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1<!--
2
3lxc: linux Container library
4
5(C) Copyright IBM Corp. 2007, 2008
6
7Authors:
8Daniel Lezcano <daniel.lezcano at free.fr>
9
10This library is free software; you can redistribute it and/or
11modify it under the terms of the GNU Lesser General Public
12License as published by the Free Software Foundation; either
13version 2.1 of the License, or (at your option) any later version.
14
15This library is distributed in the hope that it will be useful,
16but WITHOUT ANY WARRANTY; without even the implied warranty of
17MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
18Lesser General Public License for more details.
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20You should have received a copy of the GNU Lesser General Public
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24-->
25
26<!DOCTYPE refentry PUBLIC @docdtd@ [
27
28<!ENTITY seealso SYSTEM "@builddir@/see_also.sgml">
29]>
30
31<refentry>
32
33 <docinfo><date>@LXC_GENERATE_DATE@</date></docinfo>
34
35 <refmeta>
36 <refentrytitle>lxc.container.conf</refentrytitle>
37 <manvolnum>5</manvolnum>
38 </refmeta>
39
40 <refnamediv>
41 <refname>lxc.container.conf</refname>
42
43 <refpurpose>
44 LXC container configuration file
45 </refpurpose>
46 </refnamediv>
47
48 <refsect1>
49 <title>Description</title>
50
51 <para>
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52 LXC is the well-known and heavily tested low-level Linux container
53 runtime. It is in active development since 2008 and has proven itself in
54 critical production environments world-wide. Some of its core contributors
55 are the same people that helped to implement various well-known
56 containerization features inside the Linux kernel.
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57 </para>
58
59 <para>
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60 LXC's main focus is system containers. That is, containers which offer an
61 environment as close as possible as the one you'd get from a VM but
62 without the overhead that comes with running a separate kernel and
63 simulating all the hardware.
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64 </para>
65
66 <para>
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67 This is achieved through a combination of kernel security features such as
68 namespaces, mandatory access control and control groups.
69 </para>
70
71 <para>
72 LXC has supports unprivileged containers. Unprivileged containers are
73 containers that are run without any privilege. This requires support for
74 user namespaces in the kernel that the container is run on. LXC was the
75 first runtime to support unprivileged containers after user namespaces
76 were merged into the mainline kernel.
77 </para>
78
79 <para>
80 In essence, user namespaces isolate given sets of UIDs and GIDs. This is
81 achieved by establishing a mapping between a range of UIDs and GIDs on the
82 host to a different (unprivileged) range of UIDs and GIDs in the
83 container. The kernel will translate this mapping in such a way that
84 inside the container all UIDs and GIDs appear as you would expect from the
85 host whereas on the host these UIDs and GIDs are in fact unprivileged. For
86 example, a process running as UID and GID 0 inside the container might
87 appear as UID and GID 100000 on the host. The implementation and working
88 details can be gathered from the corresponding user namespace man page.
bdcbb6b3 89 UID and GID mappings can be defined with the <option>lxc.idmap</option>
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90 key.
91 </para>
92
93 <para>
94 Linux containers are defined with a simple configuration file. Each
95 option in the configuration file has the form <command>key =
96 value</command> fitting in one line. The "#" character means the line is a
97 comment. List options, like capabilities and cgroups options, can be used
98 with no value to clear any previously defined values of that option.
99 </para>
100
101 <para>
102 LXC namespaces configuration keys by using single dots. This means complex
7fa3f2e9 103 configuration keys such as <option>lxc.net.0</option> expose various
104 subkeys such as <option>lxc.net.0.type</option>,
2e44ae28 105 <option>lxc.net.0.link</option>, <option>lxc.net.0.ipv6.address</option>, and
b9986e43 106 others for even more fine-grained configuration.
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107 </para>
108
109 <refsect2>
110 <title>Configuration</title>
111 <para>
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112 In order to ease administration of multiple related containers, it is
113 possible to have a container configuration file cause another file to be
114 loaded. For instance, network configuration can be defined in one common
115 file which is included by multiple containers. Then, if the containers
116 are moved to another host, only one file may need to be updated.
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117 </para>
118
119 <variablelist>
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120 <varlistentry>
121 <term>
122 <option>lxc.include</option>
123 </term>
124 <listitem>
125 <para>
126 Specify the file to be included. The included file must be
127 in the same valid lxc configuration file format.
128 </para>
129 </listitem>
130 </varlistentry>
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131 </variablelist>
132 </refsect2>
133
134 <refsect2>
135 <title>Architecture</title>
136 <para>
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137 Allows one to set the architecture for the container. For example, set a
138 32bits architecture for a container running 32bits binaries on a 64bits
139 host. This fixes the container scripts which rely on the architecture to
140 do some work like downloading the packages.
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141 </para>
142
143 <variablelist>
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144 <varlistentry>
145 <term>
146 <option>lxc.arch</option>
147 </term>
148 <listitem>
149 <para>
150 Specify the architecture for the container.
151 </para>
152 <para>
b9986e43 153 Some valid options are
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154 <option>x86</option>,
155 <option>i686</option>,
156 <option>x86_64</option>,
157 <option>amd64</option>
158 </para>
159 </listitem>
160 </varlistentry>
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161 </variablelist>
162
163 </refsect2>
164
165 <refsect2>
166 <title>Hostname</title>
167 <para>
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168 The utsname section defines the hostname to be set for the container.
169 That means the container can set its own hostname without changing the
170 one from the system. That makes the hostname private for the container.
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171 </para>
172 <variablelist>
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173 <varlistentry>
174 <term>
b67771bc 175 <option>lxc.uts.name</option>
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176 </term>
177 <listitem>
178 <para>
179 specify the hostname for the container
180 </para>
181 </listitem>
182 </varlistentry>
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183 </variablelist>
184 </refsect2>
185
186 <refsect2>
187 <title>Halt signal</title>
188 <para>
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189 Allows one to specify signal name or number sent to the container's
190 init process to cleanly shutdown the container. Different init systems
191 could use different signals to perform clean shutdown sequence. This
192 option allows the signal to be specified in kill(1) fashion, e.g.
193 SIGPWR, SIGRTMIN+14, SIGRTMAX-10 or plain number. The default signal is
194 SIGPWR.
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195 </para>
196 <variablelist>
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197 <varlistentry>
198 <term>
55c84efc 199 <option>lxc.signal.halt</option>
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200 </term>
201 <listitem>
202 <para>
203 specify the signal used to halt the container
204 </para>
205 </listitem>
206 </varlistentry>
207 </variablelist>
208 </refsect2>
209
210 <refsect2>
211 <title>Reboot signal</title>
212 <para>
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213 Allows one to specify signal name or number to reboot the container.
214 This option allows signal to be specified in kill(1) fashion, e.g.
215 SIGTERM, SIGRTMIN+14, SIGRTMAX-10 or plain number. The default signal
216 is SIGINT.
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217 </para>
218 <variablelist>
219 <varlistentry>
220 <term>
55c84efc 221 <option>lxc.signal.reboot</option>
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222 </term>
223 <listitem>
224 <para>
225 specify the signal used to reboot the container
226 </para>
227 </listitem>
228 </varlistentry>
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229 </variablelist>
230 </refsect2>
231
232 <refsect2>
233 <title>Stop signal</title>
234 <para>
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235 Allows one to specify signal name or number to forcibly shutdown the
236 container. This option allows signal to be specified in kill(1) fashion,
237 e.g. SIGKILL, SIGRTMIN+14, SIGRTMAX-10 or plain number. The default
238 signal is SIGKILL.
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239 </para>
240 <variablelist>
241 <varlistentry>
242 <term>
55c84efc 243 <option>lxc.signal.stop</option>
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244 </term>
245 <listitem>
246 <para>
247 specify the signal used to stop the container
248 </para>
249 </listitem>
250 </varlistentry>
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251 </variablelist>
252 </refsect2>
253
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254 <refsect2>
255 <title>Init command</title>
256 <para>
257 Sets the command to use as the init system for the containers.
67c660d0 258 </para>
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259 <variablelist>
260 <varlistentry>
261 <term>
262 <option>lxc.execute.cmd</option>
263 </term>
264 <listitem>
265 <para>
266 Absolute path from container rootfs to the binary to run by default. This
fcd95ae9 267 mostly makes sense for <command>lxc-execute</command>.
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268 </para>
269 </listitem>
270 </varlistentry>
271 </variablelist>
67c660d0 272 <variablelist>
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273 <varlistentry>
274 <term>
9dcf7b4d 275 <option>lxc.init.cmd</option>
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276 </term>
277 <listitem>
278 <para>
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279 Absolute path from container rootfs to the binary to use as init. This
280 mostly makes sense for <command>lxc-start</command>. Default is <command>/sbin/init</command>.
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281 </para>
282 </listitem>
283 </varlistentry>
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284 </variablelist>
285 </refsect2>
286
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287 <refsect2>
288 <title>Init working directory</title>
289 <para>
290 Sets the absolute path inside the container as the working directory for the containers.
291 LXC will switch to this directory before executing init.
292 </para>
293 <variablelist>
294 <varlistentry>
295 <term>
296 <option>lxc.init.cwd</option>
297 </term>
298 <listitem>
299 <para>
300 Absolute path inside the container to use as the working directory.
301 </para>
302 </listitem>
303 </varlistentry>
304 </variablelist>
305 </refsect2>
306
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307 <refsect2>
308 <title>Init ID</title>
309 <para>
b9986e43 310 Sets the UID/GID to use for the init system, and subsequent commands.
14a7b0f9 311 Note that using a non-root UID when booting a system container will
b9986e43 312 likely not work due to missing privileges. Setting the UID/GID is mostly
14a7b0f9 313 useful when running application containers.
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314
315 Defaults to: UID(0), GID(0)
316 </para>
317 <variablelist>
318 <varlistentry>
319 <term>
9dcf7b4d 320 <option>lxc.init.uid</option>
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321 </term>
322 <listitem>
323 <para>
b9986e43 324 UID to use for init.
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325 </para>
326 </listitem>
327 </varlistentry>
328 <varlistentry>
329 <term>
9dcf7b4d 330 <option>lxc.init.gid</option>
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331 </term>
332 <listitem>
333 <para>
b9986e43 334 GID to use for init.
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335 </para>
336 </listitem>
337 </varlistentry>
338 </variablelist>
339 </refsect2>
340
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341 <refsect2>
342 <title>Proc</title>
343 <para>
344 Configure proc filesystem for the container.
345 </para>
346 <variablelist>
347 <varlistentry>
348 <term>
349 <option>lxc.proc.[proc file name]</option>
350 </term>
351 <listitem>
352 <para>
353 Specify the proc file name to be set. The file name available
354 are those listed under /proc/PID/.
355 Example:
356 </para>
357 <programlisting>
358 lxc.proc.oom_score_adj = 10
359 </programlisting>
360 </listitem>
361 </varlistentry>
362 </variablelist>
363 </refsect2>
364
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365 <refsect2>
366 <title>Ephemeral</title>
367 <para>
368 Allows one to specify whether a container will be destroyed on shutdown.
369 </para>
370 <variablelist>
371 <varlistentry>
372 <term>
373 <option>lxc.ephemeral</option>
374 </term>
375 <listitem>
376 <para>
377 The only allowed values are 0 and 1. Set this to 1 to destroy a
378 container on shutdown.
379 </para>
380 </listitem>
381 </varlistentry>
382 </variablelist>
383 </refsect2>
384
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385 <refsect2>
386 <title>Network</title>
387 <para>
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388 The network section defines how the network is virtualized in
389 the container. The network virtualization acts at layer
390 two. In order to use the network virtualization, parameters
391 must be specified to define the network interfaces of the
392 container. Several virtual interfaces can be assigned and used
393 in a container even if the system has only one physical
394 network interface.
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395 </para>
396 <variablelist>
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397 <varlistentry>
398 <term>
7fa3f2e9 399 <option>lxc.net</option>
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400 </term>
401 <listitem>
402 <para>
403 may be used without a value to clear all previous network options.
404 </para>
405 </listitem>
406 </varlistentry>
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407 <varlistentry>
408 <term>
7fa3f2e9 409 <option>lxc.net.[i].type</option>
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410 </term>
411 <listitem>
412 <para>
413 specify what kind of network virtualization to be used
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414 for the container.
415 Multiple networks can be specified by using an additional index
416 <option>i</option>
7fa3f2e9 417 after all <option>lxc.net.*</option> keys. For example,
418 <option>lxc.net.0.type = veth</option> and
419 <option>lxc.net.1.type = veth</option> specify two different
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420 networks of the same type. All keys sharing the same index
421 <option>i</option> will be treated as belonging to the same
7fa3f2e9 422 network. For example, <option>lxc.net.0.link = br0</option>
423 will belong to <option>lxc.net.0.type</option>.
b9986e43 424 Currently, the different virtualization types can be:
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425 </para>
426
427 <para>
428 <option>none:</option> will cause the container to share
429 the host's network namespace. This means the host
430 network devices are usable in the container. It also
431 means that if both the container and host have upstart as
432 init, 'halt' in a container (for instance) will shut down the
433 host.
434 </para>
435
436 <para>
437 <option>empty:</option> will create only the loopback
438 interface.
439 </para>
440
441 <para>
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442 <option>veth:</option> a virtual ethernet pair
443 device is created with one side assigned to the container
444 and the other side attached to a bridge specified by
7fa3f2e9 445 the <option>lxc.net.[i].link</option> option.
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446 If the bridge is not specified, then the veth pair device
447 will be created but not attached to any bridge.
448 Otherwise, the bridge has to be created on the system
449 before starting the container.
450 <command>lxc</command> won't handle any
451 configuration outside of the container.
452 By default, <command>lxc</command> chooses a name for the
c464fd7e 453 network device belonging to the outside of the
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454 container, but if you wish to handle
455 this name yourselves, you can tell <command>lxc</command>
c464fd7e 456 to set a specific name with
7fa3f2e9 457 the <option>lxc.net.[i].veth.pair</option> option (except for
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458 unprivileged containers where this option is ignored for security
459 reasons).
460 </para>
461
462 <para>
463 <option>vlan:</option> a vlan interface is linked with
464 the interface specified by
7fa3f2e9 465 the <option>lxc.net.[i].link</option> and assigned to
c464fd7e 466 the container. The vlan identifier is specified with the
7fa3f2e9 467 option <option>lxc.net.[i].vlan.id</option>.
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468 </para>
469
470 <para>
471 <option>macvlan:</option> a macvlan interface is linked
472 with the interface specified by
7fa3f2e9 473 the <option>lxc.net.[i].link</option> and assigned to
c464fd7e 474 the container.
7fa3f2e9 475 <option>lxc.net.[i].macvlan.mode</option> specifies the
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476 mode the macvlan will use to communicate between
477 different macvlan on the same upper device. The accepted
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478 modes are <option>private</option>, <option>vepa</option>,
479 <option>bridge</option> and <option>passthru</option>.
480 In <option>private</option> mode, the device never
481 communicates with any other device on the same upper_dev (default).
482 In <option>vepa</option> mode, the new Virtual Ethernet Port
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483 Aggregator (VEPA) mode, it assumes that the adjacent
484 bridge returns all frames where both source and
485 destination are local to the macvlan port, i.e. the
486 bridge is set up as a reflective relay. Broadcast
487 frames coming in from the upper_dev get flooded to all
488 macvlan interfaces in VEPA mode, local frames are not
c15ea607 489 delivered locally. In <option>bridge</option> mode, it
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490 provides the behavior of a simple bridge between
491 different macvlan interfaces on the same port. Frames
492 from one interface to another one get delivered directly
493 and are not sent out externally. Broadcast frames get
494 flooded to all other bridge ports and to the external
495 interface, but when they come back from a reflective
496 relay, we don't deliver them again. Since we know all
497 the MAC addresses, the macvlan bridge mode does not
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498 require learning or STP like the bridge module does. In
499 <option>passthru</option> mode, all frames received by
500 the physical interface are forwarded to the macvlan
501 interface. Only one macvlan interface in <option>passthru</option>
502 mode is possible for one physical interface.
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503 </para>
504
505 <para>
506 <option>phys:</option> an already existing interface
7fa3f2e9 507 specified by the <option>lxc.net.[i].link</option> is
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508 assigned to the container.
509 </para>
510 </listitem>
511 </varlistentry>
512
513 <varlistentry>
514 <term>
7fa3f2e9 515 <option>lxc.net.[i].flags</option>
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516 </term>
517 <listitem>
518 <para>
b9986e43 519 Specify an action to do for the network.
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520 </para>
521
522 <para><option>up:</option> activates the interface.
523 </para>
524 </listitem>
525 </varlistentry>
526
527 <varlistentry>
528 <term>
7fa3f2e9 529 <option>lxc.net.[i].link</option>
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530 </term>
531 <listitem>
532 <para>
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533 Specify the interface to be used for real network traffic.
534 </para>
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535 </listitem>
536 </varlistentry>
537
538 <varlistentry>
539 <term>
7fa3f2e9 540 <option>lxc.net.[i].mtu</option>
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541 </term>
542 <listitem>
543 <para>
b9986e43 544 Specify the maximum transfer unit for this interface.
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545 </para>
546 </listitem>
547 </varlistentry>
548
549 <varlistentry>
550 <term>
7fa3f2e9 551 <option>lxc.net.[i].name</option>
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552 </term>
553 <listitem>
554 <para>
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555 The interface name is dynamically allocated, but if another name
556 is needed because the configuration files being used by the
557 container use a generic name, eg. eth0, this option will rename
558 the interface in the container.
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559 </para>
560 </listitem>
561 </varlistentry>
562
563 <varlistentry>
564 <term>
7fa3f2e9 565 <option>lxc.net.[i].hwaddr</option>
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566 </term>
567 <listitem>
568 <para>
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569 The interface mac address is dynamically allocated by default to
570 the virtual interface, but in some cases, this is needed to
571 resolve a mac address conflict or to always have the same
572 link-local ipv6 address. Any "x" in address will be replaced by
573 random value, this allows setting hwaddr templates.
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574 </para>
575 </listitem>
576 </varlistentry>
577
578 <varlistentry>
579 <term>
9ff60df2 580 <option>lxc.net.[i].ipv4.address</option>
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581 </term>
582 <listitem>
583 <para>
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584 Specify the ipv4 address to assign to the virtualized interface.
585 Several lines specify several ipv4 addresses. The address is in
586 format x.y.z.t/m, eg. 192.168.1.123/24.
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587 </para>
588 </listitem>
589 </varlistentry>
590
591 <varlistentry>
592 <term>
7fa3f2e9 593 <option>lxc.net.[i].ipv4.gateway</option>
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594 </term>
595 <listitem>
596 <para>
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597 Specify the ipv4 address to use as the gateway inside the
598 container. The address is in format x.y.z.t, eg. 192.168.1.123.
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599
600 Can also have the special value <option>auto</option>,
601 which means to take the primary address from the bridge
602 interface (as specified by the
7fa3f2e9 603 <option>lxc.net.[i].link</option> option) and use that as
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604 the gateway. <option>auto</option> is only available when
605 using the <option>veth</option> and
606 <option>macvlan</option> network types.
607 </para>
608 </listitem>
609 </varlistentry>
610
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611 <varlistentry>
612 <term>
2e44ae28 613 <option>lxc.net.[i].ipv6.address</option>
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614 </term>
615 <listitem>
616 <para>
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617 Specify the ipv6 address to assign to the virtualized
618 interface. Several lines specify several ipv6 addresses. The
619 address is in format x::y/m, eg.
620 2003:db8:1:0:214:1234:fe0b:3596/64
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621 </para>
622 </listitem>
623 </varlistentry>
624
625 <varlistentry>
626 <term>
7fa3f2e9 627 <option>lxc.net.[i].ipv6.gateway</option>
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628 </term>
629 <listitem>
630 <para>
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631 Specify the ipv6 address to use as the gateway inside the
632 container. The address is in format x::y, eg. 2003:db8:1:0::1
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633
634 Can also have the special value <option>auto</option>,
635 which means to take the primary address from the bridge
636 interface (as specified by the
7fa3f2e9 637 <option>lxc.net.[i].link</option> option) and use that as
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638 the gateway. <option>auto</option> is only available when
639 using the <option>veth</option> and
640 <option>macvlan</option> network types.
641 </para>
642 </listitem>
643 </varlistentry>
644
645 <varlistentry>
646 <term>
7fa3f2e9 647 <option>lxc.net.[i].script.up</option>
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648 </term>
649 <listitem>
650 <para>
b9986e43 651 Add a configuration option to specify a script to be
c464fd7e 652 executed after creating and configuring the network used
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653 from the host side.
654 </para>
655
656 <para>
657 In addition to the information available to all hooks. The
658 following information is provided to the script:
659 <itemizedlist>
660 <listitem>
661 <para>
662 LXC_HOOK_TYPE: the hook type. This is either 'up' or 'down'.
663 </para>
664 </listitem>
665
666 <listitem>
667 <para>
668 LXC_HOOK_SECTION: the section type 'net'.
669 </para>
670 </listitem>
671
672 <listitem>
673 <para>
674 LXC_NET_TYPE: the network type. This is one of the valid
675 network types listed here (e.g. 'macvlan', 'veth').
676 </para>
677 </listitem>
678
679 <listitem>
680 <para>
681 LXC_NET_PARENT: the parent device on the host. This is only
682 set for network types 'mavclan', 'veth', 'phys'.
683 </para>
684 </listitem>
685
686 <listitem>
687 <para>
688 LXC_NET_PEER: the name of the peer device on the host. This is
689 only set for 'veth' network types. Note that this information
690 is only available when <option>lxc.hook.version</option> is set
691 to 1.
692 </para>
693 </listitem>
694 </itemizedlist>
695
696 Whether this information is provided in the form of environment
697 variables or as arguments to the script depends on the value of
698 <option>lxc.hook.version</option>. If set to 1 then information is
699 provided in the form of environment variables. If set to 0
700 information is provided as arguments to the script.
c464fd7e 701 </para>
14a7b0f9 702
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703 <para>
704 Standard output from the script is logged at debug level.
705 Standard error is not logged, but can be captured by the
706 hook redirecting its standard error to standard output.
707 </para>
708 </listitem>
709 </varlistentry>
710
711 <varlistentry>
712 <term>
7fa3f2e9 713 <option>lxc.net.[i].script.down</option>
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714 </term>
715 <listitem>
716 <para>
b9986e43 717 Add a configuration option to specify a script to be
c464fd7e 718 executed before destroying the network used from the
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719 host side.
720 </para>
721
722 <para>
723 In addition to the information available to all hooks. The
724 following information is provided to the script:
725 <itemizedlist>
726 <listitem>
727 <para>
728 LXC_HOOK_TYPE: the hook type. This is either 'up' or 'down'.
729 </para>
730 </listitem>
731
732 <listitem>
733 <para>
734 LXC_HOOK_SECTION: the section type 'net'.
735 </para>
736 </listitem>
737
738 <listitem>
739 <para>
740 LXC_NET_TYPE: the network type. This is one of the valid
741 network types listed here (e.g. 'macvlan', 'veth').
742 </para>
743 </listitem>
744
745 <listitem>
746 <para>
747 LXC_NET_PARENT: the parent device on the host. This is only
748 set for network types 'mavclan', 'veth', 'phys'.
749 </para>
750 </listitem>
751
752 <listitem>
753 <para>
754 LXC_NET_PEER: the name of the peer device on the host. This is
755 only set for 'veth' network types. Note that this information
756 is only available when <option>lxc.hook.version</option> is set
757 to 1.
758 </para>
759 </listitem>
760 </itemizedlist>
761
762 Whether this information is provided in the form of environment
763 variables or as arguments to the script depends on the value of
764 <option>lxc.hook.version</option>. If set to 1 then information is
765 provided in the form of environment variables. If set to 0
766 information is provided as arguments to the script.
c464fd7e 767 </para>
14a7b0f9 768
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769 <para>
770 Standard output from the script is logged at debug level.
771 Standard error is not logged, but can be captured by the
772 hook redirecting its standard error to standard output.
773 </para>
774 </listitem>
775 </varlistentry>
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776 </variablelist>
777 </refsect2>
778
779 <refsect2>
780 <title>New pseudo tty instance (devpts)</title>
781 <para>
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782 For stricter isolation the container can have its own private
783 instance of the pseudo tty.
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784 </para>
785 <variablelist>
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786 <varlistentry>
787 <term>
232763d6 788 <option>lxc.pty.max</option>
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789 </term>
790 <listitem>
791 <para>
792 If set, the container will have a new pseudo tty
793 instance, making this private to it. The value specifies
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794 the maximum number of pseudo ttys allowed for a pts
795 instance (this limitation is not implemented yet).
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796 </para>
797 </listitem>
798 </varlistentry>
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799 </variablelist>
800 </refsect2>
801
802 <refsect2>
803 <title>Container system console</title>
804 <para>
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805 If the container is configured with a root filesystem and the
806 inittab file is setup to use the console, you may want to specify
807 where the output of this console goes.
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808 </para>
809 <variablelist>
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810
811 <varlistentry>
812 <term>
813 <option>lxc.console.buffer.size</option>
814 </term>
815 <listitem>
816 <para>
817 Setting this option instructs liblxc to allocate an in-memory
818 ringbuffer. The container's console output will be written to the
819 ringbuffer. Note that ringbuffer must be at least as big as a
820 standard page size. When passed a value smaller than a single page
821 size liblxc will allocate a ringbuffer of a single page size. A page
822 size is usually 4kB.
823
824 The keyword 'auto' will cause liblxc to allocate a ringbuffer of
825 128kB.
826
827 When manually specifying a size for the ringbuffer the value should
828 be a power of 2 when converted to bytes. Valid size prefixes are
829 'kB', 'MB', 'GB'. (Note that all conversions are based on multiples
830 of 1024. That means 'kb' == 'KiB', 'MB' == 'MiB', 'GB' == 'GiB'.)
831 </para>
832 </listitem>
833 </varlistentry>
834
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835 <varlistentry>
836 <term>
837 <option>lxc.console.buffer.logfile</option>
838 </term>
839 <listitem>
840 <para>
841 Setting this option instructs liblxc to write the in-memory
842 ringbuffer to disk. For performance reasons liblxc will only write
843 the in-memory ringbuffer to disk when requested. Note that the this
844 option is only used by liblxc when
845 <option>lxc.console.buffer.size</option> is set.
846
847 By default liblxc will dump the contents of the in-memory ringbuffer
848 to disk when the container terminates. This allows users to diagnose
849 boot failures when the container crashed before an API request to
850 retrieve the in-memory ringbuffer could be sent or handled.
851 </para>
852 </listitem>
853 </varlistentry>
854
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855 <varlistentry>
856 <term>
857 <option>lxc.console.logfile</option>
858 </term>
859 <listitem>
860 <para>
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861 Specify a path to a file where the console output will be written.
862 Note that in contrast to the on-disk ringbuffer logfile this file
863 will keep growing potentially filling up the users disks if not
864 rotated and deleted. This problem can also be avoided by using the
865 in-memory ringbuffer options
866 <option>lxc.console.buffer.size</option> and
867 <option>lxc.console.buffer.logfile</option>.
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868 </para>
869 </listitem>
870 </varlistentry>
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871
872 <varlistentry>
873 <term>
874 <option>lxc.console.rotate</option>
875 </term>
876 <listitem>
877 <para>
878 Whether to rotate the console logfile specified in
879 <option>lxc.console.logfile</option>. Users can send an API
880 request to rotate the logfile. Note that the old logfile will have
881 the same name as the original with the suffix ".1" appended.
882
883 Users wishing to prevent the console log file from filling the
884 disk should rotate the logfile and delete it if unneeded. This
885 problem can also be avoided by using the in-memory ringbuffer
886 options <option>lxc.console.buffer.size</option> and
887 <option>lxc.console.buffer.logfile</option>.
888 </para>
889 </listitem>
890 </varlistentry>
891
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892 <varlistentry>
893 <term>
3aed4934 894 <option>lxc.console.path</option>
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895 </term>
896 <listitem>
897 <para>
898 Specify a path to a device to which the console will be
6e3bb289
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899 attached. The keyword 'none' will simply disable the
900 console. Note, when specifying 'none' and creating a device node
901 for the console in the container at /dev/console or bind-mounting
902 the hosts's /dev/console into the container at /dev/console the
903 container will have direct access to the hosts's /dev/console.
904 This is dangerous when the container has write access to the
905 device and should thus be used with caution.
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906 </para>
907 </listitem>
908 </varlistentry>
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909 </variablelist>
910 </refsect2>
911
912 <refsect2>
913 <title>Console through the ttys</title>
914 <para>
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915 This option is useful if the container is configured with a root
916 filesystem and the inittab file is setup to launch a getty on the
917 ttys. The option specifies the number of ttys to be available for
918 the container. The number of gettys in the inittab file of the
919 container should not be greater than the number of ttys specified
920 in this option, otherwise the excess getty sessions will die and
921 respawn indefinitely giving annoying messages on the console or in
922 <filename>/var/log/messages</filename>.
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923 </para>
924 <variablelist>
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925 <varlistentry>
926 <term>
fe1c5887 927 <option>lxc.tty.max</option>
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928 </term>
929 <listitem>
930 <para>
931 Specify the number of tty to make available to the
932 container.
933 </para>
934 </listitem>
935 </varlistentry>
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936 </variablelist>
937 </refsect2>
938
939 <refsect2>
940 <title>Console devices location</title>
941 <para>
942 LXC consoles are provided through Unix98 PTYs created on the
c464fd7e
SG
943 host and bind-mounted over the expected devices in the container.
944 By default, they are bind-mounted over <filename>/dev/console</filename>
945 and <filename>/dev/ttyN</filename>. This can prevent package upgrades
946 in the guest. Therefore you can specify a directory location (under
947 <filename>/dev</filename> under which LXC will create the files and
948 bind-mount over them. These will then be symbolically linked to
949 <filename>/dev/console</filename> and <filename>/dev/ttyN</filename>.
950 A package upgrade can then succeed as it is able to remove and replace
951 the symbolic links.
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952 </para>
953 <variablelist>
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954 <varlistentry>
955 <term>
fe1c5887 956 <option>lxc.tty.dir</option>
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957 </term>
958 <listitem>
959 <para>
960 Specify a directory under <filename>/dev</filename>
6e3bb289
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961 under which to create the container console devices. Note that LXC
962 will move any bind-mounts or device nodes for /dev/console into
963 this directory.
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964 </para>
965 </listitem>
966 </varlistentry>
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967 </variablelist>
968 </refsect2>
969
970 <refsect2>
971 <title>/dev directory</title>
972 <para>
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973 By default, lxc creates a few symbolic links (fd,stdin,stdout,stderr)
974 in the container's <filename>/dev</filename> directory but does not
975 automatically create device node entries. This allows the container's
976 <filename>/dev</filename> to be set up as needed in the container
977 rootfs. If lxc.autodev is set to 1, then after mounting the container's
978 rootfs LXC will mount a fresh tmpfs under <filename>/dev</filename>
c35d2909 979 (limited to 500k) and fill in a minimal set of initial devices.
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SG
980 This is generally required when starting a container containing
981 a "systemd" based "init" but may be optional at other times. Additional
982 devices in the containers /dev directory may be created through the
983 use of the <option>lxc.hook.autodev</option> hook.
984 </para>
985 <variablelist>
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986 <varlistentry>
987 <term>
988 <option>lxc.autodev</option>
989 </term>
990 <listitem>
991 <para>
124fa0a8 992 Set this to 0 to stop LXC from mounting and populating a minimal
c464fd7e
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993 <filename>/dev</filename> when starting the container.
994 </para>
995 </listitem>
996 </varlistentry>
55fc19a1 997 </variablelist>
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998 </refsect2>
999
1000 <refsect2>
1001 <title>Mount points</title>
1002 <para>
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1003 The mount points section specifies the different places to be
1004 mounted. These mount points will be private to the container
1005 and won't be visible by the processes running outside of the
1006 container. This is useful to mount /etc, /var or /home for
1007 examples.
55fc19a1 1008 </para>
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1009 <para>
1010 NOTE - LXC will generally ensure that mount targets and relative
1011 bind-mount sources are properly confined under the container
1012 root, to avoid attacks involving over-mounting host directories
1013 and files. (Symbolic links in absolute mount sources are ignored)
1014 However, if the container configuration first mounts a directory which
1015 is under the control of the container user, such as /home/joe, into
1016 the container at some <filename>path</filename>, and then mounts
1017 under <filename>path</filename>, then a TOCTTOU attack would be
1018 possible where the container user modifies a symbolic link under
1019 his home directory at just the right time.
1020 </para>
55fc19a1 1021 <variablelist>
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1022 <varlistentry>
1023 <term>
47148e96 1024 <option>lxc.mount.fstab</option>
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1025 </term>
1026 <listitem>
1027 <para>
1028 specify a file location in
1029 the <filename>fstab</filename> format, containing the
1030 mount information. The mount target location can and in
1031 most cases should be a relative path, which will become
1032 relative to the mounted container root. For instance,
1033 </para>
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CB
1034 <programlisting>
1035 proc proc proc nodev,noexec,nosuid 0 0
1036 </programlisting>
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SG
1037 <para>
1038 Will mount a proc filesystem under the container's /proc,
1039 regardless of where the root filesystem comes from. This
1040 is resilient to block device backed filesystems as well as
1041 container cloning.
1042 </para>
1043 <para>
1044 Note that when mounting a filesystem from an
1045 image file or block device the third field (fs_vfstype)
1046 cannot be auto as with
55fc19a1 1047 <citerefentry>
c464fd7e 1048 <refentrytitle>mount</refentrytitle>
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SG
1049 <manvolnum>8</manvolnum>
1050 </citerefentry>
1051 but must be explicitly specified.
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1052 </para>
1053 </listitem>
1054 </varlistentry>
1055
1056 <varlistentry>
1057 <term>
1058 <option>lxc.mount.entry</option>
1059 </term>
1060 <listitem>
1061 <para>
d840039e 1062 Specify a mount point corresponding to a line in the
c464fd7e 1063 fstab format.
f5b67b36 1064
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YT
1065 Moreover lxc supports mount propagation, such as rslave or
1066 rprivate, and adds three additional mount options.
f5b67b36
NC
1067 <option>optional</option> don't fail if mount does not work.
1068 <option>create=dir</option> or <option>create=file</option>
1069 to create dir (or file) when the point will be mounted.
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YT
1070 <option>relative</option> source path is taken to be relative to
1071 the mounted container root. For instance,
1072 </para>
1073<screen>
1074dev/null proc/kcore none bind,relative 0 0
1075</screen>
1076 <para>
1077 Will expand dev/null to ${<option>LXC_ROOTFS_MOUNT</option>}/dev/null,
1078 and mount it to proc/kcore inside the container.
1079 </para>
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1080 </listitem>
1081 </varlistentry>
1082
1083 <varlistentry>
1084 <term>
1085 <option>lxc.mount.auto</option>
1086 </term>
1087 <listitem>
1088 <para>
1089 specify which standard kernel file systems should be
1090 automatically mounted. This may dramatically simplify
1091 the configuration. The file systems are:
1092 </para>
1093 <itemizedlist>
1094 <listitem>
1095 <para>
1096 <option>proc:mixed</option> (or <option>proc</option>):
1097 mount <filename>/proc</filename> as read-write, but
1098 remount <filename>/proc/sys</filename> and
1099 <filename>/proc/sysrq-trigger</filename> read-only
1100 for security / container isolation purposes.
1101 </para>
1102 </listitem>
1103 <listitem>
1104 <para>
1105 <option>proc:rw</option>: mount
1106 <filename>/proc</filename> as read-write
1107 </para>
1108 </listitem>
1109 <listitem>
1110 <para>
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1111 <option>sys:mixed</option> (or <option>sys</option>):
1112 mount <filename>/sys</filename> as read-only but with
1113 /sys/devices/virtual/net writable.
1114 </para>
1115 </listitem>
1116 <listitem>
1117 <para>
1118 <option>sys:ro</option>:
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1119 mount <filename>/sys</filename> as read-only
1120 for security / container isolation purposes.
1121 </para>
1122 </listitem>
1123 <listitem>
1124 <para>
1125 <option>sys:rw</option>: mount
1126 <filename>/sys</filename> as read-write
1127 </para>
1128 </listitem>
3f69fb12 1129
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1130 <listitem>
1131 <para>
1132 <option>cgroup:mixed</option>:
3f69fb12
SY
1133 Mount a tmpfs to <filename>/sys/fs/cgroup</filename>,
1134 create directories for all hierarchies to which the container
1135 is added, create subdirectories in those hierarchies with the
1136 name of the cgroup, and bind-mount the container's own cgroup
1137 into that directory. The container will be able to write to
1138 its own cgroup directory, but not the parents, since they will
1139 be remounted read-only.
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1140 </para>
1141 </listitem>
3f69fb12 1142
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1143 <listitem>
1144 <para>
3f69fb12
SY
1145 <option>cgroup:mixed:force</option>:
1146 The <option>force</option> option will cause LXC to perform
1147 the cgroup mounts for the container under all circumstances.
1148 Otherwise it is similar to <option>cgroup:mixed</option>.
1149 This is mainly useful when the cgroup namespaces are enabled
1150 where LXC will normally leave mounting cgroups to the init
1151 binary of the container since it is perfectly safe to do so.
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1152 </para>
1153 </listitem>
3f69fb12
SY
1154
1155 <listitem>
1156 <para>
1157 <option>cgroup:ro</option>:
1158 similar to <option>cgroup:mixed</option>, but everything will
1159 be mounted read-only.
1160 </para>
1161 </listitem>
1162
1163 <listitem>
1164 <para>
1165 <option>cgroup:ro:force</option>:
1166 The <option>force</option> option will cause LXC to perform
1167 the cgroup mounts for the container under all circumstances.
1168 Otherwise it is similar to <option>cgroup:ro</option>.
1169 This is mainly useful when the cgroup namespaces are enabled
1170 where LXC will normally leave mounting cgroups to the init
1171 binary of the container since it is perfectly safe to do so.
1172 </para>
1173 </listitem>
1174
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1175 <listitem>
1176 <para>
1177 <option>cgroup:rw</option>: similar to
3f69fb12
SY
1178 <option>cgroup:mixed</option>, but everything will be mounted
1179 read-write. Note that the paths leading up to the container's
1180 own cgroup will be writable, but will not be a cgroup
1181 filesystem but just part of the tmpfs of
1182 <filename>/sys/fs/cgroup</filename>
1183 </para>
1184 </listitem>
1185
1186 <listitem>
1187 <para>
1188 <option>cgroup:rw:force</option>:
1189 The <option>force</option> option will cause LXC to perform
1190 the cgroup mounts for the container under all circumstances.
1191 Otherwise it is similar to <option>cgroup:rw</option>.
1192 This is mainly useful when the cgroup namespaces are enabled
1193 where LXC will normally leave mounting cgroups to the init
1194 binary of the container since it is perfectly safe to do so.
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1195 </para>
1196 </listitem>
3f69fb12 1197
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1198 <listitem>
1199 <para>
1200 <option>cgroup</option> (without specifier):
1201 defaults to <option>cgroup:rw</option> if the
1202 container retains the CAP_SYS_ADMIN capability,
1203 <option>cgroup:mixed</option> otherwise.
1204 </para>
1205 </listitem>
1206 <listitem>
1207 <para>
1208 <option>cgroup-full:mixed</option>:
1209 mount a tmpfs to <filename>/sys/fs/cgroup</filename>,
1210 create directories for all hierarchies to which
1211 the container is added, bind-mount the hierarchies
1212 from the host to the container and make everything
1213 read-only except the container's own cgroup. Note
1214 that compared to <option>cgroup</option>, where
1215 all paths leading up to the container's own cgroup
1216 are just simple directories in the underlying
1217 tmpfs, here
1218 <filename>/sys/fs/cgroup/$hierarchy</filename>
1219 will contain the host's full cgroup hierarchy,
1220 albeit read-only outside the container's own cgroup.
1221 This may leak quite a bit of information into the
1222 container.
1223 </para>
1224 </listitem>
1225 <listitem>
1226 <para>
1227 <option>cgroup-full:ro</option>: similar to
1228 <option>cgroup-full:mixed</option>, but everything
1229 will be mounted read-only.
1230 </para>
1231 </listitem>
1232 <listitem>
1233 <para>
1234 <option>cgroup-full:rw</option>: similar to
1235 <option>cgroup-full:mixed</option>, but everything
1236 will be mounted read-write. Note that in this case,
1237 the container may escape its own cgroup. (Note also
1238 that if the container has CAP_SYS_ADMIN support
1239 and can mount the cgroup filesystem itself, it may
1240 do so anyway.)
1241 </para>
1242 </listitem>
1243 <listitem>
1244 <para>
1245 <option>cgroup-full</option> (without specifier):
1246 defaults to <option>cgroup-full:rw</option> if the
1247 container retains the CAP_SYS_ADMIN capability,
1248 <option>cgroup-full:mixed</option> otherwise.
1249 </para>
1250 </listitem>
1251 </itemizedlist>
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1252 <para>
1253 If cgroup namespaces are enabled, then any <option>cgroup</option>
1254 auto-mounting request will be ignored, since the container can
1255 mount the filesystems itself, and automounting can confuse the
1256 container init.
1257 </para>
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1258 <para>
1259 Note that if automatic mounting of the cgroup filesystem
1260 is enabled, the tmpfs under
1261 <filename>/sys/fs/cgroup</filename> will always be
1262 mounted read-write (but for the <option>:mixed</option>
1263 and <option>:ro</option> cases, the individual
1264 hierarchies,
1265 <filename>/sys/fs/cgroup/$hierarchy</filename>, will be
1266 read-only). This is in order to work around a quirk in
1267 Ubuntu's
b46f0553 1268 <citerefentry>
c464fd7e 1269 <refentrytitle>mountall</refentrytitle>
b46f0553
CS
1270 <manvolnum>8</manvolnum>
1271 </citerefentry>
c464fd7e
SG
1272 command that will cause containers to wait for user
1273 input at boot if
1274 <filename>/sys/fs/cgroup</filename> is mounted read-only
1275 and the container can't remount it read-write due to a
1276 lack of CAP_SYS_ADMIN.
1277 </para>
1278 <para>
1279 Examples:
1280 </para>
1281 <programlisting>
1282 lxc.mount.auto = proc sys cgroup
1283 lxc.mount.auto = proc:rw sys:rw cgroup-full:rw
1284 </programlisting>
1285 </listitem>
1286 </varlistentry>
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1287
1288 </variablelist>
1289 </refsect2>
1290
1291 <refsect2>
1292 <title>Root file system</title>
1293 <para>
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1294 The root file system of the container can be different than that
1295 of the host system.
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1296 </para>
1297 <variablelist>
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1298 <varlistentry>
1299 <term>
7a96a068 1300 <option>lxc.rootfs.path</option>
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1301 </term>
1302 <listitem>
1303 <para>
1304 specify the root file system for the container. It can
1305 be an image file, a directory or a block device. If not
1306 specified, the container shares its root file system
1307 with the host.
1308 </para>
1309 <para>
f1c26f2c
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1310 For directory or simple block-device backed containers,
1311 a pathname can be used. If the rootfs is backed by a nbd
1312 device, then <filename>nbd:file:1</filename> specifies that
1313 <filename>file</filename> should be attached to a nbd device,
1314 and partition 1 should be mounted as the rootfs.
1315 <filename>nbd:file</filename> specifies that the nbd device
1316 itself should be mounted. <filename>overlayfs:/lower:/upper</filename>
1317 specifies that the rootfs should be an overlay with <filename>/upper</filename>
1318 being mounted read-write over a read-only mount of <filename>/lower</filename>.
1319 <filename>aufs:/lower:/upper</filename> does the same using aufs in place
280d2379
CB
1320 of overlayfs. For both <filename>overlayfs</filename> and
1321 <filename>aufs</filename> multiple <filename>/lower</filename>
1322 directories can be specified. <filename>loop:/file</filename> tells lxc to attach
f1c26f2c 1323 <filename>/file</filename> to a loop device and mount the loop device.
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1324 </para>
1325 </listitem>
1326 </varlistentry>
1327
1328 <varlistentry>
1329 <term>
1330 <option>lxc.rootfs.mount</option>
1331 </term>
1332 <listitem>
1333 <para>
7a96a068 1334 where to recursively bind <option>lxc.rootfs.path</option>
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SG
1335 before pivoting. This is to ensure success of the
1336 <citerefentry>
1337 <refentrytitle><command>pivot_root</command></refentrytitle>
1338 <manvolnum>8</manvolnum>
1339 </citerefentry>
1340 syscall. Any directory suffices, the default should
1341 generally work.
1342 </para>
1343 </listitem>
1344 </varlistentry>
1345
1346 <varlistentry>
1347 <term>
1348 <option>lxc.rootfs.options</option>
1349 </term>
1350 <listitem>
1351 <para>
1352 extra mount options to use when mounting the rootfs.
1353 </para>
1354 </listitem>
1355 </varlistentry>
a17b1e65 1356
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1357 </variablelist>
1358 </refsect2>
1359
1360 <refsect2>
1361 <title>Control group</title>
1362 <para>
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1363 The control group section contains the configuration for the
1364 different subsystem. <command>lxc</command> does not check the
1365 correctness of the subsystem name. This has the disadvantage
1366 of not detecting configuration errors until the container is
1367 started, but has the advantage of permitting any future
1368 subsystem.
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1369 </para>
1370 <variablelist>
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1371 <varlistentry>
1372 <term>
54860ed0 1373 <option>lxc.cgroup.[controller name]</option>
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1374 </term>
1375 <listitem>
1376 <para>
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CB
1377 Specify the control group value to be set on a legacy cgroup
1378 hierarchy. The controller name is the literal name of the control
1379 group. The permitted names and the syntax of their values is not
1380 dictated by LXC, instead it depends on the features of the Linux
1381 kernel running at the time the container is started, eg.
1382 <option>lxc.cgroup.cpuset.cpus</option>
1383 </para>
1384 </listitem>
1385 </varlistentry>
1386 <varlistentry>
1387 <term>
1388 <option>lxc.cgroup2.[controller name]</option>
1389 </term>
1390 <listitem>
1391 <para>
1392 Specify the control group value to be set on the unified cgroup
1393 shierarchy. The controller name is the literal name of the control
1394 group. The permitted names and the syntax of their values is not
1395 dictated by LXC, instead it depends on the features of the Linux
1396 kernel running at the time the container is started, eg.
1397 <option>lxc.cgroup2.memory.high</option>
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1398 </para>
1399 </listitem>
1400 </varlistentry>
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1401 <varlistentry>
1402 <term>
1403 <option>lxc.cgroup.dir</option>
1404 </term>
1405 <listitem>
1406 <para>
1407 specify a directory or path in which the container's cgroup will
1408 be created. For example, setting
1409 <option>lxc.cgroup.dir = my-cgroup/first</option> for a container
1410 named "c1" will create the container's cgroup as a sub-cgroup of
1411 "my-cgroup". For example, if the user's current cgroup "my-user"
78be8d75 1412 is located in the root cgroup of the cpuset controller in a
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CB
1413 cgroup v1 hierarchy this would create the cgroup
1414 "/sys/fs/cgroup/cpuset/my-user/my-cgroup/first/c1" for the
1415 container. Any missing cgroups will be created by LXC. This
1416 presupposes that the user has write access to its current cgroup.
1417 </para>
1418 </listitem>
1419 </varlistentry>
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1420 </variablelist>
1421 </refsect2>
1422
1423 <refsect2>
1424 <title>Capabilities</title>
1425 <para>
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1426 The capabilities can be dropped in the container if this one
1427 is run as root.
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SG
1428 </para>
1429 <variablelist>
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1430 <varlistentry>
1431 <term>
1432 <option>lxc.cap.drop</option>
1433 </term>
1434 <listitem>
1435 <para>
1436 Specify the capability to be dropped in the container. A
1437 single line defining several capabilities with a space
1438 separation is allowed. The format is the lower case of
1439 the capability definition without the "CAP_" prefix,
1440 eg. CAP_SYS_MODULE should be specified as
1441 sys_module. See
1442 <citerefentry>
1443 <refentrytitle><command>capabilities</command></refentrytitle>
1444 <manvolnum>7</manvolnum>
7eff30fd
MH
1445 </citerefentry>.
1446 If used with no value, lxc will clear any drop capabilities
1447 specified up to this point.
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SG
1448 </para>
1449 </listitem>
1450 </varlistentry>
1451 <varlistentry>
1452 <term>
1453 <option>lxc.cap.keep</option>
1454 </term>
1455 <listitem>
1456 <para>
1457 Specify the capability to be kept in the container. All other
1458 capabilities will be dropped. When a special value of "none" is
1459 encountered, lxc will clear any keep capabilities specified up
1460 to this point. A value of "none" alone can be used to drop all
1461 capabilities.
1462 </para>
1463 </listitem>
1464 </varlistentry>
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SG
1465 </variablelist>
1466 </refsect2>
1467
f3c9f122 1468 <refsect2>
46186acd 1469 <title>Namespaces</title>
f3c9f122 1470 <para>
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CB
1471 A namespace can be cloned (<option>lxc.namespace.clone</option>),
1472 kept (<option>lxc.namespace.keep</option>) or shared
1473 (<option>lxc.namespace.share.[namespace identifier]</option>).
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CB
1474 </para>
1475 <variablelist>
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CB
1476 <varlistentry>
1477 <term>
1478 <option>lxc.namespace.clone</option>
1479 </term>
1480 <listitem>
1481 <para>
1482 Specify namespaces which the container is supposed to be created
1483 with. The namespaces to create are specified as a space separated
1484 list. Each namespace must correspond to one of the standard
1485 namespace identifiers as seen in the
1486 <filename>/proc/PID/ns</filename> directory.
1487 When <option>lxc.namespace.clone</option> is not explicitly set all
1488 namespaces supported by the kernel and the current configuration
1489 will be used.
1490 </para>
1491
1492 <para>
1493 To create a new mount, net and ipc namespace set
1494 <option>lxc.namespace.clone=mount net ipc</option>.
1495 </para>
1496 </listitem>
1497 </varlistentry>
1498
1499 <varlistentry>
1500 <term>
1501 <option>lxc.namespace.keep</option>
1502 </term>
1503 <listitem>
1504 <para>
1505 Specify namespaces which the container is supposed to inherit from
1506 the process that created it. The namespaces to keep are specified as
1507 a space separated list. Each namespace must correspond to one of the
1508 standard namespace identifiers as seen in the
1509 <filename>/proc/PID/ns</filename> directory.
1510 The <option>lxc.namespace.keep</option> is a
1511 blacklist option, i.e. it is useful when enforcing that containers
1512 must keep a specific set of namespaces.
1513 </para>
1514
1515 <para>
1516 To keep the network, user and ipc namespace set
1517 <option>lxc.namespace.keep=user net ipc</option>.
1518 </para>
1519
1520 <para>
1521 Note that sharing pid namespaces will likely not work with most init
1522 systems.
1523 </para>
1524
1525 <para>
1526 Note that if the container requests a new user namespace and the
1527 container wants to inherit the network namespace it needs to inherit
1528 the user namespace as well.
1529 </para>
1530 </listitem>
1531 </varlistentry>
1532
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CB
1533 <varlistentry>
1534 <term>
b074bbf1 1535 <option>lxc.namespace.share.[namespace identifier]</option>
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CB
1536 </term>
1537 <listitem>
1538 <para>
1539 Specify a namespace to inherit from another container or process.
1540 The <option>[namespace identifier]</option> suffix needs to be
1541 replaced with one of the namespaces that appear in the
1542 <filename>/proc/PID/ns</filename> directory.
1543 </para>
1544
1545 <para>
1546 To inherit the namespace from another process set the
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CB
1547 <option>lxc.namespace.share.[namespace identifier]</option> to the PID of
1548 the process, e.g. <option>lxc.namespace.share.net=42</option>.
f3c9f122
CB
1549 </para>
1550
1551 <para>
1552 To inherit the namespace from another container set the
b074bbf1
CB
1553 <option>lxc.namespace.share.[namespace identifier]</option> to the name of
1554 the container, e.g. <option>lxc.namespace.share.pid=c3</option>.
f3c9f122
CB
1555 </para>
1556
1557 <para>
1558 To inherit the namespace from another container located in a
1559 different path than the standard liblxc path set the
b074bbf1 1560 <option>lxc.namespace.share.[namespace identifier]</option> to the full
f3c9f122 1561 path to the container, e.g.
b074bbf1 1562 <option>lxc.namespace.share.user=/opt/c3</option>.
f3c9f122
CB
1563 </para>
1564
1565 <para>
1566 In order to inherit namespaces the caller needs to have sufficient
1567 privilege over the process or container.
1568 </para>
1569
1570 <para>
1571 Note that sharing pid namespaces between system containers will
1572 likely not work with most init systems.
1573 </para>
1574
1575 <para>
1576 Note that if two processes are in different user namespaces and one
1577 process wants to inherit the other's network namespace it usually
1578 needs to inherit the user namespace as well.
1579 </para>
1580 </listitem>
1581 </varlistentry>
1582 </variablelist>
1583 </refsect2>
1584
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WB
1585 <refsect2>
1586 <title>Resource limits</title>
1587 <para>
1588 The soft and hard resource limits for the container can be changed.
1589 Unprivileged containers can only lower them. Resources which are not
1590 explicitly specified will be inherited.
1591 </para>
1592 <variablelist>
1593 <varlistentry>
1594 <term>
240d4b74 1595 <option>lxc.prlimit.[limit name]</option>
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WB
1596 </term>
1597 <listitem>
1598 <para>
1599 Specify the resource limit to be set. A limit is specified as two
1600 colon separated values which are either numeric or the word
1601 'unlimited'. A single value can be used as a shortcut to set both
1602 soft and hard limit to the same value. The permitted names the
1603 "RLIMIT_" resource names in lowercase without the "RLIMIT_"
1604 prefix, eg. RLIMIT_NOFILE should be specified as "nofile". See
1605 <citerefentry>
1606 <refentrytitle><command>setrlimit</command></refentrytitle>
1607 <manvolnum>2</manvolnum>
1608 </citerefentry>.
1609 If used with no value, lxc will clear the resource limit
1610 specified up to this point. A resource with no explicitly
1611 configured limitation will be inherited from the process starting
1612 up the container.
1613 </para>
1614 </listitem>
1615 </varlistentry>
1616 </variablelist>
1617 </refsect2>
1618
7edd0540
L
1619 <refsect2>
1620 <title>Sysctl</title>
1621 <para>
1622 Configure kernel parameters for the container.
1623 </para>
1624 <variablelist>
1625 <varlistentry>
1626 <term>
1627 <option>lxc.sysctl.[kernel parameters name]</option>
1628 </term>
1629 <listitem>
1630 <para>
1631 Specify the kernel parameters to be set. The parameters available
1632 are those listed under /proc/sys/.
e409b214 1633 Note that not all sysctls are namespaced. Changing Non-namespaced
7edd0540
L
1634 sysctls will cause the system-wide setting to be modified.
1635 <citerefentry>
1636 <refentrytitle><command>sysctl</command></refentrytitle>
1637 <manvolnum>8</manvolnum>
1638 </citerefentry>.
1639 If used with no value, lxc will clear the parameters specified up
1640 to this point.
1641 </para>
1642 </listitem>
1643 </varlistentry>
1644 </variablelist>
1645 </refsect2>
1646
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SG
1647 <refsect2>
1648 <title>Apparmor profile</title>
1649 <para>
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SG
1650 If lxc was compiled and installed with apparmor support, and the host
1651 system has apparmor enabled, then the apparmor profile under which the
1652 container should be run can be specified in the container
7a126ae1
SH
1653 configuration. The default is <command>lxc-container-default-cgns</command>
1654 if the host kernel is cgroup namespace aware, or
1655 <command>lxc-container-default</command> othewise.
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SG
1656 </para>
1657 <variablelist>
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SG
1658 <varlistentry>
1659 <term>
a1d5fdfd 1660 <option>lxc.apparmor.profile</option>
c464fd7e
SG
1661 </term>
1662 <listitem>
1663 <para>
1664 Specify the apparmor profile under which the container should
1665 be run. To specify that the container should be unconfined,
1666 use
1667 </para>
a1d5fdfd 1668 <programlisting>lxc.apparmor.profile = unconfined</programlisting>
7a126ae1
SH
1669 <para>
1670 If the apparmor profile should remain unchanged (i.e. if you
1671 are nesting containers and are already confined), then use
1672 </para>
a1d5fdfd 1673 <programlisting>lxc.apparmor.profile = unchanged</programlisting>
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SG
1674 </listitem>
1675 </varlistentry>
1676 <varlistentry>
1677 <term>
69e38e00 1678 <option>lxc.apparmor.allow_incomplete</option>
c464fd7e
SG
1679 </term>
1680 <listitem>
1681 <para>
1682 Apparmor profiles are pathname based. Therefore many file
1683 restrictions require mount restrictions to be effective against
1684 a determined attacker. However, these mount restrictions are not
1685 yet implemented in the upstream kernel. Without the mount
1686 restrictions, the apparmor profiles still protect against accidental
1687 damager.
1688 </para>
1689 <para>
1690 If this flag is 0 (default), then the container will not be
1691 started if the kernel lacks the apparmor mount features, so that a
1692 regression after a kernel upgrade will be detected. To start the
1693 container under partial apparmor protection, set this flag to 1.
1694 </para>
1695 </listitem>
1696 </varlistentry>
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SG
1697 </variablelist>
1698 </refsect2>
1699
1700 <refsect2>
1701 <title>SELinux context</title>
1702 <para>
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SG
1703 If lxc was compiled and installed with SELinux support, and the host
1704 system has SELinux enabled, then the SELinux context under which the
1705 container should be run can be specified in the container
1706 configuration. The default is <command>unconfined_t</command>,
1707 which means that lxc will not attempt to change contexts.
1708 See @DATADIR@/lxc/selinux/lxc.te for an example policy and more
1709 information.
55fc19a1
SG
1710 </para>
1711 <variablelist>
c464fd7e
SG
1712 <varlistentry>
1713 <term>
b84702ab 1714 <option>lxc.selinux.context</option>
c464fd7e
SG
1715 </term>
1716 <listitem>
1717 <para>
1718 Specify the SELinux context under which the container should
1719 be run or <command>unconfined_t</command>. For example
1720 </para>
b84702ab 1721 <programlisting>lxc.selinux.context = system_u:system_r:lxc_t:s0:c22</programlisting>
c464fd7e
SG
1722 </listitem>
1723 </varlistentry>
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SG
1724 </variablelist>
1725 </refsect2>
1726
1727 <refsect2>
1728 <title>Seccomp configuration</title>
1729 <para>
1730 A container can be started with a reduced set of available
c464fd7e
SG
1731 system calls by loading a seccomp profile at startup. The
1732 seccomp configuration file must begin with a version number
1733 on the first line, a policy type on the second line, followed
1734 by the configuration.
55fc19a1 1735 </para>
a7c27357
SH
1736 <para>
1737 Versions 1 and 2 are currently supported. In version 1, the
c464fd7e
SG
1738 policy is a simple whitelist. The second line therefore must
1739 read "whitelist", with the rest of the file containing one (numeric)
1740 sycall number per line. Each syscall number is whitelisted,
1741 while every unlisted number is blacklisted for use in the container
a7c27357
SH
1742 </para>
1743
1744 <para>
1745 In version 2, the policy may be blacklist or whitelist,
1746 supports per-rule and per-policy default actions, and supports
1747 per-architecture system call resolution from textual names.
1748 </para>
1749 <para>
1750 An example blacklist policy, in which all system calls are
1751 allowed except for mknod, which will simply do nothing and
1752 return 0 (success), looks like:
1753 </para>
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CB
1754
1755 <programlisting>
1756 2
1757 blacklist
1758 mknod errno 0
1759 </programlisting>
1760
55fc19a1 1761 <variablelist>
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SG
1762 <varlistentry>
1763 <term>
0b427da0 1764 <option>lxc.seccomp.profile</option>
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SG
1765 </term>
1766 <listitem>
1767 <para>
1768 Specify a file containing the seccomp configuration to
1769 load before the container starts.
1770 </para>
1771 </listitem>
1772 </varlistentry>
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SG
1773 </variablelist>
1774 </refsect2>
1775
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CB
1776 <refsect2>
1777 <title>PR_SET_NO_NEW_PRIVS</title>
1778 <para>
1779 With PR_SET_NO_NEW_PRIVS active execve() promises not to grant
1780 privileges to do anything that could not have been done without
1781 the execve() call (for example, rendering the set-user-ID and
1782 set-group-ID mode bits, and file capabilities non-functional).
1783 Once set, this bit cannot be unset. The setting of this bit is
1784 inherited by children created by fork() and clone(), and preserved
1785 across execve().
1786 Note that PR_SET_NO_NEW_PRIVS is applied after the container has
1787 changed into its intended AppArmor profile or SElinux context.
1788 </para>
1789 <variablelist>
1790 <varlistentry>
1791 <term>
1792 <option>lxc.no_new_privs</option>
1793 </term>
1794 <listitem>
1795 <para>
1796 Specify whether the PR_SET_NO_NEW_PRIVS flag should be set for the
1797 container. Set to 1 to activate.
1798 </para>
1799 </listitem>
1800 </varlistentry>
1801 </variablelist>
1802 </refsect2>
1803
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1804 <refsect2>
1805 <title>UID mappings</title>
1806 <para>
1807 A container can be started in a private user namespace with
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SG
1808 user and group id mappings. For instance, you can map userid
1809 0 in the container to userid 200000 on the host. The root
1810 user in the container will be privileged in the container,
1811 but unprivileged on the host. Normally a system container
1812 will want a range of ids, so you would map, for instance,
1813 user and group ids 0 through 20,000 in the container to the
1814 ids 200,000 through 220,000.
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SG
1815 </para>
1816 <variablelist>
c464fd7e
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1817 <varlistentry>
1818 <term>
bdcbb6b3 1819 <option>lxc.idmap</option>
c464fd7e
SG
1820 </term>
1821 <listitem>
1822 <para>
1823 Four values must be provided. First a character, either
1824 'u', or 'g', to specify whether user or group ids are
1825 being mapped. Next is the first userid as seen in the
1826 user namespace of the container. Next is the userid as
1827 seen on the host. Finally, a range indicating the number
1828 of consecutive ids to map.
1829 </para>
1830 </listitem>
1831 </varlistentry>
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SG
1832 </variablelist>
1833 </refsect2>
1834
1835 <refsect2>
1836 <title>Container hooks</title>
1837 <para>
1838 Container hooks are programs or scripts which can be executed
c464fd7e 1839 at various times in a container's lifetime.
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SG
1840 </para>
1841 <para>
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CB
1842 When a container hook is executed, additional information is passed
1843 along. The <option>lxc.hook.version</option> argument can be used to
1844 determine if the following arguments are passed as command line
1845 arguments or through environment variables. The arguments are:
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SG
1846 <itemizedlist>
1847 <listitem><para> Container name. </para></listitem>
1848 <listitem><para> Section (always 'lxc'). </para></listitem>
1849 <listitem><para> The hook type (i.e. 'clone' or 'pre-mount'). </para></listitem>
0a2b5ab1 1850 <listitem><para> Additional arguments. In the
c464fd7e 1851 case of the clone hook, any extra arguments passed to
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WB
1852 lxc-clone will appear as further arguments to the hook.
1853 In the case of the stop hook, paths to filedescriptors
1854 for each of the container's namespaces along with their types
1855 are passed. </para></listitem>
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SG
1856 </itemizedlist>
1857 The following environment variables are set:
1858 <itemizedlist>
44ae0fb6
CB
1859 <listitem><para> LXC_CGNS_AWARE: indicator whether the container is
1860 cgroup namespace aware. </para></listitem>
1861 <listitem><para> LXC_CONFIG_FILE: the path to the container
1862 configuration file. </para></listitem>
1863 <listitem><para> LXC_HOOK_TYPE: the hook type (e.g. 'clone', 'mount',
1864 'pre-mount'). Note that the existence of this environment variable is
1865 conditional on the value of <option>lxc.hook.version</option>. If it
1866 is set to 1 then LXC_HOOK_TYPE will be set.
1867 </para></listitem>
1868 <listitem><para> LXC_HOOK_SECTION: the section type (e.g. 'lxc',
1869 'net'). Note that the existence of this environment variable is
1870 conditional on the value of <option>lxc.hook.version</option>. If it
1871 is set to 1 then LXC_HOOK_SECTION will be set.
1872 </para></listitem>
a2c09be0
CB
1873 <listitem><para> LXC_HOOK_VERSION: the version of the hooks. This
1874 value is identical to the value of the container's
1875 <option>lxc.hook.version</option> config item. If it is set to 0 then
1876 old-style hooks are used. If it is set to 1 then new-style hooks are
1877 used. </para></listitem>
44ae0fb6 1878 <listitem><para> LXC_LOG_LEVEL: the container's log level. </para></listitem>
c464fd7e 1879 <listitem><para> LXC_NAME: is the container's name. </para></listitem>
18b3b9c1
CB
1880 <listitem><para> LXC_[NAMESPACE IDENTIFIER]_NS: path under
1881 /proc/PID/fd/ to a file descriptor referring to the container's
1882 namespace. For each preserved namespace type there will be a separate
1883 environment variable. These environment variables will only be set if
1884 <option>lxc.hook.version</option> is set to 1. </para></listitem>
c464fd7e 1885 <listitem><para> LXC_ROOTFS_MOUNT: the path to the mounted root filesystem. </para></listitem>
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CB
1886 <listitem><para> LXC_ROOTFS_PATH: this is the lxc.rootfs.path entry
1887 for the container. Note this is likely not where the mounted rootfs is
1888 to be found, use LXC_ROOTFS_MOUNT for that. </para></listitem>
1889 <listitem><para> LXC_SRC_NAME: in the case of the clone hook, this is
1890 the original container's name. </para></listitem>
c464fd7e 1891 </itemizedlist>
55fc19a1
SG
1892 </para>
1893 <para>
1894 Standard output from the hooks is logged at debug level.
1895 Standard error is not logged, but can be captured by the
1896 hook redirecting its standard error to standard output.
1897 </para>
1898 <variablelist>
44ae0fb6
CB
1899 <varlistentry>
1900 <term>
1901 <option>lxc.hook.version</option>
1902 </term>
1903 <listitem>
1904 <para>
1905 To pass the arguments in new style via environment variables set to
1906 1 otherwise set to 0 to pass them as arguments.
1907 This setting affects all hooks arguments that were traditionally
1908 passed as arguments to the script. Specifically, it affects the
1909 container name, section (e.g. 'lxc', 'net') and hook type (e.g.
1910 'clone', 'mount', 'pre-mount') arguments. If new-style hooks are
1911 used then the arguments will be available as environment variables.
1912 The container name will be set in LXC_NAME. (This is set
1913 independently of the value used for this config item.) The section
1914 will be set in LXC_HOOK_SECTION and the hook type will be set in
1915 LXC_HOOK_TYPE.
18b3b9c1
CB
1916 It also affects how the paths to file descriptors referring to the
1917 container's namespaces are passed. If set to 1 then for each
1918 namespace a separate environment variable LXC_[NAMESPACE
1919 IDENTIFIER]_NS will be set. If set to 0 then the paths will be
1920 passed as arguments to the stop hook.
44ae0fb6
CB
1921 </para>
1922 </listitem>
1923 </varlistentry>
1924 </variablelist>
1925 <variablelist>
c464fd7e
SG
1926 <varlistentry>
1927 <term>
1928 <option>lxc.hook.pre-start</option>
1929 </term>
1930 <listitem>
1931 <para>
1932 A hook to be run in the host's namespace before the
1933 container ttys, consoles, or mounts are up.
1934 </para>
1935 </listitem>
1936 </varlistentry>
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SG
1937 </variablelist>
1938 <variablelist>
c464fd7e
SG
1939 <varlistentry>
1940 <term>
1941 <option>lxc.hook.pre-mount</option>
1942 </term>
1943 <listitem>
1944 <para>
1945 A hook to be run in the container's fs namespace but before
1946 the rootfs has been set up. This allows for manipulation
1947 of the rootfs, i.e. to mount an encrypted filesystem. Mounts
1948 done in this hook will not be reflected on the host (apart from
1949 mounts propagation), so they will be automatically cleaned up
1950 when the container shuts down.
1951 </para>
1952 </listitem>
1953 </varlistentry>
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SG
1954 </variablelist>
1955 <variablelist>
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SG
1956 <varlistentry>
1957 <term>
1958 <option>lxc.hook.mount</option>
1959 </term>
1960 <listitem>
1961 <para>
1962 A hook to be run in the container's namespace after
1963 mounting has been done, but before the pivot_root.
1964 </para>
1965 </listitem>
1966 </varlistentry>
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SG
1967 </variablelist>
1968 <variablelist>
c464fd7e
SG
1969 <varlistentry>
1970 <term>
1971 <option>lxc.hook.autodev</option>
1972 </term>
1973 <listitem>
1974 <para>
1975 A hook to be run in the container's namespace after
1976 mounting has been done and after any mount hooks have
1977 run, but before the pivot_root, if
1978 <option>lxc.autodev</option> == 1.
1979 The purpose of this hook is to assist in populating the
1980 /dev directory of the container when using the autodev
1981 option for systemd based containers. The container's /dev
1982 directory is relative to the
1983 ${<option>LXC_ROOTFS_MOUNT</option>} environment
1984 variable available when the hook is run.
1985 </para>
1986 </listitem>
1987 </varlistentry>
55fc19a1 1988 </variablelist>
08dd2805
SH
1989 <variablelist>
1990 <varlistentry>
1991 <term>
1992 <option>lxc.hook.start-host</option>
1993 </term>
1994 <listitem>
1995 <para>
1996 A hook to be run in the host's namespace after the
1997 container has been setup, and immediately before starting
1998 the container init.
1999 </para>
2000 </listitem>
2001 </varlistentry>
2002 </variablelist>
55fc19a1 2003 <variablelist>
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SG
2004 <varlistentry>
2005 <term>
2006 <option>lxc.hook.start</option>
2007 </term>
2008 <listitem>
2009 <para>
2010 A hook to be run in the container's namespace immediately
2011 before executing the container's init. This requires the
2012 program to be available in the container.
2013 </para>
2014 </listitem>
2015 </varlistentry>
55fc19a1 2016 </variablelist>
0a2b5ab1
WB
2017 <variablelist>
2018 <varlistentry>
2019 <term>
2020 <option>lxc.hook.stop</option>
2021 </term>
2022 <listitem>
2023 <para>
2024 A hook to be run in the host's namespace with references
2025 to the container's namespaces after the container has been shut
2026 down. For each namespace an extra argument is passed to the hook
2027 containing the namespace's type and a filename that can be used to
2028 obtain a file descriptor to the corresponding namespace, separated
2029 by a colon. The type is the name as it would appear in the
2030 <filename>/proc/PID/ns</filename> directory.
2031 For instance for the mount namespace the argument usually looks
2032 like <filename>mnt:/proc/PID/fd/12</filename>.
2033 </para>
2034 </listitem>
2035 </varlistentry>
2036 </variablelist>
55fc19a1 2037 <variablelist>
c464fd7e
SG
2038 <varlistentry>
2039 <term>
2040 <option>lxc.hook.post-stop</option>
2041 </term>
2042 <listitem>
2043 <para>
2044 A hook to be run in the host's namespace after the
2045 container has been shut down.
2046 </para>
2047 </listitem>
2048 </varlistentry>
55fc19a1
SG
2049 </variablelist>
2050 <variablelist>
c464fd7e
SG
2051 <varlistentry>
2052 <term>
2053 <option>lxc.hook.clone</option>
2054 </term>
2055 <listitem>
2056 <para>
2057 A hook to be run when the container is cloned to a new one.
2058 See <citerefentry><refentrytitle><command>lxc-clone</command></refentrytitle>
2059 <manvolnum>1</manvolnum></citerefentry> for more information.
2060 </para>
2061 </listitem>
2062 </varlistentry>
55fc19a1 2063 </variablelist>
37cf711b
SY
2064 <variablelist>
2065 <varlistentry>
2066 <term>
2067 <option>lxc.hook.destroy</option>
2068 </term>
2069 <listitem>
2070 <para>
2071 A hook to be run when the container is destroyed.
2072 </para>
2073 </listitem>
2074 </varlistentry>
2075 </variablelist>
55fc19a1
SG
2076 </refsect2>
2077
2078 <refsect2>
2079 <title>Container hooks Environment Variables</title>
2080 <para>
2081 A number of environment variables are made available to the startup
2082 hooks to provide configuration information and assist in the
2083 functioning of the hooks. Not all variables are valid in all
2084 contexts. In particular, all paths are relative to the host system
2085 and, as such, not valid during the <option>lxc.hook.start</option> hook.
2086 </para>
2087 <variablelist>
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SG
2088 <varlistentry>
2089 <term>
2090 <option>LXC_NAME</option>
2091 </term>
2092 <listitem>
2093 <para>
2094 The LXC name of the container. Useful for logging messages
2095 in common log environments. [<option>-n</option>]
2096 </para>
2097 </listitem>
2098 </varlistentry>
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SG
2099 </variablelist>
2100 <variablelist>
c464fd7e
SG
2101 <varlistentry>
2102 <term>
2103 <option>LXC_CONFIG_FILE</option>
2104 </term>
2105 <listitem>
2106 <para>
2107 Host relative path to the container configuration file. This
2108 gives the container to reference the original, top level,
2109 configuration file for the container in order to locate any
2110 additional configuration information not otherwise made
2111 available. [<option>-f</option>]
2112 </para>
2113 </listitem>
2114 </varlistentry>
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SG
2115 </variablelist>
2116 <variablelist>
c464fd7e
SG
2117 <varlistentry>
2118 <term>
2119 <option>LXC_CONSOLE</option>
2120 </term>
2121 <listitem>
2122 <para>
2123 The path to the console output of the container if not NULL.
3aed4934 2124 [<option>-c</option>] [<option>lxc.console.path</option>]
c464fd7e
SG
2125 </para>
2126 </listitem>
2127 </varlistentry>
55fc19a1
SG
2128 </variablelist>
2129 <variablelist>
c464fd7e
SG
2130 <varlistentry>
2131 <term>
2132 <option>LXC_CONSOLE_LOGPATH</option>
2133 </term>
2134 <listitem>
2135 <para>
2136 The path to the console log output of the container if not NULL.
2137 [<option>-L</option>]
2138 </para>
2139 </listitem>
2140 </varlistentry>
55fc19a1
SG
2141 </variablelist>
2142 <variablelist>
c464fd7e
SG
2143 <varlistentry>
2144 <term>
2145 <option>LXC_ROOTFS_MOUNT</option>
2146 </term>
2147 <listitem>
2148 <para>
2149 The mount location to which the container is initially bound.
2150 This will be the host relative path to the container rootfs
2151 for the container instance being started and is where changes
2152 should be made for that instance.
2153 [<option>lxc.rootfs.mount</option>]
2154 </para>
2155 </listitem>
2156 </varlistentry>
55fc19a1
SG
2157 </variablelist>
2158 <variablelist>
c464fd7e
SG
2159 <varlistentry>
2160 <term>
2161 <option>LXC_ROOTFS_PATH</option>
2162 </term>
2163 <listitem>
2164 <para>
2165 The host relative path to the container root which has been
2166 mounted to the rootfs.mount location.
7a96a068 2167 [<option>lxc.rootfs.path</option>]
c464fd7e
SG
2168 </para>
2169 </listitem>
2170 </varlistentry>
55fc19a1 2171 </variablelist>
07945418
KY
2172 <variablelist>
2173 <varlistentry>
2174 <term>
2175 <option>LXC_SRC_NAME</option>
2176 </term>
2177 <listitem>
2178 <para>
2179 Only for the clone hook. Is set to the original container name.
2180 </para>
2181 </listitem>
2182 </varlistentry>
2183 </variablelist>
c154af98
SG
2184 <variablelist>
2185 <varlistentry>
2186 <term>
2187 <option>LXC_TARGET</option>
2188 </term>
2189 <listitem>
2190 <para>
2191 Only for the stop hook. Is set to "stop" for a container
2192 shutdown or "reboot" for a container reboot.
2193 </para>
2194 </listitem>
2195 </varlistentry>
c4cafa08
SH
2196 </variablelist>
2197 <variablelist>
2198 <varlistentry>
2199 <term>
2200 <option>LXC_CGNS_AWARE</option>
2201 </term>
2202 <listitem>
2203 <para>
2204 If unset, then this version of lxc is not aware of cgroup
2205 namespaces. If set, it will be set to 1, and lxc is aware
2206 of cgroup namespaces. Note this does not guarantee that
2207 cgroup namespaces are enabled in the kernel. This is used
2208 by the lxcfs mount hook.
2209 </para>
2210 </listitem>
2211 </varlistentry>
c154af98 2212 </variablelist>
55fc19a1
SG
2213 </refsect2>
2214 <refsect2>
2215 <title>Logging</title>
2216 <para>
2217 Logging can be configured on a per-container basis. By default,
2218 depending upon how the lxc package was compiled, container startup
2219 is logged only at the ERROR level, and logged to a file named after
2220 the container (with '.log' appended) either under the container path,
2221 or under @LOGPATH@.
2222 </para>
2223 <para>
2224 Both the default log level and the log file can be specified in the
2225 container configuration file, overriding the default behavior. Note
2226 that the configuration file entries can in turn be overridden by the
2227 command line options to <command>lxc-start</command>.
2228 </para>
2229 <variablelist>
c464fd7e
SG
2230 <varlistentry>
2231 <term>
46cc906d 2232 <option>lxc.log.level</option>
c464fd7e
SG
2233 </term>
2234 <listitem>
2235 <para>
2236 The level at which to log. The log level is an integer in
2237 the range of 0..8 inclusive, where a lower number means more
2238 verbose debugging. In particular 0 = trace, 1 = debug, 2 =
2239 info, 3 = notice, 4 = warn, 5 = error, 6 = critical, 7 =
2240 alert, and 8 = fatal. If unspecified, the level defaults
2241 to 5 (error), so that only errors and above are logged.
2242 </para>
2243 <para>
2244 Note that when a script (such as either a hook script or a
2245 network interface up or down script) is called, the script's
2246 standard output is logged at level 1, debug.
2247 </para>
2248 </listitem>
2249 </varlistentry>
2250 <varlistentry>
2251 <term>
5757588f 2252 <option>lxc.log.file</option>
c464fd7e
SG
2253 </term>
2254 <listitem>
2255 <para>
2256 The file to which logging info should be written.
2257 </para>
2258 </listitem>
2259 </varlistentry>
204dfdf2
BD
2260 <varlistentry>
2261 <term>
46cc906d 2262 <option>lxc.log.syslog</option>
204dfdf2
BD
2263 </term>
2264 <listitem>
2265 <para>
2266 Send logging info to syslog. It respects the log level defined in
46cc906d 2267 <command>lxc.log.level</command>. The argument should be the syslog
204dfdf2 2268 facility to use, valid ones are: daemon, local0, local1, local2,
917420dd 2269 local3, local4, local5, local5, local6, local7.
204dfdf2
BD
2270 </para>
2271 </listitem>
2272 </varlistentry>
55fc19a1
SG
2273 </variablelist>
2274 </refsect2>
2275
2276 <refsect2>
2277 <title>Autostart</title>
2278 <para>
2279 The autostart options support marking which containers should be
2280 auto-started and in what order. These options may be used by LXC tools
2281 directly or by external tooling provided by the distributions.
2282 </para>
2283
2284 <variablelist>
2285 <varlistentry>
2286 <term>
2287 <option>lxc.start.auto</option>
2288 </term>
2289 <listitem>
2290 <para>
2291 Whether the container should be auto-started.
2292 Valid values are 0 (off) and 1 (on).
2293 </para>
2294 </listitem>
2295 </varlistentry>
2296 <varlistentry>
2297 <term>
2298 <option>lxc.start.delay</option>
2299 </term>
2300 <listitem>
2301 <para>
2302 How long to wait (in seconds) after the container is
2303 started before starting the next one.
2304 </para>
2305 </listitem>
2306 </varlistentry>
2307 <varlistentry>
2308 <term>
2309 <option>lxc.start.order</option>
2310 </term>
2311 <listitem>
2312 <para>
2313 An integer used to sort the containers when auto-starting
2314 a series of containers at once.
2315 </para>
2316 </listitem>
2317 </varlistentry>
a8dfe4e0
WB
2318 <varlistentry>
2319 <term>
2320 <option>lxc.monitor.unshare</option>
2321 </term>
2322 <listitem>
2323 <para>
2324 If not zero the mount namespace will be unshared from the host
2325 before initializing the container (before running any pre-start
6039eaa2
WB
2326 hooks). This requires the CAP_SYS_ADMIN capability at startup.
2327 Default is 0.
a8dfe4e0
WB
2328 </para>
2329 </listitem>
2330 </varlistentry>
55fc19a1
SG
2331 <varlistentry>
2332 <term>
2333 <option>lxc.group</option>
2334 </term>
2335 <listitem>
2336 <para>
2337 A multi-value key (can be used multiple times) to put the
2338 container in a container group. Those groups can then be
2339 used (amongst other things) to start a series of related
2340 containers.
2341 </para>
2342 </listitem>
2343 </varlistentry>
2344 </variablelist>
2345 </refsect2>
015f0dd7
MW
2346
2347 <refsect2>
2348 <title>Autostart and System Boot</title>
2349 <para>
2350 Each container can be part of any number of groups or no group at all.
2351 Two groups are special. One is the NULL group, i.e. the container does
2352 not belong to any group. The other group is the "onboot" group.
2353 </para>
2354
2355 <para>
2356 When the system boots with the LXC service enabled, it will first
2357 attempt to boot any containers with lxc.start.auto == 1 that is a member
2358 of the "onboot" group. The startup will be in order of lxc.start.order.
2359 If an lxc.start.delay has been specified, that delay will be honored
2360 before attempting to start the next container to give the current
2361 container time to begin initialization and reduce overloading the host
2362 system. After starting the members of the "onboot" group, the LXC system
2363 will proceed to boot containers with lxc.start.auto == 1 which are not
2364 members of any group (the NULL group) and proceed as with the onboot
2365 group.
2366 </para>
2367
2368 </refsect2>
7c661726
MP
2369
2370 <refsect2>
2371 <title>Container Environment</title>
2372 <para>
c464fd7e
SG
2373 If you want to pass environment variables into the container (that
2374 is, environment variables which will be available to init and all of
2375 its descendents), you can use <command>lxc.environment</command>
2376 parameters to do so. Be careful that you do not pass in anything
2377 sensitive; any process in the container which doesn't have its
2378 environment scrubbed will have these variables available to it, and
2379 environment variables are always available via
2380 <command>/proc/PID/environ</command>.
7c661726
MP
2381 </para>
2382
2383 <para>
2384 This configuration parameter can be specified multiple times; once
2385 for each environment variable you wish to configure.
2386 </para>
2387
2388 <variablelist>
c464fd7e
SG
2389 <varlistentry>
2390 <term>
2391 <option>lxc.environment</option>
2392 </term>
2393 <listitem>
2394 <para>
2395 Specify an environment variable to pass into the container.
2396 Example:
2397 </para>
2398 <programlisting>
2399 lxc.environment = APP_ENV=production
2400 lxc.environment = SYSLOG_SERVER=192.0.2.42
2401 </programlisting>
2402 </listitem>
2403 </varlistentry>
7c661726
MP
2404 </variablelist>
2405 </refsect2>
2406
55fc19a1
SG
2407 </refsect1>
2408
2409 <refsect1>
2410 <title>Examples</title>
2411 <para>
c464fd7e
SG
2412 In addition to the few examples given below, you will find
2413 some other examples of configuration file in @DOCDIR@/examples
55fc19a1
SG
2414 </para>
2415 <refsect2>
2416 <title>Network</title>
2417 <para>This configuration sets up a container to use a veth pair
c464fd7e
SG
2418 device with one side plugged to a bridge br0 (which has been
2419 configured before on the system by the administrator). The
2420 virtual network device visible in the container is renamed to
2421 eth0.</para>
55fc19a1 2422 <programlisting>
b67771bc 2423 lxc.uts.name = myhostname
7fa3f2e9 2424 lxc.net.0.type = veth
2425 lxc.net.0.flags = up
2426 lxc.net.0.link = br0
2427 lxc.net.0.name = eth0
2428 lxc.net.0.hwaddr = 4a:49:43:49:79:bf
9ff60df2 2429 lxc.net.0.ipv4.address = 10.2.3.5/24 10.2.3.255
2e44ae28 2430 lxc.net.0.ipv6.address = 2003:db8:1:0:214:1234:fe0b:3597
55fc19a1
SG
2431 </programlisting>
2432 </refsect2>
2433
2434 <refsect2>
2435 <title>UID/GID mapping</title>
2436 <para>This configuration will map both user and group ids in the
2437 range 0-9999 in the container to the ids 100000-109999 on the host.
2438 </para>
2439 <programlisting>
bdcbb6b3
CB
2440 lxc.idmap = u 0 100000 10000
2441 lxc.idmap = g 0 100000 10000
55fc19a1
SG
2442 </programlisting>
2443 </refsect2>
2444
2445 <refsect2>
2446 <title>Control group</title>
2447 <para>This configuration will setup several control groups for
2448 the application, cpuset.cpus restricts usage of the defined cpu,
2449 cpus.share prioritize the control group, devices.allow makes
2450 usable the specified devices.</para>
2451 <programlisting>
c464fd7e
SG
2452 lxc.cgroup.cpuset.cpus = 0,1
2453 lxc.cgroup.cpu.shares = 1234
2454 lxc.cgroup.devices.deny = a
2455 lxc.cgroup.devices.allow = c 1:3 rw
2456 lxc.cgroup.devices.allow = b 8:0 rw
55fc19a1
SG
2457 </programlisting>
2458 </refsect2>
2459
2460 <refsect2>
2461 <title>Complex configuration</title>
2462 <para>This example show a complex configuration making a complex
2463 network stack, using the control groups, setting a new hostname,
2464 mounting some locations and a changing root file system.</para>
2465 <programlisting>
b67771bc 2466 lxc.uts.name = complex
7fa3f2e9 2467 lxc.net.0.type = veth
2468 lxc.net.0.flags = up
2469 lxc.net.0.link = br0
2470 lxc.net.0.hwaddr = 4a:49:43:49:79:bf
9ff60df2 2471 lxc.net.0.ipv4.address = 10.2.3.5/24 10.2.3.255
2e44ae28
CB
2472 lxc.net.0.ipv6.address = 2003:db8:1:0:214:1234:fe0b:3597
2473 lxc.net.0.ipv6.address = 2003:db8:1:0:214:5432:feab:3588
7fa3f2e9 2474 lxc.net.1.type = macvlan
2475 lxc.net.1.flags = up
2476 lxc.net.1.link = eth0
2477 lxc.net.1.hwaddr = 4a:49:43:49:79:bd
9ff60df2
CB
2478 lxc.net.1.ipv4.address = 10.2.3.4/24
2479 lxc.net.1.ipv4.address = 192.168.10.125/24
2e44ae28 2480 lxc.net.1.ipv6.address = 2003:db8:1:0:214:1234:fe0b:3596
7fa3f2e9 2481 lxc.net.2.type = phys
2482 lxc.net.2.flags = up
2483 lxc.net.2.link = dummy0
2484 lxc.net.2.hwaddr = 4a:49:43:49:79:ff
9ff60df2 2485 lxc.net.2.ipv4.address = 10.2.3.6/24
2e44ae28 2486 lxc.net.2.ipv6.address = 2003:db8:1:0:214:1234:fe0b:3297
c464fd7e
SG
2487 lxc.cgroup.cpuset.cpus = 0,1
2488 lxc.cgroup.cpu.shares = 1234
2489 lxc.cgroup.devices.deny = a
2490 lxc.cgroup.devices.allow = c 1:3 rw
2491 lxc.cgroup.devices.allow = b 8:0 rw
47148e96 2492 lxc.mount.fstab = /etc/fstab.complex
c464fd7e 2493 lxc.mount.entry = /lib /root/myrootfs/lib none ro,bind 0 0
7a96a068 2494 lxc.rootfs.path = dir:/mnt/rootfs.complex
c464fd7e
SG
2495 lxc.cap.drop = sys_module mknod setuid net_raw
2496 lxc.cap.drop = mac_override
55fc19a1
SG
2497 </programlisting>
2498 </refsect2>
2499
2500 </refsect1>
2501
2502 <refsect1>
2503 <title>See Also</title>
2504 <simpara>
2505 <citerefentry>
c464fd7e
SG
2506 <refentrytitle><command>chroot</command></refentrytitle>
2507 <manvolnum>1</manvolnum>
55fc19a1
SG
2508 </citerefentry>,
2509
2510 <citerefentry>
c464fd7e
SG
2511 <refentrytitle><command>pivot_root</command></refentrytitle>
2512 <manvolnum>8</manvolnum>
55fc19a1
SG
2513 </citerefentry>,
2514
2515 <citerefentry>
c464fd7e
SG
2516 <refentrytitle><filename>fstab</filename></refentrytitle>
2517 <manvolnum>5</manvolnum>
55fc19a1
SG
2518 </citerefentry>,
2519
2520 <citerefentry>
c464fd7e
SG
2521 <refentrytitle><filename>capabilities</filename></refentrytitle>
2522 <manvolnum>7</manvolnum>
55fc19a1
SG
2523 </citerefentry>
2524 </simpara>
2525 </refsect1>
2526
2527 &seealso;
2528
2529 <refsect1>
2530 <title>Author</title>
2531 <para>Daniel Lezcano <email>daniel.lezcano@free.fr</email></para>
2532 </refsect1>
2533
2534</refentry>
2535
2536<!-- Keep this comment at the end of the file
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2549sgml-local-ecat-files:nil
2550End:
2551-->