This needs lots of work, but it can successfully launch an LXC-based
instance.  See the docstring for the limitations/work to be done.

Signed-off-by: Iustin Pop <iustin@google.com>
Reviewed-by: Balazs Lecz <leczb@google.com>

The merge of commit 360b0dc2 into branch-2.1 broke import of backend,
since it uses hypervisor.GetHypervisor() which returns an instance of
the hypervisor. Some of the hypervisors create directories at init time,
thus the import of backend failed due this chain if it's not done on a
(proper) ganeti node, such as during unittest time.

This patch adds in hypervisor a GetHypervisorClass() function, which
returns the class not the instance of the hypervisor, and uses that in
_BuildUploadFiles(). The existing GetHypervisor is then changed to use
this function.

Signed-off-by: Iustin Pop <iustin@google.com>
Reviewed-by: Michael Hanselmann <hansmi@google.com>

This patch adds a new hypervisor implementation: a chroot manager. This
hypervisor type can be used to manage (in combination with special OS
definitions) the start and stop of chroot areas, and if used with drbd
instances, it allows (via failover) the migration of chroots between
nodes.

This is a work in progress, and the way chroots should work is not very
clear and does not fit very well in the OS definition framework.
However, the hypervisor works and (if the sshd in the chroot is well
configured) it allows login to the instance both via ssh and console as
for a normal instance.

TODOs:
  - implement instance IP add/remove to/from the bridge, if the instance
    has a defined IP
  - investigate improvements to the OS API so that the create script has
    more information available, e.g. about the hypervisor type
  - mount extra disks in the chroot or alternatively refuse to start
    with more than one disk

Signed-off-by: Iustin Pop <iustin@google.com>
Reviewed-by: Guido Trotter <ultrotter@google.com>

Since in 2.0 the user will possibly have more interaction with the
hypervisor names, we sanitize them by removing the version numbers
(the version can be a prerequisite for the ganeti installation, we
shouldn't document it in variable names).

Reviewed-by: schreiberal

This (big) patch moves the hypervisor type from the cluster to the
instance level; the cluster attribute remains as the default hypervisor,
and will be renamed accordingly in a next patch. The cluster also gains
the ‘enable_hypervisors’ attribute, and instances can be created with
any of the enabled ones (no provision yet for changing that attribute).

The many many changes in the rpc/backend layer are due to the fact that
all backend code read the hypervisor from the local copy of the config,
and now we have to send it (either in the instance object, or as a
separate parameter) for each function.

The node list by default will list the node free/total memory for the
default hypervisor, a new flag to it should exist to select another
hypervisor. Instance list has a new field, hypervisor, that shows the
instance hypervisor. Cluster verify runs for all enabled hypervisor
types.

The new FIXMEs are related to IAllocator, since now the node
total/free/used memory counts are wrong (we can't reliably compute the
free memory).

Reviewed-by: imsnah

Replacing ssconf with configuration.

Reviewed-by: iustinp

ht_kvm.py contains the code for ganeti to work under kvm.
This patch also modifies Makefile.am to ship that file, and
lib/hypervisor/__init__.py to import it, and add kvm to the
hypervisors map.

Reviewed-by: imsnah

Reviewed-by: iustinp

Reviewed-by: iustinp

Before it was a huge file with more than 700 lines. No code changes were
made except for changing imports and class names where needed. In the
future, we could even think about only importing the hypervisors we
actually need. The patch finished QA scripts and distcheck successfully.

Reviewed-by: iustinp

The whole Ganeti cluster has a single SSH key. Its fingerprint is
written to Ganeti's known_hosts file, together with an alias. This
allows us to always use that alias instead of the real hostname,
making management of the known_hosts file much easier.

This patch does not handle an upgrade from an earlier version.

Reviewed-by: ultrotter

Reviewed-by: iustinp

Reviewed-by: iustinp

Reviewed-by: schreiberal

Reviewed-by: iustinp