nss-mymachines systemd nss-mymachines 8 nss-mymachines libnss_mymachines.so.2 Hostname resolution for local container instances libnss_mymachines.so.2 Description 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.service8. 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 in systemd-nspawn1). 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 before the resolve or dns entry of the hosts: line of /etc/nsswitch.conf in order to make sure that its mappings are preferred over other resolvers such as DNS. Configuration in <filename>/etc/nsswitch.conf</filename> Here is an example /etc/nsswitch.conf file that enables nss-mymachines correctly: passwd: compat systemd group: compat [SUCCESS=merge] systemd shadow: compat hosts: mymachines resolve [!UNAVAIL=return] files myhostname dns networks: files protocols: db files services: db files ethers: db files rpc: db files netgroup: nis Example: Mappings provided by <filename>nss-mymachines</filename> The container rawhide is spawned using systemd-nspawn1: # 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. See Also systemd1, systemd-machined.service8, machinectl1, nss-systemd8, nss-resolve8, nss-myhostname8, nsswitch.conf5, getent1