man: document new varlink service

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Lennart Poettering 2020-07-07 21:29:21 +02:00
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commit 4c2cf15751
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@ -108,7 +108,7 @@ example, introspection is not available, and the resolver logic is not used.
## Other Services
The `systemd` project provides two other services implementing this
The `systemd` project provides three other services implementing this
interface. Specifically:
1. `io.systemd.DynamicUser` → This service is implemented by the service
@ -119,6 +119,10 @@ interface. Specifically:
and provides records for the users and groups defined by the home
directories it manages.
3. `io.systemd.Machine` → This service is implemented by
`systemd-machined.service` and provides records for the users and groups used
by local containers that use user namespacing.
Other projects are invited to implement these services too. For example it
would make sense for LDAP/ActiveDirectory projects to implement these
interfaces, which would provide them a way to do per-user resource management

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@ -35,8 +35,8 @@
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry> (for its
<varname>DynamicUser=</varname> feature, see
<citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry> for
details) or
<citerefentry><refentrytitle>systemd-homed.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
details),
<citerefentry><refentrytitle>systemd-homed.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>, or <citerefentry><refentrytitle>systemd-machined.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
<para>This module also ensures that the root and nobody users and groups (i.e. the users/groups with the UIDs/GIDs
0 and 65534) remain resolvable at all times, even if they aren't listed in <filename>/etc/passwd</filename> or
@ -55,7 +55,7 @@
</refsect1>
<refsect1>
<title>Example</title>
<title>Configuration in <filename>/etc/nsswitch.conf</filename></title>
<para>Here is an example <filename>/etc/nsswitch.conf</filename> file that enables
<command>nss-systemd</command> correctly:</para>
@ -77,6 +77,47 @@ netgroup: nis</programlisting>
</refsect1>
<refsect1>
<title>Example: Mappings provided by <filename>systemd-machined.service</filename></title>
<para>The container <literal>rawhide</literal> is spawned using
<citerefentry><refentrytitle>systemd-nspawn</refentrytitle><manvolnum>1</manvolnum></citerefentry>:
</para>
<programlisting># systemd-nspawn -M rawhide --boot --network-veth --private-users=pick
Spawning container rawhide on /var/lib/machines/rawhide.
Selected user namespace base 20119552 and range 65536.
...
$ machinectl --max-addresses=3
MACHINE CLASS SERVICE OS VERSION ADDRESSES
rawhide container systemd-nspawn fedora 30 169.254.40.164 fe80::94aa:3aff:fe7b:d4b9
$ getent passwd vu-rawhide-0 vu-rawhide-81
vu-rawhide-0:*:20119552:65534:vu-rawhide-0:/:/usr/sbin/nologin
vu-rawhide-81:*:20119633:65534:vu-rawhide-81:/:/usr/sbin/nologin
$ getent group vg-rawhide-0 vg-rawhide-81
vg-rawhide-0:*:20119552:
vg-rawhide-81:*:20119633:
$ ps -o user:15,pid,tty,command -e|grep '^vu-rawhide'
vu-rawhide-0 692 ? /usr/lib/systemd/systemd
vu-rawhide-0 731 ? /usr/lib/systemd/systemd-journald
vu-rawhide-192 734 ? /usr/lib/systemd/systemd-networkd
vu-rawhide-193 738 ? /usr/lib/systemd/systemd-resolved
vu-rawhide-0 742 ? /usr/lib/systemd/systemd-logind
vu-rawhide-81 744 ? /usr/bin/dbus-daemon --system --address=systemd: --nofork --nopidfile --systemd-activation --syslog-only
vu-rawhide-0 746 ? /usr/sbin/sshd -D ...
vu-rawhide-0 752 ? /usr/lib/systemd/systemd --user
vu-rawhide-0 753 ? (sd-pam)
vu-rawhide-0 1628 ? login -- zbyszek
vu-rawhide-1000 1630 ? /usr/lib/systemd/systemd --user
vu-rawhide-1000 1631 ? (sd-pam)
vu-rawhide-1000 1637 pts/8 -zsh
</programlisting>
</refsect1>
<refsect1>
<title>See Also</title>
<para>
@ -85,6 +126,9 @@ netgroup: nis</programlisting>
<citerefentry><refentrytitle>nss-resolve</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
<citerefentry><refentrytitle>nss-myhostname</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
<citerefentry><refentrytitle>nss-mymachines</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd-userdbd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd-homed.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd-machined.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
<citerefentry project='man-pages'><refentrytitle>nsswitch.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
<citerefentry project='man-pages'><refentrytitle>getent</refentrytitle><manvolnum>1</manvolnum></citerefentry>
</para>

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@ -116,6 +116,13 @@
<citerefentry><refentrytitle>systemd-importd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
is also available, which implements importing, exporting, and downloading of container and VM images.
</para>
<para>For each container registered with <filename>systemd-machined.service</filename> that employs user
namespacing, users/groups are synthesized for the used UIDs/GIDs. These are made available to the system
using the <ulink url="https://systemd.io/USER_GROUP_API">User/Group Record Lookup API via
Varlink</ulink>, and thus may be resolved with
<citerefentry><refentrytitle>userdbctl</refentrytitle><manvolnum>1</manvolnum></citerefentry> or the
usual glibc NSS calls.</para>
</refsect1>
<refsect1>

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@ -186,6 +186,15 @@
available to the system.</para></listitem>
</varlistentry>
<varlistentry>
<term><constant>io.systemd.Machine</constant></term>
<listitem><para>This service is provided by
<citerefentry><refentrytitle>systemd-machined.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
and synthesizes records for all users/groups used by a container that employs user
namespacing.</para></listitem>
</varlistentry>
<varlistentry>
<term><constant>io.systemd.Multiplexer</constant></term>