pct: move backup and restore section
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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.Storage backed mount points
367
9e44e493 368Storage backed mount points are managed by the {pve} storage subsystem and come
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369in three different flavors:
370
371- Image based: These are raw images containing a single ext4 formatted file
372 system.
373- ZFS Subvolumes: These are technically bind mounts, but with managed storage,
374 and thus allow resizing and snapshotting.
375- Directories: passing `size=0` triggers a special case where instead of a raw
376 image a directory is created.
377
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378.Bind mount points
379
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380Bind mounts are considered to not be managed by the storage subsystem, so you
381cannot make snapshots or deal with quotas from inside the container, and with
382unprivileged containers you might run into permission problems caused by the
383user mapping, and cannot use ACLs from inside an unprivileged container.
384
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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
01639994 391.Device mount points
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393Similar to bind mounts, device mounts are not managed by the storage, but for
394these the `quota` and `acl` options will be honored.
395
396.FUSE mounts
397
398WARNING: Because of existing issues in the Linux kernel's freezer
399subsystem the usage of FUSE mounts inside a container is strongly
400advised against, as containers need to be frozen for suspend or
401snapshot mode backups.
fe154a4f 402
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403If FUSE mounts cannot be replaced by other mounting mechanisms or storage
404technologies, it is possible to establish the FUSE mount on the Proxmox host
405and use a bind mount point to make it accessible inside the container.
406
407.Typical Container `rootfs` configuration
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408----
409rootfs: thin1:base-100-disk-1,size=8G
410----
411
01639994 412
d6ed3622 413Using quotas inside containers
04c569f6 414~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
d6ed3622 415
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416Quotas allow to set limits inside a container for the amount of disk
417space that each user can use. This only works on ext4 image based
418storage types and currently does not work with unprivileged
419containers.
d6ed3622 420
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421Activating the `quota` option causes the following mount options to be
422used for a mount point:
423`usrjquota=aquota.user,grpjquota=aquota.group,jqfmt=vfsv0`
d6ed3622 424
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425This allows quotas to be used like you would on any other system. You
426can initialize the `/aquota.user` and `/aquota.group` files by running
d6ed3622 427
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428----
429quotacheck -cmug /
430quotaon /
431----
d6ed3622 432
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433and edit the quotas via the `edquota` command. Refer to the documentation
434of the distribution running inside the container for details.
435
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436NOTE: You need to run the above commands for every mount point by passing
437the mount point's path instead of just `/`.
438
d6ed3622 439
6c60aebf 440Using ACLs inside containers
04c569f6 441~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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442
443The standard Posix Access Control Lists are also available inside containers.
444ACLs allow you to set more detailed file ownership than the traditional user/
445group/others model.
d6ed3622 446
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447
448Container Network
449-----------------
450
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451You can configure up to 10 network interfaces for a single
452container. The corresponding options are called 'net0' to 'net9', and
453they can contain the following setting:
454
455include::pct-network-opts.adoc[]
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456
457
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458Backup and Restore
459------------------
460
461It is possible to use the 'vzdump' tool for container backup. Please
462refer to the 'vzdump' manual page for details.
463
464
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465Managing Containers with 'pct'
466------------------------------
467
468'pct' is the tool to manage Linux Containers on {pve}. You can create
469and destroy containers, and control execution (start, stop, migrate,
470...). You can use pct to set parameters in the associated config file,
471like network configuration or memory limits.
472
473CLI Usage Examples
474~~~~~~~~~~~~~~~~~~
475
476Create a container based on a Debian template (provided you have
477already downloaded the template via the webgui)
478
479 pct create 100 /var/lib/vz/template/cache/debian-8.0-standard_8.0-1_amd64.tar.gz
480
481Start container 100
482
483 pct start 100
484
485Start a login session via getty
486
487 pct console 100
488
489Enter the LXC namespace and run a shell as root user
490
491 pct enter 100
492
493Display the configuration
494
495 pct config 100
496
497Add a network interface called eth0, bridged to the host bridge vmbr0,
498set the address and gateway, while it's running
499
500 pct set 100 -net0 name=eth0,bridge=vmbr0,ip=192.168.15.147/24,gw=192.168.15.1
501
502Reduce the memory of the container to 512MB
503
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504 pct set 100 -memory 512
505
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506
507Files
508------
509
510'/etc/pve/lxc/<CTID>.conf'::
511
512Configuration file for the container '<CTID>'.
513
514
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515Container Advantages
516--------------------
517
518- Simple, and fully integrated into {pve}. Setup looks similar to a normal
519 VM setup.
520
521 * Storage (ZFS, LVM, NFS, Ceph, ...)
522
523 * Network
524
525 * Authentification
526
527 * Cluster
528
529- Fast: minimal overhead, as fast as bare metal
530
531- High density (perfect for idle workloads)
532
533- REST API
534
535- Direct hardware access
536
537
538Technology Overview
539-------------------
540
541- Integrated into {pve} graphical user interface (GUI)
542
543- LXC (https://linuxcontainers.org/)
544
545- cgmanager for cgroup management
546
547- lxcfs to provive containerized /proc file system
548
549- apparmor
550
551- CRIU: for live migration (planned)
552
11f340ff 553- We use latest available kernels (4.4.X)
0c6b782f 554
a8e99754 555- Image based deployment (templates)
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556
557- Container setup from host (Network, DNS, Storage, ...)
558
559
560ifdef::manvolnum[]
561include::pve-copyright.adoc[]
562endif::manvolnum[]
563
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