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diff --git a/man/nss-mymachines.xml b/man/nss-mymachines.xml new file mode 100644 index 0000000..baec109 --- /dev/null +++ b/man/nss-mymachines.xml @@ -0,0 +1,137 @@ +<?xml version='1.0'?> <!--*-nxml-*--> +<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN" + "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> +<!-- SPDX-License-Identifier: LGPL-2.1-or-later --> + +<refentry id="nss-mymachines" conditional='ENABLE_NSS_MYMACHINES'> + + <refentryinfo> + <title>nss-mymachines</title> + <productname>systemd</productname> + </refentryinfo> + + <refmeta> + <refentrytitle>nss-mymachines</refentrytitle> + <manvolnum>8</manvolnum> + </refmeta> + + <refnamediv> + <refname>nss-mymachines</refname> + <refname>libnss_mymachines.so.2</refname> + <refpurpose>Hostname resolution for local container instances</refpurpose> + </refnamediv> + + <refsynopsisdiv> + <para><filename>libnss_mymachines.so.2</filename></para> + </refsynopsisdiv> + + <refsect1> + <title>Description</title> + + <para><command>nss-mymachines</command> is a plug-in module for the GNU Name Service Switch (NSS) functionality of + the GNU C Library (<command>glibc</command>), providing hostname resolution for the names of containers running + locally that are registered with + <citerefentry><refentrytitle>systemd-machined.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>. 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 + <option>--private-network</option> in + <citerefentry><refentrytitle>systemd-nspawn</refentrytitle><manvolnum>1</manvolnum></citerefentry>). + Note that the name that is resolved is the one registered with <command>systemd-machined</command>, which + may be different than the hostname configured inside of the container.</para> + + <para>Note that this NSS module only makes available names of the containers running immediately below + the current system context. It does not provide host name resolution for containers running side-by-side + with the invoking system context, or containers further up or down the container hierarchy. Or in other + words, on the host system it provides host name resolution for the containers running immediately below + the host environment. When used inside a container environment however, it will not be able to provide + name resolution for containers running on the host (as those are siblings and not children of the current + container environment), but instead only for nested containers running immediately below its own + container environment.</para> + + <para>To activate the NSS module, add <literal>mymachines</literal> to the line starting with + <literal>hosts:</literal> in <filename>/etc/nsswitch.conf</filename>.</para> + + <para>It is recommended to place <literal>mymachines</literal> before the <literal>resolve</literal> or + <literal>dns</literal> entry of the <literal>hosts:</literal> line of + <filename>/etc/nsswitch.conf</filename> in order to make sure that its mappings are preferred over other + resolvers such as DNS.</para> + </refsect1> + + <refsect1> + <title>Configuration in <filename>/etc/nsswitch.conf</filename></title> + + <para>Here is an example <filename>/etc/nsswitch.conf</filename> file that enables + <command>nss-mymachines</command> correctly:</para> + + <!-- synchronize with other nss-* man pages and factory/etc/nsswitch.conf --> + <programlisting>passwd: compat systemd +group: compat [SUCCESS=merge] systemd +shadow: compat systemd +gshadow: files systemd + +hosts: <command>mymachines</command> resolve [!UNAVAIL=return] files myhostname dns +networks: files + +protocols: db files +services: db files +ethers: db files +rpc: db files + +netgroup: nis</programlisting> + + </refsect1> + + <refsect1> + <title>Example: Mappings provided by <filename>nss-mymachines</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 + +$ 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. +</programlisting> + </refsect1> + + <refsect1> + <title>See Also</title> + <para> + <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, + <citerefentry><refentrytitle>systemd-machined.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>, + <citerefentry><refentrytitle>machinectl</refentrytitle><manvolnum>1</manvolnum></citerefentry>, + <citerefentry><refentrytitle>nss-systemd</refentrytitle><manvolnum>8</manvolnum></citerefentry>, + <citerefentry><refentrytitle>nss-resolve</refentrytitle><manvolnum>8</manvolnum></citerefentry>, + <citerefentry><refentrytitle>nss-myhostname</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> + </refsect1> + +</refentry> |