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).

       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 directly 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 2020-06-09.  (At that
       time, the date of the most recent commit that was found in the repos‐
       itory was 2020-06-09.)  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 245                                                SYSTEMD.NSPAWN(5)

Pages that refer to this page: systemd-nspawn(1)30-systemd-environment-d-generator(7)systemd.directives(7)systemd.index(7)systemd.syntax(7)