Linux Container

Introduction

NOTE: BETA Technology preview

A Linux Container is an operating-system-level virtualization environment for running multiple isolated Linux systems on a single Linux control host (Wikipedia LXC). It can be also defined as a lightweight VM but extremely fast and easy to deploy.

There is not much overhead and therefore it's the perfect solution for effective use of resources.

No extra kernel boot is necessary on startup resulting in a super fast boot.

Linux Containers are introduced in Proxmox VE 4.0 and support the Proxmox Storage Model.

System requirements

• Proxmox VE 4.0 or higher

Features

• Support of local directories, NFS, ZFS, LVM (future support for Sheepdog, Ceph, iSCSI, DRBD and GlusterFS is planned)
• manipulate disk size
• Coming soon: snapshot, rollback, clone, linked clone (all these features need storage support)
• Kernel namespaces (ipc, uts, mount, pid, network and user)
• Apparmor profiles
• Seccomp policies
• Chroots (using pivot_root)
• Kernel capabilities
• CGroups (control groups)
• Migration
• Backup and restore
• Integrated firewall
• Network support for VLAN, IPv4, IPv6

Supported OS

• Debian 5, 6, 7
• CentOS 6
• RHEL 6

Other OS are following step by step.

Manage containers

The management via command line is possible with the pct tool. But most commands can be managed via GUI.

Get a container template

All templates can be downloaded at the GUI.

DownloadContainer

NOTE: Only the supported OS work

If the containers are not yet visible use the following pve command to update the list.

pveam update

Create container

To create a container you need a container template. described below!

Create CT

A GUI wizard will guide you through the creation process.

It is also possible to create a container with the pct command line tool. More details see manpages

pct create 112 /var/lib/vz/template/cache/debian-7.0-standard_7.0-2_i386.tar.gz \
  -description LXC -disk 4 -hostname pvecontainer01 -memory 1024 -nameserver 8.8.8.8 \ 
  -net0 hwaddr=52:4A:5E:26:58:D7,ip=192.168.15.83/24,gw=192.168.15.1,bridge=vmbr0 \
  -storage local -password changeme

Start container

There are two possibilities to start a container:

either on the GUI or on the command line

Start Container

pct start 100

Stop container

Stopping a container can be done in a similar way like starting a container.

Stop Container

pct stop 100

Backup container

The backup can be done in three different modes: snapshot, suspend and stopped. This mode options have only an effect if the container is running.

Backup Container

Snapshot mode: this feature depends on the filesystem and so it must support snapshots. If snapshot mode is chosen but it's not supported by the filesystem the backup will be done in suspend mode.

Suspend mode: the container will be frozen during the time the backup is running. NOTE: Container is not running untill backup is done!

Stopped mode: the container will be turned off and restarted after backup.

The command line tool backing up Linux container is vzdump. For more information read vzdump manpage.

vzdump 100 -compress lzo -dumpdir /var/lib/vz/dump/ -mode snapshot -remove 0

Restore container

Restore Container

It is easy and fast to restore a container.

On the GUI it is only possible to restore a container with the same VMID and if there is no VM with this VMID.

If you need to change the VMID or override a VM you can use the command line tool pct.

For more information read the man page of pct.

pct restore 101 /var/lib/vz/dump/vzdump-lxc-100-2015_06_22-11_12_40.tar.lzo

Migrate container from OpenVZ to Linux container

NOTE:At the moment you must do it manually later it will work with backup and restore. Make a Backup (use gzip) of the OpenVZ container.

Then copy the backup file in /var/lib/vz/template/cache/

Now it is possible to create a new CT, using the backup as template. see create container. Create_container

References

Wikipedia Linux Container

Linux Container

GIT Linux Container