systemd.nspawn(5) — Linux manual page

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)

NAME         top

       systemd.nspawn - Container settings

SYNOPSIS         top

       /etc/systemd/nspawn/machine.nspawn

       /run/systemd/nspawn/machine.nspawn

       /var/lib/machines/machine.nspawn

DESCRIPTION         top

       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.

.NSPAWN FILE DISCOVERY         top

       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         top

       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 capability which will be passed to to
           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.

[FILES] SECTION OPTIONS         top

       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).

[NETWORK] SECTION OPTIONS         top

       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         top

       systemd(1), systemd-nspawn(1), systemd.directives(7)

COLOPHON         top

       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 2020-12-18.  (At that
       time, the date of the most recent commit that was found in the
       repository was 2020-12-18.)  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 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 247                                            SYSTEMD.NSPAWN(5)

Pages that refer to this page: systemd-nspawn(1)systemd.directives(7)systemd.index(7)systemd.syntax(7)