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[[Category:Reference Documentation]]
[[Category:Reference Documentation]]
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Containers are a lightweight alternative to fully virtualized
Containers are a lightweight alternative to fully virtualized machines (VMs).
VMs. Instead of emulating a complete Operating System (OS), containers
They use the kernel of the host system that they run on, instead of emulating a
simply use the OS of the host they run on. This implies that all
full operating system (OS). This means that containers can access resources on
containers use the same kernel, and that they can access resources
the host system directly.
from the host directly.
The runtime costs for containers is low, usually negligible. However, there are
This is great because containers do not waste CPU power nor memory due
some drawbacks that need be considered:
to kernel emulation. Container run-time costs are close to zero and
Only Linux distributions can be run in Proxmox Containers. It is not possible to run
usually negligible. But there are also some drawbacks you need to
  other operating systems like, for example, FreeBSD or Microsoft Windows
consider:
  inside a container.
You can only run Linux based OS inside containers, i.e. it is not
For security reasons, access to host resources needs to be restricted.
  possible to run FreeBSD or MS Windows inside.
   Therefore, containers run in their own separate namespaces. Additionally some
For security reasons, access to host resources needs to be
  syscalls (user space requests to the Linux kernel) are not allowed within containers.
  restricted. This is done with AppArmor, SecComp filters and other
Proxmox VE uses Linux Containers (LXC) as its underlying
   kernel features. Be prepared that some syscalls are not allowed
container technology. The &#8220;Proxmox Container Toolkit&#8221; (pct) simplifies the
  inside containers.
usage and management of LXC, by providing an interface that abstracts
Proxmox VE uses LXC as underlying container
complex tasks.
technology. We consider LXC as low-level library, which provides
Containers are tightly integrated with Proxmox VE. This means that they are aware of
countless options. It would be too difficult to use those tools
the cluster setup, and they can use the same network and storage resources as
directly. Instead, we provide a small wrapper called pct, the
virtual machines. You can also use the Proxmox VE firewall, or manage containers
"Proxmox Container Toolkit".
using the HA framework.
The toolkit is tightly coupled with Proxmox VE. That means that it is aware
Our primary goal is to offer an environment that provides the benefits of using a
of the cluster setup, and it can use the same network and storage
VM, but without the additional overhead. This means that Proxmox Containers can
resources as fully virtualized VMs. You can even use the Proxmox VE
be categorized as &#8220;System Containers&#8221;, rather than &#8220;Application Containers&#8221;.
firewall, or manage containers using the HA framework.
If you want to run application containers, for example, Docker images, it
Our primary goal is to offer an environment as one would get from a
is recommended that you run them inside a Proxmox QEMU VM. This will give you
VM, but without the additional overhead. We call this "System
all the advantages of application containerization, while also providing the
Containers".
benefits that VMs offer, such as strong isolation from the host and the ability
If you want to run micro-containers (with docker, rkt, …), it
to live-migrate, which otherwise isn&#8217;t possible with containers.
is best to run them inside a VM.
Technology Overview
Security Considerations
LXC (https://linuxcontainers.org/)
Containers use the same kernel as the host, so there is a big attack
Integrated into Proxmox VE graphical web user interface (GUI)
surface for malicious users. You should consider this fact if you
Easy to use command-line tool pct
provide containers to totally untrusted people. In general, fully
Access via Proxmox VE REST API
virtualized VMs provide better isolation.
lxcfs to provide containerized /proc file system
The good news is that LXC uses many kernel security features like
Control groups (cgroups) for resource isolation and limitation
AppArmor, CGroups and PID and user namespaces, which makes containers
AppArmor and seccomp to improve security
usage quite secure. We distinguish two types of containers:
Modern Linux kernels
Privileged Containers
Image based deployment (templates)
Security is done by dropping capabilities, using mandatory access
Uses Proxmox VE storage library
control (AppArmor), SecComp filters and namespaces. The LXC team
Container setup from host (network, DNS, storage, etc.)
considers this kind of container as unsafe, and they will not consider
Supported Distributions
new container escape exploits to be security issues worthy of a CVE
List of officially supported distributions can be found below.
and quick fix. So you should use this kind of containers only inside a
Templates for the following distributions are available through our
trusted environment, or when no untrusted task is running as root in
repositories. You can use pveam tool or the
the container.
Graphical User Interface to download them.
Unprivileged Containers
Alpine Linux
This kind of containers use a new kernel feature called user
Alpine Linux is a security-oriented, lightweight Linux distribution based on
namespaces. The root UID 0 inside the container is mapped to an
musl libc and busybox.
unprivileged user outside the container. This means that most security
&#8212; https://alpinelinux.org
issues (container escape, resource abuse, …) in those containers
For currently supported releases see:
will affect a random unprivileged user, and so would be a generic
https://alpinelinux.org/releases/
kernel security bug rather than an LXC issue. The LXC team thinks
Arch Linux
unprivileged containers are safe by design.
Arch Linux, a lightweight and flexible Linux® distribution that tries to Keep It Simple.
Configuration
&#8212; https://archlinux.org/
The /etc/pve/lxc/<CTID>.conf file stores container configuration,
Arch Linux is using a rolling-release model, see its wiki for more details:
where <CTID> is the numeric ID of the given container. Like all
https://wiki.archlinux.org/title/Arch_Linux
other files stored inside /etc/pve/, they get automatically
CentOS, Almalinux, Rocky Linux
replicated to all other cluster nodes.
CentOS / CentOS Stream
CTIDs < 100 are reserved for internal purposes, and CTIDs need to be
The CentOS Linux distribution is a stable, predictable, manageable and
unique cluster wide.
reproducible platform derived from the sources of Red Hat Enterprise Linux
Example Container Configuration
(RHEL)
ostype: debian
&#8212; https://centos.org
arch: amd64
For currently supported releases see:
hostname: www
https://en.wikipedia.org/wiki/CentOS#End-of-support_schedule
memory: 512
Almalinux
swap: 512
An Open Source, community owned and governed, forever-free enterprise Linux
net0: bridge=vmbr0,hwaddr=66:64:66:64:64:36,ip=dhcp,name=eth0,type=veth
distribution, focused on long-term stability, providing a robust
rootfs: local:107/vm-107-disk-1.raw,size=7G
production-grade platform. AlmaLinux OS is 1:1 binary compatible with RHEL® and
Those configuration files are simple text files, and you can edit them
pre-Stream CentOS.
using a normal text editor (vi, nano, …). This is sometimes
&#8212; https://almalinux.org
useful to do small corrections, but keep in mind that you need to
For currently supported releases see:
restart the container to apply such changes.
https://en.wikipedia.org/wiki/AlmaLinux#Releases
For that reason, it is usually better to use the pct command to
Rocky Linux
generate and modify those files, or do the whole thing using the GUI.
Rocky Linux is a community enterprise operating system designed to be 100%
Our toolkit is smart enough to instantaneously apply most changes to
bug-for-bug compatible with America&#8217;s top enterprise Linux distribution now
running containers. This feature is called "hot plug", and there is no
that its downstream partner has shifted direction.
need to restart the container in that case.
&#8212; https://rockylinux.org
File Format
For currently supported releases see:
Container configuration files use a simple colon separated key/value
https://en.wikipedia.org/wiki/Rocky_Linux#Releases
format. Each line has the following format:
# this is a comment
OPTION: value
Blank lines in those files are ignored, and lines starting with a #
character are treated as comments and are also ignored.
It is possible to add low-level, LXC style configuration directly, for
example:
lxc.init_cmd: /sbin/my_own_init
or
lxc.init_cmd = /sbin/my_own_init
Those settings are directly passed to the LXC low-level tools.
Snapshots
When you create a snapshot, pct stores the configuration at snapshot
time into a separate snapshot section within the same configuration
file. For example, after creating a snapshot called “testsnapshot”,
your configuration file will look like this:
Container configuration with snapshot
memory: 512
swap: 512
parent: testsnaphot
...
[testsnaphot]
memory: 512
swap: 512
snaptime: 1457170803
...
There are a few snapshot related properties like parent and
snaptime. The parent property is used to store the parent/child
relationship between snapshots. snaptime is the snapshot creation
time stamp (Unix epoch).
Guest Operating System Configuration
We normally try to detect the operating system type inside the
container, and then modify some files inside the container to make
them work as expected. Here is a short list of things we do at
container startup:
set /etc/hostname
to set the container name
modify /etc/hosts
to allow lookup of the local hostname
network setup
pass the complete network setup to the container
configure DNS
pass information about DNS servers
adapt the init system
for example, fix the number of spawned getty processes
set the root password
when creating a new container
rewrite ssh_host_keys
so that each container has unique keys
randomize crontab
so that cron does not start at the same time on all containers
Changes made by Proxmox VE are enclosed by comment markers:
# --- BEGIN PVE ---
<data>
# --- END PVE ---
Those markers will be inserted at a reasonable location in the
file. If such a section already exists, it will be updated in place
and will not be moved.
Modification of a file can be prevented by adding a .pve-ignore.
file for it.  For instance, if the file /etc/.pve-ignore.hosts
exists then the /etc/hosts file will not be touched. This can be a
simple empty file creatd via:
# touch /etc/.pve-ignore.hosts
Most modifications are OS dependent, so they differ between different
distributions and versions. You can completely disable modifications
by manually setting the ostype to unmanaged.
OS type detection is done by testing for certain files inside the
container:
Ubuntu
inspect /etc/lsb-release (DISTRIB_ID=Ubuntu)
Debian
Debian
test /etc/debian_version
Debian is a free operating system, developed and maintained by the Debian
project. A free Linux distribution with thousands of applications to meet our
users' needs.
&#8212; https://www.debian.org/intro/index#software
For currently supported releases see:
https://www.debian.org/releases/stable/releasenotes
Devuan
Devuan GNU+Linux is a fork of Debian without systemd that allows users to
reclaim control over their system by avoiding unnecessary entanglements and
ensuring Init Freedom.
&#8212; https://www.devuan.org
For currently supported releases see:
https://www.devuan.org/os/releases
Fedora
Fedora
test /etc/fedora-release
Fedora creates an innovative, free, and open source platform for hardware,
RedHat or CentOS
clouds, and containers that enables software developers and community members
test /etc/redhat-release
to build tailored solutions for their users.
ArchLinux
&#8212; https://getfedora.org
test /etc/arch-release
For currently supported releases see:
Alpine
https://fedoraproject.org/wiki/Releases
test /etc/alpine-release
Gentoo
Gentoo
test /etc/gentoo-release
a highly flexible, source-based Linux distribution.
Container start fails if the configured ostype differs from the auto
&#8212; https://www.gentoo.org
detected type.
Gentoo is using a rolling-release model.
Options
OpenSUSE
arch: (amd64 | i386) (default=amd64)
The makers' choice for sysadmins, developers and desktop users.
OS architecture type.
&#8212; https://www.opensuse.org
cmode: (console | shell | tty) (default=tty)
For currently supported releases see:
Console mode. By default, the console command tries to open a connection to one of the available tty devices. By setting cmode to console it tries to attach to /dev/console instead. If you set cmode to shell, it simply invokes a shell inside the container (no login).
https://get.opensuse.org/leap/
console: boolean (default=1)
Ubuntu
Attach a console device (/dev/console) to the container.
Ubuntu is the modern, open source operating system on Linux for the enterprise
cpulimit: number (0 - 128) (default=0)
server, desktop, cloud, and IoT.
Limit of CPU usage.
&#8212; https://ubuntu.com/
If the computer has 2 CPUs, it has a total of 2 CPU time. Value 0 indicates no CPU limit.
For currently supported releases see:
cpuunits: integer (0 - 500000) (default=1024)
https://wiki.ubuntu.com/Releases
CPU weight for a VM. Argument is used in the kernel fair scheduler. The larger the number is, the more CPU time this VM gets. Number is relative to the weights of all the other running VMs.
You can disable fair-scheduler configuration by setting this to 0.
description: string
Container description. Only used on the configuration web interface.
hostname: string
Set a host name for the container.
lock: (backup | migrate | rollback | snapshot)
Lock/unlock the VM.
memory: integer (16 - N) (default=512)
Amount of RAM for the VM in MB.
mp[n]: [volume=]<volume> ,mp=<Path> [,acl=<1|0>] [,backup=<1|0>] [,quota=<1|0>] [,ro=<1|0>] [,size=<DiskSize>]
Use volume as container mount point.
acl=boolean
Explicitly enable or disable ACL support.
backup=boolean
Whether to include the mountpoint in backups (only used for volume mountpoints).
mp=<Path>
Path to the mountpoint as seen from inside the container.
Must not contain any symlinks for security reasons.
quota=boolean
Enable user quotas inside the container (not supported with zfs subvolumes)
ro=boolean
Read-only mountpoint
size=<DiskSize>
Volume size (read only value).
volume=<volume>
Volume, device or directory to mount into the container.
nameserver: string
Sets DNS server IP address for a container. Create will automatically use the setting from the host if you neither set searchdomain nor nameserver.
net[n]: name=<string> [,bridge=<bridge>] [,firewall=<1|0>] [,gw=<GatewayIPv4>] [,gw6=<GatewayIPv6>] [,hwaddr=<XX:XX:XX:XX:XX:XX>] [,ip=<IPv4Format/CIDR>] [,ip6=<IPv6Format/CIDR>] [,mtu=<integer>] [,rate=<mbps>] [,tag=<integer>] [,trunks=<vlanid[;vlanid...]>] [,type=<veth>]
Specifies network interfaces for the container.
bridge=<bridge>
Bridge to attach the network device to.
firewall=boolean
Controls whether this interface’s firewall rules should be used.
gw=<GatewayIPv4>
Default gateway for IPv4 traffic.
gw6=<GatewayIPv6>
Default gateway for IPv6 traffic.
hwaddr=<XX:XX:XX:XX:XX:XX>
The interface MAC address. This is dynamically allocated by default, but you can set that statically if needed, for example to always have the same link-local IPv6 address. (lxc.network.hwaddr)
ip=<IPv4Format/CIDR>
IPv4 address in CIDR format.
ip6=<IPv6Format/CIDR>
IPv6 address in CIDR format.
mtu=integer (64 - N)
Maximum transfer unit of the interface. (lxc.network.mtu)
name=<string>
Name of the network device as seen from inside the container. (lxc.network.name)
rate=<mbps>
Apply rate limiting to the interface
tag=integer (1 - 4094)
VLAN tag for this interface.
trunks=<vlanid[;vlanid...]>
VLAN ids to pass through the interface
type=(veth)
Network interface type.
onboot: boolean (default=0)
Specifies whether a VM will be started during system bootup.
ostype: (alpine | archlinux | centos | debian | fedora | gentoo | opensuse | ubuntu | unmanaged)
OS type. This is used to setup configuration inside the container, and corresponds to lxc setup scripts in /usr/share/lxc/config/<ostype>.common.conf. Value unmanaged can be used to skip and OS specific setup.
protection: boolean (default=0)
Sets the protection flag of the container. This will prevent the CT or CT’s disk remove/update operation.
rootfs: [volume=]<volume> [,acl=<1|0>] [,quota=<1|0>] [,ro=<1|0>] [,size=<DiskSize>]
Use volume as container root.
acl=boolean
Explicitly enable or disable ACL support.
quota=boolean
Enable user quotas inside the container (not supported with zfs subvolumes)
ro=boolean
Read-only mountpoint
size=<DiskSize>
Volume size (read only value).
volume=<volume>
Volume, device or directory to mount into the container.
searchdomain: string
Sets DNS search domains for a container. Create will automatically use the setting from the host if you neither set searchdomain nor nameserver.
startup: `[[order=]\d+] [,up=\d+] [,down=\d+] `
Startup and shutdown behavior. Order is a non-negative number defining the general startup order. Shutdown in done with reverse ordering. Additionally you can set the up or down delay in seconds, which specifies a delay to wait before the next VM is started or stopped.
swap: integer (0 - N) (default=512)
Amount of SWAP for the VM in MB.
template: boolean (default=0)
Enable/disable Template.
tty: integer (0 - 6) (default=2)
Specify the number of tty available to the container
unprivileged: boolean (default=0)
Makes the container run as unprivileged user. (Should not be modified manually.)
unused[n]: string
Reference to unused volumes. This is used internally, and should not be modified manually.
Container Images
Container Images
Container images, sometimes also referred to as “templates” or
Container images, sometimes also referred to as &#8220;templates&#8221; or
“appliances”, are tar archives which contain everything to run a
&#8220;appliances&#8221;, are tar archives which contain everything to run a container.
container. You can think of it as a tidy container backup. Like most
Proxmox VE itself provides a variety of basic templates for the
modern container toolkits, pct uses those images when you create a
most common Linux distributions.  They can be
new container, for example:
downloaded using the GUI or the pveam (short for Proxmox VE Appliance Manager)
pct create 999 local:vztmpl/debian-8.0-standard_8.0-1_amd64.tar.gz
command-line utility. Additionally, TurnKey
Proxmox VE itself ships a set of basic templates for most common
Linux container templates are also available to download.
operating systems, and you can download them using the pveam (short
The list of available templates is updated daily through the pve-daily-update
for Proxmox VE Appliance Manager) command line utility. You can also
timer. You can also trigger an update manually by executing:
download TurnKey Linux containers using
# pveam update
that tool (or the graphical user interface).
To view the list of available images run:
Our image repositories contain a list of available images, and there
# pveam available
is a cron job run each day to download that list. You can trigger that
update manually with:
pveam update
After that you can view the list of available images using:
pveam available
You can restrict this large list by specifying the section you are
You can restrict this large list by specifying the section you are
interested in, for example basic system images:
interested in, for example basic system images:
List available system images
List available system images
# pveam available --section system
# pveam available --section system
system          archlinux-base_2015-24-29-1_x86_64.tar.gz
system          alpine-3.12-default_20200823_amd64.tar.xz
system          centos-7-default_20160205_amd64.tar.xz
system          alpine-3.13-default_20210419_amd64.tar.xz
system          debian-6.0-standard_6.0-7_amd64.tar.gz
system          alpine-3.14-default_20210623_amd64.tar.xz
system          debian-7.0-standard_7.0-3_amd64.tar.gz
system          archlinux-base_20210420-1_amd64.tar.gz
system          debian-8.0-standard_8.0-1_amd64.tar.gz
system          centos-7-default_20190926_amd64.tar.xz
system          ubuntu-12.04-standard_12.04-1_amd64.tar.gz
system          centos-8-default_20201210_amd64.tar.xz
system          ubuntu-14.04-standard_14.04-1_amd64.tar.gz
system          debian-9.0-standard_9.7-1_amd64.tar.gz
system          ubuntu-15.04-standard_15.04-1_amd64.tar.gz
system          debian-10-standard_10.7-1_amd64.tar.gz
system          ubuntu-15.10-standard_15.10-1_amd64.tar.gz
system          devuan-3.0-standard_3.0_amd64.tar.gz
Before you can use such a template, you need to download them into one
system          fedora-33-default_20201115_amd64.tar.xz
of your storages. You can simply use storage local for that
system          fedora-34-default_20210427_amd64.tar.xz
purpose. For clustered installations, it is preferred to use a shared
system          gentoo-current-default_20200310_amd64.tar.xz
storage so that all nodes can access those images.
system          opensuse-15.2-default_20200824_amd64.tar.xz
pveam download local debian-8.0-standard_8.0-1_amd64.tar.gz
system          ubuntu-16.04-standard_16.04.5-1_amd64.tar.gz
You are now ready to create containers using that image, and you can
system          ubuntu-18.04-standard_18.04.1-1_amd64.tar.gz
list all downloaded images on storage local with:
system          ubuntu-20.04-standard_20.04-1_amd64.tar.gz
system          ubuntu-20.10-standard_20.10-1_amd64.tar.gz
system          ubuntu-21.04-standard_21.04-1_amd64.tar.gz
Before you can use such a template, you need to download them into one of your
storages. If you&#8217;re unsure to which one, you can simply use the local named
storage for that purpose. For clustered installations, it is preferred to use a
shared storage so that all nodes can access those images.
# pveam download local debian-10.0-standard_10.0-1_amd64.tar.gz
You are now ready to create containers using that image, and you can list all
downloaded images on storage local with:
# pveam list local
# pveam list local
local:vztmpl/debian-8.0-standard_8.0-1_amd64.tar.gz  190.20MB
local:vztmpl/debian-10.0-standard_10.0-1_amd64.tar.gz  219.95MB
The above command shows you the full Proxmox VE volume identifiers. They include
You can also use the Proxmox VE web interface GUI to download, list and delete
the storage name, and most other Proxmox VE commands can use them. For
container templates.
example you can delete that image later with:
pct uses them to create a new container, for example:
pveam remove local:vztmpl/debian-8.0-standard_8.0-1_amd64.tar.gz
# pct create 999 local:vztmpl/debian-10.0-standard_10.0-1_amd64.tar.gz
Container Storage
The above command shows you the full Proxmox VE volume identifiers. They include the
Traditional containers use a very simple storage model, only allowing
storage name, and most other Proxmox VE commands can use them. For example you can
a single mount point, the root file system. This was further
delete that image later with:
restricted to specific file system types like ext4 and nfs.
# pveam remove local:vztmpl/debian-10.0-standard_10.0-1_amd64.tar.gz
Additional mounts are often done by user provided scripts. This turned
Container Settings
out to be complex and error prone, so we try to avoid that now.
General Settings
Our new LXC based container model is more flexible regarding
General settings of a container include
storage. First, you can have more than a single mount point. This
the Node : the physical server on which the container will run
allows you to choose a suitable storage for each application. For
the CT ID: a unique number in this Proxmox VE installation used to identify your
example, you can use a relatively slow (and thus cheap) storage for
  container
the container root file system. Then you can use a second mount point
Hostname: the hostname of the container
to mount a very fast, distributed storage for your database
Resource Pool: a logical group of containers and VMs
application.
Password: the root password of the container
The second big improvement is that you can use any storage type
SSH Public Key: a public key for connecting to the root account over SSH
supported by the Proxmox VE storage library. That means that you can store
Unprivileged container: this option allows to choose at creation time
your containers on local lvmthin or zfs, shared iSCSI storage,
  if you want to create a privileged or unprivileged container.
or even on distributed storage systems like ceph. It also enables us
Unprivileged Containers
to use advanced storage features like snapshots and clones. vzdump
Unprivileged containers use a new kernel feature called user namespaces.
can also use the snapshot feature to provide consistent container
The root UID 0 inside the container is mapped to an unprivileged user outside
backups.
the container. This means that most security issues (container escape, resource
Last but not least, you can also mount local devices directly, or
abuse, etc.) in these containers will affect a random unprivileged user, and
mount local directories using bind mounts. That way you can access
would be a generic kernel security bug rather than an LXC issue. The LXC team
local storage inside containers with zero overhead. Such bind mounts
thinks unprivileged containers are safe by design.
also provide an easy way to share data between different containers.
This is the default option when creating a new container.
If the container uses systemd as an init system, please be aware the
systemd version running inside the container should be equal to or greater than
220.
Privileged Containers
Security in containers is achieved by using mandatory access control AppArmor
restrictions, seccomp filters and Linux kernel namespaces. The LXC team
considers this kind of container as unsafe, and they will not consider new
container escape exploits to be security issues worthy of a CVE and quick fix.
That&#8217;s why privileged containers should only be used in trusted environments.
CPU
You can restrict the number of visible CPUs inside the container using the
cores option. This is implemented using the Linux cpuset cgroup
(control group).
A special task inside pvestatd tries to distribute running containers among
available CPUs periodically.
To view the assigned CPUs run the following command:
# pct cpusets
---------------------
102:              6 7
105:      2 3 4 5
108:  0 1
---------------------
Containers use the host kernel directly. All tasks inside a container are
handled by the host CPU scheduler. Proxmox VE uses the Linux CFS (Completely
Fair Scheduler) scheduler by default, which has additional bandwidth
control options.
cpulimit:
You can use this option to further limit assigned CPU time.
Please note that this is a floating point number, so it is perfectly valid to
assign two cores to a container, but restrict overall CPU consumption to half a
core.
cores: 2
cpulimit: 0.5
cpuunits:
This is a relative weight passed to the kernel scheduler. The
larger the number is, the more CPU time this container gets. Number is relative
to the weights of all the other running containers. The default is 100 (or
1024 if the host uses legacy cgroup v1). You can use this setting to
prioritize some containers.
Memory
Container memory is controlled using the cgroup memory controller.
memory:
Limit overall memory usage. This corresponds to the
memory.limit_in_bytes cgroup setting.
swap:
Allows the container to use additional swap memory from the host
swap space. This corresponds to the memory.memsw.limit_in_bytes cgroup
setting, which is set to the sum of both value (memory + swap).
Mount Points
Mount Points
The root mount point is configured with the rootfs property, and you can
The root mount point is configured with the rootfs property. You can
configure up to 10 additional mount points. The corresponding options
configure up to 256 additional mount points. The corresponding options are
are called mp0 to mp9, and they can contain the following setting:
called mp0 to mp255. They can contain the following settings:
rootfs: [volume=]<volume> [,acl=<1|0>] [,quota=<1|0>] [,ro=<1|0>] [,size=<DiskSize>]
rootfs: [volume=]&lt;volume&gt; [,acl=&lt;1|0&gt;] [,mountoptions=&lt;opt[;opt...]&gt;] [,quota=&lt;1|0&gt;] [,replicate=&lt;1|0&gt;] [,ro=&lt;1|0&gt;] [,shared=&lt;1|0&gt;] [,size=&lt;DiskSize&gt;]
mp[n]: [volume=]<volume> ,mp=<Path> [,acl=<1|0>] [,backup=<1|0>] [,quota=<1|0>] [,ro=<1|0>] [,size=<DiskSize>]
Use volume as container root. See below for a detailed description of all options.
acl: boolean
mp[n]: [volume=]&lt;volume&gt; ,mp=&lt;Path&gt; [,acl=&lt;1|0&gt;] [,backup=&lt;1|0&gt;] [,mountoptions=&lt;opt[;opt...]&gt;] [,quota=&lt;1|0&gt;] [,replicate=&lt;1|0&gt;] [,ro=&lt;1|0&gt;] [,shared=&lt;1|0&gt;] [,size=&lt;DiskSize&gt;]
Use volume as container mount point. Use the special syntax STORAGE_ID:SIZE_IN_GiB to allocate a new volume.
acl=&lt;boolean&gt;
Explicitly enable or disable ACL support.
Explicitly enable or disable ACL support.
backup: boolean
backup=&lt;boolean&gt;
Whether to include the mountpoint in backups (only used for volume mountpoints).
Whether to include the mount point in backups (only used for volume mount points).
mp: <Path>
mountoptions=&lt;opt[;opt...]&gt;
Path to the mountpoint as seen from inside the container.
Extra mount options for rootfs/mps.
mp=&lt;Path&gt;
Path to the mount point as seen from inside the container.
Must not contain any symlinks for security reasons.
Must not contain any symlinks for security reasons.
quota: boolean
quota=&lt;boolean&gt;
Enable user quotas inside the container (not supported with zfs subvolumes)
Enable user quotas inside the container (not supported with zfs subvolumes)
ro: boolean
replicate=&lt;boolean&gt; (default = 1)
Read-only mountpoint
Will include this volume to a storage replica job.
size: <DiskSize>
ro=&lt;boolean&gt;
Read-only mount point
shared=&lt;boolean&gt; (default = 0)
Mark this non-volume mount point as available on all nodes.
This option does not share the mount point automatically, it assumes it is shared already!
size=&lt;DiskSize&gt;
Volume size (read only value).
Volume size (read only value).
volume: <volume>
volume=&lt;volume&gt;
Volume, device or directory to mount into the container.
Volume, device or directory to mount into the container.
Currently there are basically three types of mount points: storage backed
Currently there are three types of mount points: storage backed mount points,
mount points, bind mounts and device mounts.
bind mounts, and device mounts.
Typical container rootfs configuration
Typical container rootfs configuration
rootfs: thin1:base-100-disk-1,size=8G
rootfs: thin1:base-100-disk-1,size=8G
Line 369: Line 282:
Directories: passing size=0 triggers a special case where instead of a raw
Directories: passing size=0 triggers a special case where instead of a raw
   image a directory is created.
   image a directory is created.
The special option syntax STORAGE_ID:SIZE_IN_GB for storage backed
mount point volumes will automatically allocate a volume of the specified size
on the specified storage. For example, calling
pct set 100 -mp0 thin1:10,mp=/path/in/container
will allocate a 10GB volume on the storage thin1 and replace the volume ID
place holder 10 with the allocated volume ID, and setup the moutpoint in the
container at /path/in/container
Bind Mount Points
Bind Mount Points
Bind mounts allow you to access arbitrary directories from your Proxmox VE host
Bind mounts allow you to access arbitrary directories from your Proxmox VE host
Line 380: Line 300:
user mapping and cannot use ACLs.
user mapping and cannot use ACLs.
The contents of bind mount points are not backed up when using vzdump.
The contents of bind mount points are not backed up when using vzdump.
For security reasons, bind mounts should only be established
For security reasons, bind mounts should only be established using
using source directories especially reserved for this purpose, e.g., a
source directories especially reserved for this purpose, e.g., a directory
directory hierarchy under /mnt/bindmounts. Never bind mount system
hierarchy under /mnt/bindmounts. Never bind mount system directories like
directories like /, /var or /etc into a container - this poses a
/, /var or /etc into a container - this poses a great security risk.
great security risk.
The bind mount source path must not contain any symlinks.
The bind mount source path must not contain any symlinks.
For example, to make the directory /mnt/bindmounts/shared accessible in the
For example, to make the directory /mnt/bindmounts/shared accessible in the
container with ID 100 under the path /shared, use a configuration line like
container with ID 100 under the path /shared, add a configuration line such as:
mp0: /mnt/bindmounts/shared,mp=/shared in /etc/pve/lxc/100.conf.
mp0: /mnt/bindmounts/shared,mp=/shared
Alternatively, use pct set 100 -mp0 /mnt/bindmounts/shared,mp=/shared to
into /etc/pve/lxc/100.conf.
achieve the same result.
Or alternatively use the pct tool:
pct set 100 -mp0 /mnt/bindmounts/shared,mp=/shared
to achieve the same result.
Device Mount Points
Device Mount Points
Device mount points allow to mount block devices of the host directly into the
Device mount points allow to mount block devices of the host directly into the
container. Similar to bind mounts, device mounts are not managed by Proxmox VE’s
container. Similar to bind mounts, device mounts are not managed by Proxmox VE&#8217;s
storage subsystem, but the quota and acl options will be honored.
storage subsystem, but the quota and acl options will be honored.
Device mount points should only be used under special circumstances. In
Device mount points should only be used under special circumstances. In
most cases a storage backed mount point offers the same performance and a lot
most cases a storage backed mount point offers the same performance and a lot
more features.
more features.
The contents of device mount points are not backed up when using vzdump.
The contents of device mount points are not backed up when using
FUSE Mounts
vzdump.
Because of existing issues in the Linux kernel’s freezer
Network
subsystem the usage of FUSE mounts inside a container is strongly
You can configure up to 10 network interfaces for a single container.
advised against, as containers need to be frozen for suspend or
The corresponding options are called net0 to net9, and they can contain the
snapshot mode backups.
following setting:
If FUSE mounts cannot be replaced by other mounting mechanisms or storage
net[n]: name=&lt;string&gt; [,bridge=&lt;bridge&gt;] [,firewall=&lt;1|0&gt;] [,gw=&lt;GatewayIPv4&gt;] [,gw6=&lt;GatewayIPv6&gt;] [,hwaddr=&lt;XX:XX:XX:XX:XX:XX&gt;] [,ip=&lt;(IPv4/CIDR|dhcp|manual)&gt;] [,ip6=&lt;(IPv6/CIDR|auto|dhcp|manual)&gt;] [,link_down=&lt;1|0&gt;] [,mtu=&lt;integer&gt;] [,rate=&lt;mbps&gt;] [,tag=&lt;integer&gt;] [,trunks=&lt;vlanid[;vlanid...]&gt;] [,type=&lt;veth&gt;]
technologies, it is possible to establish the FUSE mount on the Proxmox host
Specifies network interfaces for the container.
and use a bind mount point to make it accessible inside the container.
bridge=&lt;bridge&gt;
Using Quotas Inside Containers
Quotas allow to set limits inside a container for the amount of disk
space that each user can use.  This only works on ext4 image based
storage types and currently does not work with unprivileged
containers.
Activating the quota option causes the following mount options to be
used for a mount point:
usrjquota=aquota.user,grpjquota=aquota.group,jqfmt=vfsv0
This allows quotas to be used like you would on any other system. You
can initialize the /aquota.user and /aquota.group files by running
quotacheck -cmug /
quotaon /
and edit the quotas via the edquota command. Refer to the documentation
of the distribution running inside the container for details.
You need to run the above commands for every mount point by passing
the mount point’s path instead of just /.
Using ACLs Inside Containers
The standard Posix Access Control Lists are also available inside containers.
ACLs allow you to set more detailed file ownership than the traditional user/
group/others model.
Container Network
You can configure up to 10 network interfaces for a single
container. The corresponding options are called net0 to net9, and
they can contain the following setting:
net[n]: name=<string> [,bridge=<bridge>] [,firewall=<1|0>] [,gw=<GatewayIPv4>] [,gw6=<GatewayIPv6>] [,hwaddr=<XX:XX:XX:XX:XX:XX>] [,ip=<IPv4Format/CIDR>] [,ip6=<IPv6Format/CIDR>] [,mtu=<integer>] [,rate=<mbps>] [,tag=<integer>] [,trunks=<vlanid[;vlanid...]>] [,type=<veth>]
bridge: <bridge>
Bridge to attach the network device to.
Bridge to attach the network device to.
firewall: boolean
firewall=&lt;boolean&gt;
Controls whether this interface’s firewall rules should be used.
Controls whether this interface&#8217;s firewall rules should be used.
gw: <GatewayIPv4>
gw=&lt;GatewayIPv4&gt;
Default gateway for IPv4 traffic.
Default gateway for IPv4 traffic.
gw6: <GatewayIPv6>
gw6=&lt;GatewayIPv6&gt;
Default gateway for IPv6 traffic.
Default gateway for IPv6 traffic.
hwaddr: <XX:XX:XX:XX:XX:XX>
hwaddr=&lt;XX:XX:XX:XX:XX:XX&gt;
The interface MAC address. This is dynamically allocated by default, but you can set that statically if needed, for example to always have the same link-local IPv6 address. (lxc.network.hwaddr)
A common MAC address with the I/G (Individual/Group) bit not set.
ip: <IPv4Format/CIDR>
ip=&lt;(IPv4/CIDR|dhcp|manual)&gt;
IPv4 address in CIDR format.
IPv4 address in CIDR format.
ip6: <IPv6Format/CIDR>
ip6=&lt;(IPv6/CIDR|auto|dhcp|manual)&gt;
IPv6 address in CIDR format.
IPv6 address in CIDR format.
mtu: integer (64 - N)
link_down=&lt;boolean&gt;
Whether this interface should be disconnected (like pulling the plug).
mtu=&lt;integer&gt; (64 - 65535)
Maximum transfer unit of the interface. (lxc.network.mtu)
Maximum transfer unit of the interface. (lxc.network.mtu)
name: <string>
name=&lt;string&gt;
Name of the network device as seen from inside the container. (lxc.network.name)
Name of the network device as seen from inside the container. (lxc.network.name)
rate: <mbps>
rate=&lt;mbps&gt;
Apply rate limiting to the interface
Apply rate limiting to the interface
tag: integer (1 - 4094)
tag=&lt;integer&gt; (1 - 4094)
VLAN tag for this interface.
VLAN tag for this interface.
trunks: <vlanid[;vlanid...]>
trunks=&lt;vlanid[;vlanid...]&gt;
VLAN ids to pass through the interface
VLAN ids to pass through the interface
type: (veth)
type=&lt;veth&gt;
Network interface type.
Network interface type.
Automatic Start and Shutdown of Containers
To automatically start a container when the host system boots, select the
option Start at boot in the Options panel of the container in the web
interface or run the following command:
# pct set CTID -onboot 1
Start and Shutdown Order
If you want to fine tune the boot order of your containers, you can use the
following parameters:
Start/Shutdown order: Defines the start order priority. For example, set it
  to 1 if you want the CT to be the first to be started. (We use the reverse
  startup order for shutdown, so a container with a start order of 1 would be
  the last to be shut down)
Startup delay: Defines the interval between this container start and
  subsequent containers starts. For example, set it to 240 if you want to wait
  240 seconds before starting other containers.
Shutdown timeout: Defines the duration in seconds Proxmox VE should wait
  for the container to be offline after issuing a shutdown command.
  By default this value is set to 60, which means that Proxmox VE will issue a
  shutdown request, wait 60s for the machine to be offline, and if after 60s
  the machine is still online will notify that the shutdown action failed.
Please note that containers without a Start/Shutdown order parameter will
always start after those where the parameter is set, and this parameter only
makes sense between the machines running locally on a host, and not
cluster-wide.
If you require a delay between the host boot and the booting of the first
container, see the section on
Proxmox VE Node Management.
Hookscripts
You can add a hook script to CTs with the config property hookscript.
# pct set 100 -hookscript local:snippets/hookscript.pl
It will be called during various phases of the guests lifetime.  For an example
and documentation see the example script under
/usr/share/pve-docs/examples/guest-example-hookscript.pl.
Security Considerations
Containers use the kernel of the host system. This exposes an attack surface
for malicious users. In general, full virtual machines provide better
isolation. This should be considered if containers are provided to unknown or
untrusted people.
To reduce the attack surface, LXC uses many security features like AppArmor,
CGroups and kernel namespaces.
AppArmor
AppArmor profiles are used to restrict access to possibly dangerous actions.
Some system calls, i.e. mount, are prohibited from execution.
To trace AppArmor activity, use:
# dmesg | grep apparmor
Although it is not recommended, AppArmor can be disabled for a container. This
brings security risks with it. Some syscalls can lead to privilege escalation
when executed within a container if the system is misconfigured or if a LXC or
Linux Kernel vulnerability exists.
To disable AppArmor for a container, add the following line to the container
configuration file located at /etc/pve/lxc/CTID.conf:
lxc.apparmor.profile = unconfined
Please note that this is not recommended for production use.
Control Groups (cgroup)
cgroup is a kernel
mechanism used to hierarchically organize processes and distribute system
resources.
The main resources controlled via cgroups are CPU time, memory and swap
limits, and access to device nodes. cgroups are also used to "freeze" a
container before taking snapshots.
There are 2 versions of cgroups currently available,
legacy
and
cgroupv2.
Since Proxmox VE 7.0, the default is a pure cgroupv2 environment. Previously a
"hybrid" setup was used, where resource control was mainly done in cgroupv1
with an additional cgroupv2 controller which could take over some subsystems
via the cgroup_no_v1 kernel command-line parameter. (See the
kernel
parameter documentation for details.)
CGroup Version Compatibility
The main difference between pure cgroupv2 and the old hybrid environments
regarding Proxmox VE is that with cgroupv2 memory and swap are now controlled
independently. The memory and swap settings for containers can map directly to
these values, whereas previously only the memory limit and the limit of the
sum of memory and swap could be limited.
Another important difference is that the devices controller is configured in a
completely different way. Because of this, file system quotas are currently not
supported in a pure cgroupv2 environment.
cgroupv2 support by the container&#8217;s OS is needed to run in a pure cgroupv2
environment. Containers running systemd version 231 or newer support
cgroupv2 [this includes all newest major versions of container
templates shipped by Proxmox VE], as do containers not using systemd as init
system [for example Alpine Linux].
CentOS 7 and Ubuntu 16.10 are two prominent Linux distributions releases,
which have a systemd version that is too old to run in a cgroupv2
environment, you can either
Upgrade the whole distribution to a newer release. For the examples above, that
  could be Ubuntu 18.04 or 20.04, and CentOS 8 (or RHEL/CentOS derivatives like
  AlmaLinux or Rocky Linux). This has the benefit to get the newest bug and
  security fixes, often also new features, and moving the EOL date in the future.
Upgrade the Containers systemd version. If the distribution provides a
  backports repository this can be an easy and quick stop-gap measurement.
Move the container, or its services, to a Virtual Machine. Virtual Machines
  have a much less interaction with the host, that&#8217;s why one can install
  decades old OS versions just fine there.
Switch back to the legacy cgroup controller. Note that while it can be a
  valid solution, it&#8217;s not a permanent one. Starting from Proxmox VE 9.0, the legacy
  controller will not be supported anymore.
Changing CGroup Version
If file system quotas are not required and all containers support cgroupv2,
it is recommended to stick to the new default.
To switch back to the previous version the following kernel command-line
parameter can be used:
systemd.unified_cgroup_hierarchy=0
See this section on editing the kernel boot
command line on where to add the parameter.
Guest Operating System Configuration
Proxmox VE tries to detect the Linux distribution in the container, and modifies
some files. Here is a short list of things done at container startup:
set /etc/hostname
to set the container name
modify /etc/hosts
to allow lookup of the local hostname
network setup
pass the complete network setup to the container
configure DNS
pass information about DNS servers
adapt the init system
for example, fix the number of spawned getty processes
set the root password
when creating a new container
rewrite ssh_host_keys
so that each container has unique keys
randomize crontab
so that cron does not start at the same time on all containers
Changes made by Proxmox VE are enclosed by comment markers:
# --- BEGIN PVE ---
&lt;data&gt;
# --- END PVE ---
Those markers will be inserted at a reasonable location in the file. If such a
section already exists, it will be updated in place and will not be moved.
Modification of a file can be prevented by adding a .pve-ignore. file for it.
For instance, if the file /etc/.pve-ignore.hosts exists then the /etc/hosts
file will not be touched. This can be a simple empty file created via:
# touch /etc/.pve-ignore.hosts
Most modifications are OS dependent, so they differ between different
distributions and versions. You can completely disable modifications by
manually setting the ostype to unmanaged.
OS type detection is done by testing for certain files inside the
container. Proxmox VE first checks the /etc/os-release file
[/etc/os-release replaces the multitude of per-distribution
release files https://manpages.debian.org/stable/systemd/os-release.5.en.html].
If that file is not present, or it does not contain a clearly recognizable
distribution identifier the following distribution specific release files are
checked.
Ubuntu
inspect /etc/lsb-release (DISTRIB_ID=Ubuntu)
Debian
test /etc/debian_version
Fedora
test /etc/fedora-release
RedHat or CentOS
test /etc/redhat-release
ArchLinux
test /etc/arch-release
Alpine
test /etc/alpine-release
Gentoo
test /etc/gentoo-release
Container start fails if the configured ostype differs from the auto
detected type.
Container Storage
The Proxmox VE LXC container storage model is more flexible than traditional
container storage models. A container can have multiple mount points. This
makes it possible to use the best suited storage for each application.
For example the root file system of the container can be on slow and cheap
storage while the database can be on fast and distributed storage via a second
mount point. See section  Mount Points for further
details.
Any storage type supported by the Proxmox VE storage library can be used. This means
that containers can be stored on local (for example lvm, zfs or directory),
shared external (like iSCSI, NFS) or even distributed storage systems like
Ceph. Advanced storage features like snapshots or clones can be used if the
underlying storage supports them. The vzdump backup tool can use snapshots to
provide consistent container backups.
Furthermore, local devices or local directories can be mounted directly using
bind mounts. This gives access to local resources inside a container with
practically zero overhead. Bind mounts can be used as an easy way to share data
between containers.
FUSE Mounts
Because of existing issues in the Linux kernel&#8217;s freezer subsystem the
usage of FUSE mounts inside a container is strongly advised against, as
containers need to be frozen for suspend or snapshot mode backups.
If FUSE mounts cannot be replaced by other mounting mechanisms or storage
technologies, it is possible to establish the FUSE mount on the Proxmox host
and use a bind mount point to make it accessible inside the container.
Using Quotas Inside Containers
Quotas allow to set limits inside a container for the amount of disk space that
each user can use.
This currently requires the use of legacy cgroups.
This only works on ext4 image based storage types and currently only
works with privileged containers.
Activating the quota option causes the following mount options to be used for
a mount point:
usrjquota=aquota.user,grpjquota=aquota.group,jqfmt=vfsv0
This allows quotas to be used like on any other system. You can initialize the
/aquota.user and /aquota.group files by running:
# quotacheck -cmug /
# quotaon /
Then edit the quotas using the edquota command. Refer to the documentation of
the distribution running inside the container for details.
You need to run the above commands for every mount point by passing the
mount point&#8217;s path instead of just /.
Using ACLs Inside Containers
The standard Posix Access Control Lists are also available inside
containers. ACLs allow you to set more detailed file ownership than the
traditional user/group/others model.
Backup of Container mount points
To include a mount point in backups, enable the backup option for it in the
container configuration. For an existing mount point mp0
mp0: guests:subvol-100-disk-1,mp=/root/files,size=8G
add backup=1 to enable it.
mp0: guests:subvol-100-disk-1,mp=/root/files,size=8G,backup=1
When creating a new mount point in the GUI, this option is enabled by
default.
To disable backups for a mount point, add backup=0 in the way described
above, or uncheck the Backup checkbox on the GUI.
Replication of Containers mount points
By default, additional mount points are replicated when the Root Disk is
replicated. If you want the Proxmox VE storage replication mechanism to skip a mount
point, you can set the Skip replication option for that mount point.
As of Proxmox VE 5.0, replication requires a storage of type zfspool. Adding a
mount point to a different type of storage when the container has replication
configured requires to have Skip replication enabled for that mount point.
Backup and Restore
Backup and Restore
Container Backup
Container Backup
It is possible to use the vzdump tool for container backup. Please
It is possible to use the vzdump tool for container backup. Please refer to
refer to the vzdump manual page for details.
the vzdump manual page for details.
Restoring Container Backups
Restoring Container Backups
Restoring container backups made with vzdump is possible using the
Restoring container backups made with vzdump is possible using the pct
pct restore command. By default, pct restore will attempt to restore as much
restore command. By default, pct restore will attempt to restore as much of
of the backed up container configuration as possible. It is possible to override
the backed up container configuration as possible. It is possible to override
the backed up configuration by manually setting container options on the command
the backed up configuration by manually setting container options on the
line (see the pct manual page for details).
command line (see the pct manual page for details).
pvesm extractconfig can be used to view the backed up configuration
pvesm extractconfig can be used to view the backed up configuration
contained in a vzdump archive.
contained in a vzdump archive.
There are two basic restore modes, only differing by their handling of mount
There are two basic restore modes, only differing by their handling of mount
points:
points:
“Simple” Restore Mode
&#8220;Simple&#8221; Restore Mode
If neither the rootfs parameter nor any of the optional mpX parameters
If neither the rootfs parameter nor any of the optional mpX parameters are
are explicitly set, the mount point configuration from the backed up
explicitly set, the mount point configuration from the backed up configuration
configuration file is restored using the following steps:
file is restored using the following steps:
Extract mount points and their options from backup
Extract mount points and their options from backup
Create volumes for storage backed mount points (on storage provided with the
Create volumes for storage backed mount points on the storage provided with
storage parameter, or default local storage if unset)
  the storage parameter (default: local).
Extract files from backup archive
Extract files from backup archive
Add bind and device mount points to restored configuration (limited to root user)
Add bind and device mount points to restored configuration (limited to root
  user)
Since bind and device mount points are never backed up, no files are
Since bind and device mount points are never backed up, no files are
restored in the last step, but only the configuration options. The assumption
restored in the last step, but only the configuration options. The assumption
Line 488: Line 611:
This simple mode is also used by the container restore operations in the web
This simple mode is also used by the container restore operations in the web
interface.
interface.
“Advanced” Restore Mode
&#8220;Advanced&#8221; Restore Mode
By setting the rootfs parameter (and optionally, any combination of mpX
By setting the rootfs parameter (and optionally, any combination of mpX
parameters), the pct restore command is automatically switched into an
parameters), the pct restore command is automatically switched into an
advanced mode. This advanced mode completely ignores the rootfs and mpX
advanced mode. This advanced mode completely ignores the rootfs and mpX
configuration options contained in the backup archive, and instead only
configuration options contained in the backup archive, and instead only uses
uses the options explicitly provided as parameters.
the options explicitly provided as parameters.
This mode allows flexible configuration of mount point settings at restore time,
This mode allows flexible configuration of mount point settings at restore
for example:
time, for example:
Set target storages, volume sizes and other options for each mount point
Set target storages, volume sizes and other options for each mount point
individually
  individually
Redistribute backed up files according to new mount point scheme
Redistribute backed up files according to new mount point scheme
Restore to device and/or bind mount points (limited to root user)
Restore to device and/or bind mount points (limited to root user)
Managing Containers with pct
Managing Containers with pct
pct is the tool to manage Linux Containers on Proxmox VE. You can create
The &#8220;Proxmox Container Toolkit&#8221; (pct) is the command-line tool to manage
and destroy containers, and control execution (start, stop, migrate,
Proxmox VE containers. It enables you to create or destroy containers, as well as
…). You can use pct to set parameters in the associated config file,
control the container execution (start, stop, reboot, migrate, etc.). It can be
like network configuration or memory limits.
used to set parameters in the config file of a container, for example the
network configuration or memory limits.
CLI Usage Examples
CLI Usage Examples
Create a container based on a Debian template (provided you have
Create a container based on a Debian template (provided you have already
already downloaded the template via the web interface)
downloaded the template via the web interface)
pct create 100 /var/lib/vz/template/cache/debian-8.0-standard_8.0-1_amd64.tar.gz
# pct create 100 /var/lib/vz/template/cache/debian-10.0-standard_10.0-1_amd64.tar.gz
Start container 100
Start container 100
pct start 100
# pct start 100
Start a login session via getty
Start a login session via getty
pct console 100
# pct console 100
Enter the LXC namespace and run a shell as root user
Enter the LXC namespace and run a shell as root user
pct enter 100
# pct enter 100
Display the configuration
Display the configuration
pct config 100
# pct config 100
Add a network interface called eth0, bridged to the host bridge vmbr0,
Add a network interface called eth0, bridged to the host bridge vmbr0, set
set the address and gateway, while it’s running
the address and gateway, while it&#8217;s running
pct set 100 -net0 name=eth0,bridge=vmbr0,ip=192.168.15.147/24,gw=192.168.15.1
# pct set 100 -net0 name=eth0,bridge=vmbr0,ip=192.168.15.147/24,gw=192.168.15.1
Reduce the memory of the container to 512MB
Reduce the memory of the container to 512MB
pct set 100 -memory 512
# pct set 100 -memory 512
Destroying a container always removes it from Access Control Lists and it always
removes the firewall configuration of the container. You have to activate
--purge, if you want to additionally remove the container from replication jobs,
backup jobs and HA resource configurations.
# pct destroy 100 --purge
Move a mount point volume to a different storage.
# pct move-volume 100 mp0 other-storage
Reassign a volume to a different CT. This will remove the volume mp0 from
the source CT and attaches it as mp1 to the target CT. In the background
the volume is being renamed so that the name matches the new owner.
#  pct move-volume 100 mp0 --target-vmid 200 --target-volume mp1
Obtaining Debugging Logs
Obtaining Debugging Logs
In case pct start is unable to start a specific container, it might be
In case pct start is unable to start a specific container, it might be
helpful to collect debugging output by running lxc-start (replace ID with
helpful to collect debugging output by passing the --debug flag (replace CTID with
the container’s ID):
the container&#8217;s CTID):
lxc-start -n ID -F -l DEBUG -o /tmp/lxc-ID.log
# pct start CTID --debug
This command will attempt to start the container in foreground mode, to stop the container run pct shutdown ID or pct stop ID in a second terminal.
Alternatively, you can use the following lxc-start command, which will save
The collected debug log is written to /tmp/lxc-ID.log.
the debug log to the file specified by the -o output option:
If you have changed the container’s configuration since the last start
# lxc-start -n CTID -F -l DEBUG -o /tmp/lxc-CTID.log
This command will attempt to start the container in foreground mode, to stop
the container run pct shutdown CTID or pct stop CTID in a second terminal.
The collected debug log is written to /tmp/lxc-CTID.log.
If you have changed the container&#8217;s configuration since the last start
attempt with pct start, you need to run pct start at least once to also
attempt with pct start, you need to run pct start at least once to also
update the configuration used by lxc-start.
update the configuration used by lxc-start.
Files
Migration
/etc/pve/lxc/<CTID>.conf
If you have a cluster, you can migrate your Containers with
Configuration file for the container <CTID>.
# pct migrate &lt;ctid&gt; &lt;target&gt;
Container Advantages
This works as long as your Container is offline. If it has local volumes or
Simple, and fully integrated into Proxmox VE. Setup looks similar to a normal
mount points defined, the migration will copy the content over the network to
  VM setup.
the target host if the same storage is defined there.
Storage (ZFS, LVM, NFS, Ceph, …)
Running containers cannot live-migrated due to technical limitations. You can
Network
do a restart migration, which shuts down, moves and then starts a container
Authentication
again on the target node. As containers are very lightweight, this results
Cluster
normally only in a downtime of some hundreds of milliseconds.
Fast: minimal overhead, as fast as bare metal
A restart migration can be done through the web interface or by using the
High density (perfect for idle workloads)
--restart flag with the pct migrate command.
REST API
A restart migration will shut down the Container and kill it after the
Direct hardware access
specified timeout (the default is 180 seconds). Then it will migrate the
Technology Overview
Container like an offline migration and when finished, it starts the Container
Integrated into Proxmox VE graphical user interface (GUI)
on the target node.
LXC (https://linuxcontainers.org/)
Configuration
lxcfs to provide containerized /proc file system
The /etc/pve/lxc/&lt;CTID&gt;.conf file stores container configuration, where
AppArmor
&lt;CTID&gt; is the numeric ID of the given container. Like all other files stored
CRIU: for live migration (planned)
inside /etc/pve/, they get automatically replicated to all other cluster
We use latest available kernels (4.4.X)
nodes.
Image based deployment (templates)
CTIDs &lt; 100 are reserved for internal purposes, and CTIDs need to be
Container setup from host (network, DNS, storage, …)
unique cluster wide.
Example Container Configuration
ostype: debian
arch: amd64
hostname: www
memory: 512
swap: 512
net0: bridge=vmbr0,hwaddr=66:64:66:64:64:36,ip=dhcp,name=eth0,type=veth
rootfs: local:107/vm-107-disk-1.raw,size=7G
The configuration files are simple text files. You can edit them using a normal
text editor, for example, vi or nano.
This is sometimes useful to do small corrections, but keep in mind that you
need to restart the container to apply such changes.
For that reason, it is usually better to use the pct command to generate and
modify those files, or do the whole thing using the GUI.
Our toolkit is smart enough to instantaneously apply most changes to running
containers. This feature is called &#8220;hot plug&#8221;, and there is no need to restart
the container in that case.
In cases where a change cannot be hot-plugged, it will be registered as a
pending change (shown in red color in the GUI).
They will only be applied after rebooting the container.
File Format
The container configuration file uses a simple colon separated key/value
format. Each line has the following format:
# this is a comment
OPTION: value
Blank lines in those files are ignored, and lines starting with a # character
are treated as comments and are also ignored.
It is possible to add low-level, LXC style configuration directly, for example:
lxc.init_cmd: /sbin/my_own_init
or
lxc.init_cmd = /sbin/my_own_init
The settings are passed directly to the LXC low-level tools.
Snapshots
When you create a snapshot, pct stores the configuration at snapshot time
into a separate snapshot section within the same configuration file. For
example, after creating a snapshot called &#8220;testsnapshot&#8221;, your configuration
file will look like this:
Container configuration with snapshot
memory: 512
swap: 512
parent: testsnaphot
...
[testsnaphot]
memory: 512
swap: 512
snaptime: 1457170803
...
There are a few snapshot related properties like parent and snaptime. The
parent property is used to store the parent/child relationship between
snapshots. snaptime is the snapshot creation time stamp (Unix epoch).
Options
arch: &lt;amd64 | arm64 | armhf | i386 | riscv32 | riscv64&gt; (default = amd64)
OS architecture type.
cmode: &lt;console | shell | tty&gt; (default = tty)
Console mode. By default, the console command tries to open a connection to one of the available tty devices. By setting cmode to console it tries to attach to /dev/console instead. If you set cmode to shell, it simply invokes a shell inside the container (no login).
console: &lt;boolean&gt; (default = 1)
Attach a console device (/dev/console) to the container.
cores: &lt;integer&gt; (1 - 8192)
The number of cores assigned to the container. A container can use all available cores by default.
cpulimit: &lt;number&gt; (0 - 8192) (default = 0)
Limit of CPU usage.
If the computer has 2 CPUs, it has a total of 2 CPU time. Value 0 indicates no CPU limit.
cpuunits: &lt;integer&gt; (0 - 500000) (default = cgroup v1: 1024, cgroup v2: 100)
CPU weight for a container. Argument is used in the kernel fair scheduler. The larger the number is, the more CPU time this container gets. Number is relative to the weights of all the other running guests.
debug: &lt;boolean&gt; (default = 0)
Try to be more verbose. For now this only enables debug log-level on start.
description: &lt;string&gt;
Description for the Container. Shown in the web-interface CT&#8217;s summary. This is saved as comment inside the configuration file.
dev[n]: [[path=]&lt;Path&gt;] [,gid=&lt;integer&gt;] [,mode=&lt;Octal access mode&gt;] [,uid=&lt;integer&gt;]
Device to pass through to the container
gid=&lt;integer&gt; (0 - N)
Group ID to be assigned to the device node
mode=&lt;Octal access mode&gt;
Access mode to be set on the device node
path=&lt;Path&gt;
Path to the device to pass through to the container
uid=&lt;integer&gt; (0 - N)
User ID to be assigned to the device node
features: [force_rw_sys=&lt;1|0&gt;] [,fuse=&lt;1|0&gt;] [,keyctl=&lt;1|0&gt;] [,mknod=&lt;1|0&gt;] [,mount=&lt;fstype;fstype;...&gt;] [,nesting=&lt;1|0&gt;]
Allow containers access to advanced features.
force_rw_sys=&lt;boolean&gt; (default = 0)
Mount /sys in unprivileged containers as rw instead of mixed. This can break networking under newer (&gt;= v245) systemd-network use.
fuse=&lt;boolean&gt; (default = 0)
Allow using fuse file systems in a container. Note that interactions between fuse and the freezer cgroup can potentially cause I/O deadlocks.
keyctl=&lt;boolean&gt; (default = 0)
For unprivileged containers only: Allow the use of the keyctl() system call. This is required to use docker inside a container. By default unprivileged containers will see this system call as non-existent. This is mostly a workaround for systemd-networkd, as it will treat it as a fatal error when some keyctl() operations are denied by the kernel due to lacking permissions. Essentially, you can choose between running systemd-networkd or docker.
mknod=&lt;boolean&gt; (default = 0)
Allow unprivileged containers to use mknod() to add certain device nodes. This requires a kernel with seccomp trap to user space support (5.3 or newer). This is experimental.
mount=&lt;fstype;fstype;...&gt;
Allow mounting file systems of specific types. This should be a list of file system types as used with the mount command. Note that this can have negative effects on the container&#8217;s security. With access to a loop device, mounting a file can circumvent the mknod permission of the devices cgroup, mounting an NFS file system can block the host&#8217;s I/O completely and prevent it from rebooting, etc.
nesting=&lt;boolean&gt; (default = 0)
Allow nesting. Best used with unprivileged containers with additional id mapping. Note that this will expose procfs and sysfs contents of the host to the guest.
hookscript: &lt;string&gt;
Script that will be exectued during various steps in the containers lifetime.
hostname: &lt;string&gt;
Set a host name for the container.
lock: &lt;backup | create | destroyed | disk | fstrim | migrate | mounted | rollback | snapshot | snapshot-delete&gt;
Lock/unlock the container.
memory: &lt;integer&gt; (16 - N) (default = 512)
Amount of RAM for the container in MB.
mp[n]: [volume=]&lt;volume&gt; ,mp=&lt;Path&gt; [,acl=&lt;1|0&gt;] [,backup=&lt;1|0&gt;] [,mountoptions=&lt;opt[;opt...]&gt;] [,quota=&lt;1|0&gt;] [,replicate=&lt;1|0&gt;] [,ro=&lt;1|0&gt;] [,shared=&lt;1|0&gt;] [,size=&lt;DiskSize&gt;]
Use volume as container mount point. Use the special syntax STORAGE_ID:SIZE_IN_GiB to allocate a new volume.
acl=&lt;boolean&gt;
Explicitly enable or disable ACL support.
backup=&lt;boolean&gt;
Whether to include the mount point in backups (only used for volume mount points).
mountoptions=&lt;opt[;opt...]&gt;
Extra mount options for rootfs/mps.
mp=&lt;Path&gt;
Path to the mount point as seen from inside the container.
Must not contain any symlinks for security reasons.
quota=&lt;boolean&gt;
Enable user quotas inside the container (not supported with zfs subvolumes)
replicate=&lt;boolean&gt; (default = 1)
Will include this volume to a storage replica job.
ro=&lt;boolean&gt;
Read-only mount point
shared=&lt;boolean&gt; (default = 0)
Mark this non-volume mount point as available on all nodes.
This option does not share the mount point automatically, it assumes it is shared already!
size=&lt;DiskSize&gt;
Volume size (read only value).
volume=&lt;volume&gt;
Volume, device or directory to mount into the container.
nameserver: &lt;string&gt;
Sets DNS server IP address for a container. Create will automatically use the setting from the host if you neither set searchdomain nor nameserver.
net[n]: name=&lt;string&gt; [,bridge=&lt;bridge&gt;] [,firewall=&lt;1|0&gt;] [,gw=&lt;GatewayIPv4&gt;] [,gw6=&lt;GatewayIPv6&gt;] [,hwaddr=&lt;XX:XX:XX:XX:XX:XX&gt;] [,ip=&lt;(IPv4/CIDR|dhcp|manual)&gt;] [,ip6=&lt;(IPv6/CIDR|auto|dhcp|manual)&gt;] [,link_down=&lt;1|0&gt;] [,mtu=&lt;integer&gt;] [,rate=&lt;mbps&gt;] [,tag=&lt;integer&gt;] [,trunks=&lt;vlanid[;vlanid...]&gt;] [,type=&lt;veth&gt;]
Specifies network interfaces for the container.
bridge=&lt;bridge&gt;
Bridge to attach the network device to.
firewall=&lt;boolean&gt;
Controls whether this interface&#8217;s firewall rules should be used.
gw=&lt;GatewayIPv4&gt;
Default gateway for IPv4 traffic.
gw6=&lt;GatewayIPv6&gt;
Default gateway for IPv6 traffic.
hwaddr=&lt;XX:XX:XX:XX:XX:XX&gt;
A common MAC address with the I/G (Individual/Group) bit not set.
ip=&lt;(IPv4/CIDR|dhcp|manual)&gt;
IPv4 address in CIDR format.
ip6=&lt;(IPv6/CIDR|auto|dhcp|manual)&gt;
IPv6 address in CIDR format.
link_down=&lt;boolean&gt;
Whether this interface should be disconnected (like pulling the plug).
mtu=&lt;integer&gt; (64 - 65535)
Maximum transfer unit of the interface. (lxc.network.mtu)
name=&lt;string&gt;
Name of the network device as seen from inside the container. (lxc.network.name)
rate=&lt;mbps&gt;
Apply rate limiting to the interface
tag=&lt;integer&gt; (1 - 4094)
VLAN tag for this interface.
trunks=&lt;vlanid[;vlanid...]&gt;
VLAN ids to pass through the interface
type=&lt;veth&gt;
Network interface type.
onboot: &lt;boolean&gt; (default = 0)
Specifies whether a container will be started during system bootup.
ostype: &lt;alpine | archlinux | centos | debian | devuan | fedora | gentoo | nixos | opensuse | ubuntu | unmanaged&gt;
OS type. This is used to setup configuration inside the container, and corresponds to lxc setup scripts in /usr/share/lxc/config/&lt;ostype&gt;.common.conf. Value unmanaged can be used to skip and OS specific setup.
protection: &lt;boolean&gt; (default = 0)
Sets the protection flag of the container. This will prevent the CT or CT&#8217;s disk remove/update operation.
rootfs: [volume=]&lt;volume&gt; [,acl=&lt;1|0&gt;] [,mountoptions=&lt;opt[;opt...]&gt;] [,quota=&lt;1|0&gt;] [,replicate=&lt;1|0&gt;] [,ro=&lt;1|0&gt;] [,shared=&lt;1|0&gt;] [,size=&lt;DiskSize&gt;]
Use volume as container root.
acl=&lt;boolean&gt;
Explicitly enable or disable ACL support.
mountoptions=&lt;opt[;opt...]&gt;
Extra mount options for rootfs/mps.
quota=&lt;boolean&gt;
Enable user quotas inside the container (not supported with zfs subvolumes)
replicate=&lt;boolean&gt; (default = 1)
Will include this volume to a storage replica job.
ro=&lt;boolean&gt;
Read-only mount point
shared=&lt;boolean&gt; (default = 0)
Mark this non-volume mount point as available on all nodes.
This option does not share the mount point automatically, it assumes it is shared already!
size=&lt;DiskSize&gt;
Volume size (read only value).
volume=&lt;volume&gt;
Volume, device or directory to mount into the container.
searchdomain: &lt;string&gt;
Sets DNS search domains for a container. Create will automatically use the setting from the host if you neither set searchdomain nor nameserver.
startup: `[[order=]\d+] [,up=\d+] [,down=\d+] `
Startup and shutdown behavior. Order is a non-negative number defining the general startup order. Shutdown in done with reverse ordering. Additionally you can set the up or down delay in seconds, which specifies a delay to wait before the next VM is started or stopped.
swap: &lt;integer&gt; (0 - N) (default = 512)
Amount of SWAP for the container in MB.
tags: &lt;string&gt;
Tags of the Container. This is only meta information.
template: &lt;boolean&gt; (default = 0)
Enable/disable Template.
timezone: &lt;string&gt;
Time zone to use in the container. If option isn&#8217;t set, then nothing will be done. Can be set to host to match the host time zone, or an arbitrary time zone option from /usr/share/zoneinfo/zone.tab
tty: &lt;integer&gt; (0 - 6) (default = 2)
Specify the number of tty available to the container
unprivileged: &lt;boolean&gt; (default = 0)
Makes the container run as unprivileged user. (Should not be modified manually.)
unused[n]: [volume=]&lt;volume&gt;
Reference to unused volumes. This is used internally, and should not be modified manually.
volume=&lt;volume&gt;
The volume that is not used currently.
Locks
Container migrations, snapshots and backups (vzdump) set a lock to prevent
incompatible concurrent actions on the affected container. Sometimes you need
to remove such a lock manually (e.g., after a power failure).
# pct unlock &lt;CTID&gt;
Only do this if you are sure the action which set the lock is no
longer running.
</pvehide>
</pvehide>
<!--PVE_IMPORT_END_MARKER-->
<!--PVE_IMPORT_END_MARKER-->


=== Security ===
LXC Containers use an AppArmor profile to provide ressource isolation in the container. This works by blocking system calls
like 'mount' who are denied being executed in the container.
You can trace the AppArmor activity with:
dmesg | grep apparmor
If you want to disable AppArmor for a container, you can add the stanza
lxc.aa_profile = unconfined
at the end of the configuration file ( located in /etc/pve/lxc/CTID.conf ) Note that this is not a recommended setup for production.




Line 581: Line 916:
* [https://github.com/lxc GIT Linux Container]
* [https://github.com/lxc GIT Linux Container]


[[Category:Installation]][[Category:Technology]][[Category:HOWTO]]
[[Category:Installation]][[Category:HOWTO]]

Latest revision as of 14:11, 23 November 2023

Containers are a lightweight alternative to fully virtualized machines (VMs). They use the kernel of the host system that they run on, instead of emulating a full operating system (OS). This means that containers can access resources on the host system directly.

The runtime costs for containers is low, usually negligible. However, there are some drawbacks that need be considered:

  • Only Linux distributions can be run in Proxmox Containers. It is not possible to run other operating systems like, for example, FreeBSD or Microsoft Windows inside a container.

  • For security reasons, access to host resources needs to be restricted. Therefore, containers run in their own separate namespaces. Additionally some syscalls (user space requests to the Linux kernel) are not allowed within containers.

Proxmox VE uses Linux Containers (LXC) as its underlying container technology. The “Proxmox Container Toolkit” (pct) simplifies the usage and management of LXC, by providing an interface that abstracts complex tasks.

Containers are tightly integrated with Proxmox VE. This means that they are aware of the cluster setup, and they can use the same network and storage resources as virtual machines. You can also use the Proxmox VE firewall, or manage containers using the HA framework.

Our primary goal is to offer an environment that provides the benefits of using a VM, but without the additional overhead. This means that Proxmox Containers can be categorized as “System Containers”, rather than “Application Containers”.

Note If you want to run application containers, for example, Docker images, it is recommended that you run them inside a Proxmox QEMU VM. This will give you all the advantages of application containerization, while also providing the benefits that VMs offer, such as strong isolation from the host and the ability to live-migrate, which otherwise isn’t possible with containers.

Technology Overview

  • LXC (https://linuxcontainers.org/)

  • Integrated into Proxmox VE graphical web user interface (GUI)

  • Easy to use command-line tool pct

  • Access via Proxmox VE REST API

  • lxcfs to provide containerized /proc file system

  • Control groups (cgroups) for resource isolation and limitation

  • AppArmor and seccomp to improve security

  • Modern Linux kernels

  • Image based deployment (templates)

  • Uses Proxmox VE storage library

  • Container setup from host (network, DNS, storage, etc.)

Supported Distributions

List of officially supported distributions can be found below.

Templates for the following distributions are available through our repositories. You can use pveam tool or the Graphical User Interface to download them.

Alpine Linux

Alpine Linux is a security-oriented, lightweight Linux distribution based on musl libc and busybox.

— https://alpinelinux.org

For currently supported releases see:

https://alpinelinux.org/releases/

Arch Linux

Arch Linux, a lightweight and flexible Linux® distribution that tries to Keep It Simple.

— https://archlinux.org/

Arch Linux is using a rolling-release model, see its wiki for more details:

https://wiki.archlinux.org/title/Arch_Linux

CentOS, Almalinux, Rocky Linux

CentOS / CentOS Stream

The CentOS Linux distribution is a stable, predictable, manageable and reproducible platform derived from the sources of Red Hat Enterprise Linux (RHEL)

— https://centos.org

For currently supported releases see:

https://en.wikipedia.org/wiki/CentOS#End-of-support_schedule

Almalinux

An Open Source, community owned and governed, forever-free enterprise Linux distribution, focused on long-term stability, providing a robust production-grade platform. AlmaLinux OS is 1:1 binary compatible with RHEL® and pre-Stream CentOS.

— https://almalinux.org

For currently supported releases see:

https://en.wikipedia.org/wiki/AlmaLinux#Releases

Rocky Linux

Rocky Linux is a community enterprise operating system designed to be 100% bug-for-bug compatible with America’s top enterprise Linux distribution now that its downstream partner has shifted direction.

— https://rockylinux.org

For currently supported releases see:

https://en.wikipedia.org/wiki/Rocky_Linux#Releases

Debian

Debian is a free operating system, developed and maintained by the Debian project. A free Linux distribution with thousands of applications to meet our users' needs.

— https://www.debian.org/intro/index#software

For currently supported releases see:

https://www.debian.org/releases/stable/releasenotes

Devuan

Devuan GNU+Linux is a fork of Debian without systemd that allows users to reclaim control over their system by avoiding unnecessary entanglements and ensuring Init Freedom.

— https://www.devuan.org

For currently supported releases see:

https://www.devuan.org/os/releases

Fedora

Fedora creates an innovative, free, and open source platform for hardware, clouds, and containers that enables software developers and community members to build tailored solutions for their users.

— https://getfedora.org

For currently supported releases see:

https://fedoraproject.org/wiki/Releases

Gentoo

a highly flexible, source-based Linux distribution.

— https://www.gentoo.org

Gentoo is using a rolling-release model.

OpenSUSE

The makers' choice for sysadmins, developers and desktop users.

— https://www.opensuse.org

For currently supported releases see:

https://get.opensuse.org/leap/

Ubuntu

Ubuntu is the modern, open source operating system on Linux for the enterprise server, desktop, cloud, and IoT.

— https://ubuntu.com/

For currently supported releases see:

https://wiki.ubuntu.com/Releases

Container Images

Container images, sometimes also referred to as “templates” or “appliances”, are tar archives which contain everything to run a container.

Proxmox VE itself provides a variety of basic templates for the most common Linux distributions. They can be downloaded using the GUI or the pveam (short for Proxmox VE Appliance Manager) command-line utility. Additionally, TurnKey Linux container templates are also available to download.

The list of available templates is updated daily through the pve-daily-update timer. You can also trigger an update manually by executing:

# pveam update

To view the list of available images run:

# pveam available

You can restrict this large list by specifying the section you are interested in, for example basic system images:

List available system images
# pveam available --section system
system          alpine-3.12-default_20200823_amd64.tar.xz
system          alpine-3.13-default_20210419_amd64.tar.xz
system          alpine-3.14-default_20210623_amd64.tar.xz
system          archlinux-base_20210420-1_amd64.tar.gz
system          centos-7-default_20190926_amd64.tar.xz
system          centos-8-default_20201210_amd64.tar.xz
system          debian-9.0-standard_9.7-1_amd64.tar.gz
system          debian-10-standard_10.7-1_amd64.tar.gz
system          devuan-3.0-standard_3.0_amd64.tar.gz
system          fedora-33-default_20201115_amd64.tar.xz
system          fedora-34-default_20210427_amd64.tar.xz
system          gentoo-current-default_20200310_amd64.tar.xz
system          opensuse-15.2-default_20200824_amd64.tar.xz
system          ubuntu-16.04-standard_16.04.5-1_amd64.tar.gz
system          ubuntu-18.04-standard_18.04.1-1_amd64.tar.gz
system          ubuntu-20.04-standard_20.04-1_amd64.tar.gz
system          ubuntu-20.10-standard_20.10-1_amd64.tar.gz
system          ubuntu-21.04-standard_21.04-1_amd64.tar.gz

Before you can use such a template, you need to download them into one of your storages. If you’re unsure to which one, you can simply use the local named storage for that purpose. For clustered installations, it is preferred to use a shared storage so that all nodes can access those images.

# pveam download local debian-10.0-standard_10.0-1_amd64.tar.gz

You are now ready to create containers using that image, and you can list all downloaded images on storage local with:

# pveam list local
local:vztmpl/debian-10.0-standard_10.0-1_amd64.tar.gz  219.95MB
Tip You can also use the Proxmox VE web interface GUI to download, list and delete container templates.

pct uses them to create a new container, for example:

# pct create 999 local:vztmpl/debian-10.0-standard_10.0-1_amd64.tar.gz

The above command shows you the full Proxmox VE volume identifiers. They include the storage name, and most other Proxmox VE commands can use them. For example you can delete that image later with:

# pveam remove local:vztmpl/debian-10.0-standard_10.0-1_amd64.tar.gz

Container Settings

General Settings

screenshot/gui-create-ct-general.png

General settings of a container include

  • the Node : the physical server on which the container will run

  • the CT ID: a unique number in this Proxmox VE installation used to identify your container

  • Hostname: the hostname of the container

  • Resource Pool: a logical group of containers and VMs

  • Password: the root password of the container

  • SSH Public Key: a public key for connecting to the root account over SSH

  • Unprivileged container: this option allows to choose at creation time if you want to create a privileged or unprivileged container.

Unprivileged Containers

Unprivileged containers use a new kernel feature called user namespaces. The root UID 0 inside the container is mapped to an unprivileged user outside the container. This means that most security issues (container escape, resource abuse, etc.) in these containers will affect a random unprivileged user, and would be a generic kernel security bug rather than an LXC issue. The LXC team thinks unprivileged containers are safe by design.

This is the default option when creating a new container.

Note If the container uses systemd as an init system, please be aware the systemd version running inside the container should be equal to or greater than 220.

Privileged Containers

Security in containers is achieved by using mandatory access control AppArmor restrictions, seccomp filters and Linux kernel namespaces. The LXC team considers this kind of container as unsafe, and they will not consider new container escape exploits to be security issues worthy of a CVE and quick fix. That’s why privileged containers should only be used in trusted environments.

CPU

screenshot/gui-create-ct-cpu.png

You can restrict the number of visible CPUs inside the container using the cores option. This is implemented using the Linux cpuset cgroup (control group). A special task inside pvestatd tries to distribute running containers among available CPUs periodically. To view the assigned CPUs run the following command:

# pct cpusets
 ---------------------
 102:              6 7
 105:      2 3 4 5
 108:  0 1
 ---------------------

Containers use the host kernel directly. All tasks inside a container are handled by the host CPU scheduler. Proxmox VE uses the Linux CFS (Completely Fair Scheduler) scheduler by default, which has additional bandwidth control options.

cpulimit:

You can use this option to further limit assigned CPU time. Please note that this is a floating point number, so it is perfectly valid to assign two cores to a container, but restrict overall CPU consumption to half a core. 

cores: 2
cpulimit: 0.5
cpuunits:

This is a relative weight passed to the kernel scheduler. The larger the number is, the more CPU time this container gets. Number is relative to the weights of all the other running containers. The default is 100 (or 1024 if the host uses legacy cgroup v1). You can use this setting to prioritize some containers.

Memory

screenshot/gui-create-ct-memory.png

Container memory is controlled using the cgroup memory controller.

memory:

Limit overall memory usage. This corresponds to the memory.limit_in_bytes cgroup setting.

swap:

Allows the container to use additional swap memory from the host swap space. This corresponds to the memory.memsw.limit_in_bytes cgroup setting, which is set to the sum of both value (memory + swap).

Mount Points

screenshot/gui-create-ct-root-disk.png

The root mount point is configured with the rootfs property. You can configure up to 256 additional mount points. The corresponding options are called mp0 to mp255. They can contain the following settings:

rootfs: [volume=]<volume> [,acl=<1|0>] [,mountoptions=<opt[;opt...]>] [,quota=<1|0>] [,replicate=<1|0>] [,ro=<1|0>] [,shared=<1|0>] [,size=<DiskSize>]

Use volume as container root. See below for a detailed description of all options.

mp[n]: [volume=]<volume> ,mp=<Path> [,acl=<1|0>] [,backup=<1|0>] [,mountoptions=<opt[;opt...]>] [,quota=<1|0>] [,replicate=<1|0>] [,ro=<1|0>] [,shared=<1|0>] [,size=<DiskSize>]

Use volume as container mount point. Use the special syntax STORAGE_ID:SIZE_IN_GiB to allocate a new volume.

acl=<boolean>

Explicitly enable or disable ACL support.

backup=<boolean>

Whether to include the mount point in backups (only used for volume mount points).

mountoptions=<opt[;opt...]>

Extra mount options for rootfs/mps.

mp=<Path>

Path to the mount point as seen from inside the container.

Note Must not contain any symlinks for security reasons.
quota=<boolean>

Enable user quotas inside the container (not supported with zfs subvolumes)

replicate=<boolean> (default = 1)

Will include this volume to a storage replica job.

ro=<boolean>

Read-only mount point

shared=<boolean> (default = 0)

Mark this non-volume mount point as available on all nodes.

Warning This option does not share the mount point automatically, it assumes it is shared already!
size=<DiskSize>

Volume size (read only value).

volume=<volume>

Volume, device or directory to mount into the container.

Currently there are three types of mount points: storage backed mount points, bind mounts, and device mounts.

Typical container rootfs configuration
rootfs: thin1:base-100-disk-1,size=8G

Storage Backed Mount Points

Storage backed mount points are managed by the Proxmox VE storage subsystem and come in three different flavors:

  • Image based: these are raw images containing a single ext4 formatted file system.

  • ZFS subvolumes: these are technically bind mounts, but with managed storage, and thus allow resizing and snapshotting.

  • Directories: passing size=0 triggers a special case where instead of a raw image a directory is created.

Note The special option syntax STORAGE_ID:SIZE_IN_GB for storage backed mount point volumes will automatically allocate a volume of the specified size on the specified storage. For example, calling 
pct set 100 -mp0 thin1:10,mp=/path/in/container

will allocate a 10GB volume on the storage thin1 and replace the volume ID place holder 10 with the allocated volume ID, and setup the moutpoint in the container at /path/in/container

Bind Mount Points

Bind mounts allow you to access arbitrary directories from your Proxmox VE host inside a container. Some potential use cases are:

  • Accessing your home directory in the guest

  • Accessing an USB device directory in the guest

  • Accessing an NFS mount from the host in the guest

Bind mounts are considered to not be managed by the storage subsystem, so you cannot make snapshots or deal with quotas from inside the container. With unprivileged containers you might run into permission problems caused by the user mapping and cannot use ACLs.

Note The contents of bind mount points are not backed up when using vzdump.
Warning For security reasons, bind mounts should only be established using source directories especially reserved for this purpose, e.g., a directory hierarchy under /mnt/bindmounts. Never bind mount system directories like /, /var or /etc into a container - this poses a great security risk.
Note The bind mount source path must not contain any symlinks.

For example, to make the directory /mnt/bindmounts/shared accessible in the container with ID 100 under the path /shared, add a configuration line such as:

mp0: /mnt/bindmounts/shared,mp=/shared

into /etc/pve/lxc/100.conf.

Or alternatively use the pct tool:

pct set 100 -mp0 /mnt/bindmounts/shared,mp=/shared

to achieve the same result.

Device Mount Points

Device mount points allow to mount block devices of the host directly into the container. Similar to bind mounts, device mounts are not managed by Proxmox VE’s storage subsystem, but the quota and acl options will be honored.

Note Device mount points should only be used under special circumstances. In most cases a storage backed mount point offers the same performance and a lot more features.
Note The contents of device mount points are not backed up when using vzdump.

Network

screenshot/gui-create-ct-network.png

You can configure up to 10 network interfaces for a single container. The corresponding options are called net0 to net9, and they can contain the following setting:

net[n]: name=<string> [,bridge=<bridge>] [,firewall=<1|0>] [,gw=<GatewayIPv4>] [,gw6=<GatewayIPv6>] [,hwaddr=<XX:XX:XX:XX:XX:XX>] [,ip=<(IPv4/CIDR|dhcp|manual)>] [,ip6=<(IPv6/CIDR|auto|dhcp|manual)>] [,link_down=<1|0>] [,mtu=<integer>] [,rate=<mbps>] [,tag=<integer>] [,trunks=<vlanid[;vlanid...]>] [,type=<veth>]

Specifies network interfaces for the container.

bridge=<bridge>

Bridge to attach the network device to.

firewall=<boolean>

Controls whether this interface’s firewall rules should be used.

gw=<GatewayIPv4>

Default gateway for IPv4 traffic.

gw6=<GatewayIPv6>

Default gateway for IPv6 traffic.

hwaddr=<XX:XX:XX:XX:XX:XX>

A common MAC address with the I/G (Individual/Group) bit not set.

ip=<(IPv4/CIDR|dhcp|manual)>

IPv4 address in CIDR format.

ip6=<(IPv6/CIDR|auto|dhcp|manual)>

IPv6 address in CIDR format.

link_down=<boolean>

Whether this interface should be disconnected (like pulling the plug).

mtu=<integer> (64 - 65535)

Maximum transfer unit of the interface. (lxc.network.mtu)

name=<string>

Name of the network device as seen from inside the container. (lxc.network.name)

rate=<mbps>

Apply rate limiting to the interface

tag=<integer> (1 - 4094)

VLAN tag for this interface.

trunks=<vlanid[;vlanid...]>

VLAN ids to pass through the interface

type=<veth>

Network interface type.

Automatic Start and Shutdown of Containers

To automatically start a container when the host system boots, select the option Start at boot in the Options panel of the container in the web interface or run the following command:

# pct set CTID -onboot 1
screenshot/gui-qemu-edit-start-order.png
Start and Shutdown Order

If you want to fine tune the boot order of your containers, you can use the following parameters:

  • Start/Shutdown order: Defines the start order priority. For example, set it to 1 if you want the CT to be the first to be started. (We use the reverse startup order for shutdown, so a container with a start order of 1 would be the last to be shut down)

  • Startup delay: Defines the interval between this container start and subsequent containers starts. For example, set it to 240 if you want to wait 240 seconds before starting other containers.

  • Shutdown timeout: Defines the duration in seconds Proxmox VE should wait for the container to be offline after issuing a shutdown command. By default this value is set to 60, which means that Proxmox VE will issue a shutdown request, wait 60s for the machine to be offline, and if after 60s the machine is still online will notify that the shutdown action failed.

Please note that containers without a Start/Shutdown order parameter will always start after those where the parameter is set, and this parameter only makes sense between the machines running locally on a host, and not cluster-wide.

If you require a delay between the host boot and the booting of the first container, see the section on Proxmox VE Node Management.

Hookscripts

You can add a hook script to CTs with the config property hookscript.

# pct set 100 -hookscript local:snippets/hookscript.pl

It will be called during various phases of the guests lifetime. For an example and documentation see the example script under /usr/share/pve-docs/examples/guest-example-hookscript.pl.

Security Considerations

Containers use the kernel of the host system. This exposes an attack surface for malicious users. In general, full virtual machines provide better isolation. This should be considered if containers are provided to unknown or untrusted people.

To reduce the attack surface, LXC uses many security features like AppArmor, CGroups and kernel namespaces.

AppArmor

AppArmor profiles are used to restrict access to possibly dangerous actions. Some system calls, i.e. mount, are prohibited from execution.

To trace AppArmor activity, use:

# dmesg | grep apparmor

Although it is not recommended, AppArmor can be disabled for a container. This brings security risks with it. Some syscalls can lead to privilege escalation when executed within a container if the system is misconfigured or if a LXC or Linux Kernel vulnerability exists.

To disable AppArmor for a container, add the following line to the container configuration file located at /etc/pve/lxc/CTID.conf:

lxc.apparmor.profile = unconfined
Warning Please note that this is not recommended for production use.

Control Groups (cgroup)

cgroup is a kernel mechanism used to hierarchically organize processes and distribute system resources.

The main resources controlled via cgroups are CPU time, memory and swap limits, and access to device nodes. cgroups are also used to "freeze" a container before taking snapshots.

There are 2 versions of cgroups currently available, legacy and cgroupv2.

Since Proxmox VE 7.0, the default is a pure cgroupv2 environment. Previously a "hybrid" setup was used, where resource control was mainly done in cgroupv1 with an additional cgroupv2 controller which could take over some subsystems via the cgroup_no_v1 kernel command-line parameter. (See the kernel parameter documentation for details.)

CGroup Version Compatibility

The main difference between pure cgroupv2 and the old hybrid environments regarding Proxmox VE is that with cgroupv2 memory and swap are now controlled independently. The memory and swap settings for containers can map directly to these values, whereas previously only the memory limit and the limit of the sum of memory and swap could be limited.

Another important difference is that the devices controller is configured in a completely different way. Because of this, file system quotas are currently not supported in a pure cgroupv2 environment.

cgroupv2 support by the container’s OS is needed to run in a pure cgroupv2 environment. Containers running systemd version 231 or newer support cgroupv2
[this includes all newest major versions of container templates shipped by Proxmox VE]
, as do containers not using systemd as init system
[for example Alpine Linux]
.

Note

CentOS 7 and Ubuntu 16.10 are two prominent Linux distributions releases, which have a systemd version that is too old to run in a cgroupv2 environment, you can either

  • Upgrade the whole distribution to a newer release. For the examples above, that could be Ubuntu 18.04 or 20.04, and CentOS 8 (or RHEL/CentOS derivatives like AlmaLinux or Rocky Linux). This has the benefit to get the newest bug and security fixes, often also new features, and moving the EOL date in the future.

  • Upgrade the Containers systemd version. If the distribution provides a backports repository this can be an easy and quick stop-gap measurement.

  • Move the container, or its services, to a Virtual Machine. Virtual Machines have a much less interaction with the host, that’s why one can install decades old OS versions just fine there.

  • Switch back to the legacy cgroup controller. Note that while it can be a valid solution, it’s not a permanent one. Starting from Proxmox VE 9.0, the legacy controller will not be supported anymore.

Changing CGroup Version

Tip If file system quotas are not required and all containers support cgroupv2, it is recommended to stick to the new default.

To switch back to the previous version the following kernel command-line parameter can be used:

systemd.unified_cgroup_hierarchy=0

See this section on editing the kernel boot command line on where to add the parameter.

Guest Operating System Configuration

Proxmox VE tries to detect the Linux distribution in the container, and modifies some files. Here is a short list of things done at container startup:

set /etc/hostname

to set the container name

modify /etc/hosts

to allow lookup of the local hostname

network setup

pass the complete network setup to the container

configure DNS

pass information about DNS servers

adapt the init system

for example, fix the number of spawned getty processes

set the root password

when creating a new container

rewrite ssh_host_keys

so that each container has unique keys

randomize crontab

so that cron does not start at the same time on all containers

Changes made by Proxmox VE are enclosed by comment markers:

# --- BEGIN PVE ---
<data>
# --- END PVE ---

Those markers will be inserted at a reasonable location in the file. If such a section already exists, it will be updated in place and will not be moved.

Modification of a file can be prevented by adding a .pve-ignore. file for it. For instance, if the file /etc/.pve-ignore.hosts exists then the /etc/hosts file will not be touched. This can be a simple empty file created via:

# touch /etc/.pve-ignore.hosts

Most modifications are OS dependent, so they differ between different distributions and versions. You can completely disable modifications by manually setting the ostype to unmanaged.

OS type detection is done by testing for certain files inside the container. Proxmox VE first checks the /etc/os-release file
[/etc/os-release replaces the multitude of per-distribution release files https://manpages.debian.org/stable/systemd/os-release.5.en.html]
. If that file is not present, or it does not contain a clearly recognizable distribution identifier the following distribution specific release files are checked.

Ubuntu

inspect /etc/lsb-release (DISTRIB_ID=Ubuntu)

Debian

test /etc/debian_version

Fedora

test /etc/fedora-release

RedHat or CentOS

test /etc/redhat-release

ArchLinux

test /etc/arch-release

Alpine

test /etc/alpine-release

Gentoo

test /etc/gentoo-release

Note Container start fails if the configured ostype differs from the auto detected type.

Container Storage

The Proxmox VE LXC container storage model is more flexible than traditional container storage models. A container can have multiple mount points. This makes it possible to use the best suited storage for each application.

For example the root file system of the container can be on slow and cheap storage while the database can be on fast and distributed storage via a second mount point. See section Mount Points for further details.

Any storage type supported by the Proxmox VE storage library can be used. This means that containers can be stored on local (for example lvm, zfs or directory), shared external (like iSCSI, NFS) or even distributed storage systems like Ceph. Advanced storage features like snapshots or clones can be used if the underlying storage supports them. The vzdump backup tool can use snapshots to provide consistent container backups.

Furthermore, local devices or local directories can be mounted directly using bind mounts. This gives access to local resources inside a container with practically zero overhead. Bind mounts can be used as an easy way to share data between containers.

FUSE Mounts

Warning Because of existing issues in the Linux kernel’s freezer subsystem the usage of FUSE mounts inside a container is strongly advised against, as containers need to be frozen for suspend or snapshot mode backups.

If FUSE mounts cannot be replaced by other mounting mechanisms or storage technologies, it is possible to establish the FUSE mount on the Proxmox host and use a bind mount point to make it accessible inside the container.

Using Quotas Inside Containers

Quotas allow to set limits inside a container for the amount of disk space that each user can use.

Note This currently requires the use of legacy cgroups.
Note This only works on ext4 image based storage types and currently only works with privileged containers.

Activating the quota option causes the following mount options to be used for a mount point: usrjquota=aquota.user,grpjquota=aquota.group,jqfmt=vfsv0

This allows quotas to be used like on any other system. You can initialize the /aquota.user and /aquota.group files by running:

# quotacheck -cmug /
# quotaon /

Then edit the quotas using the edquota command. Refer to the documentation of the distribution running inside the container for details.

Note You need to run the above commands for every mount point by passing the mount point’s path instead of just /.

Using ACLs Inside Containers

The standard Posix Access Control Lists are also available inside containers. ACLs allow you to set more detailed file ownership than the traditional user/group/others model.

Backup of Container mount points

To include a mount point in backups, enable the backup option for it in the container configuration. For an existing mount point mp0

mp0: guests:subvol-100-disk-1,mp=/root/files,size=8G

add backup=1 to enable it.

mp0: guests:subvol-100-disk-1,mp=/root/files,size=8G,backup=1
Note When creating a new mount point in the GUI, this option is enabled by default.

To disable backups for a mount point, add backup=0 in the way described above, or uncheck the Backup checkbox on the GUI.

Replication of Containers mount points

By default, additional mount points are replicated when the Root Disk is replicated. If you want the Proxmox VE storage replication mechanism to skip a mount point, you can set the Skip replication option for that mount point. As of Proxmox VE 5.0, replication requires a storage of type zfspool. Adding a mount point to a different type of storage when the container has replication configured requires to have Skip replication enabled for that mount point.

Backup and Restore

Container Backup

It is possible to use the vzdump tool for container backup. Please refer to the vzdump manual page for details.

Restoring Container Backups

Restoring container backups made with vzdump is possible using the pct restore command. By default, pct restore will attempt to restore as much of the backed up container configuration as possible. It is possible to override the backed up configuration by manually setting container options on the command line (see the pct manual page for details).

Note pvesm extractconfig can be used to view the backed up configuration contained in a vzdump archive.

There are two basic restore modes, only differing by their handling of mount points:

“Simple” Restore Mode

If neither the rootfs parameter nor any of the optional mpX parameters are explicitly set, the mount point configuration from the backed up configuration file is restored using the following steps:

  1. Extract mount points and their options from backup

  2. Create volumes for storage backed mount points on the storage provided with the storage parameter (default: local).

  3. Extract files from backup archive

  4. Add bind and device mount points to restored configuration (limited to root user)

Note Since bind and device mount points are never backed up, no files are restored in the last step, but only the configuration options. The assumption is that such mount points are either backed up with another mechanism (e.g., NFS space that is bind mounted into many containers), or not intended to be backed up at all.

This simple mode is also used by the container restore operations in the web interface.

“Advanced” Restore Mode

By setting the rootfs parameter (and optionally, any combination of mpX parameters), the pct restore command is automatically switched into an advanced mode. This advanced mode completely ignores the rootfs and mpX configuration options contained in the backup archive, and instead only uses the options explicitly provided as parameters.

This mode allows flexible configuration of mount point settings at restore time, for example:

  • Set target storages, volume sizes and other options for each mount point individually

  • Redistribute backed up files according to new mount point scheme

  • Restore to device and/or bind mount points (limited to root user)

Managing Containers with pct

The “Proxmox Container Toolkit” (pct) is the command-line tool to manage Proxmox VE containers. It enables you to create or destroy containers, as well as control the container execution (start, stop, reboot, migrate, etc.). It can be used to set parameters in the config file of a container, for example the network configuration or memory limits.

CLI Usage Examples

Create a container based on a Debian template (provided you have already downloaded the template via the web interface)

# pct create 100 /var/lib/vz/template/cache/debian-10.0-standard_10.0-1_amd64.tar.gz

Start container 100

# pct start 100

Start a login session via getty

# pct console 100

Enter the LXC namespace and run a shell as root user

# pct enter 100

Display the configuration

# pct config 100

Add a network interface called eth0, bridged to the host bridge vmbr0, set the address and gateway, while it’s running

# pct set 100 -net0 name=eth0,bridge=vmbr0,ip=192.168.15.147/24,gw=192.168.15.1

Reduce the memory of the container to 512MB

# pct set 100 -memory 512

Destroying a container always removes it from Access Control Lists and it always removes the firewall configuration of the container. You have to activate --purge, if you want to additionally remove the container from replication jobs, backup jobs and HA resource configurations.

# pct destroy 100 --purge

Move a mount point volume to a different storage.

# pct move-volume 100 mp0 other-storage

Reassign a volume to a different CT. This will remove the volume mp0 from the source CT and attaches it as mp1 to the target CT. In the background the volume is being renamed so that the name matches the new owner.

#  pct move-volume 100 mp0 --target-vmid 200 --target-volume mp1

Obtaining Debugging Logs

In case pct start is unable to start a specific container, it might be helpful to collect debugging output by passing the --debug flag (replace CTID with the container’s CTID):

# pct start CTID --debug

Alternatively, you can use the following lxc-start command, which will save the debug log to the file specified by the -o output option:

# lxc-start -n CTID -F -l DEBUG -o /tmp/lxc-CTID.log

This command will attempt to start the container in foreground mode, to stop the container run pct shutdown CTID or pct stop CTID in a second terminal.

The collected debug log is written to /tmp/lxc-CTID.log.

Note If you have changed the container’s configuration since the last start attempt with pct start, you need to run pct start at least once to also update the configuration used by lxc-start.

Migration

If you have a cluster, you can migrate your Containers with

# pct migrate <ctid> <target>

This works as long as your Container is offline. If it has local volumes or mount points defined, the migration will copy the content over the network to the target host if the same storage is defined there.

Running containers cannot live-migrated due to technical limitations. You can do a restart migration, which shuts down, moves and then starts a container again on the target node. As containers are very lightweight, this results normally only in a downtime of some hundreds of milliseconds.

A restart migration can be done through the web interface or by using the --restart flag with the pct migrate command.

A restart migration will shut down the Container and kill it after the specified timeout (the default is 180 seconds). Then it will migrate the Container like an offline migration and when finished, it starts the Container on the target node.

Configuration

The /etc/pve/lxc/<CTID>.conf file stores container configuration, where <CTID> is the numeric ID of the given container. Like all other files stored inside /etc/pve/, they get automatically replicated to all other cluster nodes.

Note CTIDs < 100 are reserved for internal purposes, and CTIDs need to be unique cluster wide.
Example Container Configuration
ostype: debian
arch: amd64
hostname: www
memory: 512
swap: 512
net0: bridge=vmbr0,hwaddr=66:64:66:64:64:36,ip=dhcp,name=eth0,type=veth
rootfs: local:107/vm-107-disk-1.raw,size=7G

The configuration files are simple text files. You can edit them using a normal text editor, for example, vi or nano. This is sometimes useful to do small corrections, but keep in mind that you need to restart the container to apply such changes.

For that reason, it is usually better to use the pct command to generate and modify those files, or do the whole thing using the GUI. Our toolkit is smart enough to instantaneously apply most changes to running containers. This feature is called “hot plug”, and there is no need to restart the container in that case.

In cases where a change cannot be hot-plugged, it will be registered as a pending change (shown in red color in the GUI). They will only be applied after rebooting the container.

File Format

The container configuration file uses a simple colon separated key/value format. Each line has the following format:

# this is a comment
OPTION: value

Blank lines in those files are ignored, and lines starting with a # character are treated as comments and are also ignored.

It is possible to add low-level, LXC style configuration directly, for example:

lxc.init_cmd: /sbin/my_own_init

or

lxc.init_cmd = /sbin/my_own_init

The settings are passed directly to the LXC low-level tools.

Snapshots

When you create a snapshot, pct stores the configuration at snapshot time into a separate snapshot section within the same configuration file. For example, after creating a snapshot called “testsnapshot”, your configuration file will look like this:

Container configuration with snapshot
memory: 512
swap: 512
parent: testsnaphot
...

[testsnaphot]
memory: 512
swap: 512
snaptime: 1457170803
...

There are a few snapshot related properties like parent and snaptime. The parent property is used to store the parent/child relationship between snapshots. snaptime is the snapshot creation time stamp (Unix epoch).

Options

arch: <amd64 | arm64 | armhf | i386 | riscv32 | riscv64> (default = amd64)

OS architecture type.

cmode: <console | shell | tty> (default = tty)

Console mode. By default, the console command tries to open a connection to one of the available tty devices. By setting cmode to console it tries to attach to /dev/console instead. If you set cmode to shell, it simply invokes a shell inside the container (no login).

console: <boolean> (default = 1)

Attach a console device (/dev/console) to the container.

cores: <integer> (1 - 8192)

The number of cores assigned to the container. A container can use all available cores by default.

cpulimit: <number> (0 - 8192) (default = 0)

Limit of CPU usage.

Note If the computer has 2 CPUs, it has a total of 2 CPU time. Value 0 indicates no CPU limit.
cpuunits: <integer> (0 - 500000) (default = cgroup v1: 1024, cgroup v2: 100)

CPU weight for a container. Argument is used in the kernel fair scheduler. The larger the number is, the more CPU time this container gets. Number is relative to the weights of all the other running guests.

debug: <boolean> (default = 0)

Try to be more verbose. For now this only enables debug log-level on start.

description: <string>

Description for the Container. Shown in the web-interface CT’s summary. This is saved as comment inside the configuration file.

dev[n]: [[path=]<Path>] [,deny-write=<1|0>] [,gid=<integer>] [,mode=<Octal access mode>] [,uid=<integer>]

Device to pass through to the container

deny-write=<boolean> (default = 0)

Deny the container to write to the device

gid=<integer> (0 - N)

Group ID to be assigned to the device node

mode=<Octal access mode>

Access mode to be set on the device node

path=<Path>

Path to the device to pass through to the container

uid=<integer> (0 - N)

User ID to be assigned to the device node

features: [force_rw_sys=<1|0>] [,fuse=<1|0>] [,keyctl=<1|0>] [,mknod=<1|0>] [,mount=<fstype;fstype;...>] [,nesting=<1|0>]

Allow containers access to advanced features.

force_rw_sys=<boolean> (default = 0)

Mount /sys in unprivileged containers as rw instead of mixed. This can break networking under newer (>= v245) systemd-network use.

fuse=<boolean> (default = 0)

Allow using fuse file systems in a container. Note that interactions between fuse and the freezer cgroup can potentially cause I/O deadlocks.

keyctl=<boolean> (default = 0)

For unprivileged containers only: Allow the use of the keyctl() system call. This is required to use docker inside a container. By default unprivileged containers will see this system call as non-existent. This is mostly a workaround for systemd-networkd, as it will treat it as a fatal error when some keyctl() operations are denied by the kernel due to lacking permissions. Essentially, you can choose between running systemd-networkd or docker.

mknod=<boolean> (default = 0)

Allow unprivileged containers to use mknod() to add certain device nodes. This requires a kernel with seccomp trap to user space support (5.3 or newer). This is experimental.

mount=<fstype;fstype;...>

Allow mounting file systems of specific types. This should be a list of file system types as used with the mount command. Note that this can have negative effects on the container’s security. With access to a loop device, mounting a file can circumvent the mknod permission of the devices cgroup, mounting an NFS file system can block the host’s I/O completely and prevent it from rebooting, etc.

nesting=<boolean> (default = 0)

Allow nesting. Best used with unprivileged containers with additional id mapping. Note that this will expose procfs and sysfs contents of the host to the guest.

hookscript: <string>

Script that will be executed during various steps in the containers lifetime.

hostname: <string>

Set a host name for the container.

lock: <backup | create | destroyed | disk | fstrim | migrate | mounted | rollback | snapshot | snapshot-delete>

Lock/unlock the container.

memory: <integer> (16 - N) (default = 512)

Amount of RAM for the container in MB.

mp[n]: [volume=]<volume> ,mp=<Path> [,acl=<1|0>] [,backup=<1|0>] [,mountoptions=<opt[;opt...]>] [,quota=<1|0>] [,replicate=<1|0>] [,ro=<1|0>] [,shared=<1|0>] [,size=<DiskSize>]

Use volume as container mount point. Use the special syntax STORAGE_ID:SIZE_IN_GiB to allocate a new volume.

acl=<boolean>

Explicitly enable or disable ACL support.

backup=<boolean>

Whether to include the mount point in backups (only used for volume mount points).

mountoptions=<opt[;opt...]>

Extra mount options for rootfs/mps.

mp=<Path>

Path to the mount point as seen from inside the container.

Note Must not contain any symlinks for security reasons.
quota=<boolean>

Enable user quotas inside the container (not supported with zfs subvolumes)

replicate=<boolean> (default = 1)

Will include this volume to a storage replica job.

ro=<boolean>

Read-only mount point

shared=<boolean> (default = 0)

Mark this non-volume mount point as available on all nodes.

Warning This option does not share the mount point automatically, it assumes it is shared already!
size=<DiskSize>

Volume size (read only value).

volume=<volume>

Volume, device or directory to mount into the container.

nameserver: <string>

Sets DNS server IP address for a container. Create will automatically use the setting from the host if you neither set searchdomain nor nameserver.

net[n]: name=<string> [,bridge=<bridge>] [,firewall=<1|0>] [,gw=<GatewayIPv4>] [,gw6=<GatewayIPv6>] [,hwaddr=<XX:XX:XX:XX:XX:XX>] [,ip=<(IPv4/CIDR|dhcp|manual)>] [,ip6=<(IPv6/CIDR|auto|dhcp|manual)>] [,link_down=<1|0>] [,mtu=<integer>] [,rate=<mbps>] [,tag=<integer>] [,trunks=<vlanid[;vlanid...]>] [,type=<veth>]

Specifies network interfaces for the container.

bridge=<bridge>

Bridge to attach the network device to.

firewall=<boolean>

Controls whether this interface’s firewall rules should be used.

gw=<GatewayIPv4>

Default gateway for IPv4 traffic.

gw6=<GatewayIPv6>

Default gateway for IPv6 traffic.

hwaddr=<XX:XX:XX:XX:XX:XX>

A common MAC address with the I/G (Individual/Group) bit not set.

ip=<(IPv4/CIDR|dhcp|manual)>

IPv4 address in CIDR format.

ip6=<(IPv6/CIDR|auto|dhcp|manual)>

IPv6 address in CIDR format.

link_down=<boolean>

Whether this interface should be disconnected (like pulling the plug).

mtu=<integer> (64 - 65535)

Maximum transfer unit of the interface. (lxc.network.mtu)

name=<string>

Name of the network device as seen from inside the container. (lxc.network.name)

rate=<mbps>

Apply rate limiting to the interface

tag=<integer> (1 - 4094)

VLAN tag for this interface.

trunks=<vlanid[;vlanid...]>

VLAN ids to pass through the interface

type=<veth>

Network interface type.

onboot: <boolean> (default = 0)

Specifies whether a container will be started during system bootup.

ostype: <alpine | archlinux | centos | debian | devuan | fedora | gentoo | nixos | opensuse | ubuntu | unmanaged>

OS type. This is used to setup configuration inside the container, and corresponds to lxc setup scripts in /usr/share/lxc/config/<ostype>.common.conf. Value unmanaged can be used to skip and OS specific setup.

protection: <boolean> (default = 0)

Sets the protection flag of the container. This will prevent the CT or CT’s disk remove/update operation.

rootfs: [volume=]<volume> [,acl=<1|0>] [,mountoptions=<opt[;opt...]>] [,quota=<1|0>] [,replicate=<1|0>] [,ro=<1|0>] [,shared=<1|0>] [,size=<DiskSize>]

Use volume as container root.

acl=<boolean>

Explicitly enable or disable ACL support.

mountoptions=<opt[;opt...]>

Extra mount options for rootfs/mps.

quota=<boolean>

Enable user quotas inside the container (not supported with zfs subvolumes)

replicate=<boolean> (default = 1)

Will include this volume to a storage replica job.

ro=<boolean>

Read-only mount point

shared=<boolean> (default = 0)

Mark this non-volume mount point as available on all nodes.

Warning This option does not share the mount point automatically, it assumes it is shared already!
size=<DiskSize>

Volume size (read only value).

volume=<volume>

Volume, device or directory to mount into the container.

searchdomain: <string>

Sets DNS search domains for a container. Create will automatically use the setting from the host if you neither set searchdomain nor nameserver.

startup: `[[order=]\d+] [,up=\d+] [,down=\d+] `

Startup and shutdown behavior. Order is a non-negative number defining the general startup order. Shutdown in done with reverse ordering. Additionally you can set the up or down delay in seconds, which specifies a delay to wait before the next VM is started or stopped.

swap: <integer> (0 - N) (default = 512)

Amount of SWAP for the container in MB.

tags: <string>

Tags of the Container. This is only meta information.

template: <boolean> (default = 0)

Enable/disable Template.

timezone: <string>

Time zone to use in the container. If option isn’t set, then nothing will be done. Can be set to host to match the host time zone, or an arbitrary time zone option from /usr/share/zoneinfo/zone.tab

tty: <integer> (0 - 6) (default = 2)

Specify the number of tty available to the container

unprivileged: <boolean> (default = 0)

Makes the container run as unprivileged user. (Should not be modified manually.)

unused[n]: [volume=]<volume>

Reference to unused volumes. This is used internally, and should not be modified manually.

volume=<volume>

The volume that is not used currently.

Locks

Container migrations, snapshots and backups (vzdump) set a lock to prevent incompatible concurrent actions on the affected container. Sometimes you need to remove such a lock manually (e.g., after a power failure).

# pct unlock <CTID>
Caution Only do this if you are sure the action which set the lock is no longer running.



Migrate container from OpenVZ to Linux container

Follow this howto:

References

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