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 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 Containers run in their own separate namespaces. Additionally some syscalls
45 are not allowed within containers.
47 {pve} uses https://linuxcontainers.org/[Linux Containers (LXC)] as underlying
48 container technology. The ``Proxmox Container Toolkit'' (`pct`) simplifies the
49 usage and management of LXC containers.
51 Containers are tightly integrated with {pve}. This means that they are aware of
52 the cluster setup, and they can use the same network and storage resources as
53 virtual machines. You can also use the {pve} firewall, or manage containers
54 using the HA framework.
56 Our primary goal is to offer an environment as one would get from a VM, but
57 without the additional overhead. We call this ``System Containers''.
59 NOTE: If you want to run micro-containers, for example, 'Docker' or 'rkt', it
60 is best to run them inside a VM.
66 * LXC (https://linuxcontainers.org/)
68 * Integrated into {pve} graphical web user interface (GUI)
70 * Easy to use command line tool `pct`
72 * Access via {pve} REST API
74 * 'lxcfs' to provide containerized /proc file system
76 * Control groups ('cgroups') for resource isolation and limitation
78 * 'AppArmor' and 'seccomp' to improve security
80 * Modern Linux kernels
82 * Image based deployment (templates)
84 * Uses {pve} xref:chapter_storage[storage library]
86 * Container setup from host (network, DNS, storage, etc.)
89 Security Considerations
90 -----------------------
92 Containers use the kernel of the host system. This creates a big attack surface
93 for malicious users. This should be considered if containers are provided to
94 untrustworthy people. In general, full virtual machines provide better
97 However, LXC uses many security features like AppArmor, CGroups and kernel
98 namespaces to reduce the attack surface.
100 AppArmor profiles are used to restrict access to possibly dangerous actions.
101 Some system calls, i.e. `mount`, are prohibited from execution.
103 To trace AppArmor activity, use:
106 # dmesg | grep apparmor
109 Guest Operating System Configuration
110 ------------------------------------
112 {pve} tries to detect the Linux distribution in the container, and modifies
113 some files. Here is a short list of things done at container startup:
115 set /etc/hostname:: to set the container name
117 modify /etc/hosts:: to allow lookup of the local hostname
119 network setup:: pass the complete network setup to the container
121 configure DNS:: pass information about DNS servers
123 adapt the init system:: for example, fix the number of spawned getty processes
125 set the root password:: when creating a new container
127 rewrite ssh_host_keys:: so that each container has unique keys
129 randomize crontab:: so that cron does not start at the same time on all containers
131 Changes made by {PVE} are enclosed by comment markers:
139 Those markers will be inserted at a reasonable location in the file. If such a
140 section already exists, it will be updated in place and will not be moved.
142 Modification of a file can be prevented by adding a `.pve-ignore.` file for it.
143 For instance, if the file `/etc/.pve-ignore.hosts` exists then the `/etc/hosts`
144 file will not be touched. This can be a simple empty file created via:
147 # touch /etc/.pve-ignore.hosts
150 Most modifications are OS dependent, so they differ between different
151 distributions and versions. You can completely disable modifications by
152 manually setting the `ostype` to `unmanaged`.
154 OS type detection is done by testing for certain files inside the
157 Ubuntu:: inspect /etc/lsb-release (`DISTRIB_ID=Ubuntu`)
159 Debian:: test /etc/debian_version
161 Fedora:: test /etc/fedora-release
163 RedHat or CentOS:: test /etc/redhat-release
165 ArchLinux:: test /etc/arch-release
167 Alpine:: test /etc/alpine-release
169 Gentoo:: test /etc/gentoo-release
171 NOTE: Container start fails if the configured `ostype` differs from the auto
175 [[pct_container_images]]
179 Container images, sometimes also referred to as ``templates'' or
180 ``appliances'', are `tar` archives which contain everything to run a container.
181 `pct` uses them to create a new container, for example:
184 # pct create 999 local:vztmpl/debian-10.0-standard_10.0-1_amd64.tar.gz
187 {pve} itself provides a variety of basic templates for the most common Linux
188 distributions. They can be downloaded using the GUI or the `pveam` (short for
189 {pve} Appliance Manager) command line utility.
190 Additionally, https://www.turnkeylinux.org/[TurnKey Linux] container templates
191 are also available to download.
193 The list of available templates is updated daily via cron. To trigger it
200 To view the list of available images run:
206 You can restrict this large list by specifying the `section` you are
207 interested in, for example basic `system` images:
209 .List available system images
211 # pveam available --section system
212 system alpine-3.10-default_20190626_amd64.tar.xz
213 system alpine-3.9-default_20190224_amd64.tar.xz
214 system archlinux-base_20190924-1_amd64.tar.gz
215 system centos-6-default_20191016_amd64.tar.xz
216 system centos-7-default_20190926_amd64.tar.xz
217 system centos-8-default_20191016_amd64.tar.xz
218 system debian-10.0-standard_10.0-1_amd64.tar.gz
219 system debian-8.0-standard_8.11-1_amd64.tar.gz
220 system debian-9.0-standard_9.7-1_amd64.tar.gz
221 system fedora-30-default_20190718_amd64.tar.xz
222 system fedora-31-default_20191029_amd64.tar.xz
223 system gentoo-current-default_20190718_amd64.tar.xz
224 system opensuse-15.0-default_20180907_amd64.tar.xz
225 system opensuse-15.1-default_20190719_amd64.tar.xz
226 system ubuntu-16.04-standard_16.04.5-1_amd64.tar.gz
227 system ubuntu-18.04-standard_18.04.1-1_amd64.tar.gz
228 system ubuntu-19.04-standard_19.04-1_amd64.tar.gz
229 system ubuntu-19.10-standard_19.10-1_amd64.tar.gz
232 Before you can use such a template, you need to download them into one of your
233 storages. You can simply use storage `local` for that purpose. For clustered
234 installations, it is preferred to use a shared storage so that all nodes can
238 # pveam download local debian-10.0-standard_10.0-1_amd64.tar.gz
241 You are now ready to create containers using that image, and you can list all
242 downloaded images on storage `local` with:
246 local:vztmpl/debian-10.0-standard_10.0-1_amd64.tar.gz 219.95MB
249 The above command shows you the full {pve} volume identifiers. They include the
250 storage name, and most other {pve} commands can use them. For example you can
251 delete that image later with:
254 # pveam remove local:vztmpl/debian-10.0-standard_10.0-1_amd64.tar.gz
257 [[pct_container_storage]]
261 The {pve} LXC container storage model is more flexible than traditional
262 container storage models. A container can have multiple mount points. This
263 makes it possible to use the best suited storage for each application.
265 For example the root file system of the container can be on slow and cheap
266 storage while the database can be on fast and distributed storage via a second
267 mount point. See section <<pct_mount_points, Mount Points>> for further
270 Any storage type supported by the {pve} storage library can be used. This means
271 that containers can be stored on local (for example `lvm`, `zfs` or directory),
272 shared external (like `iSCSI`, `NFS`) or even distributed storage systems like
273 Ceph. Advanced storage features like snapshots or clones can be used if the
274 underlying storage supports them. The `vzdump` backup tool can use snapshots to
275 provide consistent container backups.
277 Furthermore, local devices or local directories can be mounted directly using
278 'bind mounts'. This gives access to local resources inside a container with
279 practically zero overhead. Bind mounts can be used as an easy way to share data
286 WARNING: Because of existing issues in the Linux kernel's freezer subsystem the
287 usage of FUSE mounts inside a container is strongly advised against, as
288 containers need to be frozen for suspend or snapshot mode backups.
290 If FUSE mounts cannot be replaced by other mounting mechanisms or storage
291 technologies, it is possible to establish the FUSE mount on the Proxmox host
292 and use a bind mount point to make it accessible inside the container.
295 Using Quotas Inside Containers
296 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
298 Quotas allow to set limits inside a container for the amount of disk space that
301 NOTE: This only works on ext4 image based storage types and currently only
302 works with privileged containers.
304 Activating the `quota` option causes the following mount options to be used for
306 `usrjquota=aquota.user,grpjquota=aquota.group,jqfmt=vfsv0`
308 This allows quotas to be used like on any other system. You can initialize the
309 `/aquota.user` and `/aquota.group` files by running:
316 Then edit the quotas using the `edquota` command. Refer to the documentation of
317 the distribution running inside the container for details.
319 NOTE: You need to run the above commands for every mount point by passing the
320 mount point's path instead of just `/`.
323 Using ACLs Inside Containers
324 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
326 The standard Posix **A**ccess **C**ontrol **L**ists are also available inside
327 containers. ACLs allow you to set more detailed file ownership than the
328 traditional user/group/others model.
331 Backup of Container mount points
332 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
334 To include a mount point in backups, enable the `backup` option for it in the
335 container configuration. For an existing mount point `mp0`
338 mp0: guests:subvol-100-disk-1,mp=/root/files,size=8G
341 add `backup=1` to enable it.
344 mp0: guests:subvol-100-disk-1,mp=/root/files,size=8G,backup=1
347 NOTE: When creating a new mount point in the GUI, this option is enabled by
350 To disable backups for a mount point, add `backup=0` in the way described
351 above, or uncheck the *Backup* checkbox on the GUI.
353 Replication of Containers mount points
354 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
356 By default, additional mount points are replicated when the Root Disk is
357 replicated. If you want the {pve} storage replication mechanism to skip a mount
358 point, you can set the *Skip replication* option for that mount point.
359 As of {pve} 5.0, replication requires a storage of type `zfspool`. Adding a
360 mount point to a different type of storage when the container has replication
361 configured requires to have *Skip replication* enabled for that mount point.
371 [thumbnail="screenshot/gui-create-ct-general.png"]
373 General settings of a container include
375 * the *Node* : the physical server on which the container will run
376 * the *CT ID*: a unique number in this {pve} installation used to identify your
378 * *Hostname*: the hostname of the container
379 * *Resource Pool*: a logical group of containers and VMs
380 * *Password*: the root password of the container
381 * *SSH Public Key*: a public key for connecting to the root account over SSH
382 * *Unprivileged container*: this option allows to choose at creation time
383 if you want to create a privileged or unprivileged container.
385 Unprivileged Containers
386 ^^^^^^^^^^^^^^^^^^^^^^^
388 Unprivileged containers use a new kernel feature called user namespaces.
389 The root UID 0 inside the container is mapped to an unprivileged user outside
390 the container. This means that most security issues (container escape, resource
391 abuse, etc.) in these containers will affect a random unprivileged user, and
392 would be a generic kernel security bug rather than an LXC issue. The LXC team
393 thinks unprivileged containers are safe by design.
395 This is the default option when creating a new container.
397 NOTE: If the container uses systemd as an init system, please be aware the
398 systemd version running inside the container should be equal to or greater than
402 Privileged Containers
403 ^^^^^^^^^^^^^^^^^^^^^
405 Security in containers is achieved by using mandatory access control
406 ('AppArmor'), 'seccomp' filters and namespaces. The LXC team considers this
407 kind of container as unsafe, and they will not consider new container escape
408 exploits to be security issues worthy of a CVE and quick fix. That's why
409 privileged containers should only be used in trusted environments.
411 Although it is not recommended, AppArmor can be disabled for a container. This
412 brings security risks with it. Some syscalls can lead to privilege escalation
413 when executed within a container if the system is misconfigured or if a LXC or
414 Linux Kernel vulnerability exists.
416 To disable AppArmor for a container, add the following line to the container
417 configuration file located at `/etc/pve/lxc/CTID.conf`:
420 lxc.apparmor_profile = unconfined
423 WARNING: Please note that this is not recommended for production use.
430 [thumbnail="screenshot/gui-create-ct-cpu.png"]
432 You can restrict the number of visible CPUs inside the container using the
433 `cores` option. This is implemented using the Linux 'cpuset' cgroup
434 (**c**ontrol *group*).
435 A special task inside `pvestatd` tries to distribute running containers among
436 available CPUs periodically.
437 To view the assigned CPUs run the following command:
441 ---------------------
445 ---------------------
448 Containers use the host kernel directly. All tasks inside a container are
449 handled by the host CPU scheduler. {pve} uses the Linux 'CFS' (**C**ompletely
450 **F**air **S**cheduler) scheduler by default, which has additional bandwidth
455 `cpulimit`: :: You can use this option to further limit assigned CPU time.
456 Please note that this is a floating point number, so it is perfectly valid to
457 assign two cores to a container, but restrict overall CPU consumption to half a
465 `cpuunits`: :: This is a relative weight passed to the kernel scheduler. The
466 larger the number is, the more CPU time this container gets. Number is relative
467 to the weights of all the other running containers. The default is 1024. You
468 can use this setting to prioritize some containers.
475 [thumbnail="screenshot/gui-create-ct-memory.png"]
477 Container memory is controlled using the cgroup memory controller.
481 `memory`: :: Limit overall memory usage. This corresponds to the
482 `memory.limit_in_bytes` cgroup setting.
484 `swap`: :: Allows the container to use additional swap memory from the host
485 swap space. This corresponds to the `memory.memsw.limit_in_bytes` cgroup
486 setting, which is set to the sum of both value (`memory + swap`).
493 [thumbnail="screenshot/gui-create-ct-root-disk.png"]
495 The root mount point is configured with the `rootfs` property. You can
496 configure up to 256 additional mount points. The corresponding options are
497 called `mp0` to `mp255`. They can contain the following settings:
499 include::pct-mountpoint-opts.adoc[]
501 Currently there are three types of mount points: storage backed mount points,
502 bind mounts, and device mounts.
504 .Typical container `rootfs` configuration
506 rootfs: thin1:base-100-disk-1,size=8G
510 Storage Backed Mount Points
511 ^^^^^^^^^^^^^^^^^^^^^^^^^^^
513 Storage backed mount points are managed by the {pve} storage subsystem and come
514 in three different flavors:
516 - Image based: these are raw images containing a single ext4 formatted file
518 - ZFS subvolumes: these are technically bind mounts, but with managed storage,
519 and thus allow resizing and snapshotting.
520 - Directories: passing `size=0` triggers a special case where instead of a raw
521 image a directory is created.
523 NOTE: The special option syntax `STORAGE_ID:SIZE_IN_GB` for storage backed
524 mount point volumes will automatically allocate a volume of the specified size
525 on the specified storage. For example, calling
528 pct set 100 -mp0 thin1:10,mp=/path/in/container
531 will allocate a 10GB volume on the storage `thin1` and replace the volume ID
532 place holder `10` with the allocated volume ID, and setup the moutpoint in the
533 container at `/path/in/container`
539 Bind mounts allow you to access arbitrary directories from your Proxmox VE host
540 inside a container. Some potential use cases are:
542 - Accessing your home directory in the guest
543 - Accessing an USB device directory in the guest
544 - Accessing an NFS mount from the host in the guest
546 Bind mounts are considered to not be managed by the storage subsystem, so you
547 cannot make snapshots or deal with quotas from inside the container. With
548 unprivileged containers you might run into permission problems caused by the
549 user mapping and cannot use ACLs.
551 NOTE: The contents of bind mount points are not backed up when using `vzdump`.
553 WARNING: For security reasons, bind mounts should only be established using
554 source directories especially reserved for this purpose, e.g., a directory
555 hierarchy under `/mnt/bindmounts`. Never bind mount system directories like
556 `/`, `/var` or `/etc` into a container - this poses a great security risk.
558 NOTE: The bind mount source path must not contain any symlinks.
560 For example, to make the directory `/mnt/bindmounts/shared` accessible in the
561 container with ID `100` under the path `/shared`, use a configuration line like
562 `mp0: /mnt/bindmounts/shared,mp=/shared` in `/etc/pve/lxc/100.conf`.
563 Alternatively, use `pct set 100 -mp0 /mnt/bindmounts/shared,mp=/shared` to
564 achieve the same result.
570 Device mount points allow to mount block devices of the host directly into the
571 container. Similar to bind mounts, device mounts are not managed by {PVE}'s
572 storage subsystem, but the `quota` and `acl` options will be honored.
574 NOTE: Device mount points should only be used under special circumstances. In
575 most cases a storage backed mount point offers the same performance and a lot
578 NOTE: The contents of device mount points are not backed up when using
582 [[pct_container_network]]
586 [thumbnail="screenshot/gui-create-ct-network.png"]
588 You can configure up to 10 network interfaces for a single container.
589 The corresponding options are called `net0` to `net9`, and they can contain the
592 include::pct-network-opts.adoc[]
595 [[pct_startup_and_shutdown]]
596 Automatic Start and Shutdown of Containers
597 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
599 To automatically start a container when the host system boots, select the
600 option 'Start at boot' in the 'Options' panel of the container in the web
601 interface or run the following command:
604 # pct set CTID -onboot 1
607 .Start and Shutdown Order
608 // use the screenshot from qemu - its the same
609 [thumbnail="screenshot/gui-qemu-edit-start-order.png"]
611 If you want to fine tune the boot order of your containers, you can use the
612 following parameters:
614 * *Start/Shutdown order*: Defines the start order priority. For example, set it
615 to 1 if you want the CT to be the first to be started. (We use the reverse
616 startup order for shutdown, so a container with a start order of 1 would be
617 the last to be shut down)
618 * *Startup delay*: Defines the interval between this container start and
619 subsequent containers starts. For example, set it to 240 if you want to wait
620 240 seconds before starting other containers.
621 * *Shutdown timeout*: Defines the duration in seconds {pve} should wait
622 for the container to be offline after issuing a shutdown command.
623 By default this value is set to 60, which means that {pve} will issue a
624 shutdown request, wait 60s for the machine to be offline, and if after 60s
625 the machine is still online will notify that the shutdown action failed.
627 Please note that containers without a Start/Shutdown order parameter will
628 always start after those where the parameter is set, and this parameter only
629 makes sense between the machines running locally on a host, and not
635 You can add a hook script to CTs with the config property `hookscript`.
638 # pct set 100 -hookscript local:snippets/hookscript.pl
641 It will be called during various phases of the guests lifetime. For an example
642 and documentation see the example script under
643 `/usr/share/pve-docs/examples/guest-example-hookscript.pl`.
652 It is possible to use the `vzdump` tool for container backup. Please refer to
653 the `vzdump` manual page for details.
656 Restoring Container Backups
657 ~~~~~~~~~~~~~~~~~~~~~~~~~~~
659 Restoring container backups made with `vzdump` is possible using the `pct
660 restore` command. By default, `pct restore` will attempt to restore as much of
661 the backed up container configuration as possible. It is possible to override
662 the backed up configuration by manually setting container options on the
663 command line (see the `pct` manual page for details).
665 NOTE: `pvesm extractconfig` can be used to view the backed up configuration
666 contained in a vzdump archive.
668 There are two basic restore modes, only differing by their handling of mount
672 ``Simple'' Restore Mode
673 ^^^^^^^^^^^^^^^^^^^^^^^
675 If neither the `rootfs` parameter nor any of the optional `mpX` parameters are
676 explicitly set, the mount point configuration from the backed up configuration
677 file is restored using the following steps:
679 . Extract mount points and their options from backup
680 . Create volumes for storage backed mount points (on storage provided with the
681 `storage` parameter, or default local storage if unset)
682 . Extract files from backup archive
683 . Add bind and device mount points to restored configuration (limited to root
686 NOTE: Since bind and device mount points are never backed up, no files are
687 restored in the last step, but only the configuration options. The assumption
688 is that such mount points are either backed up with another mechanism (e.g.,
689 NFS space that is bind mounted into many containers), or not intended to be
692 This simple mode is also used by the container restore operations in the web
696 ``Advanced'' Restore Mode
697 ^^^^^^^^^^^^^^^^^^^^^^^^^
699 By setting the `rootfs` parameter (and optionally, any combination of `mpX`
700 parameters), the `pct restore` command is automatically switched into an
701 advanced mode. This advanced mode completely ignores the `rootfs` and `mpX`
702 configuration options contained in the backup archive, and instead only uses
703 the options explicitly provided as parameters.
705 This mode allows flexible configuration of mount point settings at restore
708 * Set target storages, volume sizes and other options for each mount point
710 * Redistribute backed up files according to new mount point scheme
711 * Restore to device and/or bind mount points (limited to root user)
714 Managing Containers with `pct`
715 ------------------------------
717 The ``Proxmox Container Toolkit'' (`pct`) is the command line tool to manage
718 {pve} containers. It enables you to create or destroy containers, as well as
719 control the container execution (start, stop, reboot, migrate, etc.). It can be
720 used to set parameters in the config file of a container, for example the
721 network configuration or memory limits.
726 Create a container based on a Debian template (provided you have already
727 downloaded the template via the web interface)
730 # pct create 100 /var/lib/vz/template/cache/debian-10.0-standard_10.0-1_amd64.tar.gz
739 Start a login session via getty
745 Enter the LXC namespace and run a shell as root user
751 Display the configuration
757 Add a network interface called `eth0`, bridged to the host bridge `vmbr0`, set
758 the address and gateway, while it's running
761 # pct set 100 -net0 name=eth0,bridge=vmbr0,ip=192.168.15.147/24,gw=192.168.15.1
764 Reduce the memory of the container to 512MB
767 # pct set 100 -memory 512
771 Obtaining Debugging Logs
772 ~~~~~~~~~~~~~~~~~~~~~~~~
774 In case `pct start` is unable to start a specific container, it might be
775 helpful to collect debugging output by running `lxc-start` (replace `ID` with
779 # lxc-start -n ID -F -l DEBUG -o /tmp/lxc-ID.log
782 This command will attempt to start the container in foreground mode, to stop
783 the container run `pct shutdown ID` or `pct stop ID` in a second terminal.
785 The collected debug log is written to `/tmp/lxc-ID.log`.
787 NOTE: If you have changed the container's configuration since the last start
788 attempt with `pct start`, you need to run `pct start` at least once to also
789 update the configuration used by `lxc-start`.
795 If you have a cluster, you can migrate your Containers with
798 # pct migrate <ctid> <target>
801 This works as long as your Container is offline. If it has local volumes or
802 mount points defined, the migration will copy the content over the network to
803 the target host if the same storage is defined there.
805 Running containers cannot live-migrated due to techincal limitations. You can
806 do a restart migration, which shuts down, moves and then starts a container
807 again on the target node. As containers are very lightweight, this results
808 normally only in a downtime of some hundreds of milliseconds.
810 A restart migration can be done through the web interface or by using the
811 `--restart` flag with the `pct migrate` command.
813 A restart migration will shut down the Container and kill it after the
814 specified timeout (the default is 180 seconds). Then it will migrate the
815 Container like an offline migration and when finished, it starts the Container
818 [[pct_configuration]]
822 The `/etc/pve/lxc/<CTID>.conf` file stores container configuration, where
823 `<CTID>` is the numeric ID of the given container. Like all other files stored
824 inside `/etc/pve/`, they get automatically replicated to all other cluster
827 NOTE: CTIDs < 100 are reserved for internal purposes, and CTIDs need to be
830 .Example Container Configuration
837 net0: bridge=vmbr0,hwaddr=66:64:66:64:64:36,ip=dhcp,name=eth0,type=veth
838 rootfs: local:107/vm-107-disk-1.raw,size=7G
841 The configuration files are simple text files. You can edit them using a normal
842 text editor (`vi`, `nano`, etc).
843 This is sometimes useful to do small corrections, but keep in mind that you
844 need to restart the container to apply such changes.
846 For that reason, it is usually better to use the `pct` command to generate and
847 modify those files, or do the whole thing using the GUI.
848 Our toolkit is smart enough to instantaneously apply most changes to running
849 containers. This feature is called "hot plug", and there is no need to restart
850 the container in that case.
852 In cases where a change cannot be hot plugged, it will be registered as a
853 pending change (shown in red color in the GUI).
854 They will only be applied after rebooting the container.
860 The container configuration file uses a simple colon separated key/value
861 format. Each line has the following format:
868 Blank lines in those files are ignored, and lines starting with a `#` character
869 are treated as comments and are also ignored.
871 It is possible to add low-level, LXC style configuration directly, for example:
874 lxc.init_cmd: /sbin/my_own_init
880 lxc.init_cmd = /sbin/my_own_init
883 The settings are passed directly to the LXC low-level tools.
890 When you create a snapshot, `pct` stores the configuration at snapshot time
891 into a separate snapshot section within the same configuration file. For
892 example, after creating a snapshot called ``testsnapshot'', your configuration
893 file will look like this:
895 .Container configuration with snapshot
909 There are a few snapshot related properties like `parent` and `snaptime`. The
910 `parent` property is used to store the parent/child relationship between
911 snapshots. `snaptime` is the snapshot creation time stamp (Unix epoch).
918 include::pct.conf.5-opts.adoc[]
924 Container migrations, snapshots and backups (`vzdump`) set a lock to prevent
925 incompatible concurrent actions on the affected container. Sometimes you need
926 to remove such a lock manually (e.g., after a power failure).
932 CAUTION: Only do this if you are sure the action which set the lock is no
941 `/etc/pve/lxc/<CTID>.conf`::
943 Configuration file for the container '<CTID>'.
946 include::pve-copyright.adoc[]