to the
136 --no-new-privileges= command line switch. See systemd-nspawn(1) for
137 details.
138 KillSignal=
140 Specify the process signal to send to the container's PID 1 when
141 nspawn itself receives SIGTERM, in order to trigger an orderly
142 shutdown of the container. Defaults to SIGRTMIN+3 if Boot= is used
143 (on systemd-compatible init systems SIGRTMIN+3 triggers an orderly
144 shutdown). For a list of valid signals, see signal(7).
145 Personality=
147 Configures the kernel personality for the container. This is
148 equivalent to the --personality= switch.
149 MachineID=
151 Configures the 128-bit machine ID (UUID) to pass to the container.
152 This is equivalent to the --uuid= command line switch. This option
153 is privileged (see above).
154 PrivateUsers=
156 Configures support for usernamespacing. This is equivalent to the
157 --private-users= command line switch, and takes the same options.
158 This option is privileged (see above). This option is the default
159 if the systemd-nspawn@.service template unit file is used.
160 NotifyReady=
162 Configures support for notifications from the container's init
163 process. This is equivalent to the --notify-ready= command line
164 switch, and takes the same parameters. See systemd-nspawn(1) for
165 details about the specific options supported.
166 SystemCallFilter=
168 Configures the system call filter applied to containers. This is
169 equivalent to the --system-call-filter= command line switch, and
170 takes the same list parameter. See systemd-nspawn(1) for details.
171 LimitCPU=, LimitFSIZE=, LimitDATA=, LimitSTACK=, LimitCORE=, LimitRSS=,
173 LimitNOFILE=, LimitAS=, LimitNPROC=, LimitMEMLOCK=, LimitLOCKS=,
174 LimitSIGPENDING=, LimitMSGQUEUE=, LimitNICE=, LimitRTPRIO=,
175 LimitRTTIME=
176 Configures various types of resource limits applied to containers.
177 This is equivalent to the --rlimit= command line switch, and takes
178 the same arguments. See systemd-nspawn(1) for details.
179 OOMScoreAdjust=
181 Configures the OOM score adjustment value. This is equivalent to
182 the --oom-score-adjust= command line switch, and takes the same
183 argument. See systemd-nspawn(1) for details.
184 CPUAffinity=
186 Configures the CPU affinity. This is equivalent to the
187 --cpu-affinity= command line switch, and takes the same argument.
188 See systemd-nspawn(1) for details.
189 Hostname=
191 Configures the kernel hostname set for the container. This is
192 equivalent to the --hostname= command line switch, and takes the
193 same argument. See systemd-nspawn(1) for details.
194 ResolvConf=
196 Configures how /etc/resolv.conf in the container shall be handled.
197 This is equivalent to the --resolv-conf= command line switch, and
198 takes the same argument. See systemd-nspawn(1) for details.
199 Timezone=
201 Configures how /etc/localtime in the container shall be handled.
202 This is equivalent to the --timezone= command line switch, and
203 takes the same argument. See systemd-nspawn(1) for details.
204 LinkJournal=
206 Configures how to link host and container journal setups. This is
207 equivalent to the --link-journal= command line switch, and takes
208 the same parameter. See systemd-nspawn(1) for details.
209
211 Settings files may include a "[Files]" section, which carries various
212 parameters configuring the file system of the container:
213 ReadOnly=
215 Takes a boolean argument, which defaults to off. If specified, the
216 container will be run with a read-only file system. This setting
217 corresponds to the --read-only command line switch.
218 Volatile=
220 Takes a boolean argument, or the special value "state". This
221 configures whether to run the container with volatile state and/or
222 configuration. This option is equivalent to --volatile=, see
223 systemd-nspawn(1) for details about the specific options supported.
224 Bind=, BindReadOnly=
226 Adds a bind mount from the host into the container. Takes a single
227 path, a pair of two paths separated by a colon, or a triplet of two
228 paths plus an option string separated by colons. This option may be
229 used multiple times to configure multiple bind mounts. This option
230 is equivalent to the command line switches --bind= and --bind-ro=,
231 see systemd-nspawn(1) for details about the specific options
232 supported. This setting is privileged (see above).
233 TemporaryFileSystem=
235 Adds a "tmpfs" mount to the container. Takes a path or a pair of
236 path and option string, separated by a colon. This option may be
237 used multiple times to configure multiple "tmpfs" mounts. This
238 option is equivalent to the command line switch --tmpfs=, see
239 systemd-nspawn(1) for details about the specific options supported.
240 This setting is privileged (see above).
241 Inaccessible=
243 Masks the specified file or directly in the container, by
244 over-mounting it with an empty file node of the same type with the
245 most restrictive access mode. Takes a file system path as argument.
246 This option may be used multiple times to mask multiple files or
247 directories. This option is equivalent to the command line switch
248 --inaccessible=, see systemd-nspawn(1) for details about the
249 specific options supported. This setting is privileged (see above).
250 Overlay=, OverlayReadOnly=
252 Adds an overlay mount point. Takes a colon-separated list of paths.
253 This option may be used multiple times to configure multiple
254 overlay mounts. This option is equivalent to the command line
255 switches --overlay= and --overlay-ro=, see systemd-nspawn(1) for
256 details about the specific options supported. This setting is
257 privileged (see above).
258 PrivateUsersChown=
260 Configures whether the ownership of the files and directories in
261 the container tree shall be adjusted to the UID/GID range used, if
262 necessary and user namespacing is enabled. This is equivalent to
263 the --private-users-chown command line switch. This option is
264 privileged (see above).
265
267 Settings files may include a "[Network]" section, which carries various
268 parameters configuring the network connectivity of the container:
269 Private=
271 Takes a boolean argument, which defaults to off. If enabled, the
272 container will run in its own network namespace and not share
273 network interfaces and configuration with the host. This setting
274 corresponds to the --private-network command line switch.
275 VirtualEthernet=
277 Takes a boolean argument. Configures whether to create a virtual
278 Ethernet connection ("veth") between host and the container. This
279 setting implies Private=yes. This setting corresponds to the
280 --network-veth command line switch. This option is privileged (see
281 above). This option is the default if the systemd-nspawn@.service
282 template unit file is used.
283 VirtualEthernetExtra=
285 Takes a colon-separated pair of interface names. Configures an
286 additional virtual Ethernet connection ("veth") between host and
287 the container. The first specified name is the interface name on
288 the host, the second the interface name in the container. The
289 latter may be omitted in which case it is set to the same name as
290 the host side interface. This setting implies Private=yes. This
291 setting corresponds to the --network-veth-extra= command line
292 switch, and maybe be used multiple times. It is independent of
293 VirtualEthernet=. This option is privileged (see above).
294 Interface=
296 Takes a space-separated list of interfaces to add to the container.
297 This option corresponds to the --network-interface= command line
298 switch and implies Private=yes. This option is privileged (see
299 above).
300 MACVLAN=, IPVLAN=
302 Takes a space-separated list of interfaces to add MACLVAN or IPVLAN
303 interfaces to, which are then added to the container. These options
304 correspond to the --network-macvlan= and --network-ipvlan= command
305 line switches and imply Private=yes. These options are privileged
306 (see above).
307 Bridge=
309 Takes an interface name. This setting implies VirtualEthernet=yes
310 and Private=yes and has the effect that the host side of the
311 created virtual Ethernet link is connected to the specified bridge
312 interface. This option corresponds to the --network-bridge= command
313 line switch. This option is privileged (see above).
314 Zone=
316 Takes a network zone name. This setting implies VirtualEthernet=yes
317 and Private=yes and has the effect that the host side of the
318 created virtual Ethernet link is connected to an automatically
319 managed bridge interface named after the passed argument, prefixed
320 with "vz-". This option corresponds to the --network-zone= command
321 line switch. This option is privileged (see above).
322 Port=
324 Exposes a TCP or UDP port of the container on the host. This option
325 corresponds to the --port= command line switch, see systemd-
326 nspawn(1) for the precise syntax of the argument this option takes.
327 This option is privileged (see above).
328
330 systemd(1), systemd-nspawn(1), systemd.directives(7)
331systemd 245 SYSTEMD.NSPAWN(5)