SYSTEMD-MACHINED.SERVICE(8)systemd-machined.serviceSYSTEMD-MACHINED.SERVICE(8)
NAME
systemd-machined.service, systemd-machined - Virtual machine and
container registration manager
SYNOPSIS
systemd-machined.service
/lib/systemd/systemd-machined
DESCRIPTION
systemd-machined is a system service that keeps track of locally
running virtual machines and containers.
systemd-machined is useful for registering and keeping track of both OS
containers (containers that share the host kernel but run a full init
system of their own and behave in most regards like a full virtual
operating system rather than just one virtualized app) and full virtual
machines (virtualized hardware running normal operating systems and
possibly different kernels).
systemd-machined should not be used for registering/keeping track of
application sandbox containers. A machine in the context of
systemd-machined is supposed to be an abstract term covering both OS
containers and full virtual machines, but not application sandboxes.
Machines registered with machined are exposed in various ways in the
system. For example:
• Tools like ps(1) will show to which machine a specific process
belongs in a column of its own, and so will gnome-system-monitor[1]
or systemd-cgls(1).
• systemd's various tools (systemctl(1), journalctl(1), loginctl(1),
hostnamectl(1), timedatectl(1), localectl(1), machinectl(1), ...)
support the -M switch to operate on local containers instead of the
host system.
• systemctl list-machines will show the system state of all local
containers, connecting to the container's init system for that.
• systemctl's --recursive switch has the effect of not only showing
the locally running services, but recursively showing the services
of all registered containers.
• The machinectl command provides access to a number of useful
operations on registered containers, such as introspecting them,
rebooting, shutting them down, and getting a login prompt on them.
• The sd-bus(3) library exposes the sd_bus_open_system_machine(3)
call to connect to the system bus of any registered container.
• The nss-mymachines(8) module makes sure all registered containers
can be resolved via normal glibc gethostbyname(3) or getaddrinfo(3)
calls.
See systemd-nspawn(1) for some examples on how to run containers with
OS tools.
If you are interested in writing a VM or container manager that makes
use of machined, please have look at Writing Virtual Machine or
Container Managers[2]. Also see the New Control Group Interfaces[3].
The daemon provides both a C library interface (which is shared with
systemd-logind.service(8)) as well as a D-Bus interface. The library
interface may be used to introspect and watch the state of virtual
machines/containers. The bus interface provides the same but in
addition may also be used to register or terminate machines. For more
information please consult sd-login(3) and org.freedesktop.machine1(5)
and org.freedesktop.LogControl1(5).
A small companion daemon systemd-importd.service(8) is also available,
which implements importing, exporting, and downloading of container and
VM images.
For each container registered with systemd-machined.service that
employs user namespacing, users/groups are synthesized for the used
UIDs/GIDs. These are made available to the system using the User/Group
Record Lookup API via Varlink[4], and thus may be resolved with
userdbctl(1) or the usual glibc NSS calls.
SEE ALSO
systemd(1), machinectl(1), systemd-nspawn(1), nss-mymachines(8),
systemd.special(7)
NOTES
1. gnome-system-monitor
https://help.gnome.org/users/gnome-system-monitor/
2. Writing Virtual Machine or Container Managers
https://www.freedesktop.org/wiki/Software/systemd/writing-vm-managers
3. New Control Group Interfaces
https://www.freedesktop.org/wiki/Software/systemd/ControlGroupInterface
4. User/Group Record Lookup API via Varlink
https://systemd.io/USER_GROUP_API
systemd 252 SYSTEMD-MACHINED.SERVICE(8)
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