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NAME | SYNOPSIS | DESCRIPTION | .NSPAWN FILE DISCOVERY | [EXEC] SECTION OPTIONS | [FILES] SECTION OPTIONS | [NETWORK] SECTION OPTIONS | SEE ALSO | COLOPHON |
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 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.
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.
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.
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'.
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.
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.
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.
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.
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).
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.
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).
Personality=
Configures the kernel personality for the container. This is
equivalent to the --personality= switch.
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).
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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).
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).
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).
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).
PrivateUsersChown=
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-chown command line switch. This option is
privileged (see above).
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.
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.
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 maybe 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).
Interface=
Takes a space-separated list of interfaces to add to the
container. This option corresponds to the --network-interface=
command line switch and implies Private=yes. This option is
privileged (see above).
MACVLAN=, IPVLAN=
Takes a space-separated list of interfaces to add MACLVAN or
IPVLAN interfaces to, which are then added to 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).
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).
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).
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).
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 2020-08-13. (At that
time, the date of the most recent commit that was found in the repos‐
itory was 2020-08-11.) 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
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of the original manual page), send a mail to man-pages@man7.org
systemd 246 SYSTEMD.NSPAWN(5)
Pages that refer to this page: systemd-nspawn(1) , 30-systemd-environment-d-generator(7) , systemd.directives(7) , systemd.index(7) , systemd.syntax(7)