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NAME | SYNOPSIS | DESCRIPTION | .NSPAWN FILE DISCOVERY | [EXEC] SECTION OPTIONS | [FILES] SECTION OPTIONS | [NETWORK] SECTION OPTIONS | SEE ALSO | NOTES | 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) encodes additional
runtime information about a local container, and is searched, read
and used by systemd-nspawn(1) when starting a container. 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 following the XDG Desktop Entry Specification[1],
which in turn are inspired by Microsoft Windows .ini files.
Boolean arguments used in these settings files can be written in
various formats. For positive settings, the strings 1, yes, true and
on are equivalent. For negative settings, the strings 0, no, false
and off are equivalent.
Empty lines and lines starting with # or ; are ignored. This may be
used for commenting. Lines ending in a backslash are concatenated
with the following line while reading and the backslash is replaced
by a space character. This may be used to wrap long lines.
Files are searched 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 in /etc/systemd/nspawn/ and
/run/systemd/nspawn/. If found in these directories, its settings are
read and all of them take full effect (but are possibly overridden by
corresponding command line arguments). If not found, the file will
then be searched 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 the default if the
systemd-nspawn@.service template unit file is used.
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 space-separated list of arguments. 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.
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.
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 use --notify-ready= command line
switch, and takes the same options. See systemd-nspawn(1) for
details about the specific options supported.
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).
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=. 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)
1. XDG Desktop Entry Specification
http://standards.freedesktop.org/desktop-entry-spec/latest/
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 2017-07-05. If you dis‐
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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 234 SYSTEMD.NSPAWN(5)
Pages that refer to this page: systemd-nspawn(1), systemd.directives(7), systemd.index(7)