reorder docs (pct after qm)
[pve-docs.git] / pct.adoc
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1ifdef::manvolnum[]
2PVE({manvolnum})
3================
38fd0958 4include::attributes.txt[]
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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[]
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25endif::manvolnum[]
26
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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
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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
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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
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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.
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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.
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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
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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
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98unprivileged containers are safe by design.
99
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100
101Configuration
102-------------
103
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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
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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
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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
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131running containers. This feature is called "hot plug", and there is no
132need to restart the container in that case.
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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
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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
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179There are a few snapshot related properties like 'parent' and
180'snaptime'. The 'parent' property is used to store the parent/child
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181relationship between snapshots. 'snaptime' is the snapshot creation
182time stamp (unix epoch).
7fc230db 183
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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
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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
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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
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208Changes made by {PVE} are enclosed by comment markers:
209
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210----
211# --- BEGIN PVE ---
212<data>
213# --- END PVE ---
214----
25535d34 215
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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
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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:
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224
225 # touch /etc/.pve-ignore.hosts
226
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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'.
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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
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246Gentoo:: test /etc/gentoo-release
247
a8e99754 248NOTE: Container start fails if the configured 'ostype' differs from the auto
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249detected type.
250
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251Options
252~~~~~~~
253
254include::pct.conf.5-opts.adoc[]
255
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256
257Container Images
258----------------
259
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260Container Images, sometimes also referred to as "templates" or
261"appliances", are 'tar' archives which contain everything to run a
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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
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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
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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
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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
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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
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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.
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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
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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
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354Mount Points
355~~~~~~~~~~~~
eeecce95 356
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357The root mount point is configured with the `rootfs` property, and you can
358configure up to 10 additional mount points. The corresponding options
359are called `mp0` to `mp9`, and they can contain the following setting:
360
361include::pct-mountpoint-opts.adoc[]
362
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363Currently there are basically three types of mount points: storage backed
364mount points, bind mounts and device mounts.
365
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366.Typical Container `rootfs` configuration
367----
368rootfs: thin1:base-100-disk-1,size=8G
369----
370
371
372Storage backed mount points
373^^^^^^^^^^^^^^^^^^^^^^^^^^^
01639994 374
9e44e493 375Storage backed mount points are managed by the {pve} storage subsystem and come
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376in three different flavors:
377
378- Image based: These are raw images containing a single ext4 formatted file
379 system.
380- ZFS Subvolumes: These are technically bind mounts, but with managed storage,
381 and thus allow resizing and snapshotting.
382- Directories: passing `size=0` triggers a special case where instead of a raw
383 image a directory is created.
384
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385
386Bind mount points
387^^^^^^^^^^^^^^^^^
01639994 388
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389Bind mounts are considered to not be managed by the storage subsystem, so you
390cannot make snapshots or deal with quotas from inside the container, and with
391unprivileged containers you might run into permission problems caused by the
392user mapping, and cannot use ACLs from inside an unprivileged container.
393
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394WARNING: For security reasons, bind mounts should only be established
395using source directories especially reserved for this purpose, e.g., a
396directory hierarchy under `/mnt/bindmounts`. Never bind mount system
397directories like `/`, `/var` or `/etc` into a container - this poses a
398great security risk. The bind mount source path must not contain any symlinks.
399
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400
401Device mount points
402^^^^^^^^^^^^^^^^^^^
fe154a4f 403
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404Similar to bind mounts, device mounts are not managed by the storage, but for
405these the `quota` and `acl` options will be honored.
406
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407
408FUSE mounts
409~~~~~~~~~~~
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410
411WARNING: Because of existing issues in the Linux kernel's freezer
412subsystem the usage of FUSE mounts inside a container is strongly
413advised against, as containers need to be frozen for suspend or
414snapshot mode backups.
fe154a4f 415
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416If FUSE mounts cannot be replaced by other mounting mechanisms or storage
417technologies, it is possible to establish the FUSE mount on the Proxmox host
418and use a bind mount point to make it accessible inside the container.
419
01639994 420
d6ed3622 421Using quotas inside containers
04c569f6 422~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
d6ed3622 423
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424Quotas allow to set limits inside a container for the amount of disk
425space that each user can use. This only works on ext4 image based
426storage types and currently does not work with unprivileged
427containers.
d6ed3622 428
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429Activating the `quota` option causes the following mount options to be
430used for a mount point:
431`usrjquota=aquota.user,grpjquota=aquota.group,jqfmt=vfsv0`
d6ed3622 432
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433This allows quotas to be used like you would on any other system. You
434can initialize the `/aquota.user` and `/aquota.group` files by running
d6ed3622 435
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436----
437quotacheck -cmug /
438quotaon /
439----
d6ed3622 440
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441and edit the quotas via the `edquota` command. Refer to the documentation
442of the distribution running inside the container for details.
443
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444NOTE: You need to run the above commands for every mount point by passing
445the mount point's path instead of just `/`.
446
d6ed3622 447
6c60aebf 448Using ACLs inside containers
04c569f6 449~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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450
451The standard Posix Access Control Lists are also available inside containers.
452ACLs allow you to set more detailed file ownership than the traditional user/
453group/others model.
d6ed3622 454
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455
456Container Network
457-----------------
458
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459You can configure up to 10 network interfaces for a single
460container. The corresponding options are called 'net0' to 'net9', and
461they can contain the following setting:
462
463include::pct-network-opts.adoc[]
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464
465
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466Backup and Restore
467------------------
468
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469Container Backup
470~~~~~~~~~~~~~~~~
471
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472It is possible to use the 'vzdump' tool for container backup. Please
473refer to the 'vzdump' manual page for details.
474
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475Restoring Container Backups
476~~~~~~~~~~~~~~~~~~~~~~~~~~~
477
478Restoring container backups made with 'vzdump' is possible using the
479'pct restore' command. By default, 'pct restore' will attempt to restore as much
480of the backed up container configuration as possible. It is possible to override
481the backed up configuration by manually setting container options on the command
482line (see the 'pct' manual page for details).
483
484NOTE: 'pvesm extractconfig' can be used to view the backed up configuration
485contained in a vzdump archive.
486
487There are two basic restore modes, only differing by their handling of mount
488points:
489
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490
491"Simple" restore mode
492^^^^^^^^^^^^^^^^^^^^^
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493
494If neither the `rootfs` parameter nor any of the optional `mpX` parameters
495are explicitly set, the mount point configuration from the backed up
496configuration file is restored using the following steps:
497
498. Extract mount points and their options from backup
499. Create volumes for storage backed mount points (on storage provided with the
500`storage` parameter, or default local storage if unset)
501. Extract files from backup archive
502. Add bind and device mount points to restored configuration (limited to root user)
503
504NOTE: Since bind and device mount points are never backed up, no files are
505restored in the last step, but only the configuration options. The assumption
506is that such mount points are either backed up with another mechanism (e.g.,
507NFS space that is bind mounted into many containers), or not intended to be
508backed up at all.
509
510This simple mode is also used by the container restore operations in the web
511interface.
512
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513
514"Advanced" restore mode
515^^^^^^^^^^^^^^^^^^^^^^^
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516
517By setting the `rootfs` parameter (and optionally, any combination of `mpX`
518parameters), the 'pct restore' command is automatically switched into an
519advanced mode. This advanced mode completely ignores the `rootfs` and `mpX`
520configuration options contained in the backup archive, and instead only
521uses the options explicitly provided as parameters.
522
523This mode allows flexible configuration of mount point settings at restore time,
524for example:
525
526* Set target storages, volume sizes and other options for each mount point
527individually
528* Redistribute backed up files according to new mount point scheme
529* Restore to device and/or bind mount points (limited to root user)
530
51e33128 531
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532Managing Containers with 'pct'
533------------------------------
534
535'pct' is the tool to manage Linux Containers on {pve}. You can create
536and destroy containers, and control execution (start, stop, migrate,
537...). You can use pct to set parameters in the associated config file,
538like network configuration or memory limits.
539
540CLI Usage Examples
541~~~~~~~~~~~~~~~~~~
542
543Create a container based on a Debian template (provided you have
544already downloaded the template via the webgui)
545
546 pct create 100 /var/lib/vz/template/cache/debian-8.0-standard_8.0-1_amd64.tar.gz
547
548Start container 100
549
550 pct start 100
551
552Start a login session via getty
553
554 pct console 100
555
556Enter the LXC namespace and run a shell as root user
557
558 pct enter 100
559
560Display the configuration
561
562 pct config 100
563
564Add a network interface called eth0, bridged to the host bridge vmbr0,
565set the address and gateway, while it's running
566
567 pct set 100 -net0 name=eth0,bridge=vmbr0,ip=192.168.15.147/24,gw=192.168.15.1
568
569Reduce the memory of the container to 512MB
570
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571 pct set 100 -memory 512
572
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573
574Files
575------
576
577'/etc/pve/lxc/<CTID>.conf'::
578
579Configuration file for the container '<CTID>'.
580
581
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582Container Advantages
583--------------------
584
585- Simple, and fully integrated into {pve}. Setup looks similar to a normal
586 VM setup.
587
588 * Storage (ZFS, LVM, NFS, Ceph, ...)
589
590 * Network
591
592 * Authentification
593
594 * Cluster
595
596- Fast: minimal overhead, as fast as bare metal
597
598- High density (perfect for idle workloads)
599
600- REST API
601
602- Direct hardware access
603
604
605Technology Overview
606-------------------
607
608- Integrated into {pve} graphical user interface (GUI)
609
610- LXC (https://linuxcontainers.org/)
611
612- cgmanager for cgroup management
613
614- lxcfs to provive containerized /proc file system
615
616- apparmor
617
618- CRIU: for live migration (planned)
619
11f340ff 620- We use latest available kernels (4.4.X)
0c6b782f 621
a8e99754 622- Image based deployment (templates)
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623
624- Container setup from host (Network, DNS, Storage, ...)
625
626
627ifdef::manvolnum[]
628include::pve-copyright.adoc[]
629endif::manvolnum[]
630
631
632
633
634
635
636