| SYSTEMD.NSPAWN(5) | systemd.nspawn | SYSTEMD.NSPAWN(5) |
.SH "NAME" systemd.nspawn - Container settings
.SH "SYNOPSIS"
.PP
.SH "DESCRIPTION"
.PP 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.
.SH ".NSPAWN FILE DISCOVERY"
.PP 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.
.PP 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.
.SH "[EXEC] SECTION OPTIONS"
.PP Settings files may include an [Exec] section, which carries various
execution parameters:
.PP 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.
.RE
.PP 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.
.RE
.PP 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.
.RE
.PP 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.
.RE
.PP 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.
.RE
.PP 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.
.RE
.PP 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.
.RE
.PP 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.
.RE
.PP 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.
.RE
.PP 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.
.RE
.PP 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.
.RE
.PP 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.
.RE
.PP Personality=
Configures the kernel personality for the container. This is equivalent to
the --personality= switch.
Added in version 226.
.RE
.PP 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.
.RE
.PP 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.
.RE
.PP PrivateUsersDelegate=
Takes a non-negative integer. Configures delegation of additional 64K UID/GID
ranges into the container's user namespace for use by nested containers.
When set to a value greater than zero, the
systemd-nsresourced.service(8) varlink socket will be bind-mounted
into the container so that processes inside the container can allocate
further user namespaces from the delegated ranges. This is equivalent to the
--private-users-delegate= command line switch. Requires
PrivateUsers=managed. Defaults to 0. See systemd-nspawn(1) for
details.
Added in version 260.
.RE
.PP 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.
.RE
.PP 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.
.RE
.PP RestrictAddressFamilies=
Restricts the socket address families accessible to the container. This is
equivalent to the --restrict-address-families= command line switch,
and takes the same list parameter. See systemd-nspawn(1) for
details.
Added in version 261.
.RE
.PP 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.
.RE
.PP 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.
.RE
.PP 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.
.RE
.PP 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.
.RE
.PP 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.
.RE
.PP 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.
.RE
.PP 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.
.RE
.PP 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.
.RE
.SH "[FILES] SECTION OPTIONS"
.PP Settings files may include a [Files] section, which carries various
parameters configuring the file system of the container:
.PP 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.
.RE
.PP 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.
.RE
.PP 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.
.RE
.PP 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.
.RE
.PP BindUserShell=
When used with BindUser, specifies the shell that is included in the
user record of users bound from the host into the container. This option is
equivalent to the command line switch --bind-user-shell=, see
systemd-nspawn(1) for details about the specific options supported.
This setting is privileged (see above).
Added in version 258.
.RE
.PP 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.
.RE
.PP 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.
.RE
.PP 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.
.RE
.PP 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.
This is equivalent to the --private-users-ownership= command line
switch. This option is privileged (see above). Defaults to auto if
PrivateUsers=pick or PrivateUsers=managed is used. This option
has no effect if user namespacing is not used.
Added in version 249.
.RE
.SH "[NETWORK] SECTION OPTIONS"
.PP Settings files may include a [Network] section, which carries various
parameters configuring the network connectivity of the container:
.PP 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.
.RE
.PP NamespacePath=
Takes the path to a file representing a kernel network namespace that the
container shall run in. The specified path should refer to a (possibly
bind-mounted) network namespace file, as exposed by the kernel below
/proc/$PID/ns/net. This makes the container enter the given network
namespace. One of the typical use cases is to give a network namespace under
/run/netns created by ip-netns(8), for example,
NamespacePath=/run/netns/foo. Note that this option cannot be used
together with other network-related options, such as Private= or
Interface=. This option corresponds to the
--network-namespace-path command line switch.
Added in version 259.
.RE
.PP 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 the default if the
systemd-nspawn@.service template unit file is used.
Added in version 226.
.RE
.PP 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.
.RE
.PP 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.
.RE
.PP 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.
.RE
.PP 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.
.RE
.PP 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.
.RE
.PP 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.
.RE
.SH "SEE ALSO"
.PP systemd(1), systemd-nspawn(1),
systemd.directives(7)
| systemd 262.2 |