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) encodes additional
17 runtime information about a local container, and is searched, read and
18 used by systemd-nspawn(1) when starting a container. Files of this type
19 are named after the containers they define settings for. They are
20 optional, and only required for containers whose execution environment
21 shall differ from the defaults. Files of this type mostly contain
22 settings that may also be set on the systemd-nspawn command line, and
23 make it easier to persistently attach specific settings to specific
24 containers. The syntax of these files is inspired by .desktop files
25 following the XDG Desktop Entry Specification[1], which in turn are
26 inspired by Microsoft Windows .ini files.
27 Boolean arguments used in these settings files can be written in
29 various formats. For positive settings, the strings 1, yes, true and on
30 are equivalent. For negative settings, the strings 0, no, false and off
31 are equivalent.
32 Empty lines and lines starting with # or ; are ignored. This may be
34 used for commenting. Lines ending in a backslash are concatenated with
35 the following line while reading and the backslash is replaced by a
36 space character. This may be used to wrap long lines.
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39 Files are searched by appending the .nspawn suffix to the machine name
40 of the container, as specified with the --machine= switch of
41 systemd-nspawn, or derived from the directory or image file name. This
42 file is first searched in /etc/systemd/nspawn/ and
43 /run/systemd/nspawn/. If found in these directories, its settings are
44 read and all of them take full effect (but are possibly overridden by
45 corresponding command line arguments). If not found, the file will then
46 be searched next to the image file or in the immediate parent of the
47 root directory of the container. If the file is found there, only a
48 subset of the settings will take effect however. All settings that
49 possibly elevate privileges or grant additional access to resources of
50 the host (such as files or directories) are ignored. To which options
51 this applies is documented below.
52 Persistent settings files created and maintained by the administrator
54 (and thus trusted) should be placed in /etc/systemd/nspawn/, while
55 automatically downloaded (and thus potentially untrusted) settings
56 files are placed in /var/lib/machines/ instead (next to the container
57 images), where their security impact is limited. In order to add
58 privileged settings to .nspawn files acquired from the image vendor, it
59 is recommended to copy the settings files into /etc/systemd/nspawn/ and
60 edit them there, so that the privileged options become available. The
61 precise algorithm for how the files are searched and interpreted may be
62 configured with systemd-nspawn's --settings= switch, see systemd-
63 nspawn(1) for details.
64
66 Settings files may include an "[Exec]" section, which carries various
67 execution parameters:
68 Boot=
70 Takes a boolean argument, which defaults to off. If enabled,
71 systemd-nspawn will automatically search for an init executable and
72 invoke it. In this case, the specified parameters using Parameters=
73 are passed as additional arguments to the init process. This
74 setting corresponds to the --boot switch on the systemd-nspawn
75 command line. This option may not be combined with ProcessTwo=yes.
76 This option is the default if the systemd-nspawn@.service template
77 unit file is used.
78 ProcessTwo=
80 Takes a boolean argument, which defaults to off. If enabled, the
81 specified program is run as PID 2. A stub init process is run as
82 PID 1. This setting corresponds to the --as-pid2 switch on the
83 systemd-nspawn command line. This option may not be combined with
84 Boot=yes.
85 Parameters=
87 Takes a space-separated list of arguments. This is either a command
88 line, beginning with the binary name to execute, or – if Boot= is
89 enabled – the list of arguments to pass to the init process. This
90 setting corresponds to the command line parameters passed on the
91 systemd-nspawn command line.
92 Environment=
94 Takes an environment variable assignment consisting of key and
95 value, separated by "=". Sets an environment variable for the main
96 process invoked in the container. This setting may be used multiple
97 times to set multiple environment variables. It corresponds to the
98 --setenv= command line switch.
99 User=
101 Takes a UNIX user name. Specifies the user name to invoke the main
102 process of the container as. This user must be known in the
103 container's user database. This corresponds to the --user= command
104 line switch.
105 WorkingDirectory=
107 Selects the working directory for the process invoked in the
108 container. Expects an absolute path in the container's file system
109 namespace. This corresponds to the --chdir= command line switch.
110 PivotRoot=
112 Selects a directory to pivot to / inside the container when
113 starting up. Takes a single path, or a pair of two paths separated
114 by a colon. Both paths must be absolute, and are resolved in the
115 container's file system namespace. This corresponds to the
116 --pivot-root= command line switch.
117 Capability=, DropCapability=
119 Takes a space-separated list of Linux process capabilities (see
120 capabilities(7) for details). The Capability= setting specifies
121 additional capabilities to pass on top of the default set of
122 capabilities. The DropCapability= setting specifies capabilities to
123 drop from the default set. These settings correspond to the
124 --capability= and --drop-capability= command line switches. Note
125 that Capability= is a privileged setting, and only takes effect in
126 .nspawn files in /etc/systemd/nspawn/ and /run/system/nspawn/ (see
127 above). On the other hand, DropCapability= takes effect in all
128 cases.
129 NoNewPrivileges=
131 Takes a boolean argument that controls the PR_SET_NO_NEW_PRIVS flag
132 for the container payload. This is equivalent to the
133 --no-new-privileges= command line switch. See systemd-nspawn(1) for
134 details.
135 KillSignal=
137 Specify the process signal to send to the container's PID 1 when
138 nspawn itself receives SIGTERM, in order to trigger an orderly
139 shutdown of the container. Defaults to SIGRTMIN+3 if Boot= is used
140 (on systemd-compatible init systems SIGRTMIN+3 triggers an orderly
141 shutdown). For a list of valid signals, see signal(7).
142 Personality=
144 Configures the kernel personality for the container. This is
145 equivalent to the --personality= switch.
146 MachineID=
148 Configures the 128-bit machine ID (UUID) to pass to the container.
149 This is equivalent to the --uuid= command line switch. This option
150 is privileged (see above).
151 PrivateUsers=
153 Configures support for usernamespacing. This is equivalent to the
154 --private-users= command line switch, and takes the same options.
155 This option is privileged (see above). This option is the default
156 if the systemd-nspawn@.service template unit file is used.
157 NotifyReady=
159 Configures support for notifications from the container's init
160 process. This is equivalent to the --notify-ready= command line
161 switch, and takes the same parameters. See systemd-nspawn(1) for
162 details about the specific options supported.
163 SystemCallFilter=
165 Configures the system call filter applied to containers. This is
166 equivalent to the --system-call-filter= command line switch, and
167 takes the same list parameter. See systemd-nspawn(1) for details.
168 LimitCPU=, LimitFSIZE=, LimitDATA=, LimitSTACK=, LimitCORE=, LimitRSS=,
170 LimitNOFILE=, LimitAS=, LimitNPROC=, LimitMEMLOCK=, LimitLOCKS=,
171 LimitSIGPENDING=, LimitMSGQUEUE=, LimitNICE=, LimitRTPRIO=,
172 LimitRTTIME=
173 Configures various types of resource limits applied to containers.
174 This is equivalent to the --rlimit= command line switch, and takes
175 the same arguments. See systemd-nspawn(1) for details.
176 OOMScoreAdjust=
178 Configures the OOM score adjustment value. This is equivalent to
179 the --oom-score-adjust= command line switch, and takes the same
180 argument. See systemd-nspawn(1) for details.
181 CPUAffinity=
183 Configures the CPU affinity. This is equivalent to the
184 --cpu-affinity= command line switch, and takes the same argument.
185 See systemd-nspawn(1) for details.
186 Hostname=
188 Configures the kernel hostname set for the container. This is
189 equivalent to the --hostname= command line switch, and takes the
190 same argument. See systemd-nspawn(1) for details.
191 ResolvConf=
193 Configures how /etc/resolv.conf in the container shall be handled.
194 This is equivalent to the --resolv-conf= command line switch, and
195 takes the same argument. See systemd-nspawn(1) for details.
196 Timezone=
198 Configures how /etc/localtime in the container shall be handled.
199 This is equivalent to the --timezone= command line switch, and
200 takes the same argument. See systemd-nspawn(1) for details.
201 LinkJournal=
203 Configures how to link host and container journal setups. This is
204 equivalent to the --link-journal= command line switch, and takes
205 the same parameter. See systemd-nspawn(1) for details.
206
208 Settings files may include a "[Files]" section, which carries various
209 parameters configuring the file system of the container:
210 ReadOnly=
212 Takes a boolean argument, which defaults to off. If specified, the
213 container will be run with a read-only file system. This setting
214 corresponds to the --read-only command line switch.
215 Volatile=
217 Takes a boolean argument, or the special value "state". This
218 configures whether to run the container with volatile state and/or
219 configuration. This option is equivalent to --volatile=, see
220 systemd-nspawn(1) for details about the specific options supported.
221 Bind=, BindReadOnly=
223 Adds a bind mount from the host into the container. Takes a single
224 path, a pair of two paths separated by a colon, or a triplet of two
225 paths plus an option string separated by colons. This option may be
226 used multiple times to configure multiple bind mounts. This option
227 is equivalent to the command line switches --bind= and --bind-ro=,
228 see systemd-nspawn(1) for details about the specific options
229 supported. This setting is privileged (see above).
230 TemporaryFileSystem=
232 Adds a "tmpfs" mount to the container. Takes a path or a pair of
233 path and option string, separated by a colon. This option may be
234 used multiple times to configure multiple "tmpfs" mounts. This
235 option is equivalent to the command line switch --tmpfs=, see
236 systemd-nspawn(1) for details about the specific options supported.
237 This setting is privileged (see above).
238 Overlay=, OverlayReadOnly=
240 Adds an overlay mount point. Takes a colon-separated list of paths.
241 This option may be used multiple times to configure multiple
242 overlay mounts. This option is equivalent to the command line
243 switches --overlay= and --overlay-ro=, see systemd-nspawn(1) for
244 details about the specific options supported. This setting is
245 privileged (see above).
246 PrivateUsersChown=
248 Configures whether the ownership of the files and directories in
249 the container tree shall be adjusted to the UID/GID range used, if
250 necessary and user namespacing is enabled. This is equivalent to
251 the --private-users-chown command line switch. This option is
252 privileged (see above).
253
255 Settings files may include a "[Network]" section, which carries various
256 parameters configuring the network connectivity of the container:
257 Private=
259 Takes a boolean argument, which defaults to off. If enabled, the
260 container will run in its own network namespace and not share
261 network interfaces and configuration with the host. This setting
262 corresponds to the --private-network command line switch.
263 VirtualEthernet=
265 Takes a boolean argument. Configures whether to create a virtual
266 Ethernet connection ("veth") between host and the container. This
267 setting implies Private=yes. This setting corresponds to the
268 --network-veth command line switch. This option is privileged (see
269 above). This option is the default if the systemd-nspawn@.service
270 template unit file is used.
271 VirtualEthernetExtra=
273 Takes a colon-separated pair of interface names. Configures an
274 additional virtual Ethernet connection ("veth") between host and
275 the container. The first specified name is the interface name on
276 the host, the second the interface name in the container. The
277 latter may be omitted in which case it is set to the same name as
278 the host side interface. This setting implies Private=yes. This
279 setting corresponds to the --network-veth-extra= command line
280 switch, and maybe be used multiple times. It is independent of
281 VirtualEthernet=. This option is privileged (see above).
282 Interface=
284 Takes a space-separated list of interfaces to add to the container.
285 This option corresponds to the --network-interface= command line
286 switch and implies Private=yes. This option is privileged (see
287 above).
288 MACVLAN=, IPVLAN=
290 Takes a space-separated list of interfaces to add MACLVAN or IPVLAN
291 interfaces to, which are then added to the container. These options
292 correspond to the --network-macvlan= and --network-ipvlan= command
293 line switches and imply Private=yes. These options are privileged
294 (see above).
295 Bridge=
297 Takes an interface name. This setting implies VirtualEthernet=yes
298 and Private=yes and has the effect that the host side of the
299 created virtual Ethernet link is connected to the specified bridge
300 interface. This option corresponds to the --network-bridge= command
301 line switch. This option is privileged (see above).
302 Zone=
304 Takes a network zone name. This setting implies VirtualEthernet=yes
305 and Private=yes and has the effect that the host side of the
306 created virtual Ethernet link is connected to an automatically
307 managed bridge interface named after the passed argument, prefixed
308 with "vz-". This option corresponds to the --network-zone= command
309 line switch. This option is privileged (see above).
310 Port=
312 Exposes a TCP or UDP port of the container on the host. This option
313 corresponds to the --port= command line switch, see systemd-
314 nspawn(1) for the precise syntax of the argument this option takes.
315 This option is privileged (see above).
316
318 systemd(1), systemd-nspawn(1), systemd.directives(7)
319
321 1. XDG Desktop Entry Specification
322 http://standards.freedesktop.org/desktop-entry-spec/latest/
323systemd 239 SYSTEMD.NSPAWN(5)