NAME
systemd.nspawn - Container settingsSYNOPSIS
/etc/systemd/nspawn/ machine.nspawn /run/systemd/nspawn/ machine.nspawn /var/lib/machines/ machine.nspawnDESCRIPTION
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
[email protected] 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 [email protected] 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
[email protected] 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)systemd 252 |