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
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
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. Use machinectl(1)'s login command to request
an additional login prompt in a running container.
systemd-nspawn implements the Container Interface 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.
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
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:
Prints a short help text and exits.
Prints a version string and exits.
Directory to use as file system root for the namespace container.
If omitted, the current directory will be used.
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.
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.
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.
Make the container part of the specified slice, instead of the
Sets the mandatory access control (MAC/SELinux) file label to be
used by virtual API file systems in the container.
Sets the mandatory access control (MAC/SELinux) label to be used
by processes in the container.
Set the specified UUID for the container. The init system will
initialize /etc/machine-id from this if this file is not set yet.
Turn off networking in the container. This makes all network
interfaces unavailable in the container, with the exception of
the loopback device.
Mount the root file system read-only for the container.
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,
Specify one or more additional capabilities to drop for the
container. This allows running the container with fewer
capabilities than the default (see above).
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.
Equivalent to --link-journal=guest.
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.
Specifies an environment variable assignment to pass to the init
process in the container, in the format "NAME=VALUE". This may be
used to override the default variables or to set additional
variables. This parameter may be used more than once.
Turns off any status output by the tool itself. When this switch
is used, then the only output by nspawn will be the console
output of the container OS itself.
# 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
# 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.
# 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.
# mv ~/arch-tree /var/lib/container/arch
# systemctl enable firstname.lastname@example.org
# systemctl start email@example.com
This makes the Arch Linux container part of the multi-user.target on
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
page was obtained from the project's upstream Git repository
(git://anongit.freedesktop.org/systemd/systemd) on 2014-02-08. 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 firstname.lastname@example.org
systemd 208 SYSTEMD-NSPAWN(1)