10 pct - Tool to manage Linux Containers (LXC) on Proxmox VE
16 include::pct.1-synopsis.adoc[]
23 Proxmox Container Toolkit
24 =========================
28 :title: Linux Container
31 Containers are a lightweight alternative to fully virtualized machines (VMs).
32 They use the kernel of the host system that they run on, instead of emulating a
33 full operating system (OS). This means that containers can access resources on
34 the host system directly.
36 The runtime costs for containers is low, usually negligible. However, there are
37 some drawbacks that need be considered:
39 * Only Linux distributions can be run in Proxmox Containers. It is not possible to run
40 other operating systems like, for example, FreeBSD or Microsoft Windows
43 * For security reasons, access to host resources needs to be restricted.
44 Therefore, containers run in their own separate namespaces. Additionally some
45 syscalls (user space requests to the Linux kernel) are not allowed within containers.
47 {pve} uses https://linuxcontainers.org/lxc/introduction/[Linux Containers (LXC)] as its underlying
48 container technology. The ``Proxmox Container Toolkit'' (`pct`) simplifies the
49 usage and management of LXC, by providing an interface that abstracts
52 Containers are tightly integrated with {pve}. This means that they are aware of
53 the cluster setup, and they can use the same network and storage resources as
54 virtual machines. You can also use the {pve} firewall, or manage containers
55 using the HA framework.
57 Our primary goal is to offer an environment that provides the benefits of using a
58 VM, but without the additional overhead. This means that Proxmox Containers can
59 be categorized as ``System Containers'', rather than ``Application Containers''.
61 NOTE: If you want to run application containers, for example, 'Docker' images, it
62 is recommended that you run them inside a Proxmox Qemu VM. This will give you
63 all the advantages of application containerization, while also providing the
64 benefits that VMs offer, such as strong isolation from the host and the ability
65 to live-migrate, which otherwise isn't possible with containers.
71 * LXC (https://linuxcontainers.org/)
73 * Integrated into {pve} graphical web user interface (GUI)
75 * Easy to use command line tool `pct`
77 * Access via {pve} REST API
79 * 'lxcfs' to provide containerized /proc file system
81 * Control groups ('cgroups') for resource isolation and limitation
83 * 'AppArmor' and 'seccomp' to improve security
85 * Modern Linux kernels
87 * Image based deployment (templates)
89 * Uses {pve} xref:chapter_storage[storage library]
91 * Container setup from host (network, DNS, storage, etc.)
94 [[pct_container_images]]
98 Container images, sometimes also referred to as ``templates'' or
99 ``appliances'', are `tar` archives which contain everything to run a container.
101 {pve} itself provides a variety of basic templates for the most common Linux
102 distributions. They can be downloaded using the GUI or the `pveam` (short for
103 {pve} Appliance Manager) command line utility.
104 Additionally, https://www.turnkeylinux.org/[TurnKey Linux] container templates
105 are also available to download.
107 The list of available templates is updated daily through the 'pve-daily-update'
108 timer. You can also trigger an update manually by executing:
114 To view the list of available images run:
120 You can restrict this large list by specifying the `section` you are
121 interested in, for example basic `system` images:
123 .List available system images
125 # pveam available --section system
126 system alpine-3.12-default_20200823_amd64.tar.xz
127 system alpine-3.13-default_20210419_amd64.tar.xz
128 system alpine-3.14-default_20210623_amd64.tar.xz
129 system archlinux-base_20210420-1_amd64.tar.gz
130 system centos-7-default_20190926_amd64.tar.xz
131 system centos-8-default_20201210_amd64.tar.xz
132 system debian-9.0-standard_9.7-1_amd64.tar.gz
133 system debian-10-standard_10.7-1_amd64.tar.gz
134 system devuan-3.0-standard_3.0_amd64.tar.gz
135 system fedora-33-default_20201115_amd64.tar.xz
136 system fedora-34-default_20210427_amd64.tar.xz
137 system gentoo-current-default_20200310_amd64.tar.xz
138 system opensuse-15.2-default_20200824_amd64.tar.xz
139 system ubuntu-16.04-standard_16.04.5-1_amd64.tar.gz
140 system ubuntu-18.04-standard_18.04.1-1_amd64.tar.gz
141 system ubuntu-20.04-standard_20.04-1_amd64.tar.gz
142 system ubuntu-20.10-standard_20.10-1_amd64.tar.gz
143 system ubuntu-21.04-standard_21.04-1_amd64.tar.gz
146 Before you can use such a template, you need to download them into one of your
147 storages. If you're unsure to which one, you can simply use the `local` named
148 storage for that purpose. For clustered installations, it is preferred to use a
149 shared storage so that all nodes can access those images.
152 # pveam download local debian-10.0-standard_10.0-1_amd64.tar.gz
155 You are now ready to create containers using that image, and you can list all
156 downloaded images on storage `local` with:
160 local:vztmpl/debian-10.0-standard_10.0-1_amd64.tar.gz 219.95MB
163 TIP: You can also use the {pve} web interface GUI to download, list and delete
166 `pct` uses them to create a new container, for example:
169 # pct create 999 local:vztmpl/debian-10.0-standard_10.0-1_amd64.tar.gz
172 The above command shows you the full {pve} volume identifiers. They include the
173 storage name, and most other {pve} commands can use them. For example you can
174 delete that image later with:
177 # pveam remove local:vztmpl/debian-10.0-standard_10.0-1_amd64.tar.gz
189 [thumbnail="screenshot/gui-create-ct-general.png"]
191 General settings of a container include
193 * the *Node* : the physical server on which the container will run
194 * the *CT ID*: a unique number in this {pve} installation used to identify your
196 * *Hostname*: the hostname of the container
197 * *Resource Pool*: a logical group of containers and VMs
198 * *Password*: the root password of the container
199 * *SSH Public Key*: a public key for connecting to the root account over SSH
200 * *Unprivileged container*: this option allows to choose at creation time
201 if you want to create a privileged or unprivileged container.
203 Unprivileged Containers
204 ^^^^^^^^^^^^^^^^^^^^^^^
206 Unprivileged containers use a new kernel feature called user namespaces.
207 The root UID 0 inside the container is mapped to an unprivileged user outside
208 the container. This means that most security issues (container escape, resource
209 abuse, etc.) in these containers will affect a random unprivileged user, and
210 would be a generic kernel security bug rather than an LXC issue. The LXC team
211 thinks unprivileged containers are safe by design.
213 This is the default option when creating a new container.
215 NOTE: If the container uses systemd as an init system, please be aware the
216 systemd version running inside the container should be equal to or greater than
220 Privileged Containers
221 ^^^^^^^^^^^^^^^^^^^^^
223 Security in containers is achieved by using mandatory access control 'AppArmor'
224 restrictions, 'seccomp' filters and Linux kernel namespaces. The LXC team
225 considers this kind of container as unsafe, and they will not consider new
226 container escape exploits to be security issues worthy of a CVE and quick fix.
227 That's why privileged containers should only be used in trusted environments.
234 [thumbnail="screenshot/gui-create-ct-cpu.png"]
236 You can restrict the number of visible CPUs inside the container using the
237 `cores` option. This is implemented using the Linux 'cpuset' cgroup
238 (**c**ontrol *group*).
239 A special task inside `pvestatd` tries to distribute running containers among
240 available CPUs periodically.
241 To view the assigned CPUs run the following command:
245 ---------------------
249 ---------------------
252 Containers use the host kernel directly. All tasks inside a container are
253 handled by the host CPU scheduler. {pve} uses the Linux 'CFS' (**C**ompletely
254 **F**air **S**cheduler) scheduler by default, which has additional bandwidth
259 `cpulimit`: :: You can use this option to further limit assigned CPU time.
260 Please note that this is a floating point number, so it is perfectly valid to
261 assign two cores to a container, but restrict overall CPU consumption to half a
269 `cpuunits`: :: This is a relative weight passed to the kernel scheduler. The
270 larger the number is, the more CPU time this container gets. Number is relative
271 to the weights of all the other running containers. The default is 1024. You
272 can use this setting to prioritize some containers.
279 [thumbnail="screenshot/gui-create-ct-memory.png"]
281 Container memory is controlled using the cgroup memory controller.
285 `memory`: :: Limit overall memory usage. This corresponds to the
286 `memory.limit_in_bytes` cgroup setting.
288 `swap`: :: Allows the container to use additional swap memory from the host
289 swap space. This corresponds to the `memory.memsw.limit_in_bytes` cgroup
290 setting, which is set to the sum of both value (`memory + swap`).
297 [thumbnail="screenshot/gui-create-ct-root-disk.png"]
299 The root mount point is configured with the `rootfs` property. You can
300 configure up to 256 additional mount points. The corresponding options are
301 called `mp0` to `mp255`. They can contain the following settings:
303 include::pct-mountpoint-opts.adoc[]
305 Currently there are three types of mount points: storage backed mount points,
306 bind mounts, and device mounts.
308 .Typical container `rootfs` configuration
310 rootfs: thin1:base-100-disk-1,size=8G
314 Storage Backed Mount Points
315 ^^^^^^^^^^^^^^^^^^^^^^^^^^^
317 Storage backed mount points are managed by the {pve} storage subsystem and come
318 in three different flavors:
320 - Image based: these are raw images containing a single ext4 formatted file
322 - ZFS subvolumes: these are technically bind mounts, but with managed storage,
323 and thus allow resizing and snapshotting.
324 - Directories: passing `size=0` triggers a special case where instead of a raw
325 image a directory is created.
327 NOTE: The special option syntax `STORAGE_ID:SIZE_IN_GB` for storage backed
328 mount point volumes will automatically allocate a volume of the specified size
329 on the specified storage. For example, calling
332 pct set 100 -mp0 thin1:10,mp=/path/in/container
335 will allocate a 10GB volume on the storage `thin1` and replace the volume ID
336 place holder `10` with the allocated volume ID, and setup the moutpoint in the
337 container at `/path/in/container`
343 Bind mounts allow you to access arbitrary directories from your Proxmox VE host
344 inside a container. Some potential use cases are:
346 - Accessing your home directory in the guest
347 - Accessing an USB device directory in the guest
348 - Accessing an NFS mount from the host in the guest
350 Bind mounts are considered to not be managed by the storage subsystem, so you
351 cannot make snapshots or deal with quotas from inside the container. With
352 unprivileged containers you might run into permission problems caused by the
353 user mapping and cannot use ACLs.
355 NOTE: The contents of bind mount points are not backed up when using `vzdump`.
357 WARNING: For security reasons, bind mounts should only be established using
358 source directories especially reserved for this purpose, e.g., a directory
359 hierarchy under `/mnt/bindmounts`. Never bind mount system directories like
360 `/`, `/var` or `/etc` into a container - this poses a great security risk.
362 NOTE: The bind mount source path must not contain any symlinks.
364 For example, to make the directory `/mnt/bindmounts/shared` accessible in the
365 container with ID `100` under the path `/shared`, use a configuration line like
366 `mp0: /mnt/bindmounts/shared,mp=/shared` in `/etc/pve/lxc/100.conf`.
367 Alternatively, use `pct set 100 -mp0 /mnt/bindmounts/shared,mp=/shared` to
368 achieve the same result.
374 Device mount points allow to mount block devices of the host directly into the
375 container. Similar to bind mounts, device mounts are not managed by {PVE}'s
376 storage subsystem, but the `quota` and `acl` options will be honored.
378 NOTE: Device mount points should only be used under special circumstances. In
379 most cases a storage backed mount point offers the same performance and a lot
382 NOTE: The contents of device mount points are not backed up when using
386 [[pct_container_network]]
390 [thumbnail="screenshot/gui-create-ct-network.png"]
392 You can configure up to 10 network interfaces for a single container.
393 The corresponding options are called `net0` to `net9`, and they can contain the
396 include::pct-network-opts.adoc[]
399 [[pct_startup_and_shutdown]]
400 Automatic Start and Shutdown of Containers
401 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
403 To automatically start a container when the host system boots, select the
404 option 'Start at boot' in the 'Options' panel of the container in the web
405 interface or run the following command:
408 # pct set CTID -onboot 1
411 .Start and Shutdown Order
412 // use the screenshot from qemu - its the same
413 [thumbnail="screenshot/gui-qemu-edit-start-order.png"]
415 If you want to fine tune the boot order of your containers, you can use the
416 following parameters:
418 * *Start/Shutdown order*: Defines the start order priority. For example, set it
419 to 1 if you want the CT to be the first to be started. (We use the reverse
420 startup order for shutdown, so a container with a start order of 1 would be
421 the last to be shut down)
422 * *Startup delay*: Defines the interval between this container start and
423 subsequent containers starts. For example, set it to 240 if you want to wait
424 240 seconds before starting other containers.
425 * *Shutdown timeout*: Defines the duration in seconds {pve} should wait
426 for the container to be offline after issuing a shutdown command.
427 By default this value is set to 60, which means that {pve} will issue a
428 shutdown request, wait 60s for the machine to be offline, and if after 60s
429 the machine is still online will notify that the shutdown action failed.
431 Please note that containers without a Start/Shutdown order parameter will
432 always start after those where the parameter is set, and this parameter only
433 makes sense between the machines running locally on a host, and not
439 You can add a hook script to CTs with the config property `hookscript`.
442 # pct set 100 -hookscript local:snippets/hookscript.pl
445 It will be called during various phases of the guests lifetime. For an example
446 and documentation see the example script under
447 `/usr/share/pve-docs/examples/guest-example-hookscript.pl`.
449 Security Considerations
450 -----------------------
452 Containers use the kernel of the host system. This exposes an attack surface
453 for malicious users. In general, full virtual machines provide better
454 isolation. This should be considered if containers are provided to unknown or
457 To reduce the attack surface, LXC uses many security features like AppArmor,
458 CGroups and kernel namespaces.
463 AppArmor profiles are used to restrict access to possibly dangerous actions.
464 Some system calls, i.e. `mount`, are prohibited from execution.
466 To trace AppArmor activity, use:
469 # dmesg | grep apparmor
472 Although it is not recommended, AppArmor can be disabled for a container. This
473 brings security risks with it. Some syscalls can lead to privilege escalation
474 when executed within a container if the system is misconfigured or if a LXC or
475 Linux Kernel vulnerability exists.
477 To disable AppArmor for a container, add the following line to the container
478 configuration file located at `/etc/pve/lxc/CTID.conf`:
481 lxc.apparmor.profile = unconfined
484 WARNING: Please note that this is not recommended for production use.
488 Control Groups ('cgroup')
489 ~~~~~~~~~~~~~~~~~~~~~~~~~
492 mechanism used to hierarchically organize processes and distribute system
495 The main resources controlled via 'cgroups' are CPU time, memory and swap
496 limits, and access to device nodes. 'cgroups' are also used to "freeze" a
497 container before taking snapshots.
499 There are 2 versions of 'cgroups' currently available,
500 https://www.kernel.org/doc/html/v5.11/admin-guide/cgroup-v1/index.html[legacy]
502 https://www.kernel.org/doc/html/v5.11/admin-guide/cgroup-v2.html['cgroupv2'].
504 Since {pve} 7.0, the default is a pure 'cgroupv2' environment. Previously a
505 "hybrid" setup was used, where resource control was mainly done in 'cgroupv1'
506 with an additional 'cgroupv2' controller which could take over some subsystems
507 via the 'cgroup_no_v1' kernel command line parameter. (See the
508 https://www.kernel.org/doc/html/latest/admin-guide/kernel-parameters.html[kernel
509 parameter documentation] for details.)
511 [[pct_cgroup_compat]]
512 CGroup Version Compatibility
513 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
514 The main difference between pure 'cgroupv2' and the old hybrid environments
515 regarding {pve} is that with 'cgroupv2' memory and swap are now controlled
516 independently. The memory and swap settings for containers can map directly to
517 these values, whereas previously only the memory limit and the limit of the
518 *sum* of memory and swap could be limited.
520 Another important difference is that the 'devices' controller is configured in a
521 completely different way. Because of this, file system quotas are currently not
522 supported in a pure 'cgroupv2' environment.
524 'cgroupv2' support by the container's OS is needed to run in a pure 'cgroupv2'
525 environment. Containers running 'systemd' version 231 or newer support
526 'cgroupv2' footnote:[this includes all newest major versions of container
527 templates shipped by {pve}], as do containers not using 'systemd' as init
528 system footnote:[for example Alpine Linux].
532 CentOS 7 and Ubuntu 16.10 are two prominent Linux distributions releases,
533 which have a 'systemd' version that is too old to run in a 'cgroupv2'
534 environment, you can either
536 * Upgrade the whole distribution to a newer release. For the examples above, that
537 could be Ubuntu 18.04 or 20.04, and CentOS 8 (or RHEL/CentOS derivatives like
538 AlmaLinux or Rocky Linux). This has the benefit to get the newest bug and
539 security fixes, often also new features, and moving the EOL date in the future.
541 * Upgrade the Containers systemd version. If the distribution provides a
542 backports repository this can be an easy and quick stop-gap measurement.
544 * Move the container, or its services, to a Virtual Machine. Virtual Machines
545 have a much less interaction with the host, that's why one can install
546 decades old OS versions just fine there.
548 * Switch back to the legacy 'cgroup' controller. Note that while it can be a
549 valid solution, it's not a permanent one. There's a high likelihood that a
550 future {pve} major release, for example 8.0, cannot support the legacy
554 [[pct_cgroup_change_version]]
555 Changing CGroup Version
556 ^^^^^^^^^^^^^^^^^^^^^^^
558 TIP: If file system quotas are not required and all containers support 'cgroupv2',
559 it is recommended to stick to the new default.
561 To switch back to the previous version the following kernel command line
562 parameter can be used:
565 systemd.unified_cgroup_hierarchy=0
568 See xref:sysboot_edit_kernel_cmdline[this section] on editing the kernel boot
569 command line on where to add the parameter.
571 // TODO: seccomp a bit more.
572 // TODO: pve-lxc-syscalld
575 Guest Operating System Configuration
576 ------------------------------------
578 {pve} tries to detect the Linux distribution in the container, and modifies
579 some files. Here is a short list of things done at container startup:
581 set /etc/hostname:: to set the container name
583 modify /etc/hosts:: to allow lookup of the local hostname
585 network setup:: pass the complete network setup to the container
587 configure DNS:: pass information about DNS servers
589 adapt the init system:: for example, fix the number of spawned getty processes
591 set the root password:: when creating a new container
593 rewrite ssh_host_keys:: so that each container has unique keys
595 randomize crontab:: so that cron does not start at the same time on all containers
597 Changes made by {PVE} are enclosed by comment markers:
605 Those markers will be inserted at a reasonable location in the file. If such a
606 section already exists, it will be updated in place and will not be moved.
608 Modification of a file can be prevented by adding a `.pve-ignore.` file for it.
609 For instance, if the file `/etc/.pve-ignore.hosts` exists then the `/etc/hosts`
610 file will not be touched. This can be a simple empty file created via:
613 # touch /etc/.pve-ignore.hosts
616 Most modifications are OS dependent, so they differ between different
617 distributions and versions. You can completely disable modifications by
618 manually setting the `ostype` to `unmanaged`.
620 OS type detection is done by testing for certain files inside the
621 container. {pve} first checks the `/etc/os-release` file
622 footnote:[/etc/os-release replaces the multitude of per-distribution
623 release files https://manpages.debian.org/stable/systemd/os-release.5.en.html].
624 If that file is not present, or it does not contain a clearly recognizable
625 distribution identifier the following distribution specific release files are
628 Ubuntu:: inspect /etc/lsb-release (`DISTRIB_ID=Ubuntu`)
630 Debian:: test /etc/debian_version
632 Fedora:: test /etc/fedora-release
634 RedHat or CentOS:: test /etc/redhat-release
636 ArchLinux:: test /etc/arch-release
638 Alpine:: test /etc/alpine-release
640 Gentoo:: test /etc/gentoo-release
642 NOTE: Container start fails if the configured `ostype` differs from the auto
646 [[pct_container_storage]]
650 The {pve} LXC container storage model is more flexible than traditional
651 container storage models. A container can have multiple mount points. This
652 makes it possible to use the best suited storage for each application.
654 For example the root file system of the container can be on slow and cheap
655 storage while the database can be on fast and distributed storage via a second
656 mount point. See section <<pct_mount_points, Mount Points>> for further
659 Any storage type supported by the {pve} storage library can be used. This means
660 that containers can be stored on local (for example `lvm`, `zfs` or directory),
661 shared external (like `iSCSI`, `NFS`) or even distributed storage systems like
662 Ceph. Advanced storage features like snapshots or clones can be used if the
663 underlying storage supports them. The `vzdump` backup tool can use snapshots to
664 provide consistent container backups.
666 Furthermore, local devices or local directories can be mounted directly using
667 'bind mounts'. This gives access to local resources inside a container with
668 practically zero overhead. Bind mounts can be used as an easy way to share data
675 WARNING: Because of existing issues in the Linux kernel's freezer subsystem the
676 usage of FUSE mounts inside a container is strongly advised against, as
677 containers need to be frozen for suspend or snapshot mode backups.
679 If FUSE mounts cannot be replaced by other mounting mechanisms or storage
680 technologies, it is possible to establish the FUSE mount on the Proxmox host
681 and use a bind mount point to make it accessible inside the container.
684 Using Quotas Inside Containers
685 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
687 Quotas allow to set limits inside a container for the amount of disk space that
690 NOTE: This currently requires the use of legacy 'cgroups'.
692 NOTE: This only works on ext4 image based storage types and currently only
693 works with privileged containers.
695 Activating the `quota` option causes the following mount options to be used for
697 `usrjquota=aquota.user,grpjquota=aquota.group,jqfmt=vfsv0`
699 This allows quotas to be used like on any other system. You can initialize the
700 `/aquota.user` and `/aquota.group` files by running:
707 Then edit the quotas using the `edquota` command. Refer to the documentation of
708 the distribution running inside the container for details.
710 NOTE: You need to run the above commands for every mount point by passing the
711 mount point's path instead of just `/`.
714 Using ACLs Inside Containers
715 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
717 The standard Posix **A**ccess **C**ontrol **L**ists are also available inside
718 containers. ACLs allow you to set more detailed file ownership than the
719 traditional user/group/others model.
722 Backup of Container mount points
723 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
725 To include a mount point in backups, enable the `backup` option for it in the
726 container configuration. For an existing mount point `mp0`
729 mp0: guests:subvol-100-disk-1,mp=/root/files,size=8G
732 add `backup=1` to enable it.
735 mp0: guests:subvol-100-disk-1,mp=/root/files,size=8G,backup=1
738 NOTE: When creating a new mount point in the GUI, this option is enabled by
741 To disable backups for a mount point, add `backup=0` in the way described
742 above, or uncheck the *Backup* checkbox on the GUI.
744 Replication of Containers mount points
745 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
747 By default, additional mount points are replicated when the Root Disk is
748 replicated. If you want the {pve} storage replication mechanism to skip a mount
749 point, you can set the *Skip replication* option for that mount point.
750 As of {pve} 5.0, replication requires a storage of type `zfspool`. Adding a
751 mount point to a different type of storage when the container has replication
752 configured requires to have *Skip replication* enabled for that mount point.
762 It is possible to use the `vzdump` tool for container backup. Please refer to
763 the `vzdump` manual page for details.
766 Restoring Container Backups
767 ~~~~~~~~~~~~~~~~~~~~~~~~~~~
769 Restoring container backups made with `vzdump` is possible using the `pct
770 restore` command. By default, `pct restore` will attempt to restore as much of
771 the backed up container configuration as possible. It is possible to override
772 the backed up configuration by manually setting container options on the
773 command line (see the `pct` manual page for details).
775 NOTE: `pvesm extractconfig` can be used to view the backed up configuration
776 contained in a vzdump archive.
778 There are two basic restore modes, only differing by their handling of mount
782 ``Simple'' Restore Mode
783 ^^^^^^^^^^^^^^^^^^^^^^^
785 If neither the `rootfs` parameter nor any of the optional `mpX` parameters are
786 explicitly set, the mount point configuration from the backed up configuration
787 file is restored using the following steps:
789 . Extract mount points and their options from backup
790 . Create volumes for storage backed mount points (on storage provided with the
791 `storage` parameter, or default local storage if unset)
792 . Extract files from backup archive
793 . Add bind and device mount points to restored configuration (limited to root
796 NOTE: Since bind and device mount points are never backed up, no files are
797 restored in the last step, but only the configuration options. The assumption
798 is that such mount points are either backed up with another mechanism (e.g.,
799 NFS space that is bind mounted into many containers), or not intended to be
802 This simple mode is also used by the container restore operations in the web
806 ``Advanced'' Restore Mode
807 ^^^^^^^^^^^^^^^^^^^^^^^^^
809 By setting the `rootfs` parameter (and optionally, any combination of `mpX`
810 parameters), the `pct restore` command is automatically switched into an
811 advanced mode. This advanced mode completely ignores the `rootfs` and `mpX`
812 configuration options contained in the backup archive, and instead only uses
813 the options explicitly provided as parameters.
815 This mode allows flexible configuration of mount point settings at restore
818 * Set target storages, volume sizes and other options for each mount point
820 * Redistribute backed up files according to new mount point scheme
821 * Restore to device and/or bind mount points (limited to root user)
824 Managing Containers with `pct`
825 ------------------------------
827 The ``Proxmox Container Toolkit'' (`pct`) is the command line tool to manage
828 {pve} containers. It enables you to create or destroy containers, as well as
829 control the container execution (start, stop, reboot, migrate, etc.). It can be
830 used to set parameters in the config file of a container, for example the
831 network configuration or memory limits.
836 Create a container based on a Debian template (provided you have already
837 downloaded the template via the web interface)
840 # pct create 100 /var/lib/vz/template/cache/debian-10.0-standard_10.0-1_amd64.tar.gz
849 Start a login session via getty
855 Enter the LXC namespace and run a shell as root user
861 Display the configuration
867 Add a network interface called `eth0`, bridged to the host bridge `vmbr0`, set
868 the address and gateway, while it's running
871 # pct set 100 -net0 name=eth0,bridge=vmbr0,ip=192.168.15.147/24,gw=192.168.15.1
874 Reduce the memory of the container to 512MB
877 # pct set 100 -memory 512
880 Destroying a container always removes it from Access Control Lists and it always
881 removes the firewall configuration of the container. You have to activate
882 '--purge', if you want to additionally remove the container from replication jobs,
883 backup jobs and HA resource configurations.
886 # pct destroy 100 --purge
891 Obtaining Debugging Logs
892 ~~~~~~~~~~~~~~~~~~~~~~~~
894 In case `pct start` is unable to start a specific container, it might be
895 helpful to collect debugging output by passing the `--debug` flag (replace `CTID` with
896 the container's CTID):
899 # pct start CTID --debug
902 Alternatively, you can use the following `lxc-start` command, which will save
903 the debug log to the file specified by the `-o` output option:
906 # lxc-start -n CTID -F -l DEBUG -o /tmp/lxc-CTID.log
909 This command will attempt to start the container in foreground mode, to stop
910 the container run `pct shutdown CTID` or `pct stop CTID` in a second terminal.
912 The collected debug log is written to `/tmp/lxc-CTID.log`.
914 NOTE: If you have changed the container's configuration since the last start
915 attempt with `pct start`, you need to run `pct start` at least once to also
916 update the configuration used by `lxc-start`.
922 If you have a cluster, you can migrate your Containers with
925 # pct migrate <ctid> <target>
928 This works as long as your Container is offline. If it has local volumes or
929 mount points defined, the migration will copy the content over the network to
930 the target host if the same storage is defined there.
932 Running containers cannot live-migrated due to technical limitations. You can
933 do a restart migration, which shuts down, moves and then starts a container
934 again on the target node. As containers are very lightweight, this results
935 normally only in a downtime of some hundreds of milliseconds.
937 A restart migration can be done through the web interface or by using the
938 `--restart` flag with the `pct migrate` command.
940 A restart migration will shut down the Container and kill it after the
941 specified timeout (the default is 180 seconds). Then it will migrate the
942 Container like an offline migration and when finished, it starts the Container
945 [[pct_configuration]]
949 The `/etc/pve/lxc/<CTID>.conf` file stores container configuration, where
950 `<CTID>` is the numeric ID of the given container. Like all other files stored
951 inside `/etc/pve/`, they get automatically replicated to all other cluster
954 NOTE: CTIDs < 100 are reserved for internal purposes, and CTIDs need to be
957 .Example Container Configuration
964 net0: bridge=vmbr0,hwaddr=66:64:66:64:64:36,ip=dhcp,name=eth0,type=veth
965 rootfs: local:107/vm-107-disk-1.raw,size=7G
968 The configuration files are simple text files. You can edit them using a normal
969 text editor, for example, `vi` or `nano`.
970 This is sometimes useful to do small corrections, but keep in mind that you
971 need to restart the container to apply such changes.
973 For that reason, it is usually better to use the `pct` command to generate and
974 modify those files, or do the whole thing using the GUI.
975 Our toolkit is smart enough to instantaneously apply most changes to running
976 containers. This feature is called ``hot plug'', and there is no need to restart
977 the container in that case.
979 In cases where a change cannot be hot-plugged, it will be registered as a
980 pending change (shown in red color in the GUI).
981 They will only be applied after rebooting the container.
987 The container configuration file uses a simple colon separated key/value
988 format. Each line has the following format:
995 Blank lines in those files are ignored, and lines starting with a `#` character
996 are treated as comments and are also ignored.
998 It is possible to add low-level, LXC style configuration directly, for example:
1001 lxc.init_cmd: /sbin/my_own_init
1007 lxc.init_cmd = /sbin/my_own_init
1010 The settings are passed directly to the LXC low-level tools.
1017 When you create a snapshot, `pct` stores the configuration at snapshot time
1018 into a separate snapshot section within the same configuration file. For
1019 example, after creating a snapshot called ``testsnapshot'', your configuration
1020 file will look like this:
1022 .Container configuration with snapshot
1032 snaptime: 1457170803
1036 There are a few snapshot related properties like `parent` and `snaptime`. The
1037 `parent` property is used to store the parent/child relationship between
1038 snapshots. `snaptime` is the snapshot creation time stamp (Unix epoch).
1045 include::pct.conf.5-opts.adoc[]
1051 Container migrations, snapshots and backups (`vzdump`) set a lock to prevent
1052 incompatible concurrent actions on the affected container. Sometimes you need
1053 to remove such a lock manually (e.g., after a power failure).
1059 CAUTION: Only do this if you are sure the action which set the lock is no
1068 `/etc/pve/lxc/<CTID>.conf`::
1070 Configuration file for the container '<CTID>'.
1073 include::pve-copyright.adoc[]