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NAME | SYNOPSIS | DESCRIPTION | CONFIGURATION IN /ETC/NSSWITCH.CONF | EXAMPLE: MAPPINGS PROVIDED BY NSS-MYMACHINES | SEE ALSO | COLOPHON |
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NSS-MYMACHINES(8) nss-mymachines NSS-MYMACHINES(8)
nss-mymachines, libnss_mymachines.so.2 - Hostname resolution for
local container instances
libnss_mymachines.so.2
nss-mymachines is a plug-in module for the GNU Name Service Switch
(NSS) functionality of the GNU C Library (glibc), providing hostname
resolution for the names of containers running locally that are
registered with systemd-machined.service(8). The container names are
resolved to the IP addresses of the specific container, ordered by
their scope. This functionality only applies to containers using
network namespacing (see the description of --private-network in
systemd-nspawn(1)). Note that the name that is resolved is the one
registered with systemd-machined, which may be different than the
hostname configured inside of the container.
To activate the NSS module, add "mymachines" to the line starting
with "hosts:" in /etc/nsswitch.conf.
It is recommended to place "mymachines" after the "files" or "compat"
entry of the /etc/nsswitch.conf line to make sure that its mappings
are preferred over other resolvers such as DNS, but so that
/etc/hosts based mappings take precedence.
Here is an example /etc/nsswitch.conf file that enables
nss-mymachines correctly:
passwd: compat systemd
group: compat systemd
shadow: compat
hosts: mymachines resolve [!UNAVAIL=return] myhostname files dns
networks: files
protocols: db files
services: db files
ethers: db files
rpc: db files
netgroup: nis
The container "rawhide" is spawned using systemd-nspawn(1):
# 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
$ ping -c1 rawhide
PING rawhide(fe80::94aa:3aff:fe7b:d4b9%ve-rawhide (fe80::94aa:3aff:fe7b:d4b9%ve-rawhide)) 56 data bytes
64 bytes from fe80::94aa:3aff:fe7b:d4b9%ve-rawhide (fe80::94aa:3aff:fe7b:d4b9%ve-rawhide): icmp_seq=1 ttl=64 time=0.045 ms
...
$ ping -c1 -4 rawhide
PING rawhide (169.254.40.164) 56(84) bytes of data.
64 bytes from 169.254.40.164 (169.254.40.164): icmp_seq=1 ttl=64 time=0.064 ms
...
# machinectl shell rawhide /sbin/ip a
Connected to machine rawhide. Press ^] three times within 1s to exit session.
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
...
2: host0@if21: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
link/ether 96:aa:3a:7b:d4:b9 brd ff:ff:ff:ff:ff:ff link-netnsid 0
inet 169.254.40.164/16 brd 169.254.255.255 scope link host0
valid_lft forever preferred_lft forever
inet6 fe80::94aa:3aff:fe7b:d4b9/64 scope link
valid_lft forever preferred_lft forever
Connection to machine rawhide terminated.
systemd(1), systemd-machined.service(8), machinectl(1),
nss-systemd(8), nss-resolve(8), nss-myhostname(8), nsswitch.conf(5),
getent(1)
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
⟨http://www.freedesktop.org/wiki/Software/systemd/#bugreports⟩. This
page was obtained from the project's upstream Git repository
⟨https://github.com/systemd/systemd.git⟩ on 2020-08-13. (At that
time, the date of the most recent commit that was found in the repos‐
itory was 2020-08-11.) 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 man-pages@man7.org
systemd 246 NSS-MYMACHINES(8)
Pages that refer to this page: org.freedesktop.machine1(5), 30-systemd-environment-d-generator(7), systemd.directives(7), systemd.index(7), libnss_myhostname.so.2(8), libnss_resolve.so.2(8), libnss_systemd.so.2(8), nss-myhostname(8), nss-resolve(8), nss-systemd(8), systemd-machined(8), systemd-machined.service(8)
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