This patch changes Cluster.loadData to return a Result, instead of
directly the values; this will allow us to return meaningful error
values (e.g. when an instances lives on unknown node) rather than simply
abort. Currently the result is always an Ok, the actual signalling of
errors will come later.

Its callers are changed to accommodate for the new return type and to
display errors as needed.

This patch adds a very dumb way to override the port and scheme for
RAPI: if the master string doesn't contain a colon, we consider it a
simple hostname specification, and thus prepend ‘https://’ and append
‘:5080’, (the default RAPI port); otherwise, we consider it a fully
specified URL, and don't do any mangling to it.

This allows to use saved RAPI responses in testing, with the “file://”
scheme, or to use another port or non https mode with an actual RAPI
instance.

Now that we dropped 1.2 compatibility, we can removed the special casing
for RAPI differences.

We don't really needed, but is more clean like this.

This big patch converts from our home-grown monad-like constructs
(the Either stuff) to a real, Either-like-but-another-name monad.

We introduce a “Result a” monad, and this allows dropping many of the
extra constructs. Hopefully the code is also more clear.

Many of the functions could now be written in a generic-monad style,
instead of Result specifically, but that will come in future patches.

IAlloc.hs also has some unrelated patches.

Adding a small request type data structure.

This is just a cosmetic (I hope) change; the nodes shouldn't be used
anyway, and we only correct the display message.

Since we only support Ganeti 2.0, we drop the 1.2 compatibility.

This patch drops compatiblity with Ganeti 1.2 and adds support for
offline nodes in the cluster. When reading from RAPI, the drained nodes
are considered offline so that we don't allocate on them too.

We know have a working parseData function that returns the node and
instance data. This uncovered bad support for non-drbd instances ☹️

This patch moves the generic/reusable JSON functions to Utils.hs, so
that they're shared between RAPI/IAlloc.

This will be used in two ways:
  - format the response to Ganeti (easy, implemented)
  - parse the input data and build the node/instance lists (hard :)

This new parameter causes the algorithm to finish (or even not start at
all) if we reach/have a score better than it.

In some case we manually do “if isNothing … then Nothing else …”, which
can be very easily replaced with a monadic construct in the Maybe monad.

Since Xen seems to “steal” some amounts of memory (depending on total
node memory), we increase the maximum allowed missing memory to 512MB,
based on gathered data from multiple machines.

This patch adds support for selecting the instance/node file names via
two environment variables (HTOOLS_NODES, HTOOLS_INSTANCES).

Unfortunately we still have lots of duplicated code, since the options
are not unified.

This patch adds support in hbal for writing the command list to a shell
script, with error checking and allowing for early exit.

Since it's easy to pass a wrong node name as offline, we should abort
instead of silently ignoring it.

This removes most of the content of the README file (obsoleted by new
algorithm and man pages), modifies the Makefile to include the built
documentation in the source archive (so that haddock/hscolour are not
needed) and updates the haddock-prologue with current information.

This small patch adds disk space checks to the Cluster.checkData
function, and simplifies a little the warning messages.

For Ganeti 1.2 which doesn't have the ‘disk_usage’ instance query field,
we need to manually include the DRBD overhead (per disk). This patch
modifies the RAPI collection to do this, but loading from disk does not
as it's unknown if the query came from hscan or RAPI 1.2 or RAPI 2.0...

This fixes the setFmem function which didn't compute other related
fields after free memory change. Ideally, this should be abstracted so
that add/remove Pri and similar functions could reuse it instead of
duplicating code.

If an instance is down, it's memory is not reflected in the node used
memory, and thus the node free memory is higher than the actual value.
This patch deducts the memory for such instances from the node free
memory, allowing a correct calculation for such cases.

This patch modifies Rapi, the Cluster.loadData and hscan serialization to load
and save the instance run status. At instance level, we add both a boolean
field denoting the true/false run status, and a string field which holds the
original value (since we don't have a 1-to-1 mapping) for use in hscan
serialization.

The run status is not yet used.

This patch adds checking of cluster data in the binaries and display of
node's x_mem/i_mem in the node list.

This patch adds a checkData function which goes over the node list and computes
the unaccounted memory, returning a list of warning messages (if any) and the
update nodes.

Nodes can have some memory unaccounted for, due to (e.g.) hypervisor
overhead, rounding errors in reporting, etc.

It is better if we model this memory explicitly instead of hiding it,
and actually since the n_mem addition it is actually required to do so.

The new attribute is not yet used.

This patch moves the common CLI functionality (as much as currently
possible) into a separate module. This means we only have one parseOpts
and that Utils.hs doesn't keep this kind of functions anymore.

The Node.str function is very old and is not useful since the node
objects have much more fields today. This patch removes it, and if
needed a full node display can be done via ‘show’.

This patch adds a new n_mem field to the node objects, and implements
read/save/show support for it. The field is not currently used (except
in the node list) but will be used for checking data consistency and
instance up/down status.

This patch changes the parameters passed to the node and instance
constructors from generic Strings (which are then parsed via “read”) to
the actual used types, by converting them earlier in Cluster.loadData.

This patch does some small changes:
  - fixes a comment
  - export more node functions (unneeded now, but hscan will use them)
  - fixes Makefile rule for building the programs

This is added for better readability, since this is very often used in
declarations.

This patch changes two things with regard to offline nodes:
  - first, it only calculates the various coefficients across online
	nodes
  - second, it adds a new score denoting the percentage of instances
	which live on such nodes

The first change allows correct score computation in presence of offline
nodes (whose properties we don't need to take into account), while the
second change actively evacuates offline nodes.

This patch adds a new ‘-’ flag for the node status which denotes offline
nodes.

This patch changes the Cluster.checkInstanceMove function to restrict
the target move list based on which nodes are online.

This patch modifies hbal (only, hn1 not yet) for setting nodes offline.

This patch adds a new node attribute - offline - which will serve to
skip nodes from the target candidate list.