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NAME | SYNOPSIS | DESCRIPTION | .NSPAWN FILE DISCOVERY | [EXEC] SECTION OPTIONS | [FILES] SECTION OPTIONS | [NETWORK] SECTION OPTIONS | SEE ALSO | COLOPHON |
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SYSTEMD.NSPAWN(5) systemd.nspawn SYSTEMD.NSPAWN(5)
systemd.nspawn - Container settings
/etc/systemd/nspawn/machine.nspawn
/run/systemd/nspawn/machine.nspawn
/var/lib/machines/machine.nspawn
An nspawn container settings file (suffix .nspawn) contains
runtime configuration for a local container, and is used by
systemd-nspawn(1). Files of this type are named after the
containers they define settings for. They are optional, and only
required for containers whose execution environment shall differ
from the defaults. Files of this type mostly contain settings that
may also be set on the systemd-nspawn command line, and make it
easier to persistently attach specific settings to specific
containers. The syntax of these files is inspired by .desktop
files, similarly to other configuration files supported by the
systemd project. See systemd.syntax(7) for an overview.
Files are searched for by appending the .nspawn suffix to the
machine name of the container, as specified with the --machine=
switch of systemd-nspawn, or derived from the directory or image
file name. This file is first searched for in /etc/systemd/nspawn/
and /run/systemd/nspawn/. If found there, the settings are read
and all of them take full effect (but may still be overridden by
corresponding command line arguments). Otherwise, the file will
then be searched for next to the image file or in the immediate
parent of the root directory of the container. If the file is
found there, only a subset of the settings will take effect
however. All settings that possibly elevate privileges or grant
additional access to resources of the host (such as files or
directories) are ignored. To which options this applies is
documented below.
Persistent settings files created and maintained by the
administrator (and thus trusted) should be placed in
/etc/systemd/nspawn/, while automatically downloaded (and thus
potentially untrusted) settings files are placed in
/var/lib/machines/ instead (next to the container images), where
their security impact is limited. In order to add privileged
settings to .nspawn files acquired from the image vendor, it is
recommended to copy the settings files into /etc/systemd/nspawn/
and edit them there, so that the privileged options become
available. The precise algorithm for how the files are searched
and interpreted may be configured with systemd-nspawn's
--settings= switch, see systemd-nspawn(1) for details.
Settings files may include an [Exec] section, which carries
various execution parameters:
Boot=
Takes a boolean argument, which defaults to off. If enabled,
systemd-nspawn will automatically search for an init
executable and invoke it. In this case, the specified
parameters using Parameters= are passed as additional
arguments to the init process. This setting corresponds to the
--boot switch on the systemd-nspawn command line. This option
may not be combined with ProcessTwo=yes. This option is
specified by default in the systemd-nspawn@.service template
unit.
Added in version 226.
Ephemeral=
Takes a boolean argument, which defaults to off, If enabled,
the container is run with a temporary snapshot of its file
system that is removed immediately when the container
terminates. This is equivalent to the --ephemeral command line
switch. See systemd-nspawn(1) for details about the specific
options supported.
Added in version 240.
ProcessTwo=
Takes a boolean argument, which defaults to off. If enabled,
the specified program is run as PID 2. A stub init process is
run as PID 1. This setting corresponds to the --as-pid2 switch
on the systemd-nspawn command line. This option may not be
combined with Boot=yes.
Added in version 229.
Parameters=
Takes a whitespace-separated list of arguments. Single ("'")
and double (""") quotes may be used around arguments with
whitespace. This is either a command line, beginning with the
binary name to execute, or – if Boot= is enabled – the list of
arguments to pass to the init process. This setting
corresponds to the command line parameters passed on the
systemd-nspawn command line.
Note: Boot=no, Parameters=a b "c c" is the same as
systemd-nspawn a b "c c", and Boot=yes, Parameters=b 'c c' is
the same as systemd-nspawn --boot b 'c c'.
Added in version 226.
Environment=
Takes an environment variable assignment consisting of key and
value, separated by "=". Sets an environment variable for the
main process invoked in the container. This setting may be
used multiple times to set multiple environment variables. It
corresponds to the --setenv= command line switch.
Added in version 226.
User=
Takes a UNIX user name. Specifies the user name to invoke the
main process of the container as. This user must be known in
the container's user database. This corresponds to the --user=
command line switch.
Added in version 226.
WorkingDirectory=
Selects the working directory for the process invoked in the
container. Expects an absolute path in the container's file
system namespace. This corresponds to the --chdir= command
line switch.
Added in version 229.
PivotRoot=
Selects a directory to pivot to / inside the container when
starting up. Takes a single path, or a pair of two paths
separated by a colon. Both paths must be absolute, and are
resolved in the container's file system namespace. This
corresponds to the --pivot-root= command line switch.
Added in version 233.
Capability=, DropCapability=
Takes a space-separated list of Linux process capabilities
(see capabilities(7) for details). The Capability= setting
specifies additional capabilities to pass on top of the
default set of capabilities. The DropCapability= setting
specifies capabilities to drop from the default set. These
settings correspond to the --capability= and
--drop-capability= command line switches. Note that
Capability= is a privileged setting, and only takes effect in
.nspawn files in /etc/systemd/nspawn/ and /run/system/nspawn/
(see above). On the other hand, DropCapability= takes effect
in all cases. If the special value "all" is passed, all
capabilities are retained (or dropped).
These settings change the bounding set of capabilities which
also limits the ambient capabilities as given with the
AmbientCapability=.
Added in version 226.
AmbientCapability=
Takes a space-separated list of Linux process capabilities
(see capabilities(7) for details). The AmbientCapability=
setting specifies capabilities which will be passed to the
started program in the inheritable and ambient capability
sets. This will grant these capabilities to this process. This
setting correspond to the --ambient-capability= command line
switch.
The value "all" is not supported for this setting.
The setting of AmbientCapability= must be covered by the
bounding set settings which were established by Capability=
and DropCapability=.
Note that AmbientCapability= is a privileged setting (see
above).
Added in version 248.
NoNewPrivileges=
Takes a boolean argument that controls the PR_SET_NO_NEW_PRIVS
flag for the container payload. This is equivalent to the
--no-new-privileges= command line switch. See
systemd-nspawn(1) for details.
Added in version 239.
KillSignal=
Specify the process signal to send to the container's PID 1
when nspawn itself receives SIGTERM, in order to trigger an
orderly shutdown of the container. Defaults to SIGRTMIN+3 if
Boot= is used (on systemd-compatible init systems SIGRTMIN+3
triggers an orderly shutdown). For a list of valid signals,
see signal(7).
Added in version 230.
Personality=
Configures the kernel personality for the container. This is
equivalent to the --personality= switch.
Added in version 226.
MachineID=
Configures the 128-bit machine ID (UUID) to pass to the
container. This is equivalent to the --uuid= command line
switch. This option is privileged (see above).
Added in version 226.
PrivateUsers=
Configures support for usernamespacing. This is equivalent to
the --private-users= command line switch, and takes the same
options. This option is privileged (see above). This option is
the default if the systemd-nspawn@.service template unit file
is used.
Added in version 230.
NotifyReady=
Configures support for notifications from the container's init
process. This is equivalent to the --notify-ready= command
line switch, and takes the same parameters. See
systemd-nspawn(1) for details about the specific options
supported.
Added in version 231.
SystemCallFilter=
Configures the system call filter applied to containers. This
is equivalent to the --system-call-filter= command line
switch, and takes the same list parameter. See
systemd-nspawn(1) for details.
Added in version 235.
LimitCPU=, LimitFSIZE=, LimitDATA=, LimitSTACK=, LimitCORE=,
LimitRSS=, LimitNOFILE=, LimitAS=, LimitNPROC=, LimitMEMLOCK=,
LimitLOCKS=, LimitSIGPENDING=, LimitMSGQUEUE=, LimitNICE=,
LimitRTPRIO=, LimitRTTIME=
Configures various types of resource limits applied to
containers. This is equivalent to the --rlimit= command line
switch, and takes the same arguments. See systemd-nspawn(1)
for details.
Added in version 239.
OOMScoreAdjust=
Configures the OOM score adjustment value. This is equivalent
to the --oom-score-adjust= command line switch, and takes the
same argument. See systemd-nspawn(1) for details.
Added in version 239.
CPUAffinity=
Configures the CPU affinity. This is equivalent to the
--cpu-affinity= command line switch, and takes the same
argument. See systemd-nspawn(1) for details.
Added in version 239.
Hostname=
Configures the kernel hostname set for the container. This is
equivalent to the --hostname= command line switch, and takes
the same argument. See systemd-nspawn(1) for details.
Added in version 239.
ResolvConf=
Configures how /etc/resolv.conf in the container shall be
handled. This is equivalent to the --resolv-conf= command line
switch, and takes the same argument. See systemd-nspawn(1) for
details.
Added in version 239.
Timezone=
Configures how /etc/localtime in the container shall be
handled. This is equivalent to the --timezone= command line
switch, and takes the same argument. See systemd-nspawn(1) for
details.
Added in version 239.
LinkJournal=
Configures how to link host and container journal setups. This
is equivalent to the --link-journal= command line switch, and
takes the same parameter. See systemd-nspawn(1) for details.
Added in version 239.
SuppressSync=
Configures whether to suppress disk synchronization for the
container payload. This is equivalent to the --suppress-sync=
command line switch, and takes the same parameter. See
systemd-nspawn(1) for details.
Added in version 250.
Settings files may include a [Files] section, which carries
various parameters configuring the file system of the container:
ReadOnly=
Takes a boolean argument, which defaults to off. If specified,
the container will be run with a read-only file system. This
setting corresponds to the --read-only command line switch.
Added in version 226.
Volatile=
Takes a boolean argument, or the special value "state". This
configures whether to run the container with volatile state
and/or configuration. This option is equivalent to
--volatile=, see systemd-nspawn(1) for details about the
specific options supported.
Added in version 226.
Bind=, BindReadOnly=
Adds a bind mount from the host into the container. Takes a
single path, a pair of two paths separated by a colon, or a
triplet of two paths plus an option string separated by
colons. This option may be used multiple times to configure
multiple bind mounts. This option is equivalent to the command
line switches --bind= and --bind-ro=, see systemd-nspawn(1)
for details about the specific options supported. This setting
is privileged (see above).
Added in version 226.
BindUser=
Binds a user from the host into the container. This option is
equivalent to the command line switch --bind-user=, see
systemd-nspawn(1) for details about the specific options
supported. This setting is privileged (see above).
Added in version 249.
TemporaryFileSystem=
Adds a "tmpfs" mount to the container. Takes a path or a pair
of path and option string, separated by a colon. This option
may be used multiple times to configure multiple "tmpfs"
mounts. This option is equivalent to the command line switch
--tmpfs=, see systemd-nspawn(1) for details about the specific
options supported. This setting is privileged (see above).
Added in version 226.
Inaccessible=
Masks the specified file or directory in the container, by
over-mounting it with an empty file node of the same type with
the most restrictive access mode. Takes a file system path as
argument. This option may be used multiple times to mask
multiple files or directories. This option is equivalent to
the command line switch --inaccessible=, see systemd-nspawn(1)
for details about the specific options supported. This setting
is privileged (see above).
Added in version 242.
Overlay=, OverlayReadOnly=
Adds an overlay mount point. Takes a colon-separated list of
paths. This option may be used multiple times to configure
multiple overlay mounts. This option is equivalent to the
command line switches --overlay= and --overlay-ro=, see
systemd-nspawn(1) for details about the specific options
supported. This setting is privileged (see above).
Added in version 233.
PrivateUsersOwnership=
Configures whether the ownership of the files and directories
in the container tree shall be adjusted to the UID/GID range
used, if necessary and user namespacing is enabled. This is
equivalent to the --private-users-ownership= command line
switch. This option is privileged (see above).
Added in version 249.
Settings files may include a [Network] section, which carries
various parameters configuring the network connectivity of the
container:
Private=
Takes a boolean argument, which defaults to off. If enabled,
the container will run in its own network namespace and not
share network interfaces and configuration with the host. This
setting corresponds to the --private-network command line
switch.
Added in version 226.
VirtualEthernet=
Takes a boolean argument. Configures whether to create a
virtual Ethernet connection ("veth") between host and the
container. This setting implies Private=yes. This setting
corresponds to the --network-veth command line switch. This
option is privileged (see above). This option is the default
if the systemd-nspawn@.service template unit file is used.
Added in version 226.
VirtualEthernetExtra=
Takes a colon-separated pair of interface names. Configures an
additional virtual Ethernet connection ("veth") between host
and the container. The first specified name is the interface
name on the host, the second the interface name in the
container. The latter may be omitted in which case it is set
to the same name as the host side interface. This setting
implies Private=yes. This setting corresponds to the
--network-veth-extra= command line switch, and may be used
multiple times. It is independent of VirtualEthernet=. Note
that this option is unrelated to the Bridge= setting below,
and thus any connections created this way are not
automatically added to any bridge device on the host side.
This option is privileged (see above).
Added in version 228.
Interface=
Takes a space-separated list of interfaces to add to the
container. The interface object is defined either by a single
interface name, referencing the name on the host, or a
colon-separated pair of interfaces, in which case the first
one references the name on the host, and the second one the
name in the container. This option corresponds to the
--network-interface= command line switch and implies
Private=yes. This option is privileged (see above).
Added in version 226.
MACVLAN=, IPVLAN=
Takes a space-separated list of interfaces to add MACLVAN or
IPVLAN interfaces to, which are then added to the container.
The interface object is defined either by a single interface
name, referencing the name on the host, or a colon-separated
pair of interfaces, in which case the first one references the
name on the host, and the second one the name in the
container. These options correspond to the --network-macvlan=
and --network-ipvlan= command line switches and imply
Private=yes. These options are privileged (see above).
Added in version 226.
Bridge=
Takes an interface name. This setting implies
VirtualEthernet=yes and Private=yes and has the effect that
the host side of the created virtual Ethernet link is
connected to the specified bridge interface. This option
corresponds to the --network-bridge= command line switch. This
option is privileged (see above).
Added in version 226.
Zone=
Takes a network zone name. This setting implies
VirtualEthernet=yes and Private=yes and has the effect that
the host side of the created virtual Ethernet link is
connected to an automatically managed bridge interface named
after the passed argument, prefixed with "vz-". This option
corresponds to the --network-zone= command line switch. This
option is privileged (see above).
Added in version 230.
Port=
Exposes a TCP or UDP port of the container on the host. This
option corresponds to the --port= command line switch, see
systemd-nspawn(1) for the precise syntax of the argument this
option takes. This option is privileged (see above).
Added in version 226.
systemd(1), systemd-nspawn(1), systemd.directives(7)
This page is part of the systemd (systemd system and service
manager) project. Information about the project can be found at
⟨http://www.freedesktop.org/wiki/Software/systemd⟩. If you have a
bug report for this manual page, see
⟨http://www.freedesktop.org/wiki/Software/systemd/#bugreports⟩.
This page was obtained from the project's upstream Git repository
⟨https://github.com/systemd/systemd.git⟩ on 2025-02-02. (At that
time, the date of the most recent commit that was found in the
repository was 2025-02-02.) If you discover any rendering
problems in this HTML version of the page, or you believe there is
a better or more up-to-date source for the page, or you have
corrections or improvements to the information in this COLOPHON
(which is not part of the original manual page), send a mail to
man-pages@man7.org
systemd 258~devel SYSTEMD.NSPAWN(5)
Pages that refer to this page: machinectl(1), systemd-nspawn(1), systemd.directives(7), systemd.index(7), systemd.syntax(7)
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HTML rendering created 2025-02-02 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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