X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?p=elogind.git;a=blobdiff_plain;f=man%2Fsystemd-nspawn.xml;h=1bc61e83a76b048e3f27582a30fc30e4aed65fbc;hp=6a01ffd450aff17b573633131960762212205160;hb=77b6e19458f37cfde127ec6aa9494c0ac45ad890;hpb=e670b166a08b7c1031a9e7d7675fa9a29c3e19c9

diff --git a/man/systemd-nspawn.xml b/man/systemd-nspawn.xml
index 6a01ffd45..1bc61e83a 100644
--- a/man/systemd-nspawn.xml
+++ b/man/systemd-nspawn.xml
@@ -49,7 +49,17 @@
 
         <refsynopsisdiv>
                 <cmdsynopsis>
-                        <command>systemd-nspawn <arg choice="opt" rep="repeat">OPTIONS</arg> <arg choice="opt">COMMAND</arg> <arg choice="opt" rep="repeat">ARGS</arg></command>
+                        <command>systemd-nspawn</command>
+                        <arg choice="opt" rep="repeat">OPTIONS</arg>
+                        <arg choice="opt"><replaceable>COMMAND</replaceable>
+                        <arg choice="opt" rep="repeat">ARGS</arg>
+                        </arg>
+                </cmdsynopsis>
+                <cmdsynopsis>
+                        <command>systemd-nspawn</command>
+                        <arg choice="plain">-b</arg>
+                        <arg choice="opt" rep="repeat">OPTIONS</arg>
+                        <arg choice="opt" rep="repeat">ARGS</arg>
                 </cmdsynopsis>
         </refsynopsisdiv>
 
@@ -114,21 +124,52 @@
                 see each other. The PID namespace separation of the
                 two containers is complete and the containers will
                 share very few runtime objects except for the
-                underlying file system.</para>
+                underlying file system. It is however possible to
+                enter an existing container, see
+                <link linkend='example-nsenter'>Example 4</link> below.
+                </para>
 
                 <para><command>systemd-nspawn</command> implements the
                 <ulink
                 url="http://www.freedesktop.org/wiki/Software/systemd/ContainerInterface">Container
                 Interface</ulink> specification.</para>
+
+                <para>As a safety check
+                <command>systemd-nspawn</command> will verify the
+                existance of <filename>/etc/os-release</filename> in
+                the container tree before starting the container (see
+                <citerefentry><refentrytitle>os-release</refentrytitle><manvolnum>5</manvolnum></citerefentry>). It
+                might be necessary to add this file to the container
+                tree manually if the OS of the container is too old to
+                contain this file out-of-the-box.</para>
+        </refsect1>
+
+        <refsect1>
+                <title>Incompatibility with Auditing</title>
+
+                <para>Note that the kernel auditing subsystem is
+                currently broken when used together with
+                containers. We hence recommend turning it off entirely
+                by booting with <literal>audit=0</literal> on the
+                kernel command line, or by turning it off at kernel
+                build time. If auditing is enabled in the kernel
+                operating systems booted in an nspawn container might
+                refuse log-in attempts.</para>
         </refsect1>
 
         <refsect1>
                 <title>Options</title>
 
-                <para>If no arguments are passed the container is set
-                up and a shell started in it, otherwise the passed
-                command and arguments are executed in it. The
-                following options are understood:</para>
+                <para>If option <option>-b</option> is specified, the
+                arguments are used as arguments for the init
+                binary. Otherwise, <replaceable>COMMAND</replaceable>
+                specifies the program to launch in the container, and
+                the remaining arguments are used as arguments for this
+                program. If <option>-b</option> is not used and no
+                arguments are specifed, a shell is launched in the
+                container.</para>
+
+                <para>The following options are understood:</para>
 
                 <variablelist>
                         <varlistentry>
@@ -164,7 +205,10 @@
                                 <listitem><para>Automatically search
                                 for an init binary and invoke it
                                 instead of a shell or a user supplied
-                                program.</para></listitem>
+                                program. If this option is used, arguments
+                                specified on the command line are used
+                                as arguments for the init binary.
+                                </para></listitem>
                         </varlistentry>
 
                         <varlistentry>
@@ -180,6 +224,21 @@
                                 </para></listitem>
                         </varlistentry>
 
+                        <varlistentry>
+                                <term><option>-M</option></term>
+                                <term><option>--machine=</option></term>
+
+                                <listitem><para>Sets the machine name
+                                for this container. This name may be
+                                used to identify this container on the
+                                host, and is used to initialize the
+                                container's hostname (which the
+                                container can choose to override,
+                                however). If not specified the last
+                                component of the root directory of the
+                                container is used.</para></listitem>
+                        </varlistentry>
+
                         <varlistentry>
                                 <term><option>--uuid=</option></term>
 
@@ -292,6 +351,26 @@
                                 <listitem><para>Equivalent to
                                 <option>--link-journal=guest</option>.</para></listitem>
                         </varlistentry>
+
+                        <varlistentry>
+                                <term><option>--bind=</option></term>
+                                <term><option>--bind-ro=</option></term>
+
+                                <listitem><para>Bind mount a file or
+                                directory from the host into the
+                                container. Either takes a path
+                                argument -- in which case the
+                                specified path will be mounted from
+                                the host to the same path in the
+                                container --, or a colon-separated
+                                pair of paths -- in which case the
+                                first specified path is the source in
+                                the host, and the second path is the
+                                destination in the container. The
+                                <option>--bind-ro=</option> option
+                                creates read-only bind
+                                mount.</para></listitem>
+                        </varlistentry>
                 </variablelist>
 
         </refsect1>
@@ -303,7 +382,7 @@
 # systemd-nspawn -bD /srv/mycontainer</programlisting>
 
                 <para>This installs a minimal Fedora distribution into
-                the directory <filename>/srv/mycontainer/</filename> and
+                the directory <filename noindex='true'>/srv/mycontainer/</filename> and
                 then boots an OS in a namespace container in
                 it.</para>
         </refsect1>
@@ -318,7 +397,6 @@
                 distribution into the directory
                 <filename>~/debian-tree/</filename> and then spawns a
                 shell in a namespace container in it.</para>
-
         </refsect1>
 
         <refsect1>
@@ -332,6 +410,24 @@
                 boots an OS in a namespace container in it.</para>
         </refsect1>
 
+        <refsect1 id='example-nsenter'>
+                <title>Example 4</title>
+
+                <para>To enter the container, PID of one of the
+                processes sharing the new namespaces must be used.
+                <command>systemd-nspawn</command> prints the PID
+                (as viewed from the outside) of the launched process,
+                and it can be used to enter the container.</para>
+
+                <programlisting># nsenter -m -u -i -n -p -t $PID</programlisting>
+
+                <para><citerefentry><refentrytitle>nsenter</refentrytitle><manvolnum>1</manvolnum></citerefentry>
+                is part of
+                <ulink url="https://github.com/karelzak/util-linux">util-linux</ulink>.
+                Kernel support for entering namespaces was added in
+                Linux 3.8.</para>
+        </refsect1>
+
         <refsect1>
                 <title>Exit status</title>
 
@@ -344,6 +440,7 @@
                 <para>
                         <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
                         <citerefentry><refentrytitle>chroot</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
+                        <citerefentry><refentrytitle>unshare</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
                         <citerefentry><refentrytitle>yum</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
                         <citerefentry><refentrytitle>debootstrap</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
                         <citerefentry><refentrytitle>pacman</refentrytitle><manvolnum>8</manvolnum></citerefentry>