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) encodes additional runtime information
       about a local container, and is searched, read and used by systemd-nspawn(1) when starting
       a container. 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
       following the XDG Desktop Entry Specification[1], which in turn are inspired by Microsoft
       Windows .ini files.

       Boolean arguments used in these settings files can be written in various formats. For
       positive settings, the strings 1, yes, true and on are equivalent. For negative settings,
       the strings 0, no, false and off are equivalent.

       Empty lines and lines starting with # or ; are ignored. This may be used for commenting.
       Lines ending in a backslash are concatenated with the following line while reading and the
       backslash is replaced by a space character. This may be used to wrap long lines.

.NSPAWN FILE DISCOVERY

       Files are searched 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 in /etc/systemd/nspawn/ and
       /run/systemd/nspawn/. If found in these directories, its settings are read and all of them
       take full effect (but are possibly overridden by corresponding command line arguments). If
       not found, the file will then be searched 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.

       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 space-separated list of arguments. 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.

       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.

       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.

       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).

[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).

       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).

[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).

       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=. 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).

       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)

NOTES

        1. XDG Desktop Entry Specification
           http://standards.freedesktop.org/desktop-entry-spec/latest/