man/nss-mymachines.xml

<?xml version='1.0'?> <!--*-nxml-*-->
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
  "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">

<!--
  This file is part of systemd.

  Copyright 2014 Lennart Poettering

  systemd is free software; you can redistribute it and/or modify it
  under the terms of the GNU Lesser General Public License as published by
  the Free Software Foundation; either version 2.1 of the License, or
  (at your option) any later version.

  systemd is distributed in the hope that it will be useful, but
  WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  Lesser General Public License for more details.

  You should have received a copy of the GNU Lesser General Public License
  along with systemd; If not, see <http://www.gnu.org/licenses/>.
-->

<refentry id="nss-mymachines" conditional='ENABLE_MACHINED'>

  <refentryinfo>
    <title>nss-mymachines</title>
    <productname>systemd</productname>

    <authorgroup>
      <author>
        <contrib>Developer</contrib>
        <firstname>Lennart</firstname>
        <surname>Poettering</surname>
        <email>lennart@poettering.net</email>
      </author>
    </authorgroup>
  </refentryinfo>

  <refmeta>
    <refentrytitle>nss-mymachines</refentrytitle>
    <manvolnum>8</manvolnum>
  </refmeta>

  <refnamediv>
    <refname>nss-mymachines</refname>
    <refname>libnss_mymachines.so.2</refname>
    <refpurpose>Provide 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.</para>

    <para>The module also resolves user and group IDs used by containers to user and group names indicating the
    container name, and back. This functionality only applies to containers using user namespacing.</para>

    <para>To activate the NSS module, add <literal>mymachines</literal> to the lines starting with
    <literal>hosts:</literal>, <literal>passwd:</literal> and <literal>group:</literal> in
    <filename>/etc/nsswitch.conf</filename>.</para>

    <para>It is recommended to place <literal>mymachines</literal> after the <literal>files</literal> or
    <literal>compat</literal> entry of the <filename>/etc/nsswitch.conf</filename> lines to make sure that its mappings
    are preferred over other resolvers such as DNS, but so that <filename>/etc/hosts</filename>,
    <filename>/etc/passwd</filename> and <filename>/etc/group</filename> based mappings take precedence.</para>
  </refsect1>

  <refsect1>
    <title>Example</title>

    <para>Here is an example <filename>/etc/nsswitch.conf</filename> file that enables
    <command>nss-mymachines</command> correctly:</para>

    <programlisting>passwd:         compat <command>mymachines</command> systemd
group:          compat <command>mymachines</command> systemd
shadow:         compat

hosts:          files <command>mymachines</command> resolve [!UNAVAIL=return] dns myhostname
networks:       files

protocols:      db files
services:       db files
ethers:         db files
rpc:            db files

netgroup:       nis</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>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>