SYSTEMD-NSPAWN(1) systemd-nspawn SYSTEMD-NSPAWN(1)
systemd-nspawn - Spawn a namespace container for debugging, testing and building
systemd-nspawn [OPTIONS...] [COMMAND] [ARGS...]
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
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
In contrast to chroot(1) systemd-nspawn may be used to boot full Linux-based operating systems in a container.
Use a tool like debootstrap(8) or mock(1) 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
If no arguments are passed the container is set up and a shell started in it, otherwise the passed command and arguments are executed in
it. The following options are understood:
Prints a short help text and exits.
Directory to use as file system root for the namespace container. If omitted the current directory will be used.
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.
Turn off networking in the container. This makes all network interfaces unavailable in the container, with the exception of the
# 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
# mock --init
# systemd-nspawn -D /var/lib/mock/fedora-rawhide-x86_64/root/ /sbin/init systemd.log_level=debug
This installs a minimal Fedora distribution into a subdirectory of /var/lib/mock/ and then boots an OS in a namespace container in it, with
systemd as init system, configured for debug logging.
The exit code of the program executed in the container is returned.
systemd(1), chroot(1), debootstrap(8), mock(1)
Lennart Poettering <email@example.com>
systemd 10/07/2013 SYSTEMD-NSPAWN(1)