mclu (mini cluster) is a virtualization cluster manager.

The key features:

 - Entirely command line driven.

 - No required dependencies except libvirt and ssh.

 - Only designed for tiny clusters (up to around 10 hosts).

 - Nothing to install on the nodes except libvirtd and sshd.

 - Single, simple configuration file.

Example commands
----------------------------------------------------------------------

   mclu status                   Display status of the cluster
   mclu list                     List all virtual machines on the cluster
   mclu wake ham0                Wake up node 'ham0' in the cluster
   mclu shutdown ham0            Shut down node 'ham0' in the cluster
   mclu start ham0:vm            Start vm on node 'ham0'
   mclu stop ham0:*              Stop all VMs on node 'ham0'
   mclu migrate *:* ham2:        Live migrate all VMs to 'ham2'
   mclu build ham3:vm fedora-20  Build and run a new Fedora 20 VM on node 'ham3'
   mclu console ham3:fedora-20   Show me the serial console of a VM
   mclu viewer ham3:fedora-20    Show me the graphical console of a VM
   mclu info                     Print general configuration information
   mclu --help                   Print help on all commands

Configuration notes
----------------------------------------------------------------------

mclu is based around the idea that you have a small collection of
fairly similar "nodes".  Ideally they would be identical nodes, if you
want live migration to work seamlessly, but they don't have to be.

Here is a picture of the cluster that I run mclu on:
http://rwmj.wordpress.com/2014/04/28/caseless-virtualization-cluster-part-5/#content

The nodes can be up or down.  mclu deals transparently with nodes
being switched off.  If you configure wake-on-LAN (usually a BIOS
setting) then mclu will be able to wake up nodes.

There is also one "control" node, which could be your laptop or could
be one of the cluster nodes.  This is where you run the 'mclu'
command, and also where the single configuration file is located
(mclu.conf, usually located in /etc/mclu).  The guest libvirt XML
files are also stored on the control node (usually /etc/mclu/xmls).

Each node must be accessible from the control node over ssh.  Each
node must be running the libvirt daemon (libvirtd).

mclu uses a mix of ssh commands and remote libvirt to manage the
nodes.  You should configure ssh so it can access the nodes without
needing passwords (eg. using ssh-agent).  If you use the default
libvirt URI (see config file) then you also need to set up
passwordless root ssh access to the nodes; there are other ways to
configure this, eg. opening the libvirtd port on each node, but they
are probably not as secure.

Each node, including the control node, must have access to shared
storage where the guest disk images are stored.  The easiest way to do
this is to export /var/lib/libvirt/images from one machine and
NFS-mount it on all the nodes (and also to have a nice fast network).
Cluster filesystems are another possibility.  mclu does NOT support
non-shared storage nor storage migration.

Guests run on a single node at a time.  You can list/start/stop/
migrate them using mclu.  The requirement for a guest to be running on
a single node may be enforced if you run libvirt sanlock or virtlockd.
This requires further configuration, see:
http://libvirt.org/locking.html
https://rwmj.wordpress.com/2014/05/08/setting-up-virtlockd-on-nfs/#content

If sanlock/virtlockd is not running then mclu will try its best not to
have the guest running in two places at once (if it happens, this will
cause permanent disk corruption in the guest).

For guest live migration to work transparently, you will probably want
to configure libvirt bridged networking and open firewall ports
49152-49215 on every node.

Bridged networking means that each guest appears as a local machine on
your network, and if it migrates then network connections will not be
interrupted.  See:
http://wiki.libvirt.org/page/Networking#Bridged_networking_.28aka_.22shared_physical_device.22.29

The firewall ports have to be opened because libvirt cannot (yet?)  do
fully managed migration over two SSH connections (even though the
documentation says it can).  Hopefully they will fix this soon.

Dependencies
----------------------------------------------------------------------

To get a full list of the required and optional dependencies, look at:

 - configure.ac
 - mclu.spec.in

Building it
----------------------------------------------------------------------

If building straight from git, then do:

  autoreconf -i

To build:

  ./configure --prefix /usr --sysconfdir /etc
  make

To run without installing:

 - Edit the configuration file (mclu.conf).

 - Run commands such as:

   ./run status
   ./run list

To install:

 - sudo make install

 - Edit the configuration file (/etc/mclu/mclu.conf).

 - Run commands such as:

   mclu status
   mclu list

Developer information
----------------------------------------------------------------------

The license is GPLv2+.

The git repo is:

  http://git.annexia.org/?p=mclu.git;a=summary

There is no mclu mailing list.  Send patches to the virt-tools mailing list:

  http://www.redhat.com/mailman/listinfo/virt-tools-list