Editing Installation on Debian 9

This is a guide to install OpenVZ 6 (legacy) on your Debian 9 "Stretch" (amd64 or i386) machine.

{{Note|The best and latest Debian version for OpenVZ 6 is [[Installation on Debian 8|Devuan 1.0]], but Debian 9 makes really easy the coexistence of OVZ and unprivileged LXC containers.}}
{{Out|Current commercial version of OpenVZ ([[Virtuozzo]] 7) is not installable on Devuan or Debian because is developed as an independent GNU/Linux distribution}}

= '''Volumes and file systems''' =

It is recommended to use a separate partition for containers (by default '''/var/lib/vz''') and format it to '''compatible ext4'''.

== Ext4 ==
Debian 9 installer (and tools by default) formats Ext4 with new features, and concrete "metadata_csum" is incompatible with OpenVZ6 kernel. Then it's necessary to boot without requiring the mount of volumes with "metadata_csum". Ordered alternatives:
# After a fresh Debian 9 install, remove metadata_csum feature from filesystems.
# Upgrade from Debian 8 to Debian 9 (metadata_csum not inherited)
# Root volume (/ and others) as Ext3 and deploy /var/lib/vz in a later created Ext4 volume, without metadata_csum.
# Use Ext3

=== How to remove metadata_csum from a mounted partition ===
If your host altready mounts r/w volumes on boot and you can't tune2fs+e2fsck because volumes are in use, this is the solution (example for /dev/sda1):
* First check if the partition is affected.
 Volume=/dev/sda1
 sudo dumpe2fs -h $Volume 2>/dev/null | grep -e metadata_csum
* If last command didn't return a line with metadata_csum, nothing to do. Otherwise, continue:
 echo copy_exec /sbin/e2fsck | sudo tee -a /usr/share/initramfs-tools/hooks/fsck
 echo copy_exec /sbin/tune2fs | sudo tee -a /usr/share/initramfs-tools/hooks/fsck
 Script=/etc/initramfs-tools/scripts/local-premount/tune
 echo '#!/bin/sh' | sudo tee $Script
 echo 'if [ "$1" = "prereqs" ] ; then exit 0 ; fi' | sudo tee -a $Script
 echo e2fsck -f $Volume | sudo tee -a $Script
 echo tune2fs -O -metadata_csum $Volume | sudo tee -a $Script
 echo e2fsck -f $Volume | sudo tee -a $Script
 sudo chmod a+x $Script
 sudo update-initramfs -u -k all
* Reboot and check that metadata_csum disappeared:
 sudo reboot
 (...)
 Volume=/dev/sda1
 sudo dumpe2fs -h $Volume 2>/dev/null | grep -e metadata_csum
* Restore initrd behaviour
 sudo rm /etc/initramfs-tools/scripts/local-premount/tune
 sudo apt --reinstall install initramfs-tools-core
 sudo update-initramfs -u -k all
This recipe is useful for any volume that can't be neither unmounted nor remounted readonly.

=== How to remove metadata_csum from a not mounted partition ===
This procedure can be applied when partition can be mounted readonly
* Example for /dev/sda9
 sudo e2fsck -f /dev/sda9
 sudo tune2fs -O -metadata_csum /dev/sda9
 sudo e2fsck -f /dev/sda9

=== How to format a volume to be a compatible Ext4 ===
* Example for /dev/sda9
 sudo mkfs -t ext4 -O -metadata_csum /dev/sda9

== btrfs ==
You might want btrfs to use per-directory (subvolume) quotas for other simfs/dir containers, such as LXC. Only vzquota doesn't work on a btrfs volume; for OVZ containers it's better to mount /var/lib/vz to an Ext4 volume.

Debian 9 installer (and tools by default) formats btrfs with modern features as: mixed-bg, extref, skinny-metadata, no-holes. All of these are incompatible with OpenVZ6 kernel. Then it's necessary to boot without requiring the mount of volumes with these attributes. Ordered alternatives:

# Pre-format '''compatible btrfs''' for a fresh Debian 9 install on root volume (/ and others) and deploy /var/lib/vz in a later created Ext4 volume. Debian 9 installer must not format btrfs but "keep existing data" as allowed in manual partitioning stage.
# Use '''compatible Ext4''' volumes and deploy later the secondary btrfs partitions.

=== How to format a volume to be a compatible btrfs ===
* Example for /dev/sda1
 sudo mkfs -t btrfs -O ^mixed-bg,^extref,^skinny-metadata,^no-holes /dev/sda1
You must not format btrfs with Debian installer because features cannot be disabled after.

= '''Change Systemd to SystemV''' =

{{Note|Warning! This operation can make some desktop software to stop working.}}

 sudo apt install sysvinit-core sysvinit-utils
 # Must boot with SystemV to release Systemd
 sudo reboot
 sudo apt --auto-remove remove systemd
 echo -e 'Package: *systemd*\nPin: release *\nPin-Priority: -1\n' | sudo tee /etc/apt/preferences.d/systemd

* More recipes at [http://without-systemd.org/wiki/index.php/Debian_Stretch without-systemd.org]

= '''Register OVZ updated repository''' =

 RepoFile=/etc/apt/sources.list.d/openvz.list
 RepoUrl=http://download.openvz.org/debian
 echo "deb $RepoUrl jessie main" | sudo tee "$RepoFile"
 echo "deb $RepoUrl wheezy main" | sudo tee -a "$RepoFile"
 wget -qO - http://ftp.openvz.org/debian/archive.key | sudo apt-key add -
 sudo apt-get --allow-unauthenticated update
As of July 2017, release key at openvz.org site is invalid, and last command will complain:
 W: GPG error: http://download.openvz.org/debian jessie Release: The following signatures were invalid: DA2458173935F9DE9B76BA7547B5DBAB0FCA9BAC
 W: The repository 'http://download.openvz.org/debian jessie Release' is not signed.
 N: Data from such a repository can't be authenticated and is therefore potentially dangerous to use.
 N: See apt-secure(8) manpage for repository creation and user configuration details.
 W: GPG error: http://download.openvz.org/debian wheezy Release: The following signatures were invalid: DA2458173935F9DE9B76BA7547B5DBAB0FCA9BAC
 W: The repository 'http://download.openvz.org/debian wheezy Release' is not signed.
 N: Data from such a repository can't be authenticated and is therefore potentially dangerous to use.
 N: See apt-secure(8) manpage for repository creation and user configuration details.
You can continue.

{{Note|For more info about Debian repositories, see http://download.openvz.org/debian.}}

= '''Install packages''' =

 KPackage="linux-image-openvz-$(dpkg --print-architecture)"
 sudo apt --allow-unauthenticated --install-recommends install $KPackage vzdump ploop initramfs-tools dirmngr
 if [ ! -d /vz ] ; then sudo ln -s /var/lib/vz/ /vz ; fi

* Create file /etc/vz/vznet.conf with the following line:
 EXTERNAL_SCRIPT="/usr/sbin/vznetaddbr"
* Optionally you can set containers completely stop when service stops at /etc/vz/vz.conf
 VE_STOP_MODE=stop

= '''Reboot into OpenVZ kernel''' =

{{Note|At boot manager, in "Advanced options for Debian GNU/Linux", you will find kernels named "2.6.32-openvz". Select the first listed.}}

 sudo reboot

Check the OpenVZ processes are running:
 sudo ps ax | grep -v 'grep' | grep 'vzmond'

== Set OpenVZ as default to boot ==

Because of GRUB2 default criteria, default kernel to boot can still be the one from Debian's repository (non OVZ). Probably you don't want this behaviour; once you've booted fine into OpenVZ kernel, you can remove other unuseful kernels:

 Packages="$(apt list --installed 'linux-image-*' 2>/dev/null | grep -e '^linux-image-' | grep -ve 'openvz' | cut -f 1 -d '/')"
 sudo apt --autoremove remove $Packages

= Download OS templates =

This step is optional, vzctl is able to download templates on demand.

An OS template is a GNU distribution for Linux, installed into a container
and then packed into a gzipped tarball. Using such a cache, a new container
can be created in a minute.

 # Register official container templates:
 OpenvzKey="$(echo $(sudo gpg --batch --search-keys security@openvz.org 2>&1 | grep -ie ' key.*created' | sed -e 's|key|@|g' | cut -f 2 -d '@') | cut -f 1 -d ' ' | cut -f 1 -d ',')"
 sudo gpg --recv-keys $OpenvzKey
 sudo vztmpl-dl --gpg-check --list-remote

 # Example:
 sudo vztmpl-dl --gpg-check debian-8.0-x86_64-minimal

Alternatives:
* Download precreated template caches from [[Download/template/precreated|Download » Template » Precreated]] or from one of the [https://mirrors.openvz.org/ mirrors]. Put those tarballs '''as-is (no unpacking needed)''' to the <tt>/vz/template/cache/</tt> directory.
* '''[https://downloads.actiu.net/ctctl/ ctctl]''' helper to create Debian (or derivative) container without template (caches it as a local template). This tool manages unprivileged LXC containers too.

= Next steps =

OpenVZ is now set up on your machine. Follow on to [[basic operations in OpenVZ environment]] document.

= See also =
* [[Installation on Debian 8]] (oldstable) or Devuan 1.0 (Jessie, stable, SystemV)

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