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Containers are a lightweight alternative to fully virtualized
VMs. Instead of emulating a complete Operating System (OS), containers
simply use the OS of the host they run on. This implies that all
containers use the same kernel, and that they can access resources
from the host directly.
This is great because containers do not waste CPU power nor memory due
to kernel emulation. Container run-time costs are close to zero and
usually negligible. But there are also some drawbacks you need to
consider:
You can only run Linux based OS inside containers, i.e. it is not
  possible to run FreeBSD or MS Windows inside.
For security reasons, access to host resources needs to be
  restricted. This is done with AppArmor, SecComp filters and other
  kernel features. Be prepared that some syscalls are not allowed
  inside containers.
Proxmox VE uses LXC as underlying container
technology. We consider LXC as low-level library, which provides
countless options. It would be too difficult to use those tools
directly. Instead, we provide a small wrapper called pct, the
"Proxmox Container Toolkit".
The toolkit is tightly coupled with Proxmox VE. That means that it is aware
of the cluster setup, and it can use the same network and storage
resources as fully virtualized VMs. You can even use the Proxmox VE
firewall, or manage containers using the HA framework.
Our primary goal is to offer an environment as one would get from a
VM, but without the additional overhead. We call this "System
Containers".
If you want to run micro-containers (with docker, rkt, &#8230;), it
is best to run them inside a VM.
Technology Overview
LXC (https://linuxcontainers.org/)
Integrated into Proxmox VE graphical user interface (GUI)
Easy to use command line tool pct
Access via Proxmox VE REST API
lxcfs to provide containerized /proc file system
AppArmor/Seccomp to improve security
CRIU: for live migration (planned)
Runs on modern Linux kernels
Image based deployment (templates)
Use Proxmox VE storage library
Container setup from host (network, DNS, storage, &#8230;)
Security Considerations
Containers use the same kernel as the host, so there is a big attack
surface for malicious users. You should consider this fact if you
provide containers to totally untrusted people. In general, fully
virtualized VMs provide better isolation.
The good news is that LXC uses many kernel security features like
AppArmor, CGroups and PID and user namespaces, which makes containers
usage quite secure.
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 ---
&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:
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 Images
Container images, sometimes also referred to as &#8220;templates&#8221; or
&#8220;appliances&#8221;, are tar archives which contain everything to run a
container. You can think of it as a tidy container backup. Like most
modern container toolkits, pct uses those images when you create a
new container, for example:
pct create 999 local:vztmpl/debian-8.0-standard_8.0-1_amd64.tar.gz
Proxmox VE itself ships a set of basic templates for most common
operating systems, and you can download them using the pveam (short
for Proxmox VE Appliance Manager) command line utility. You can also
download TurnKey Linux containers using
that tool (or the graphical user interface).
Our image repositories contain a list of available images, and there
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
interested in, for example basic system images:
List available system images
# pveam available --section system
system          archlinux-base_2015-24-29-1_x86_64.tar.gz
system          centos-7-default_20160205_amd64.tar.xz
system          debian-6.0-standard_6.0-7_amd64.tar.gz
system          debian-7.0-standard_7.0-3_amd64.tar.gz
system          debian-8.0-standard_8.0-1_amd64.tar.gz
system          ubuntu-12.04-standard_12.04-1_amd64.tar.gz
system          ubuntu-14.04-standard_14.04-1_amd64.tar.gz
system          ubuntu-15.04-standard_15.04-1_amd64.tar.gz
system          ubuntu-15.10-standard_15.10-1_amd64.tar.gz
Before you can use such a template, you need to download them into one
of your storages. You can simply use storage local 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-8.0-standard_8.0-1_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-8.0-standard_8.0-1_amd64.tar.gz  190.20MB
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-8.0-standard_8.0-1_amd64.tar.gz
Container Storage
Traditional containers use a very simple storage model, only allowing
a single mount point, the root file system. This was further
restricted to specific file system types like ext4 and nfs.
Additional mounts are often done by user provided scripts. This turned
out to be complex and error prone, so we try to avoid that now.
Our new LXC based container model is more flexible regarding
storage. First, you can have more than a single mount point. This
allows you to choose a suitable storage for each application. For
example, you can use a relatively slow (and thus cheap) storage for
the container root file system. Then you can use a second mount point
to mount a very fast, distributed storage for your database
application. See section Mount Points for further
details.
The second big improvement is that you can use any storage type
supported by the Proxmox VE storage library. That means that you can store
your containers on local lvmthin or zfs, shared iSCSI storage,
or even on distributed storage systems like ceph. It also enables us
to use advanced storage features like snapshots and clones. vzdump
can also use the snapshot feature to provide consistent container
backups.
Last but not least, you can also mount local devices directly, or
mount local directories using bind mounts. That way you can access
local storage inside containers with zero overhead. Such bind mounts
also provide an easy way to share data between different 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 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&#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 Containers mount points
By default additional mount points besides the Root Disk mount point are not
included in backups. You can reverse this default behavior by setting the
Backup option on a mount point.
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 when starting  a replication job, you can set the
Skip replication option on that mount point.
As of Proxmox VE 5.0, replication requires a storage of type zfspool, so adding a
 mount point to a different type of storage when the container has replication
 configured requires to Skip replication for that mount point.
Container Settings
General Settings
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.
Privileged Containers
Security is done by dropping capabilities, using mandatory access
control (AppArmor), SecComp filters and 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. So you should use this kind of containers only inside a
trusted environment, or when no untrusted task is running as root in
the container.
Unprivileged Containers
This kind of 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, &#8230;) in those containers
will affect a random unprivileged user, and so would be a generic
kernel security bug rather than an LXC issue. The LXC team thinks
unprivileged containers are safe by design.
If the container uses systemd as an init system, please be
aware the systemd version running inside the container should be equal
or greater than 220.
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. You can view
the assigned CPUs using the following command:
# pct cpusets
 ---------------------
 102:              6 7
 105:      2 3 4 5
 108:  0 1
 ---------------------
Containers use the host kernel directly, so all task 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 1024. 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
The root mount point is configured with the rootfs property, and you can
configure up to 10 additional mount points. The corresponding options
are called mp0 to mp9, and they can contain the following setting:
rootfs: [volume=]&lt;volume&gt; [,acl=&lt;1|0&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. See below for a detailed description of all options.
mp[n]: [volume=]&lt;volume&gt; ,mp=&lt;Path&gt; [,acl=&lt;1|0&gt;] [,backup=&lt;1|0&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.
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).
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.
Currently there are basically 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.
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. E.g., 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.
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.
The contents of bind mount points are not backed up when using vzdump.
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.
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, use a configuration line like
mp0: /mnt/bindmounts/shared,mp=/shared in /etc/pve/lxc/100.conf.
Alternatively, use 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&#8217;s
storage subsystem, but the quota and acl options will be honored.
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.
The contents of device mount points are not backed up when using vzdump.
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=&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;] [,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.
mtu=&lt;integer&gt; (64 - N)
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.
Automatic Start and Shutdown of Containers
After creating your containers, you probably want them to start automatically
when the host system boots. For this you need to select the option Start at
boot from the Options Tab of your container in the web interface, or set it with
the following command:
pct set &lt;ctid&gt; -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. E.g. 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 . E.g. 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.
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.
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).
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:
&#8220;Simple&#8221; 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:
Extract mount points and their options from backup
Create volumes for storage backed mount points (on storage provided with the
storage parameter, or default local storage if unset)
Extract files from backup archive
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
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.
&#8220;Advanced&#8221; 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
pct is the tool to manage Linux Containers on Proxmox VE. You can create
and destroy containers, and control execution (start, stop, migrate,
&#8230;). You can use pct to set parameters in the associated config file,
like 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-8.0-standard_8.0-1_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&#8217;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
Obtaining Debugging Logs
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
the container&#8217;s ID):
lxc-start -n ID -F -l DEBUG -o /tmp/lxc-ID.log
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.
The collected debug log is written to /tmp/lxc-ID.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
update the configuration used by lxc-start.
Migration
If you have a cluster, you can migrate your Containers with
pct migrate &lt;vmid&gt; &lt;target&gt;
This works as long as your Container is offline. If it has local volumes or
mountpoints defined, the migration will copy the content over the network to
the target host if there is the same storage defined.
If you want to migrate online Containers, the only way is to use
restart migration. This can be initiated with the -restart flag and the optional
-timeout parameter.
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/&lt;CTID&gt;.conf file stores container configuration,
where &lt;CTID&gt; 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.
CTIDs &lt; 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
Those configuration files are simple text files, and you can edit them
using a normal text editor (vi, nano, &#8230;). 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.
File Format
Container configuration files use 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
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 &#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&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 - 128)
The number of cores assigned to the container. A container can use all available cores by default.
cpulimit: &lt;number&gt; (0 - 128) (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 = 1024)
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: &lt;string&gt;
Container description. Only used on the configuration web interface.
features: [fuse=&lt;1|0&gt;] [,keyctl=&lt;1|0&gt;] [,mount=&lt;fstype;fstype;...&gt;] [,nesting=&lt;1|0&gt;]
Allow containers access to advanced features.
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.
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 | disk | migrate | mounted | rollback | snapshot | snapshot-delete&gt;
Lock/unlock the VM.
memory: &lt;integer&gt; (16 - N) (default = 512)
Amount of RAM for the VM in MB.
mp[n]: [volume=]&lt;volume&gt; ,mp=&lt;Path&gt; [,acl=&lt;1|0&gt;] [,backup=&lt;1|0&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.
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).
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;] [,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.
mtu=&lt;integer&gt; (64 - N)
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 VM will be started during system bootup.
ostype: &lt;alpine | archlinux | centos | debian | fedora | gentoo | 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;] [,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.
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 VM in MB.
template: &lt;boolean&gt; (default = 0)
Enable/disable Template.
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]: &lt;string&gt;
Reference to unused volumes. This is used internally, and should not be modified manually.
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 that if you are sure the action which set the lock is
no longer running.
</pvehide>
<!--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.


== Migrate container from OpenVZ to Linux container ==
Follow this howto:
* [[Convert OpenVZ to LXC]]

== References ==
* [https://en.wikipedia.org/wiki/LXC Wikipedia Linux Container]
* [https://linuxcontainers.org/ Linux Container]
* [https://github.com/lxc GIT Linux Container]

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