pve-package-repos.adoc: add section about SecureApt
[pve-docs.git] / pct.adoc
CommitLineData
0c6b782f
DM
1ifdef::manvolnum[]
2PVE({manvolnum})
3================
38fd0958 4include::attributes.txt[]
0c6b782f
DM
5
6NAME
7----
8
9pct - Tool to manage Linux Containers (LXC) on Proxmox VE
10
11
12SYNOPSYS
13--------
14
15include::pct.1-synopsis.adoc[]
16
17DESCRIPTION
18-----------
19endif::manvolnum[]
20
21ifndef::manvolnum[]
22Proxmox Container Toolkit
23=========================
38fd0958 24include::attributes.txt[]
0c6b782f
DM
25endif::manvolnum[]
26
4a2ae9ed
DM
27
28Containers are a lightweight alternative to fully virtualized
29VMs. Instead of emulating a complete Operating System (OS), containers
30simply use the OS of the host they run on. This implies that all
31containers use the same kernel, and that they can access resources
32from the host directly.
33
34This is great because containers do not waste CPU power nor memory due
35to kernel emulation. Container run-time costs are close to zero and
36usually negligible. But there are also some drawbacks you need to
37consider:
38
39* You can only run Linux based OS inside containers, i.e. it is not
a8e99754 40 possible to run FreeBSD or MS Windows inside.
4a2ae9ed 41
a8e99754 42* For security reasons, access to host resources needs to be
4a2ae9ed 43 restricted. This is done with AppArmor, SecComp filters and other
a8e99754 44 kernel features. Be prepared that some syscalls are not allowed
4a2ae9ed
DM
45 inside containers.
46
47{pve} uses https://linuxcontainers.org/[LXC] as underlying container
48technology. We consider LXC as low-level library, which provides
a8e99754 49countless options. It would be too difficult to use those tools
4a2ae9ed
DM
50directly. Instead, we provide a small wrapper called `pct`, the
51"Proxmox Container Toolkit".
52
a8e99754 53The toolkit is tightly coupled with {pve}. That means that it is aware
4a2ae9ed
DM
54of the cluster setup, and it can use the same network and storage
55resources as fully virtualized VMs. You can even use the {pve}
56firewall, or manage containers using the HA framework.
57
58Our primary goal is to offer an environment as one would get from a
59VM, but without the additional overhead. We call this "System
60Containers".
61
99d2e25b 62NOTE: If you want to run micro-containers (with docker, rkt, ...), it
70a42028 63is best to run them inside a VM.
4a2ae9ed
DM
64
65
66Security Considerations
67-----------------------
68
69Containers use the same kernel as the host, so there is a big attack
70surface for malicious users. You should consider this fact if you
71provide containers to totally untrusted people. In general, fully
a8e99754 72virtualized VMs provide better isolation.
4a2ae9ed
DM
73
74The good news is that LXC uses many kernel security features like
75AppArmor, CGroups and PID and user namespaces, which makes containers
76usage quite secure. We distinguish two types of containers:
77
78Privileged containers
79~~~~~~~~~~~~~~~~~~~~~
80
81Security is done by dropping capabilities, using mandatory access
82control (AppArmor), SecComp filters and namespaces. The LXC team
83considers this kind of container as unsafe, and they will not consider
84new container escape exploits to be security issues worthy of a CVE
85and quick fix. So you should use this kind of containers only inside a
86trusted environment, or when no untrusted task is running as root in
87the container.
88
89Unprivileged containers
90~~~~~~~~~~~~~~~~~~~~~~~
91
a8e99754 92This kind of containers use a new kernel feature called user
4a2ae9ed
DM
93namespaces. The root uid 0 inside the container is mapped to an
94unprivileged user outside the container. This means that most security
95issues (container escape, resource abuse, ...) in those containers
96will affect a random unprivileged user, and so would be a generic
a8e99754 97kernel security bug rather than an LXC issue. The LXC team thinks
4a2ae9ed
DM
98unprivileged containers are safe by design.
99
7fc230db
DM
100
101Configuration
102-------------
103
166e63d6
FG
104The '/etc/pve/lxc/<CTID>.conf' file stores container configuration,
105where '<CTID>' is the numeric ID of the given container. Like all
106other files stored inside '/etc/pve/', they get automatically
107replicated to all other cluster nodes.
108
109NOTE: CTIDs < 100 are reserved for internal purposes, and CTIDs need to be
110unique cluster wide.
7fc230db 111
105bc8f1
DM
112.Example Container Configuration
113----
114ostype: debian
115arch: amd64
116hostname: www
117memory: 512
118swap: 512
119net0: bridge=vmbr0,hwaddr=66:64:66:64:64:36,ip=dhcp,name=eth0,type=veth
120rootfs: local:107/vm-107-disk-1.raw,size=7G
121----
122
7fc230db 123Those configuration files are simple text files, and you can edit them
55fb2a21
DM
124using a normal text editor ('vi', 'nano', ...). This is sometimes
125useful to do small corrections, but keep in mind that you need to
126restart the container to apply such changes.
127
128For that reason, it is usually better to use the 'pct' command to
129generate and modify those files, or do the whole thing using the GUI.
130Our toolkit is smart enough to instantaneously apply most changes to
105bc8f1
DM
131running containers. This feature is called "hot plug", and there is no
132need to restart the container in that case.
7fc230db
DM
133
134File Format
135~~~~~~~~~~~
136
137Container configuration files use a simple colon separated key/value
138format. Each line has the following format:
139
140 # this is a comment
141 OPTION: value
142
143Blank lines in those files are ignored, and lines starting with a '#'
144character are treated as comments and are also ignored.
145
146It is possible to add low-level, LXC style configuration directly, for
147example:
148
149 lxc.init_cmd: /sbin/my_own_init
150
151or
152
153 lxc.init_cmd = /sbin/my_own_init
154
155Those settings are directly passed to the LXC low-level tools.
156
105bc8f1
DM
157Snapshots
158~~~~~~~~~
159
160When you create a snapshot, 'pct' stores the configuration at snapshot
161time into a separate snapshot section within the same configuration
162file. For example, after creating a snapshot called 'testsnapshot',
163your configuration file will look like this:
164
165.Container Configuration with Snapshot
166----
167memory: 512
168swap: 512
169parent: testsnaphot
170...
171
172[testsnaphot]
173memory: 512
174swap: 512
175snaptime: 1457170803
176...
177----
178
a8e99754
FG
179There are a few snapshot related properties like 'parent' and
180'snaptime'. The 'parent' property is used to store the parent/child
105bc8f1
DM
181relationship between snapshots. 'snaptime' is the snapshot creation
182time stamp (unix epoch).
7fc230db 183
3f13c1c3
DM
184Guest Operating System Configuration
185~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
186
187We normally try to detect the operating system type inside the
188container, and then modify some files inside the container to make
189them work as expected. Here is a short list of things we do at
190container startup:
191
192set /etc/hostname:: to set the container name
193
a8e99754 194modify /etc/hosts:: to allow lookup of the local hostname
3f13c1c3
DM
195
196network setup:: pass the complete network setup to the container
197
198configure DNS:: pass information about DNS servers
199
a8e99754 200adapt the init system:: for example, fix the number of spawned getty processes
3f13c1c3
DM
201
202set the root password:: when creating a new container
203
204rewrite ssh_host_keys:: so that each container has unique keys
205
a8e99754 206randomize crontab:: so that cron does not start at the same time on all containers
3f13c1c3 207
25535d34
WB
208Changes made by {PVE} are enclosed by comment markers:
209
37638f59
DM
210----
211# --- BEGIN PVE ---
212<data>
213# --- END PVE ---
214----
25535d34 215
37638f59
DM
216Those markers will be inserted at a reasonable location in the
217file. If such a section already exists, it will be updated in place
218and will not be moved.
25535d34 219
37638f59
DM
220Modification of a file can be prevented by adding a `.pve-ignore.`
221file for it. For instance, if the file `/etc/.pve-ignore.hosts`
222exists then the `/etc/hosts` file will not be touched. This can be a
223simple empty file creatd via:
25535d34
WB
224
225 # touch /etc/.pve-ignore.hosts
226
37638f59
DM
227Most modifications are OS dependent, so they differ between different
228distributions and versions. You can completely disable modifications
229by manually setting the 'ostype' to 'unmanaged'.
3f13c1c3
DM
230
231OS type detection is done by testing for certain files inside the
232container:
233
234Ubuntu:: inspect /etc/lsb-release ('DISTRIB_ID=Ubuntu')
235
236Debian:: test /etc/debian_version
237
238Fedora:: test /etc/fedora-release
239
240RedHat or CentOS:: test /etc/redhat-release
241
242ArchLinux:: test /etc/arch-release
243
244Alpine:: test /etc/alpine-release
245
c617d721
WB
246Gentoo:: test /etc/gentoo-release
247
a8e99754 248NOTE: Container start fails if the configured 'ostype' differs from the auto
3f13c1c3
DM
249detected type.
250
a7f36905
DM
251Options
252~~~~~~~
253
254include::pct.conf.5-opts.adoc[]
255
d61bab51
DM
256
257Container Images
258----------------
259
a8e99754
FG
260Container Images, sometimes also referred to as "templates" or
261"appliances", are 'tar' archives which contain everything to run a
d61bab51
DM
262container. You can think of it as a tidy container backup. Like most
263modern container toolkits, 'pct' uses those images when you create a
264new container, for example:
265
266 pct create 999 local:vztmpl/debian-8.0-standard_8.0-1_amd64.tar.gz
267
268Proxmox itself ships a set of basic templates for most common
269operating systems, and you can download them using the 'pveam' (short
270for {pve} Appliance Manager) command line utility. You can also
271download https://www.turnkeylinux.org/[TurnKey Linux] containers using
272that tool (or the graphical user interface).
273
3a6fa247
DM
274Our image repositories contain a list of available images, and there
275is a cron job run each day to download that list. You can trigger that
276update manually with:
277
278 pveam update
279
280After that you can view the list of available images using:
281
282 pveam available
283
284You can restrict this large list by specifying the 'section' you are
285interested in, for example basic 'system' images:
286
287.List available system images
288----
289# pveam available --section system
290system archlinux-base_2015-24-29-1_x86_64.tar.gz
291system centos-7-default_20160205_amd64.tar.xz
292system debian-6.0-standard_6.0-7_amd64.tar.gz
293system debian-7.0-standard_7.0-3_amd64.tar.gz
294system debian-8.0-standard_8.0-1_amd64.tar.gz
295system ubuntu-12.04-standard_12.04-1_amd64.tar.gz
296system ubuntu-14.04-standard_14.04-1_amd64.tar.gz
297system ubuntu-15.04-standard_15.04-1_amd64.tar.gz
298system ubuntu-15.10-standard_15.10-1_amd64.tar.gz
299----
300
a8e99754 301Before you can use such a template, you need to download them into one
3a6fa247
DM
302of your storages. You can simply use storage 'local' for that
303purpose. For clustered installations, it is preferred to use a shared
304storage so that all nodes can access those images.
305
306 pveam download local debian-8.0-standard_8.0-1_amd64.tar.gz
307
24f73a63
DM
308You are now ready to create containers using that image, and you can
309list all downloaded images on storage 'local' with:
310
311----
312# pveam list local
313local:vztmpl/debian-8.0-standard_8.0-1_amd64.tar.gz 190.20MB
314----
315
a8e99754 316The above command shows you the full {pve} volume identifiers. They include
24f73a63
DM
317the storage name, and most other {pve} commands can use them. For
318examply you can delete that image later with:
319
320 pveam remove local:vztmpl/debian-8.0-standard_8.0-1_amd64.tar.gz
3a6fa247 321
d61bab51 322
70a42028
DM
323Container Storage
324-----------------
325
326Traditional containers use a very simple storage model, only allowing
327a single mount point, the root file system. This was further
328restricted to specific file system types like 'ext4' and 'nfs'.
329Additional mounts are often done by user provided scripts. This turend
a8e99754 330out to be complex and error prone, so we try to avoid that now.
70a42028
DM
331
332Our new LXC based container model is more flexible regarding
333storage. First, you can have more than a single mount point. This
334allows you to choose a suitable storage for each application. For
335example, you can use a relatively slow (and thus cheap) storage for
336the container root file system. Then you can use a second mount point
337to mount a very fast, distributed storage for your database
338application.
339
340The second big improvement is that you can use any storage type
341supported by the {pve} storage library. That means that you can store
342your containers on local 'lvmthin' or 'zfs', shared 'iSCSI' storage,
a8e99754 343or even on distributed storage systems like 'ceph'. It also enables us
70a42028 344to use advanced storage features like snapshots and clones. 'vzdump'
a8e99754 345can also use the snapshot feature to provide consistent container
70a42028
DM
346backups.
347
348Last but not least, you can also mount local devices directly, or
349mount local directories using bind mounts. That way you can access
350local storage inside containers with zero overhead. Such bind mounts
a8e99754 351also provide an easy way to share data between different containers.
70a42028 352
eeecce95 353
9e44e493
DM
354Mount Points
355~~~~~~~~~~~~
eeecce95 356
9e44e493
DM
357Beside the root directory the container can also have additional mount points.
358Currently there are basically three types of mount points: storage backed
359mount points, bind mounts and device mounts.
360
361Storage backed mount points are managed by the {pve} storage subsystem and come
eeecce95
WB
362in three different flavors:
363
364- Image based: These are raw images containing a single ext4 formatted file
365 system.
366- ZFS Subvolumes: These are technically bind mounts, but with managed storage,
367 and thus allow resizing and snapshotting.
368- Directories: passing `size=0` triggers a special case where instead of a raw
369 image a directory is created.
370
371Bind mounts are considered to not be managed by the storage subsystem, so you
372cannot make snapshots or deal with quotas from inside the container, and with
373unprivileged containers you might run into permission problems caused by the
374user mapping, and cannot use ACLs from inside an unprivileged container.
375
376Similarly device mounts are not managed by the storage, but for these the
377`quota` and `acl` options will be honored.
378
22a74065
FG
379WARNING: Because of existing issues in the Linux kernel's freezer
380subsystem the usage of FUSE mounts inside a container is strongly
381advised against, as containers need to be frozen for suspend or
382snapshot mode backups. If FUSE mounts cannot be replaced by other
383mounting mechanisms or storage technologies, it is possible to
384establish the FUSE mount on the Proxmox host and use a bind
9e44e493 385mount point to make it accessible inside the container.
eeecce95 386
6b707f2c
FG
387WARNING: For security reasons, bind mounts should only be established
388using source directories especially reserved for this purpose, e.g., a
389directory hierarchy under `/mnt/bindmounts`. Never bind mount system
390directories like `/`, `/var` or `/etc` into a container - this poses a
391great security risk. The bind mount source path must not contain any symlinks.
392
9e44e493 393The root mount point is configured with the 'rootfs' property, and you can
fe154a4f
DM
394configure up to 10 additional mount points. The corresponding options
395are called 'mp0' to 'mp9', and they can contain the following setting:
396
397include::pct-mountpoint-opts.adoc[]
398
399.Typical Container 'rootfs' configuration
400----
401rootfs: thin1:base-100-disk-1,size=8G
402----
403
d6ed3622 404Using quotas inside containers
04c569f6 405~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
d6ed3622 406
9e44e493
DM
407Quotas allow to set limits inside a container for the amount of disk
408space that each user can use. This only works on ext4 image based
409storage types and currently does not work with unprivileged
410containers.
d6ed3622 411
9e44e493
DM
412Activating the `quota` option causes the following mount options to be
413used for a mount point:
414`usrjquota=aquota.user,grpjquota=aquota.group,jqfmt=vfsv0`
d6ed3622 415
9e44e493
DM
416This allows quotas to be used like you would on any other system. You
417can initialize the `/aquota.user` and `/aquota.group` files by running
d6ed3622 418
9e44e493
DM
419----
420quotacheck -cmug /
421quotaon /
422----
d6ed3622 423
166e63d6
FG
424and edit the quotas via the `edquota` command. Refer to the documentation
425of the distribution running inside the container for details.
426
9e44e493
DM
427NOTE: You need to run the above commands for every mount point by passing
428the mount point's path instead of just `/`.
429
d6ed3622 430
6c60aebf 431Using ACLs inside containers
04c569f6 432~~~~~~~~~~~~~~~~~~~~~~~~~~~~
6c60aebf
EK
433
434The standard Posix Access Control Lists are also available inside containers.
435ACLs allow you to set more detailed file ownership than the traditional user/
436group/others model.
d6ed3622 437
04c569f6
DM
438
439Container Network
440-----------------
441
bac8c385
DM
442You can configure up to 10 network interfaces for a single
443container. The corresponding options are called 'net0' to 'net9', and
444they can contain the following setting:
445
446include::pct-network-opts.adoc[]
04c569f6
DM
447
448
449Managing Containers with 'pct'
450------------------------------
451
452'pct' is the tool to manage Linux Containers on {pve}. You can create
453and destroy containers, and control execution (start, stop, migrate,
454...). You can use pct to set parameters in the associated config file,
455like network configuration or memory limits.
456
457CLI Usage Examples
458~~~~~~~~~~~~~~~~~~
459
460Create a container based on a Debian template (provided you have
461already downloaded the template via the webgui)
462
463 pct create 100 /var/lib/vz/template/cache/debian-8.0-standard_8.0-1_amd64.tar.gz
464
465Start container 100
466
467 pct start 100
468
469Start a login session via getty
470
471 pct console 100
472
473Enter the LXC namespace and run a shell as root user
474
475 pct enter 100
476
477Display the configuration
478
479 pct config 100
480
481Add a network interface called eth0, bridged to the host bridge vmbr0,
482set the address and gateway, while it's running
483
484 pct set 100 -net0 name=eth0,bridge=vmbr0,ip=192.168.15.147/24,gw=192.168.15.1
485
486Reduce the memory of the container to 512MB
487
0585f29a
DM
488 pct set 100 -memory 512
489
04c569f6 490
3fafadf5
DM
491Backup and Restore
492------------------
493
494It is possible to use the 'vzdump' tool for container backup. Please
495refer to the 'vzdump' manual page for details.
496
497
04c569f6
DM
498Files
499------
500
501'/etc/pve/lxc/<CTID>.conf'::
502
503Configuration file for the container '<CTID>'.
504
505
0c6b782f
DM
506Container Advantages
507--------------------
508
509- Simple, and fully integrated into {pve}. Setup looks similar to a normal
510 VM setup.
511
512 * Storage (ZFS, LVM, NFS, Ceph, ...)
513
514 * Network
515
516 * Authentification
517
518 * Cluster
519
520- Fast: minimal overhead, as fast as bare metal
521
522- High density (perfect for idle workloads)
523
524- REST API
525
526- Direct hardware access
527
528
529Technology Overview
530-------------------
531
532- Integrated into {pve} graphical user interface (GUI)
533
534- LXC (https://linuxcontainers.org/)
535
536- cgmanager for cgroup management
537
538- lxcfs to provive containerized /proc file system
539
540- apparmor
541
542- CRIU: for live migration (planned)
543
11f340ff 544- We use latest available kernels (4.4.X)
0c6b782f 545
a8e99754 546- Image based deployment (templates)
0c6b782f
DM
547
548- Container setup from host (Network, DNS, Storage, ...)
549
550
551ifdef::manvolnum[]
552include::pve-copyright.adoc[]
553endif::manvolnum[]
554
555
556
557
558
559
560