NAME
systemd-machined.service, systemd-machined - Virtual machine and container registration managerSYNOPSIS
systemd-machined.service /lib/systemd/systemd-machinedDESCRIPTION
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
- 2.
- Writing Virtual Machine or Container Managers
- 3.
- New Control Group Interfaces
- 4.
- User/Group Record Lookup API via Varlink
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