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1 | <?xml version='1.0'?> <!--*-nxml-*--> |
2 | <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" | |
3 | "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> | |
4 | ||
5 | <!-- | |
6 | This file is part of systemd. | |
7 | ||
8 | Copyright 2010 Lennart Poettering | |
9 | ||
10 | systemd is free software; you can redistribute it and/or modify it | |
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11 | under the terms of the GNU Lesser General Public License as published by |
12 | the Free Software Foundation; either version 2.1 of the License, or | |
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13 | (at your option) any later version. |
14 | ||
15 | systemd is distributed in the hope that it will be useful, but | |
16 | WITHOUT ANY WARRANTY; without even the implied warranty of | |
17 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
5430f7f2 | 18 | Lesser General Public License for more details. |
8f7a3c14 | 19 | |
5430f7f2 | 20 | You should have received a copy of the GNU Lesser General Public License |
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21 | along with systemd; If not, see <http://www.gnu.org/licenses/>. |
22 | --> | |
23 | ||
24 | <refentry id="systemd-nspawn"> | |
25 | ||
26 | <refentryinfo> | |
27 | <title>systemd-nspawn</title> | |
28 | <productname>systemd</productname> | |
29 | ||
30 | <authorgroup> | |
31 | <author> | |
32 | <contrib>Developer</contrib> | |
33 | <firstname>Lennart</firstname> | |
34 | <surname>Poettering</surname> | |
35 | <email>lennart@poettering.net</email> | |
36 | </author> | |
37 | </authorgroup> | |
38 | </refentryinfo> | |
39 | ||
40 | <refmeta> | |
41 | <refentrytitle>systemd-nspawn</refentrytitle> | |
42 | <manvolnum>1</manvolnum> | |
43 | </refmeta> | |
44 | ||
45 | <refnamediv> | |
46 | <refname>systemd-nspawn</refname> | |
47 | <refpurpose>Spawn a namespace container for debugging, testing and building</refpurpose> | |
48 | </refnamediv> | |
49 | ||
50 | <refsynopsisdiv> | |
51 | <cmdsynopsis> | |
52 | <command>systemd-nspawn <arg choice="opt" rep="repeat">OPTIONS</arg> <arg choice="opt">COMMAND</arg> <arg choice="opt" rep="repeat">ARGS</arg></command> | |
53 | </cmdsynopsis> | |
54 | </refsynopsisdiv> | |
55 | ||
56 | <refsect1> | |
57 | <title>Description</title> | |
58 | ||
59 | <para><command>systemd-nspawn</command> may be used to | |
60 | run a command or OS in a light-weight namespace | |
61 | container. In many ways it is similar to | |
62 | <citerefentry><refentrytitle>chroot</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
63 | but more powerful since it fully virtualizes the file | |
9f7dad77 | 64 | system hierarchy, as well as the process tree, the |
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65 | various IPC subsystems and the host and domain |
66 | name.</para> | |
67 | ||
68 | <para><command>systemd-nspawn</command> limits access | |
69 | to various kernel interfaces in the container to | |
70 | read-only, such as <filename>/sys</filename>, | |
71 | <filename>/proc/sys</filename> or | |
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72 | <filename>/sys/fs/selinux</filename>. Network |
73 | interfaces and the system clock may not be changed | |
74 | from within the container. Device nodes may not be | |
75 | created. The host system cannot be rebooted and kernel | |
76 | modules may not be loaded from within the | |
77 | container.</para> | |
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78 | |
79 | <para>Note that even though these security precautions | |
80 | are taken <command>systemd-nspawn</command> is not | |
81 | suitable for secure container setups. Many of the | |
82 | security features may be circumvented and are hence | |
83 | primarily useful to avoid accidental changes to the | |
84 | host system from the container. The intended use of | |
85 | this program is debugging and testing as well as | |
86 | building of packages, distributions and software | |
87 | involved with boot and systems management.</para> | |
88 | ||
89 | <para>In contrast to | |
90 | <citerefentry><refentrytitle>chroot</refentrytitle><manvolnum>1</manvolnum></citerefentry> | |
91 | <command>systemd-nspawn</command> may be used to boot | |
92 | full Linux-based operating systems in a | |
93 | container.</para> | |
94 | ||
95 | <para>Use a tool like | |
96 | <citerefentry><refentrytitle>debootstrap</refentrytitle><manvolnum>8</manvolnum></citerefentry> or <citerefentry><refentrytitle>mock</refentrytitle><manvolnum>1</manvolnum></citerefentry> | |
97 | to set up an OS directory tree suitable as file system | |
98 | hierarchy for <command>systemd-nspawn</command> containers.</para> | |
99 | ||
100 | <para>Note that <command>systemd-nspawn</command> will | |
101 | mount file systems private to the container to | |
102 | <filename>/dev</filename>, | |
2b583ce6 | 103 | <filename>/run</filename> and similar. These will |
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104 | not be visible outside of the container, and their |
105 | contents will be lost when the container exits.</para> | |
106 | ||
107 | <para>Note that running two | |
108 | <command>systemd-nspawn</command> containers from the | |
109 | same directory tree will not make processes in them | |
9f7dad77 | 110 | see each other. The PID namespace separation of the |
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111 | two containers is complete and the containers will |
112 | share very few runtime objects except for the | |
113 | underlying file system.</para> | |
114 | </refsect1> | |
115 | ||
116 | <refsect1> | |
117 | <title>Options</title> | |
118 | ||
119 | <para>If no arguments are passed the container is set | |
120 | up and a shell started in it, otherwise the passed | |
121 | command and arguments are executed in it. The | |
122 | following options are understood:</para> | |
123 | ||
124 | <variablelist> | |
125 | <varlistentry> | |
126 | <term><option>--help</option></term> | |
a41fe3a2 | 127 | <term><option>-h</option></term> |
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128 | |
129 | <listitem><para>Prints a short help | |
130 | text and exits.</para></listitem> | |
131 | </varlistentry> | |
132 | ||
133 | <varlistentry> | |
134 | <term><option>--directory=</option></term> | |
ab1f0633 | 135 | <term><option>-D</option></term> |
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136 | |
137 | <listitem><para>Directory to use as | |
138 | file system root for the namespace | |
139 | container. If omitted the current | |
140 | directory will be | |
141 | used.</para></listitem> | |
142 | </varlistentry> | |
143 | ||
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144 | <varlistentry> |
145 | <term><option>--user=</option></term> | |
4f755fc6 | 146 | <term><option>-u</option></term> |
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147 | |
148 | <listitem><para>Run the command | |
149 | under specified user, create home | |
150 | directory and cd into it. As rest | |
151 | of systemd-nspawn, this is not | |
152 | the security feature and limits | |
153 | against accidental changes only. | |
154 | </para></listitem> | |
155 | </varlistentry> | |
156 | ||
a41fe3a2 | 157 | <varlistentry> |
ff01d048 | 158 | <term><option>--private-network</option></term> |
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159 | |
160 | <listitem><para>Turn off networking in | |
161 | the container. This makes all network | |
162 | interfaces unavailable in the | |
163 | container, with the exception of the | |
164 | loopback device.</para></listitem> | |
165 | </varlistentry> | |
166 | ||
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167 | </variablelist> |
168 | ||
169 | </refsect1> | |
170 | ||
171 | <refsect1> | |
172 | <title>Example 1</title> | |
173 | ||
174 | <programlisting># debootstrap --arch=amd64 unstable debian-tree/ | |
175 | # systemd-nspawn -D debian-tree/</programlisting> | |
176 | ||
177 | <para>This installs a minimal Debian unstable | |
178 | distribution into the directory | |
179 | <filename>debian-tree/</filename> and then spawns a | |
180 | shell in a namespace container in it.</para> | |
181 | ||
182 | </refsect1> | |
183 | ||
184 | <refsect1> | |
185 | <title>Example 2</title> | |
186 | ||
187 | <programlisting># mock --init | |
e0d25329 | 188 | # systemd-nspawn -D /var/lib/mock/fedora-rawhide-x86_64/root/ /sbin/init systemd.log_level=debug</programlisting> |
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189 | |
190 | <para>This installs a minimal Fedora distribution into | |
191 | a subdirectory of <filename>/var/lib/mock/</filename> | |
192 | and then boots an OS in a namespace container in it, | |
193 | with systemd as init system, configured for debug | |
194 | logging.</para> | |
195 | ||
196 | </refsect1> | |
197 | ||
198 | <refsect1> | |
199 | <title>Exit status</title> | |
200 | ||
201 | <para>The exit code of the program executed in the | |
202 | container is returned.</para> | |
203 | </refsect1> | |
204 | ||
205 | <refsect1> | |
206 | <title>See Also</title> | |
207 | <para> | |
208 | <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
209 | <citerefentry><refentrytitle>chroot</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
ab1f0633 | 210 | <citerefentry><refentrytitle>debootstrap</refentrytitle><manvolnum>8</manvolnum></citerefentry>, |
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211 | <citerefentry><refentrytitle>mock</refentrytitle><manvolnum>1</manvolnum></citerefentry> |
212 | </para> | |
213 | </refsect1> | |
214 | ||
215 | </refentry> |