Provided by: systemd-container_251.4-1ubuntu7_amd64 
NAME
systemd.nspawn - Container settings
SYNOPSIS
/etc/systemd/nspawn/machine.nspawn
/run/systemd/nspawn/machine.nspawn
/var/lib/machines/machine.nspawn
DESCRIPTION
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.
.NSPAWN FILE DISCOVERY
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.
[EXEC] SECTION OPTIONS
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).
These settings change the bounding set of capabilities which also limits the ambient
capabilities as given with the AmbientCapability=.
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).
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.
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.
[FILES] SECTION OPTIONS
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).
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).
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).
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).
[NETWORK] SECTION OPTIONS
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).
SEE ALSO
systemd(1), systemd-nspawn(1), systemd.directives(7)