]> git.proxmox.com Git - pve-docs.git/blame - pct.adoc
doc: update stdexcludes
[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
70a42028
DM
62NOTE: If you want to run micro-containers (with docker, rct, ...), it
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
a8e99754 246NOTE: Container start fails if the configured 'ostype' differs from the auto
3f13c1c3
DM
247detected type.
248
a7f36905
DM
249Options
250~~~~~~~
251
252include::pct.conf.5-opts.adoc[]
253
d61bab51
DM
254
255Container Images
256----------------
257
a8e99754
FG
258Container Images, sometimes also referred to as "templates" or
259"appliances", are 'tar' archives which contain everything to run a
d61bab51
DM
260container. You can think of it as a tidy container backup. Like most
261modern container toolkits, 'pct' uses those images when you create a
262new container, for example:
263
264 pct create 999 local:vztmpl/debian-8.0-standard_8.0-1_amd64.tar.gz
265
266Proxmox itself ships a set of basic templates for most common
267operating systems, and you can download them using the 'pveam' (short
268for {pve} Appliance Manager) command line utility. You can also
269download https://www.turnkeylinux.org/[TurnKey Linux] containers using
270that tool (or the graphical user interface).
271
3a6fa247
DM
272Our image repositories contain a list of available images, and there
273is a cron job run each day to download that list. You can trigger that
274update manually with:
275
276 pveam update
277
278After that you can view the list of available images using:
279
280 pveam available
281
282You can restrict this large list by specifying the 'section' you are
283interested in, for example basic 'system' images:
284
285.List available system images
286----
287# pveam available --section system
288system archlinux-base_2015-24-29-1_x86_64.tar.gz
289system centos-7-default_20160205_amd64.tar.xz
290system debian-6.0-standard_6.0-7_amd64.tar.gz
291system debian-7.0-standard_7.0-3_amd64.tar.gz
292system debian-8.0-standard_8.0-1_amd64.tar.gz
293system ubuntu-12.04-standard_12.04-1_amd64.tar.gz
294system ubuntu-14.04-standard_14.04-1_amd64.tar.gz
295system ubuntu-15.04-standard_15.04-1_amd64.tar.gz
296system ubuntu-15.10-standard_15.10-1_amd64.tar.gz
297----
298
a8e99754 299Before you can use such a template, you need to download them into one
3a6fa247
DM
300of your storages. You can simply use storage 'local' for that
301purpose. For clustered installations, it is preferred to use a shared
302storage so that all nodes can access those images.
303
304 pveam download local debian-8.0-standard_8.0-1_amd64.tar.gz
305
24f73a63
DM
306You are now ready to create containers using that image, and you can
307list all downloaded images on storage 'local' with:
308
309----
310# pveam list local
311local:vztmpl/debian-8.0-standard_8.0-1_amd64.tar.gz 190.20MB
312----
313
a8e99754 314The above command shows you the full {pve} volume identifiers. They include
24f73a63
DM
315the storage name, and most other {pve} commands can use them. For
316examply you can delete that image later with:
317
318 pveam remove local:vztmpl/debian-8.0-standard_8.0-1_amd64.tar.gz
3a6fa247 319
d61bab51 320
70a42028
DM
321Container Storage
322-----------------
323
324Traditional containers use a very simple storage model, only allowing
325a single mount point, the root file system. This was further
326restricted to specific file system types like 'ext4' and 'nfs'.
327Additional mounts are often done by user provided scripts. This turend
a8e99754 328out to be complex and error prone, so we try to avoid that now.
70a42028
DM
329
330Our new LXC based container model is more flexible regarding
331storage. First, you can have more than a single mount point. This
332allows you to choose a suitable storage for each application. For
333example, you can use a relatively slow (and thus cheap) storage for
334the container root file system. Then you can use a second mount point
335to mount a very fast, distributed storage for your database
336application.
337
338The second big improvement is that you can use any storage type
339supported by the {pve} storage library. That means that you can store
340your containers on local 'lvmthin' or 'zfs', shared 'iSCSI' storage,
a8e99754 341or even on distributed storage systems like 'ceph'. It also enables us
70a42028 342to use advanced storage features like snapshots and clones. 'vzdump'
a8e99754 343can also use the snapshot feature to provide consistent container
70a42028
DM
344backups.
345
346Last but not least, you can also mount local devices directly, or
347mount local directories using bind mounts. That way you can access
348local storage inside containers with zero overhead. Such bind mounts
a8e99754 349also provide an easy way to share data between different containers.
70a42028 350
eeecce95 351
9e44e493
DM
352Mount Points
353~~~~~~~~~~~~
eeecce95 354
9e44e493
DM
355Beside the root directory the container can also have additional mount points.
356Currently there are basically three types of mount points: storage backed
357mount points, bind mounts and device mounts.
358
359Storage backed mount points are managed by the {pve} storage subsystem and come
eeecce95
WB
360in three different flavors:
361
362- Image based: These are raw images containing a single ext4 formatted file
363 system.
364- ZFS Subvolumes: These are technically bind mounts, but with managed storage,
365 and thus allow resizing and snapshotting.
366- Directories: passing `size=0` triggers a special case where instead of a raw
367 image a directory is created.
368
369Bind mounts are considered to not be managed by the storage subsystem, so you
370cannot make snapshots or deal with quotas from inside the container, and with
371unprivileged containers you might run into permission problems caused by the
372user mapping, and cannot use ACLs from inside an unprivileged container.
373
374Similarly device mounts are not managed by the storage, but for these the
375`quota` and `acl` options will be honored.
376
22a74065
FG
377WARNING: Because of existing issues in the Linux kernel's freezer
378subsystem the usage of FUSE mounts inside a container is strongly
379advised against, as containers need to be frozen for suspend or
380snapshot mode backups. If FUSE mounts cannot be replaced by other
381mounting mechanisms or storage technologies, it is possible to
382establish the FUSE mount on the Proxmox host and use a bind
9e44e493 383mount point to make it accessible inside the container.
eeecce95 384
6b707f2c
FG
385WARNING: For security reasons, bind mounts should only be established
386using source directories especially reserved for this purpose, e.g., a
387directory hierarchy under `/mnt/bindmounts`. Never bind mount system
388directories like `/`, `/var` or `/etc` into a container - this poses a
389great security risk. The bind mount source path must not contain any symlinks.
390
9e44e493 391The root mount point is configured with the 'rootfs' property, and you can
fe154a4f
DM
392configure up to 10 additional mount points. The corresponding options
393are called 'mp0' to 'mp9', and they can contain the following setting:
394
395include::pct-mountpoint-opts.adoc[]
396
397.Typical Container 'rootfs' configuration
398----
399rootfs: thin1:base-100-disk-1,size=8G
400----
401
d6ed3622 402Using quotas inside containers
04c569f6 403~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
d6ed3622 404
9e44e493
DM
405Quotas allow to set limits inside a container for the amount of disk
406space that each user can use. This only works on ext4 image based
407storage types and currently does not work with unprivileged
408containers.
d6ed3622 409
9e44e493
DM
410Activating the `quota` option causes the following mount options to be
411used for a mount point:
412`usrjquota=aquota.user,grpjquota=aquota.group,jqfmt=vfsv0`
d6ed3622 413
9e44e493
DM
414This allows quotas to be used like you would on any other system. You
415can initialize the `/aquota.user` and `/aquota.group` files by running
d6ed3622 416
9e44e493
DM
417----
418quotacheck -cmug /
419quotaon /
420----
d6ed3622 421
166e63d6
FG
422and edit the quotas via the `edquota` command. Refer to the documentation
423of the distribution running inside the container for details.
424
9e44e493
DM
425NOTE: You need to run the above commands for every mount point by passing
426the mount point's path instead of just `/`.
427
d6ed3622 428
6c60aebf 429Using ACLs inside containers
04c569f6 430~~~~~~~~~~~~~~~~~~~~~~~~~~~~
6c60aebf
EK
431
432The standard Posix Access Control Lists are also available inside containers.
433ACLs allow you to set more detailed file ownership than the traditional user/
434group/others model.
d6ed3622 435
04c569f6
DM
436
437Container Network
438-----------------
439
bac8c385
DM
440You can configure up to 10 network interfaces for a single
441container. The corresponding options are called 'net0' to 'net9', and
442they can contain the following setting:
443
444include::pct-network-opts.adoc[]
04c569f6
DM
445
446
447Managing Containers with 'pct'
448------------------------------
449
450'pct' is the tool to manage Linux Containers on {pve}. You can create
451and destroy containers, and control execution (start, stop, migrate,
452...). You can use pct to set parameters in the associated config file,
453like network configuration or memory limits.
454
455CLI Usage Examples
456~~~~~~~~~~~~~~~~~~
457
458Create a container based on a Debian template (provided you have
459already downloaded the template via the webgui)
460
461 pct create 100 /var/lib/vz/template/cache/debian-8.0-standard_8.0-1_amd64.tar.gz
462
463Start container 100
464
465 pct start 100
466
467Start a login session via getty
468
469 pct console 100
470
471Enter the LXC namespace and run a shell as root user
472
473 pct enter 100
474
475Display the configuration
476
477 pct config 100
478
479Add a network interface called eth0, bridged to the host bridge vmbr0,
480set the address and gateway, while it's running
481
482 pct set 100 -net0 name=eth0,bridge=vmbr0,ip=192.168.15.147/24,gw=192.168.15.1
483
484Reduce the memory of the container to 512MB
485
0585f29a
DM
486 pct set 100 -memory 512
487
04c569f6
DM
488
489Files
490------
491
492'/etc/pve/lxc/<CTID>.conf'::
493
494Configuration file for the container '<CTID>'.
495
496
0c6b782f
DM
497Container Advantages
498--------------------
499
500- Simple, and fully integrated into {pve}. Setup looks similar to a normal
501 VM setup.
502
503 * Storage (ZFS, LVM, NFS, Ceph, ...)
504
505 * Network
506
507 * Authentification
508
509 * Cluster
510
511- Fast: minimal overhead, as fast as bare metal
512
513- High density (perfect for idle workloads)
514
515- REST API
516
517- Direct hardware access
518
519
520Technology Overview
521-------------------
522
523- Integrated into {pve} graphical user interface (GUI)
524
525- LXC (https://linuxcontainers.org/)
526
527- cgmanager for cgroup management
528
529- lxcfs to provive containerized /proc file system
530
531- apparmor
532
533- CRIU: for live migration (planned)
534
11f340ff 535- We use latest available kernels (4.4.X)
0c6b782f 536
a8e99754 537- Image based deployment (templates)
0c6b782f
DM
538
539- Container setup from host (Network, DNS, Storage, ...)
540
541
542ifdef::manvolnum[]
543include::pve-copyright.adoc[]
544endif::manvolnum[]
545
546
547
548
549
550
551