systemd-nspawn man page on OpenMandriva

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SYSTEMD-NSPAWN(1)		systemd-nspawn		     SYSTEMD-NSPAWN(1)

NAME
       systemd-nspawn - Spawn a namespace container for debugging, testing and
       building

SYNOPSIS
       systemd-nspawn [OPTIONS...] [COMMAND [ARGS...]]

       systemd-nspawn -b [OPTIONS...] [ARGS...]

DESCRIPTION
       systemd-nspawn may be used to run a command or OS in a light-weight
       namespace container. In many ways it is similar to chroot(1), but more
       powerful since it fully virtualizes the file system hierarchy, as well
       as the process tree, the various IPC subsystems and the host and domain
       name.

       systemd-nspawn limits access to various kernel interfaces in the
       container to read-only, such as /sys, /proc/sys or /sys/fs/selinux.
       Network interfaces and the system clock may not be changed from within
       the container. Device nodes may not be created. The host system cannot
       be rebooted and kernel modules may not be loaded from within the
       container.

       Note that even though these security precautions are taken
       systemd-nspawn is not suitable for secure container setups. Many of the
       security features may be circumvented and are hence primarily useful to
       avoid accidental changes to the host system from the container. The
       intended use of this program is debugging and testing as well as
       building of packages, distributions and software involved with boot and
       systems management.

       In contrast to chroot(1) systemd-nspawn may be used to boot full
       Linux-based operating systems in a container.

       Use a tool like yum(8), debootstrap(8), or pacman(8) to set up an OS
       directory tree suitable as file system hierarchy for systemd-nspawn
       containers.

       Note that systemd-nspawn will mount file systems private to the
       container to /dev, /run and similar. These will not be visible outside
       of the container, and their contents will be lost when the container
       exits.

       Note that running two systemd-nspawn containers from the same directory
       tree will not make processes in them see each other. The PID namespace
       separation of the two containers is complete and the containers will
       share very few runtime objects except for the underlying file system.
       It is however possible to enter an existing container, see Example 4
       below.

       systemd-nspawn implements the Container Interface[1] specification.

       As a safety check systemd-nspawn will verify the existence of
       /etc/os-release in the container tree before starting the container
       (see os-release(5)). It might be necessary to add this file to the
       container tree manually if the OS of the container is too old to
       contain this file out-of-the-box.

INCOMPATIBILITY WITH AUDITING
       Note that the kernel auditing subsystem is currently broken when used
       together with containers. We hence recommend turning it off entirely by
       booting with "audit=0" on the kernel command line, or by turning it off
       at kernel build time. If auditing is enabled in the kernel, operating
       systems booted in an nspawn container might refuse log-in attempts.

OPTIONS
       If option -b is specified, the arguments are used as arguments for the
       init binary. Otherwise, COMMAND specifies the program to launch in the
       container, and the remaining arguments are used as arguments for this
       program. If -b is not used and no arguments are specifed, a shell is
       launched in the container.

       The following options are understood:

       -h, --help
	   Prints a short help text and exits.

       --version
	   Prints a version string and exits.

       -D, --directory=
	   Directory to use as file system root for the namespace container.
	   If omitted, the current directory will be used.

       -b, --boot
	   Automatically search for an init binary and invoke it instead of a
	   shell or a user supplied program. If this option is used, arguments
	   specified on the command line are used as arguments for the init
	   binary.

       -u, --user=
	   Run the command under specified user, create home directory and cd
	   into it. As rest of systemd-nspawn, this is not the security
	   feature and limits against accidental changes only.

       -M, --machine=
	   Sets the machine name for this container. This name may be used to
	   identify this container on the host, and is used to initialize the
	   container's hostname (which the container can choose to override,
	   however). If not specified, the last component of the root
	   directory of the container is used.

       --slice=
	   Make the container part of the specified slice, instead of the
	   machine.slice.

       --uuid=
	   Set the specified UUID for the container. The init system will
	   initialize /etc/machine-id from this if this file is not set yet.

       --private-network
	   Turn off networking in the container. This makes all network
	   interfaces unavailable in the container, with the exception of the
	   loopback device.

       --read-only
	   Mount the root file system read-only for the container.

       --capability=
	   List one or more additional capabilities to grant the container.
	   Takes a comma-separated list of capability names, see
	   capabilities(7) for more information. Note that the following
	   capabilities will be granted in any way: CAP_CHOWN,
	   CAP_DAC_OVERRIDE, CAP_DAC_READ_SEARCH, CAP_FOWNER, CAP_FSETID,
	   CAP_IPC_OWNER, CAP_KILL, CAP_LEASE, CAP_LINUX_IMMUTABLE,
	   CAP_NET_BIND_SERVICE, CAP_NET_BROADCAST, CAP_NET_RAW, CAP_SETGID,
	   CAP_SETFCAP, CAP_SETPCAP, CAP_SETUID, CAP_SYS_ADMIN,
	   CAP_SYS_CHROOT, CAP_SYS_NICE, CAP_SYS_PTRACE, CAP_SYS_TTY_CONFIG,
	   CAP_SYS_RESOURCE, CAP_SYS_BOOT, CAP_AUDIT_WRITE, CAP_AUDIT_CONTROL.

       --drop-capability=
	   Specify one or more additional capabilities to drop for the
	   container. This allows running the container with fewer
	   capabilities than the default (see above).

       --link-journal=
	   Control whether the container's journal shall be made visible to
	   the host system. If enabled, allows viewing the container's journal
	   files from the host (but not vice versa). Takes one of "no",
	   "host", "guest", "auto". If "no", the journal is not linked. If
	   "host", the journal files are stored on the host file system
	   (beneath /var/log/journal/machine-id) and the subdirectory is
	   bind-mounted into the container at the same location. If "guest",
	   the journal files are stored on the guest file system (beneath
	   /var/log/journal/machine-id) and the subdirectory is symlinked into
	   the host at the same location. If "auto" (the default), and the
	   right subdirectory of /var/log/journal exists, it will be bind
	   mounted into the container. If the subdirectory does not exist, no
	   linking is performed. Effectively, booting a container once with
	   "guest" or "host" will link the journal persistently if further on
	   the default of "auto" is used.

       -j
	   Equivalent to --link-journal=guest.

       --bind=, --bind-ro=
	   Bind mount a file or directory from the host into the container.
	   Either takes a path argument -- in which case the specified path
	   will be mounted from the host to the same path in the container --,
	   or a colon-separated pair of paths -- in which case the first
	   specified path is the source in the host, and the second path is
	   the destination in the container. The --bind-ro= option creates
	   read-only bind mount.

EXAMPLE 1
	   # yum -y --releasever=19 --nogpg --installroot=/srv/mycontainer --disablerepo='*' --enablerepo=fedora install systemd passwd yum fedora-release vim-minimal
	   # systemd-nspawn -bD /srv/mycontainer

       This installs a minimal Fedora distribution into the directory
       /srv/mycontainer/ and then boots an OS in a namespace container in it.

EXAMPLE 2
	   # debootstrap --arch=amd64 unstable ~/debian-tree/
	   # systemd-nspawn -D ~/debian-tree/

       This installs a minimal Debian unstable distribution into the directory
       ~/debian-tree/ and then spawns a shell in a namespace container in it.

EXAMPLE 3
	   # pacstrap -c -d ~/arch-tree/ base
	   # systemd-nspawn -bD ~/arch-tree/

       This installs a mimimal Arch Linux distribution into the directory
       ~/arch-tree/ and then boots an OS in a namespace container in it.

EXAMPLE 4
       To enter the container, PID of one of the processes sharing the new
       namespaces must be used.	 systemd-nspawn prints the PID (as viewed from
       the outside) of the launched process, and it can be used to enter the
       container.

	   # nsenter -m -u -i -n -p -t $PID

       nsenter(1) is part of util-linux[2]. Kernel support for entering
       namespaces was added in Linux 3.8.

EXAMPLE 4
	   # mv ~/arch-tree /var/lib/container/arch
	   # systemctl enable systemd-nspawn@arch.service
	   # systemctl start systemd-nspawn@arch.service

       This makes the Arch Linux container part of the multi-user.target on
       the host.

EXIT STATUS
       The exit code of the program executed in the container is returned.

SEE ALSO
       systemd(1), chroot(1), unshare(1), yum(8), debootstrap(8), pacman(8),
       systemd.slice(5)

NOTES
	1. Container Interface
	   http://www.freedesktop.org/wiki/Software/systemd/ContainerInterface

	2. util-linux
	   https://github.com/karelzak/util-linux

systemd 208						     SYSTEMD-NSPAWN(1)
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