This patch switches from plain read to a wrapper over readsPrec that
returns better error messages than the buildin 'Prelude: no parse'.

This allows easy checking for valid format of the input data (row-wise).

This patch converts loadTabular and loadData to a monadic form, thus
allowing meaningful error messages from the node/instance load routines.

D'oh, one can extract from a wrapped variable, not only from functions.

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.

In case we pass a fully-specified URL to hscan, currently it will use as
is and that means the directory in which we want to save the status
files changes from what we mean. This patch changes hscan to replace all
slashes in the cluster name with underscores when generating the output
filenames.

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 option is the opposite of the --verbose option, and it allows
decreasing the verbosity level from the default of one to zero (which
currently doesn't show the warning messages for missing disk/memory).

This patch moves the oneline format into a separate function for easier
usage.

For clusters with no instances, there is no point in computing either
the score or in running the algorithm. In this case, we exit prematurely
and when running in one-line mode we show dummy information.

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.

It was missing a dependency on the Version.hs file, so right after “make
clean”, a “make dist” used to fail.

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 documents the environment variables in the man pages of hbal
and hn1.

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.

Neither hbal nor hn1 take any arguments beside the options, so if any
are passed is most likely an unintended error. This patch aborts in such
cases.

Use the $HPROGS variable instead of hardcoding the program names.

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 moves some data from README to the man pages and has other general
improvements.

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...