nss-mymachines(8)

1NSS-MYMACHINES(8)               nss-mymachines               NSS-MYMACHINES(8)
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NAME

6       nss-mymachines, libnss_mymachines.so.2 - Hostname resolution for local
7       container instances
8

SYNOPSIS

10       libnss_mymachines.so.2
11

DESCRIPTION

13       nss-mymachines is a plug-in module for the GNU Name Service Switch
14       (NSS) functionality of the GNU C Library (glibc), providing hostname
15       resolution for the names of containers running locally that are
16       registered with systemd-machined.service(8). The container names are
17       resolved to the IP addresses of the specific container, ordered by
18       their scope. This functionality only applies to containers using
19       network namespacing (see the description of --private-network in
20       systemd-nspawn(1)). Note that the name that is resolved is the one
21       registered with systemd-machined, which may be different than the
22       hostname configured inside of the container.
23
24       To activate the NSS module, add "mymachines" to the line starting with
25       "hosts:" in /etc/nsswitch.conf.
26
27       It is recommended to place "mymachines" after the "files" or "compat"
28       entry of the /etc/nsswitch.conf line to make sure that its mappings are
29       preferred over other resolvers such as DNS, but so that /etc/hosts
30       based mappings take precedence.
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CONFIGURATION IN /ETC/NSSWITCH.CONF

33       Here is an example /etc/nsswitch.conf file that enables nss-mymachines
34       correctly:
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36           passwd:         compat systemd
37           group:          compat systemd
38           shadow:         compat
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40           hosts:          mymachines resolve [!UNAVAIL=return] myhostname files dns
41           networks:       files
42
43           protocols:      db files
44           services:       db files
45           ethers:         db files
46           rpc:            db files
47
48           netgroup:       nis
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EXAMPLE: MAPPINGS PROVIDED BY NSS-MYMACHINES

51       The container "rawhide" is spawned using systemd-nspawn(1):
52
53           # systemd-nspawn -M rawhide --boot --network-veth --private-users=pick
54           Spawning container rawhide on /var/lib/machines/rawhide.
55           Selected user namespace base 20119552 and range 65536.
56           ...
57
58           $ machinectl --max-addresses=3
59           MACHINE CLASS     SERVICE        OS     VERSION ADDRESSES
60           rawhide container systemd-nspawn fedora 30      169.254.40.164 fe80::94aa:3aff:fe7b:d4b9
61
62           $ ping -c1 rawhide
63           PING rawhide(fe80::94aa:3aff:fe7b:d4b9%ve-rawhide (fe80::94aa:3aff:fe7b:d4b9%ve-rawhide)) 56 data bytes
64           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
65           ...
66           $ ping -c1 -4 rawhide
67           PING rawhide (169.254.40.164) 56(84) bytes of data.
68           64 bytes from 169.254.40.164 (169.254.40.164): icmp_seq=1 ttl=64 time=0.064 ms
69           ...
70
71           # machinectl shell rawhide /sbin/ip a
72           Connected to machine rawhide. Press ^] three times within 1s to exit session.
73           1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
74               ...
75           2: host0@if21: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
76               link/ether 96:aa:3a:7b:d4:b9 brd ff:ff:ff:ff:ff:ff link-netnsid 0
77               inet 169.254.40.164/16 brd 169.254.255.255 scope link host0
78                  valid_lft forever preferred_lft forever
79               inet6 fe80::94aa:3aff:fe7b:d4b9/64 scope link
80                  valid_lft forever preferred_lft forever
81           Connection to machine rawhide terminated.
82

NAME

SYNOPSIS

DESCRIPTION

CONFIGURATION IN /ETC/NSSWITCH.CONF

EXAMPLE: MAPPINGS PROVIDED BY NSS-MYMACHINES

SEE ALSO